This PDF file contains the front matter associated with SPIE Proceedings Volume 8553, including the Title Page, Copyright Information, Table of Contents, and the Conference Committee listing.

The optical signal on microfluidic chip is hard to be collected. To improve the excitation power and collection efficiency, we introduced a simple, inexpensive fabrication method to increase the couple rate of optical fiber. This small element is a polymer and air integrated microlens that can improve the optical signal detection. Compared to other established protocols, this procedure allows a simple, miniaturizing and inexpensive microlens fabrication with high reproducibility. The air microlens was produced by using direct lithograph of SU-8 resist to reduce the beam divergence of optical fiber. Owing to its ability to achieve customized microlens for specific applications, this technique can be used in a variety of applications, such as a blood cell counting system based on microfluidic chip.

Optical mapping is a well established technique for recording monophasic action potential traces either within myocardial slices or on the epicardial surface of isolated hearts. This measuring technique offers a high spatial and sufficient temporal resolution but it is sensitive towards myocardial motion. Motion artifacts occur because the mapping between a certain tissue portion sending out fluorescent light and a pixel of the photodetector changes over time. So far this problem has been adressed in two different ways: Suppressing the motion or ratiometric imaging. Working with beating rat heart slices we developed a different approach to noninvasively record simultaneously optical mapping data and motion of the slices. Our approach is based on image registration. We use the background fluorescent light to perform first a rigid transformation to detect translational and and rotational motion. The contractive motion is recovered using a non-rigid demons registration algorithm afterwards. The investigation is based on recordings of four different slices stained with Di-4-ANEPPS.

Nonlinear biomedical imaging has not benefited from the well-known techniques of fiber supercontinuum generation for reasons such as poor coherence (or high noise), insufficient controllability, low spectral power intensity, and inadequate portability. Fortunately, a few techniques involving nonlinear fiber optics and femtosecond fiber laser development have emerged to overcome these critical limitations. These techniques pave the way for conducting point-of-care nonlinear biomedical imaging by a low-maintenance cost-effective coherent fiber supercontinuum laser, which covers a broad emission wavelength of 350-1700 nm. A prototype of this laser has been demonstrated in label-free multimodal nonlinear imaging of cell and tissue samples.

Wide field-of-view (FOV) microscopy is useful for high-throughput applications because of the capability to obtain large amount of information from a single image. One way to implement a wide FOV microscope is to scan the sample with a two-dimensional focus grid. The transmission or reflection of the focal spots can then be used to reconstruct the sample image. This scheme is effectively a parallel scanning optical microscope (SOM), where the FOV depends on the area of the focus grid and the imaging resolution depends on the spot size of the foci. We use the Talbot image of a twodimensional aperture grid as the focus grid and developed a wide FOV microscope. Preliminary experimental results show the capability of our microscope to acquire wide FOV images of US air force target and MCF-7 cancer cell samples. Fluorescence images of fluorescence beads are also acquired. Because the diffraction of incident beam by the aperture grid contains complicated angular frequencies, the focal spots in Talbot pattern cannot be approximated as Gaussian beams as in conventional SOM. We characterized the focal spots in Talbot pattern and studied the evolution of the full width at half maximum (FWHM). We also simulated the SOM imaging under Talbot pattern illumination using the razor blade as the sample objects.

Photobiomodulation (PBM) is a non-damaged modulation of laser irradiation or monochromatic light (LI) on a biosystem function. It depends on whether the function is in its function-specific homeostasis (FSH), a negative feedback response for the function to be performed perfectly. Many redundant pathways (RPs) maintain the same cellular function. The full activation of any of RPs can maintain a normal function in its FSH, but partial activation of all the RPs can only maintain a dysfunctional function far from its FSH. A PBM may self-adaptively modulate the activation of a partially activated RP of a normal function until it is fully activated and the normal function is then upgraded. This PBM is called indirect PBM (iPBM). The iPBM on cells such as tumor cells, myoblast cells and fibroblasts and other biosystems and their applications would be reviewed in this paper.

Photodynamic therapy (PDT) is based on the generation of highly reactive singlet oxygen through interactions of photosensitizer, light and molecular oxygen. PDT has become a clinically approved, minimally invasive therapeutic modality for a wide variety of malignant and nonmalignant diseases. The main dosimetric parameters for predicting the PDT efficacy include the delivered light dose, the quantification and photobleaching of the administrated photosensitizer, the tissue oxygen concentration, the amount of singlet oxygen generation and the resulting biological responses. This review article presents the emerging optical techniques that in use or under development for monitoring dosimetric parameters during PDT treatment. Moreover, the main challenges in developing real-time and noninvasive optical techniques for monitoring dosimetric parameters in PDT will be described.

Photodynamic therapy is a revolutionary treatment aimed at treating cancers without surgery or chemotherapy. It is based on the discovery that certain chemicals known as photosensitizing agents (e.g. porphyrins, phthalocyanines, etc.) can kill cancerous cells when exposed to low level laser light at a specific wavelength. The present study investigates the cellular uptake and photodynamic effect of gallium (III) phthalocyanine chloride (GaPcCl) on Caco-2 cancer cells. Caco-2 cells were treated with different concentrations of GaPcCl for 2 h before treatment with a diode laser (λ = 661 nm, laser power = 90 mW) delivering a light dose of 2.5 J/cm², 4.5 J/cm² or 8.5 J/cm². After 24 h, the cell viability of post-irradiated cells was measured using the MTT assay. Cellular uptake studies were performed by photosensitizing cells with GaPcCl for 30 min, 2 h, 10 h, 12 h, 18 h and 24 h before lysing the treated cells into solution to measure the GaPcCl fluorescence emission at an excitation wavelength of 600 nm. Results showed an increase in fluorescence intensity of emission peaks at longer incubation times, indicating a greater cellular uptake of GaPcCl by Caco-2 cells at 24 h in comparison to 30 min. GaPcCl at a concentration of 100 μg/ml activated with a laser light dose of 8.5 J/cm² reduced the cell viability of Caco-2 cells to 27%. This concludes that GaPcCl activated with low level laser light can be used as a photosensitizing agent for the in vitro PDT treatment of colon cancer.

[Ru(bpy)₂(dppn)]²⁺, one of Ru(II) polypyridyl complexes, present inner dicationic charge and high ¹O₂ quantum yield. In this study, the synthetic compound was used as photosensitizer (PS) to photoinactivate a reference strain of Staphylococcus aureus ATCC 25923. Bacterial suspensions consisting of 10⁸ colony-forming units (CFU) per milliliter were incubated with PS of different concentrations (0.025μM ~ 25μM). After a 30 minutes period, the suspensions were exposed to 457nm laser light, determined by the absorption spectra of the PS in phosphate buffered saline (PBS), with a power density of 40 mW/cm² for 10 minutes (energy density of 24 J/cm²). PS group, light group and the blank control were also concerned. Viability of bacteria was determined by pour plates. The Log₁₀ reductions were calculated and killing effects in photodynamic inactivation (PDI) group were analysed contrast to the blank control. We observed that neither the laser light nor the PS per se had any inhibitory effect on the viability of the bacteria. PS at low dose (0.025μM) followed by illumination yielded no significant decrease in the viable number. PS at 0.25μM and 2.5μM with irradiation induced reductions of 1.69 Log₁₀ and 5.97 Log₁₀, respectively. PS at 10μM and 25μM combined with light brought viable bacterial cells down to undetectable levels (reductions < 7 Log₁₀). We concluded that with the PS of appropriate doses, [Ru(bpy)₂(dppn)]²⁺ mediated PDI inactivated S.aureus efficiently. At the concentration of 2.5μM, bactericidal activity was reached where the viability of bacteria fell more than 3 Log₁₀ based on previous researches.

We report the properties of two series of polyethylene glycol-functionalized bis(arylidene)cycloalkanone photosensitizers designed for two-photon excited photodynamic therapy (PDT) with the aim to reveal the effect of the size of central ring on the two-photon excited PDT efficiency. These photosensitizers are the derivatives of bis(arylidene) cyclopentanone (B2, B3) and bis(arylidene) cyclobutanone (Q1-Q4). The bis(arylidene) cyclopentanone type photosensitizers were found to have larger two-photon absorption cross sections than the bis(arylidene) cyclopentanone ones with the same substituents. The singlet oxygen yields of the bis(arylidene) cyclobutanone derivatives are higher than the data of bis(arylidene) cyclopentanone derivatives. All the studied photosensitizers showed no obvious toxicity under dark situation. One- and two-photon excited PDT activities were successfully demonstrated by in vitro cell experiments. Owing to the capability of destructing the cancerous cells under two-photon irradiation, bis(arylidene)cycloalkanone based photosensitizers with proper substituents can be good candidates for two-photon excited PDT applications in the future.

Confocal fluorescence microscopes are a promising imaging tool in medical diagnostics due to their capability to selectively survey cross-sections of individual layers from ‘thick’ samples. Non-invasive depth resolved investigation of neoplastic skin disorders is one example among other applications. However these microscopes are at present uncommon in medical practice. This is due to their main application area in research. The instruments dealt with here are generally complex, stationary units and are accordingly cost-intensive. It is for this reason, that we have designed a robust and portable MEMS based confocal fluorescence microscope with a field of view of 0.6mm x 0.6mm. This has been made possible by the integration of a 2D micro scanner mirror developed at Fraunhofer IPMS. A variable acquisition depth of cross-sectional images of the fluorescence specimen is enabled by an integrated z-shifter. With the use of commercially available optics an optical demonstrator set up has been realized. To characterize and to demonstrate the ability of this system test measurements were performed. The resolution of the microscope is better than 228 lp/mm determined by 1951 USAF resolution test target. Images of various biological samples are presented and optical sectioning capabilities are shown. A comparison of the measured with the predicted system performance will be given.

Accurate and in vivo characterization of structural, functional, and molecular characteristics of biological tissue will facilitate quantitative diagnosis, therapeutic guidance, and outcome assessment in many clinical applications, such as wound healing, cancer surgery, and organ transplantation. However, many clinical imaging systems have limitations and fail to provide noninvasive, real time, and quantitative assessment of biological tissue in an operation room. To overcome these limitations, we developed and tested a multiview hyperspectral imaging system. The multiview hyperspectral imaging system integrated the multiview and the hyperspectral imaging techniques in a single portable unit. Four plane mirrors are cohered together as a multiview reflective mirror set with a rectangular cross section. The multiview reflective mirror set was placed between a hyperspectral camera and the measured biological tissue. For a single image acquisition task, a hyperspectral data cube with five views was obtained. The five-view hyperspectral image consisted of a main objective image and four reflective images. Three-dimensional topography of the scene was achieved by correlating the matching pixels between the objective image and the reflective images. Three-dimensional mapping of tissue oxygenation was achieved using a hyperspectral oxygenation algorithm. The multiview hyperspectral imaging technique is currently under quantitative validation in a wound model, a tissue-simulating blood phantom, and an in vivo biological tissue model. The preliminary results have demonstrated the technical feasibility of using multiview hyperspectral imaging for three-dimensional topography of tissue functional properties.

This paper reports recent advances in spectral domain Doppler optical coherence tomography (SD-DOCT) in our group. A high speed SD-DOCT system is developed and applied to animal study and microchip evaluation. Further improvements concerning SD-DOCT are presented, those including higher-order cross-correlation for phase retrieval, transit-time analysis for velocity quantification, and orthogonal dispersive SD-OCT for depth extension.

Optical coherence tomography is a novel imaging technique providing potentially high resolution tri-dimensional images of tissue microstructure up to 2-3mm deep. We present pre-clinical data from a novel miniaturised OCT probe utilised for endoscopic imaging of laryngeal mucosa. A 1300nm SS-OCT probe was passed in tandem with a flexible fibreoptic nasoendoscope into the larynx of a manikin. Ex vivo OCT images were acquired using a desktop 1300nm TD-OCT imaging system. The feasibility, robustness and safety of this set-up was demonstrated as a preliminary step to extending the use of this assembly to a clinical patient cohort with varying laryngeal pathologies.

The physiological and pathological properties of retina are closely associated with various optical contrasts. Hence, integrating different ophthalmic imaging technologies is more beneficial in both fundamental investigation and clinical diagnosis of several blinding diseases. Recently, photoacoustic ophthalmoscopy (PAOM) was developed for in vivo retinal imaging in small animals, which demonstrated the capability of imaging retinal vascular networks and retinal pigment epithelium (RPE) at high sensitivity. We combined PAOM with traditional imaging modalities, such as fluorescein angiography (FA), spectral-domain optical coherence tomography (SD-OCT), and auto-fluorescence scanning laser ophthalmoscopy (AF-SLO), for imaging rats and mice. The multimodal imaging system provided more comprehensive evaluation of the retina based on the complementary imaging contrast mechanisms. The high-quality retinal images show that the integrated ophthalmic imaging system has great potential in the investigation of blinding disorders.

Metastasis is a very complicated multi-step process and accounts for the low survival rate of the cancerous patients. To metastasize, the malignant cells must detach from the primary tumor and migrate to secondary sites in the body through either blood or lymph circulation. Macrophages appear to be directly involved in tumor progression and metastasis. However, the role of macrophages in affecting cancer metastasis has not been fully elucidated. Here, we have utilized an emerging technique, namely in vivo flow cytometry (IVFC) to study the depletion kinetics of circulating prostate cancer cells in mice and how depletion of macrophages by the liposome-encapsulated clodronate affects the depletion kinetics. Our results show different depletion kinetics of PC-3 cells between macrophage-deficient group and the control group. The number of circulating tumor cells (CTCs) in macrophage-deficient group decreases in a slower manner compared to the control mice group. The differences in depletion kinetics indicate that the absence of macrophages facilitates the stay of prostate cancer cells in circulation. We speculate that macrophages might be able to arrest, phagocytose and digest PC-3 cells. Therefore, the phagocytosis may mainly contribute to the depletion kinetic differences. The developed methods here would be useful to study the relationship between macrophages and tumor metastasis in small animal cancer model.

Demyelination of a nerve fiber was simulated by action potential encoded second harmonic generation (SHG). The dynamics of action potential propagation along a nerve fiber with a multi-internode demyelination happening to successive internodes or intermittent internodes was studied. The results showed the attenuation and delay of action potential could obviously occur, and the refractory period increased when a nerve was demyelinated. In addition, under the same thickness and number of the demyelination, the peak of SHG signals attenuated much more along successive injured internodes than along intermittent injured internodes. It indicated that action potential encoded SHG could be a useful tool for detecting nerve demyelination.

Gastric polyps can be broadly defined as luminal lesions projecting above the plane of the mucosal surface. They are generally divided into non-neoplastic and neoplastic polyps. Accurate diagnosis of neoplastic polyps is important because of their well-known relationship with gastric cancer. Multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) is one of the most important recent inventions in biological imaging. In this study, we used MPM to image the microstructure of gastric polyps, including fundic gland polyps, hyperplastic polyps, inflammatory fibroid polyps and adenomas, then compared with gold-standard hematoxylin- eosin(H-E)-stained histopathology. MPM images showed that different gastric polyps have different gland architecture and cell morphology. Dilated, elongated or branch-like hyperplastic polyps are arranged by columnar epithelial cells. Inflammatory fibroid polyps are composed of small, thin-walled blood vessels surrounded by short spindle cells. Fundic glands polyps are lined by parietal cells and chief cells, admixed with normal glands. Gastric adenomas are generally composed of tubules or villi of dysplastic epithelium, which usually show some degree of intestinal-type differentiation toward absorptive cells, goblet cells, endocrine cells. Our results demonstrated that MPM can be used to identify non- neoplastic and neoplastic gastric polyps without the need of any staining procedure.

Collagen, the main structural protein in vertebrates, possesses different structural organization that is responsible for specific functions of the tissues. Polarization dependence of the second harmonic generation (SHG) signal on spatial orientation of optically nonlinear materials, such as collagen, provides information on characteristic organization and architecture not available from intensity measurements alone. Here we describe a simple approach for determining both the azimuth and elevation angles of collagen fiber orientation in biological tissues. Azimuth angle of the fiber orientation is determined as an orthogonal angle to the laser polarization direction, when laser-induced total SHG signal is minimal, whereas the elevation angle is estimated from the ratio of the minimal SHG intensity to the intensity when laser polarization and fiber directions are parallel to each other. Using this approach pixel-resolved mapping of the spatial orientation of collagen fibers in tendon and cornea is demonstrated. The new approach may be used for analyzing of biological tissues in vivo. Spatial orientation mapping method provides additional information concerning fiber organization, and may be incorporated into nonlinear optical imaging systems.

Nitric oxide (NO) has been reported to have the ability to promote or inhibit the proliferation and metastasis of cancer cells. It appears to have an effect on inducing calcium transient, which participates in essential cellular signaling in the physiological and pathological processes. Our work was intended to study the effects of exogenous NO on intracellular calcium dynamics of HeLa cells with Fluo-3, a calcium fluorescent indicator by microplate fluorescence reader. The results showed that after NO donor was injected into the wells, intracellular Ca²⁺ fluorescence intensity increased significantly compared with that of control group. Furthermore, the calcium transient activated by NO was mainly due to the calcium release from intracellular calcium stores. These would be helpful to further recognize the role of NO involved in cancer cell proliferation and metastasis.

Adenosine exerts multiple effects on pain transmission in the peripheral nervous system. This study was performed to use confocal microscopy to evaluate whether adenosine could affect dorsal root ganglia (DRG) neurons in vitro and test which adenosine receptor mediates the effect of adenosine on DRG neurons. After adding adenosine with different concentration, we compared the metabolic changes by the real time imaging of calcium and mitochondria membrane potential using confocal microscopy. The results showed that the effect of 500 μM adenosine on the metabolic changes of DRG neurons was more significant than others. Furthermore, four different adenosine receptor antagonists were used to study which receptor mediated the influences of adenosine on the cultured DRG neurons. All adenosine receptor antagonists especially A₁ receptor antagonist (DPCPX) had effect on the Ca²⁺ and mitochondria membrane potential dynamics of DRG neurons. The above studies demonstrated that the effect of adenosine which may be involved in the signal transmission on the sensory neurons was dose-dependent, and all the four adenosine receptors especially the A1R may mediate the transmission.

Multiphoton microscopy (MPM), a noninvasive optical method with high resolution and high sensitivity, can obtain detailed microstructures of biotissues at submolecular level. In this study, MPM is used to image microstructure varieties of human colonic mucosa and submucosa with adenocarcinoma. Some parameters, such as gland configuration, SHG/TPEF intensity ratio, and collagen orientation and so on, should serve the indicators of early colorectal cancer. The exploratory results show that it's potential for the development of multiphoton mini-endoscopy in real-time early diagnosis of colorectal cancer.

Spectral imaging is an advanced photo-acoustic (PA) mode that can discern optical absorption of contrast agent(s) in the tissue micro-environment. This advancement is made possible by precise control of optical wavelength using a tunable pulsed laser, ranging from 680-970 nm. Differential optical absorption of blood oxygenation states makes spectral imaging of hemoglobin ideal to investigate remodeling of the tumor microenvironment- a molecular change that renders resistance to standard cancer treatment. Approach: Photo-acoustic imaging was performed on the Vevo® LAZR system (VisualSonics) at 5-20 Hz. Deep abdominal imaging was accomplished with a LZ250D probe at a center frequency of 21MHz and an axial resolution of 75 μm. The tumor model was generated in an immune compromised mouse by surgical implantation of primary patient derived tumors, in the pancreas. Results: Spectral imaging for oxygen saturation at 750 nm and 850 nm characterized this tumor with a poorly oxygenated core surrounded by a well oxygenated periphery. Multispectral imaging identified a sub region in the core with a four-fold signal exclusively at 750 and 800 nm. A co-registered 2D image of this region was shown to be echogenic and calcification was suspected. Perfusion imaging with contrast enhanced ultrasound using microbubbles (Vevo MicroMarker® contrast agents, VisualSonics) identified functional vessels towards this sub region. Histology confirmed calcification and vascularization in the tumor core. Taken together, non-invasive characterization of the tumor microenvironment using photo-acoustics rendered spectral imaging a sensitive tool to monitor molecular changes representative of progression of pancreatic cancer that kills within 6 months of diagnosis.

We present the results of theoretical and experimental studies of the polarized fluorescence in fluorophores excited by two-photon two-color (2P2C) femtosecond laser pulses. Quantum mechanical expressions describing the fluorescence polarization have been derived using the spherical tensor technique for asymmetric top molecules under the condition of isotropic rotation diffusion for arbitrary polarization of each of the three photons involved in the photoprocess. The expressions are presented in terms of the molecular parameters M_K(R, R´, t) which contain all information about the photoprocess dynamics and can be directly determined from experiment. Ab initio computations of the flurophore structure and two-photon dynamics have been performed for p-terphenyl and indole in vacuum and in solutes using the polarizable continuum model and TD-DFT method, respectively. In case of p-terphenyl, full geometry optimization of the low-lying excited singlet electronic of the D_2h symmetry has been performed. The results obtained indicate that that the solute molecules do not affect noticeably the position of the p-terphenyl energy levels which conclusion nicely fits the results reported elsewhere. In case of indole, the energy of low-lying molecular states, their permanent dipole moments, and transition dipole moments to the ground state have been computed both for non-relaxed and relaxed geometries. The results obtained manifests strong influence of the polar solute (methanol) on the position of the lowlying molecular energy levels and on the dipole moments. Using the results of the computation obtained three molecular parameters of the zero-th order, M₀(0,0), M₀(2,0), M₀(2,2) have been calculated and compared with their values obtained experimentally. The comparison shows excellent agreement between the theory and experiment.

Fluorescence microscopy has become an essential tool to study biological molecules, pathways and events in living cells, tissues and animals. Meanwhile, the conventional optical microscopy is limited by the wavelength of the light. Even the most advanced confocal microscopy or multiphoton microscopy can only yield optical resolution approaching the diffraction limit of ~200 nm. This is still larger than many subcellular structures, which are too small to be resolved in detail. These limitations have driven the development of super-resolution optical imaging methodologies over the past decade. The stimulated emission depletion (STED) microscopy was the first and most direct approach to overcoming the diffraction limit for far-field nanoscopy. Typically, the excitation focus is overlapped by an intense doughnut-shaped spot to instantly de-excite markers from their fluorescent state to the ground state by stimulated emission. This effectively eliminates the periphery of the Point Spread Function (PSF), resulting in a narrower focal region, or super-resolution. Scanning a sharpened spot through the specimen renders images with sub-diffraction resolution. Multi-color STED imaging can present important structural and functional information for protein-protein interaction. In this work, we presented a dual color, synchronization-free STED stimulated emission depletion (STED) microscopy with a Ti:Sapphire oscillator. The excitation wavelengths were 532nm and 635nm, respectively. With pump power of 4.6 W and sample irradiance of 310 mW, we achieved super-resolution as high as 71 nm. We also imaged 200 nm nanospheres as well as all three cytoskeletal elements (microtubules, intermediate filaments, and actin filaments), clearly demonstrating the super-resolution resolving power over conventional diffraction limited imaging. It also allowed us to discover that, Dylight 650, exhibits improved performance over ATTO647N, a fluorophore frequently used in STED. Furthermore, we applied synchronization-free STED to image fluorescently-labeled intracellular viral RNA granules, which otherwise cannot be differentiated by confocal microscopy. Thanks to the widely available Ti:Sapphire oscillators in multiphoton imaging system, this work suggests easier access to setup super-resolution microscope via the synchronization-free STED A series of biological specimens were imaged with our dual-color STED.

We reported recently that laser oblique scanning optical microscopy (LOSOM) is able to obtain a relief image in transparent sample directly. To optimize the performance of LOSOM, the parameters such as numerical aperture, the distance between the specimen and the fluorescent medium and the pinhole size are investigated in this work. A beam blocker is introduced in light path which enhances dramatically the visualization of local phase difference.

A portable video-rate confocal laser scanning microscope (CLSM) is implemented with polygon mirror and galvanometric mirror employed as the fast and slow axis scanner, respectively. The system can be applied for noninvasively imaging skin and other tissue. The dimension of this real-time CLSM is only 33×20×12cm³ with weigh of 1.780 kg. Here we used a single Complex Programmable Logic Device (CPLD) to generate the control and synchronization signals for real time confocal microscopy. Utilizing NI image acquisition card, the CLSM system can acquire and store the real-time images. So that high resolution confocal microscopy is achieved simultaneously.

Photo-acoustic (PA) excitation was combined with skeletal quantitative ultrasound (QUS) for multi-mode ultrasonic assessment of human long bones. This approach permits tailoring of the ultrasonic excitation and detection so as to efficiently detect the fundamental flexural guided wave (FFGW) through a coating of soft tissue. FFGW is a clinically relevant indicator of cortical thickness. An OPO laser with tunable optical wavelength, was used to excite a photo-acoustic source in the shaft of a porcine femur. Ultrasonic signals were detected by a piezoelectric transducer, scanning along the long axis of the bone, 20-50 mm away from the source. Five femurs were measured without and with a soft coating. The coating was made of an aqueous gelatin-intralipid suspension that optically and acoustically mimicked real soft tissue. An even coating thickness was ensured by using a specific mold. The optical wave length of the source (1250 nm) was tuned to maximize the amplitude of FFGW excitation at 50 kHz frequency. The experimentally determined FFGW phase velocity in the uncoated samples was consistent with that of the fundamental antisymmetric Lamb mode (A₀). Using appropriate signal processing, FFGW was also identified in the coated bone samples, this time with a phase velocity consistent with that theoretically predicted for the first mode of a fluid-solid bilayer waveguide (BL₁). Our results suggest that photo-acoustic quantitative ultrasound enables assessment of the thickness-sensitive FFGW in bone through a layer of soft tissue. Photo-acoustic characterization of the cortical bone thickness may thus become possible.

A dual-mode imaging technique has been developed for intraoperative imaging of bile ducts and real-time identification of iatrogenic injuries in cholecystectomy. The technique is based on ultrasound (US) and fluorescence (FL) imaging of a dual-mode microbubble (MB) agent comprising a poly (lactic-co-glycolic acid) (PLGA) shell and a core of Indocyanine Green. During cholecystectomy, a clinical US probe is used to localize the bile duct structure after bolus injection of dual-mode MBs. As the surrounding adipose tissue is removed and the Calot’s triangle is exposed, FL imaging is used to identify the MB distribution and to determine the potential bile duct injury. The contrast-enhanced bile duct imaging technique has been demonstrated in both a surgical simulation model and an ex vivo porcine tissue model under two surgical scenarios. The first scenario simulates the correct procedure where the cystic duct is clipped. The second scenario simulates the incorrect procedure where the common bile duct is clipped, leading to consequent bile duct injury. Benchtop experiments in both the phantom and the ex vivo models show that the dual-mode imaging technique is able to identify the potential bile duct injury during cholecystectomy. A phantom system has also been established for future device calibration and surgical training in image-guided cholecystectomy. Further in vivo animal validation tests are necessary before the technique can be implemented in a clinical setting.

The wound healing process involves the reparative phases of inflammation, proliferation, and remodeling. Interrupting any of these phases may result in chronically unhealed wounds, amputation, or even patient death. Quantitative assessment of wound tissue ischemia, perfusion, and inflammation provides critical information for appropriate detection, staging, and treatment of chronic wounds. However, no method is available for noninvasive, simultaneous, and quantitative imaging of these tissue parameters. We integrated hyperspectral, laser speckle, and thermographic imaging modalities into a single setup for multimodal assessment of tissue oxygenation, perfusion, and inflammation characteristics. Advanced algorithms were developed for accurate reconstruction of wound oxygenation and appropriate co-registration between different imaging modalities. The multimodal wound imaging system was validated by an ongoing clinical trials approved by OSU IRB. In the clinical trial, a wound of 3mm in diameter was introduced on a healthy subject’s lower extremity and the healing process was serially monitored by the multimodal imaging setup. Our experiments demonstrated the clinical usability of multimodal wound imaging.

Experimental and theoretical studies on coaxial atomization process of fabricating multifunctional microcapsules were performed to overcome the limitation of commonly used microfabrication processes. The coaxial electrospray was first developed, and then a novel process named coaxial electro-flow focusing which combined coaxial electrospray with coaxial flow focusing was proposed. The process was characterized by the formation of a coaxial liquid jet in the core of a high-speed co-flowing gas stream under an axial electric field and the breakup of the liquid jet into fine microcapsules. The effects of main process parameters on the meniscus attached to the mouth of the coaxial needle were tested. A theoretical model was further implemented for instability analysis of the coaxial jet to guide the process control and optimization. As a result, stable cone-jet configurations in a wide range of process parameters and microcapsules with good morphologies were obtained. The reported research represents the first step toward quantitative control and optimization of the coaxial atomization process for the microfabrication of multifunctional microcapsules in multimodal imaging and image-guided therapy.

Based on the mathematical models of the experimentally fitted spectrum of index inhomogeneities, we analyze the electromagnetic field scattered from biological tissue. The resulting cross-spectral density matrices are expressed in spherical polar coordinates and the two-dimensional definition of polarization could be used. The results show that the polarization characteristics of the far scattered field depend closely on the types of the tissue.

3D reconstruction, an important point in computer vision, has a promising application potential in endoscopic-assisted minimally invasive surgery. In this paper, a 3D reconstruction method based on image sequences is proposed, in which the improved SIFT feature is applied for point extraction and matching, as well as an optical tracker is used to get the orientation of the camera in real time. The proposed approach is evaluated on sequence digital images gotten from an 1394 camera and the experimental results show that the proposed approach is effective.

The potential application of photoacoustic imaging (PAI) technology to diagnostic imaging and therapeutic monitoring of inflammatory arthritis has been explored. The feasibility of our bench-top joint imaging systems in delineating soft articular tissue structures in a noninvasive manner was validated first on rat models and then on human peripheral joints. Based on the study on commonly used arthritis rat models, the capability of PAI to differentiate arthritic joints from the normal was also examined. With sufficient imaging depth, PAI can realize tomographic imaging of a human peripheral joint or a small-animal joint as a whole organ noninvasively. By presenting additional optical contrast and tissue functional information such as blood volume and blood oxygen saturation, PAI may provide an opportunity for early diagnosis of inflammatory joint disorders, e.g. rheumatoid arthritis, and for monitoring of therapeutic outcomes with improved sensitivity and accuracy.

The progression of epithelial dysplasia is accompanied by changes of sub-cellular structures which alter light scattering, particularly backscattering, properties of epithelial cells. In this study, we quantified the refractive index (RI) distributions of normal and cancerous epithelial cells of skin and oral cavity using digital holographic microtomography and investigated the backscattering characteristics of the cells using finite-difference time-domain simulations. The results show that cancerous cells present higher average values of nuclear and nucleolar RI and a higher standard deviation of cytoplasmic RI than normal cells. Both the total scattering and backscattering cross-sections of the cancerous cells are significantly higher than those of the normal cells.

Optical imaging based on time-stretch process has recently been proven as a powerful tool for delivering ultra-high frame rate (< 1MHz) which is not achievable by the conventional image sensors. Together with the capability of optical image amplification for overcoming the trade-off between detection sensitivity and speed, this new imaging modality is particularly valuable in high-throughput biomedical diagnostic practice, e.g. imaging flow cytometry. The ultra-high frame rate in time-stretch imaging is attained by two key enabling elements: dispersive fiber providing the time-stretch process via group-velocity-dispersion (GVD), and electronic digitizer. It is well-known that many biophotonic applications favor the spectral window of ~1μm. However, reasonably high GVD (< 0.1 ns/nm) in this range can only be achieved by using specialty single-mode fiber (SMF) at 1μm. Moreover, the ultrafast detection has to rely on the state-of- the-art digitizer with significantly wide-bandwidth and high sampling rate (e.g. <10 GHz, <40 GS/s). These stringent requirements imply the prohibitively high-cost of the system and hinder its practical use in biomedical diagnostics. We here demonstrate two cost-effective approaches for realizing time-stretch confocal microscopy at 1μm: (i) using the standard telecommunication SMF (e.g. SMF28) to act as a few-mode fiber (FMF) at 1μm for the time-stretch process, and (ii) implementing the pixel super-resolution (SR) algorithm to restore the high-resolution (HR) image when using a lower-bandwidth digitizer. By using a FMF (with a GVD of ~ 0.15ns/nm) and a modified pixel-SR algorithm, we can achieve time-stretch confocal microscopy at 1μm with cellular resolution (~ 3μm) at a frame rate 1 MHz.

Phase distribution detection of cells and tissues is concerned since it is an important auxiliary method for observing biological samples. Here, in this paper, we have proposed phase retrieval algorithms dealing with microscopic interferograms in order to solve two-dimensional phase distribution. Based on phase distributions solved by phase retrieval algorithms, three-dimensional refractive index distribution of biological sample is reconstructed which could reflect inner structure of the cell. We believe these methods could be powerful tools in biological and medical fields.

Raman spectroscopy has demonstrated great potential in the study of biological molecules in a variety of biomedical applications. But slow data acquisition due to weak Raman signals from these molecules has prevented its wide use especially in an imaging setup. We propose a novel method to reconstruct the entire Raman spectrum from a few narrow-band measurements based on Wiener estimation. This method has been tested on Raman spectra from individual cells and shown fast speed and excellent accuracy. This method represents a new direction to speed up Raman data acquisition in an imaging setup to investigate fast changing phenomena.

The aim of this study is to evaluate the demineralization process in human dentine using Raman spectroscopy (RS). Nine human molars from Chinese subjects were cut into twelve tooth sections. The sections were painted with an acidresistant varnish leaving one dentine surface exposed and then immersed into 0.3% citric acid to simulate the oral natural demineralization. According to the acid-etch time, specimens were randomly divided into four groups: Ⅰ5 min, Ⅱ 10 min, Ⅲ 20 min and Ⅳ 40 min. Raman spectra were measured before and after each treatment. The result showed that no new bands, bands shifts, or disappearance of bands occurred in the whole process. However, the peak intensities of inorganic constituents decreased with the increase of acid-etch time, while the trends of organic constituents were opposite. In conclusion, RS could be able to efficiently monitor the demineralization status of human dentine.

The accurate assessment of skin flap viability is vitally important in reconstructive surgery. Early identification of vascular compromise increases the change of successful flap salvage. The ability to determine tissue viability intraoperatively is also extremely useful when the reconstructive surgeon must decide how to inset the flap and whether any tissue must be discarded. Visible diffuse reflectance and auto-fluorescence spectroscopy, which yield different sets of biochemical information, have not been used in the characterization of skin flap viability simultaneously to our best knowledge. We performed both diffuse reflectance and fluorescence measurements on a reverse MacFarlane rat dorsal skin flap model to identify the additional value of auto-fluorescence spectroscopy to the assessment of flap viability. Our result suggests that auto-fluorescence spectroscopy appears to be more sensitive to early biochemical changes in a failed flap than diffuse reflectance spectroscopy, which could be a valuable complement to diffuse reflectance spectroscopy for the assessment of flap viability.

Growth in the percentage of male infertility has caused extensive concerns. The fast and reliable method is urgently required for diagnosis of semen samples. In our study, micro-Raman spectroscopy was employed to characterize and differentiate the normal and abnormal semen samples based on the differences of their specific Raman spectra which originated from biochemical components. Our preliminary results demonstrate that micro-Raman spectroscopy combined with multivariate analysis methods has the potential of being used to detect and differentiate semen samples.

Optical biopsy spectroscopy was applied to diagnosis human brain cancer in vitro. The spectra of native fluorescence, Stokes shift and excitation spectra were obtained from malignant meningioma, benign, normal meningeal tissues and acoustic neuroma benign tissues. The wide excitation wavelength ranges were used to establish the criterion for distinguishing brain diseases. The alteration of fluorescence spectra between normal and abnormal brain tissues were identified by the characteristic fluorophores under the excitation with UV to visible wavelength range. It was found that the ratios of the peak intensities and peak position in both spectra of fluorescence and Stokes shift may be used to diagnose human brain meninges diseases. The preliminary analysis of fluorescence spectral data from cancer and normal meningeal tissues by basic biochemical component analysis model (BBCA) and Bayes classification model based on statistical methods revealed the changes of components, and classified the difference between cancer and normal human brain meningeal tissues in a predictions accuracy rate is 0.93 in comparison with histopathology and immunohistochemistry reports (gold standard).

The flash electroretinography is a standard electrophysiological method and widely employed in basic research and ophthalmology clinics, of which the stimulus is usually white flash from dome stimulator. However, little is known about the electroretinograms (ERGs) evoked by monochromatic laser flash stimuli. The goal of this research effort is to quantify the ERGs of dark-adapted New Zealand rabbits elicited by He-Ne laser flash with wavelength 632.8 nm. The flash field was a Maxwellian viewing disc with angular subtense of 8.5°, 13.3° or 20.2°. The stimulus duration was 12 ms, 22 ms, 70 ms or 220 ms. The laser flash power incident on the cornea varied from 2.2 nW through 22 mW. Under the condition of 20 ms stimulus duration and 20.2° flash field, the ERG of New Zealand rabbit was compared with that of Chinchilla gray rabbit. Results showed that for the ERG b-wave, with the increase of laser energy, the amplitude first increased, then met a trough and finally increased again, the implicit time decreased first and then met a platform. While for the ERG a-wave, the amplitude increased and the implicit time decreased monotonically. Longer stimulus duration led to lower b-wave amplitude under equal flash power level. The flash field size showed limited effect on the ERG, especially on the low energy end. As compared with the pigmented rabbit, the albino rabbit was more sensitive and the threshold energy for b-wave excitation was about 10 times lower.

Water plays an important role in laser ablation. There are two main interpretations of laser-water interaction: hydrokinetic effect and vapor phenomenon. The two explanations are reasonable in some way, but they can’t explain the mechanism of laser-water interaction completely. In this study, the dynamic process of vapor channel formation induced by pulsed CO₂ laser in static water layer was monitored by high-speed camera. The wavelength of pulsed CO₂ laser is 10.64 um, and pulse repetition rate is 60 Hz. The laser power ranged from 1 to 7 W with a step of 0.5 W. The frame rate of high-speed camera used in the experiment was 80025 fps. Based on high-speed camera pictures, the dynamic process of vapor channel formation was examined, and the threshold of vapor channel formation, pulsation period, the volume, the maximum depth and corresponding width of vapor channel were determined. The results showed that the threshold of vapor channel formation was about 2.5 W. Moreover, pulsation period, the maximum depth and corresponding width of vapor channel increased with the increasing of the laser power.

The aim of this work is to improve the understanding of the interaction between photoacoustic waves and skin. We employ photoacoustic waves with 1 MPa amplitude and center frequencies of 100 MHz to transiently perturb model lipid membranes and the stratum corneum of mini pigs. The lipid structure transient perturbation observed is tentatively attributed to a temperature rise mechanism. We also try to show that the dynamic acoustic radiation force mechanism can explain the perturbation induced by photoacoustic waves in skin. Indeed, 15 bar pressure gradients across 5 corneocytes (approx. 5 μm wide) are shown to transiently perturb the skin structure.

In this paper, we present a new method to simulate the signal of polarization-sensitive optical coherence tomography (for short, PS-OCT) by the use of the sphere cylinder birefringence Monte Carlo program developed by our laboratory. Using the program, we can simulate various turbid media based on different optical models and analyze the scattering and polarization information of the simulated media. The detecting area and angle range and the scattering times of the photons are three main conditions we can use to screen out the photons which contribute to the signal of PS-OCT, and in this paper, we study the effects of these three factors on simulation results using our program, and find that the scattering times of the photon is the main factor to affect the signal, and the detecting area and angle range are less important but necessary conditions. In order to test and verify the feasibility of our simulation, we use two methods as a reference. One is called Extended Huygens Fresnel (for short, EHF) method, which is based on electromagnetism theory and can describe the single scattering and multiple scattering of light. By comparison of the results obtained from EHF method and ours, we explore the screening regularities of the photons in the simulation. Meanwhile, we also compare our simulation with another polarization related simulation presented by a Russian group, and our experimental results. Both the comparisons find that our simulation is efficient for PS-OCT at the superficial depth range, and should be further corrected in order to simulate the signal of PS-OCT at deeper depth.

To examine the temperature changes in the pulp chamber during cavity preparation in dentin with the Er:YAG laser (2940 nm), a total 20 intact premolars teeth were divided into 4 groups for dentin ablation with different radiant exposures at 4Hz and 8Hz with and without water spray. A K-type thermocouple was used to monitor the temperature changes in pulp chamber during laser treatment. The total time of irradiation was 70 sec. the water spray rate was 3 mL/min. It showed that maximum temperature rise increases with the increasing of radiant exposure and pulse repetition rate and the additional water cooling during laser ablation can significantly reduce the temperature rise in pulp chamber which will benefit to avoid or reduce thermal damage to tooth structure and dental pulp. The highest rise of temperature in the pulp was achieved with 20 J/cm² and 8 Hz (19.83°C ). For all sample without water spray, the rise of temperature was exceed 5 °C . In contrast, with water spray, the temperature rise in the pulp can be firmly controlled under 1°C. The results also indicated that ablation rate and efficiency can be enhanced by increasing the incident radiant exposure and pulse repetition rate, which simultaneously producing more heat accumulation in dental tissue and causing thermal damage to dental tissue. By applying an additional water spray, thermal damage can be significantly reduced in clinical application.

Skin wound healing and scarring in rabbit ears was examined by second harmonic generation (SHG) microscopy. Rabbit ear wound model was created by punching from the ventral surface with removal of epidermis, dermis and perichondrium. The samples were collected weekly, and cut into 100 μm thickness sections for SHG imaging. SHG imaging system was operated at 810 nm, producing SHG signals at half the excitation wavelength 405 nm. A Plan-Neofluar objective (x40 and NA=0.75) was employed for focusing the excitation beam into tissue samples and was also used to collect the backscattered intrinsic SHG signals. Our results showed apparent difference in collagen content and microstructure at various wound healing and scarring time points. It suggested that SHG signals from collagen can serve as a good indicator for characterization of wound status. With the advancement on miniaturization, microscopy based on SHG will become a valuable tool for monitoring the wound healing and scarring in vivo, and help to guide the improvement of scar appearance with appropriate and subtle modulation during wound healing based on better understanding of scarring response mechanism.

The molecular characterization of ABO blood types, which is clinically significant in blood transfusion, has clinical and anthropological importance. Polymerase chain reaction sequence-based typing (PCR-SBT) is one of the most commonly used methods for the analysis of genetic bases of ABO blood types. However, such methods as PCR-SBT are time-consuming and are high in demand of equipments and manipulative skill. Here we showed that membrane electrophoresis based SERS method employed for studying the molecular bases of ABO blood types can provide rapidand easy-operation with high sensitivity and specificity. The plasma proteins were firstly purified by membrane electrophoresis and then mixed with silver nanoparticles to perform SERS detection. We use this method to classify different blood types, including blood type A (n=13), blood type B (n=9) and blood type O (n=10). Combination of principal component analysis (PCA) and liner discriminant analysis (LDA) was then performed on the SERS spectra of purified albumin, showing good classification results among different blood types. Our experimental outcomes represent a critical step towards the rapid, convenient and accurate identification of ABO blood types.

Due to its high sensitivity, flexibility, and “fingerprints” sensing capability, Surface-enhanced Raman Spectroscopy (SERS) is a very powerful method for characterization of substances. In this paper, two kinds of Radix Astragali with different quality were firstly extracted through continuous circumfluence extraction method and then mixed with silver nanoparticles for SERS detection. Most Raman bands obtained in Radix Astragali extraction solution are found at 300-7000cm^-1 and 900-1390 cm^-1. Although, major peak positions at 470, 556, 949, 1178 and 1286 cm^-1 found in these two kinds of Radix Astragali appear nearly the same, Raman bands of 556 and 1178 cm^-1 are different in intensity, thus may be used as a characteristic marker of Radix Astragali quality. In detail, we can make full use of the different intensity of two different kinds but the same state at 556 cm^-1 to describe the quality standard of Radix Astragali. Our preliminary results show that SERS combining with continuous circumfluence extraction method may provide a direct, accurate and rapid detection method of Radix Astragali.

The intermolecular electron transfer between carboxylic dendritic zinc(II) phthalocyanine bearing carboxylic terminal groups(G₁-ZnPc(COOH)₈) and methyl viologens (MV²⁺) was studied by steady-state fluorescence and UV/Vis spectroscopy. The effect of different concentrations of MV²⁺ on intermolecular electron transfer was investigated. The results show that the fluorescence emission of this dendritic phthalocyanine could be greatly quenched with an increasing amount of MV²⁺ upon excitation at 610 nm. Our study suggests that this novel dendritic phthalocyanine is an effective new electron donor and transmission complex and could be used as a potential biosensor conjugated with suitable fluorescence quencher.

The near infrared laser technique can activate cutaneous nociceptors with high specificity and reproducibility and be used in anti-riot equipment. This study aimed to explore cutaneous pain effect and determine the threshold induced by Nd:YAG and CO₂ laser stimuli. The corresponding wavelength was 1.32μm and 10.6μm. The pain effect was assessed in three healthy subjects (1 woman and 2 men) on the skin of dorsum of both hands. The energy of each pulse and whether the subjects felt a painful sensation after each stimulus were recorded. A simplified Bliss Method was used to calculate the pain threshold which were determined under three pulse durations for Nd:YAG laser and one pulse duration for CO₂ laser. As a result the pain thresholds were determined to be 5.6J/cm², 5.4J/cm² and 5.0J/cm² respectively when using Nd:YAG laser, 4.0mm beam diameter, 8ms, 0.1s and 1s pulse duration. The pain threshold was 1.0J/cm² when using CO₂ laser, 4.0mm beam diameter and 0.1s pulse duration. We concluded that the threshold of cutaneous pain elicited by 1.32μm laser was independent upon the pulse duration when the exposure time ranged from 8ms to 1s. Under the same exposure condition, the threshold of cutaneous pain elicited by 1.32μm laser was higher than that elicited by 10.6μm laser.

Gastric cancer is one of the most common malignant tumors with high recurrence rate and mortality rate in China. This study aimed to evaluate the diagnostic capability of Surface-enhanced Raman spectroscopy (SERS) based on gold colloids for distinguishing gastric tissues. Gold colloids were directly mixed with the supernatant of homogenized tissues to heighten the Raman signal of various biomolecule. A total of 56 samples were collected from normal (30) and cancer (26). Raman spectra were obtained with a 785nm excitation in the range of 600-1800 cm^-1. Significant spectral differences in SERS mainly belong to nucleic acid, proteins and lipids, particularly in the range of 653, 726, 828, 963, 1004, 1032, 1088, 1130, 1243, 1369, 1474, 1596, 1723 cm^-1. PCA-LDA algorithms with leave-one-patient-out cross validation yielded diagnostic sensitivities of 90% (27/30), specificities of 88.5% (23/26), and accuracy of 89.3% (50/56), for classification of normal and cancer tissues. The receiver operating characteristic (ROC) surface is 0.917, illustrating the diagnostic utility of SERS together with PCA-LDA to identify gastric cancer from normal tissue. This work demonstrated the SERS techniques can be useful for gastric cancer detection, and it is also a potential technique for accurately identifying cancerous tumor, which is of considerable clinical importance to real-time diagnosis.

In the digital confocal microscopy technology, voltage ceramic is used to drive axial moving of objective lens to collect image slices, which is simple and flexible, easy to control and will get a large precision. But as a result of the movement, the corresponding parameters of the system, even the point spread function changes, which will bring error to the image restoration. According to the principle of optical imaging, the change of the point spread function is quantitative calculated in this paper, through the experiment of recover the image slices collected by moving objective lens and the image slices collected by moving the loading platform, the error is calculated, compared and analyzed. The results can verify the feasibility of moving lens to collect image slices.

There have been many reports on tapered micro-nano optical fiber used in cell monitoring, so it is necessary to discuss the reverse propagation properties in tapered fiber. In this paper, we use Finite Difference Time Domain (FDTD) algorithm to simulate the propagation of light wave propagating back and forward in fiber taper, respectively. The results indicate that most of the light is remain in core in the back way. But little light propagates at a relatively far distance from core in cladding and most of light energy will back to core at the end part of fiber taper, which is different from forward propagation. In the subsequent experiment, the conclusion is further proved. Based on this feature, the light signal in living cell can be easily guided out and the true sense of “endoscopic” for cell detection would be realized.

A novel series of zinc (II) phthalocyanines bearing four poly (aryl benzyl ether) dendritic substituents with carboxylic acid functionalities (G_n-DPcZn (G_n=n-generation dendrimer, n=1-2)) loaded polymeric micelles (G_n-DPcZn/m) were formed. The time-dependent intracellular uptake of G_n-DPcZn in RPE cells increased as they were incorporated into micelles, but inversely correlated with the generation. The photocytoxity of G_n-DPcZn was improved by incorporation into polymeric micelles and increased with the generation.

Spectral domain optical coherence tomography (SD-OCT) was developed in order to image the anterior segment of human eye. The optical path at reference arm was switched to compensate the sensitivity drop in OCT images. An scan depth of 12.28 mm and an axial resolution of 12.8 μm in air were achieved. The anterior segment from cornea to posterior surface of crystalline lens was clearly imaged and measured using this system. A custom designed Badal optometer was coupled into the sample arm to induce the accommodation, and the movement of crystalline lens was traced after the image registration. Our research demonstrates that SD-OCT with ultra-long scan depth can be used to image the human eye for accommodation research.

Finite element method is a general approach for diffuse optical tomography, and the accuracy of which is closely related to the type of elements used. In this paper, we investigate the differences between linear element and quadratic triangular element in the forward problem of diffuse optical tomography. The results show that quadratic element is a better compromise between high accuracy and low time consumption compared to the linear element. This means high order element is a better choice for the diffuse optical tomography.

Noninvasive measurement of blood glucose concentration (BGC) has become a research hotspot. BGC measurement based on photoacoustic spectroscopy (PAS) was employed to detect the photoacoustic (PA) signal of blood glucose due to the advantages of avoiding the disturbance of optical scattering. In this paper, a set of custom-built BGC measurement system based on tunable optical parametric oscillator (OPO) pulsed laser and ultrasonic transducer was established to test the PA response effect of the glucose solution. In the experiments, we successfully acquired the time resolved PA signals of distilled water and glucose aqueous solution, and the PA peak-to-peak values(PPV) were gotten under the condition of excitated pulsed laser with changed wavelength from 1340nm to 2200nm by increasing interval of 10nm, the optimal characteristic wavelengths of distilled water and glucose solution were determined. Finally, to get the concentration prediction error, we used the linear fitting of ordinary least square (OLS) algorithm to fit the PPV of 1510nm, and we got the predicted concentration error was about 0.69mmol/L via the fitted linear equation. So, this system and scheme have some values in the research of noninvasive BGC measurement.

There exists three variables in the radiative transfer equation based on dynamic energy conservation, including polar angle, azimuth angle and normalized penetrate depth. In order to solute this equation with double integral on polar angle and azimuth angle, the first step is to introduce proper method to isolate azimuthal dependency from polar angle. In this paper, we propose a novel phase matrix expansion with Zernike polynomials, which represents the probability of scattering events. The results show that it can provide a new improved strategy for the solution of radiative transfer equations in Discrete-Ordinate Method (DOM), which is different from commonly used Fourier series and Legendre polynomials expansion and we make conclusion that there are three principles for polynomials’ selection, including orthogonal performance, special theorem for polynomial derivation and triangle function generation.

An optical-resolution photoacoustic microscopy system was designed and fabricated by integration of a two-dimensional scanning galvanometer, an objective lens, an unfocused ultrasound transducer and a sample stage for imaging blood vessels in vivo. In vivo blood vessels of mouse ear were clearly shown and the injured blood vessels were also monitored. The experimental results demonstrate that galvanometer-based photoacoustic microscopy holds clinical potential in detecting lesion of blood vessels.

The incidence rate of the prostatic hyperplasia is increasing in near decade, early detection is important for preventing the prostatic cancer (PCa). In this study, the images of prostate and cavernous nerves were carried out using intrinsic fluorescence and scattering properties of the tissues without any exogenous dye or contrast agent based on nonlinear optical microscope. The texture feature and optical property of the interfibrillar substance in prostate tissue were extracted and analyzed for charactering the prostate structure. It will be the feature parameter to differentiate the normal, the inflammation or cancer of prostate tissue in clinical with the application of miniature endoscope nonlinear optical microscope in vivo.

Improving signal to noise ratio in ultrasound-modulated optical tomography (UOT) is a research topic. Laying apertures in front of a photomultiplier tube (PMT) can reduce the ambient noise collected by the PMT, and efficiently improve the signal to noise ratio of UOT. In addition, the effective area of detection and the off-axis position of the PMT would be varied by changing the aperture size and position in front of the PMT. Experimental results indicated that ultrasound-modulated signal is dependent on the area of detection. The greater the detector area, the smaller the ultrasound-modulated signal and its modulation depth. The modulated signal also depended on the off-axis position of the PMT from the optic axis. In particular, the modulated signal did not reach the biggest value when the PMT just placed on the optics axis. Choosing appropriate size, position of aperture, can improve the signal to noise ratio and image contrast.

We propose a novel tapered-tip single fiber optical tweezers, which can realize micro particles multi-trapping. The theory analysis about multi-trapping was finished with the finite difference time domain (FDTD) method. The theory and experiment results showed that the particle refractive index affects the multi-trapping obviously.

In order to study scattering properties of normal and cancerous tissues from human stomach, we collect images for human gastric specimens by using phase-contrast microscope. The images were processed by the way of mathematics morphology. The equivalent particle size distribution of tissues can be obtained. Combining with Mie scattering theory, the scattering properties of tissues can be calculated. Assume scattering of light in biological tissue can be seen as separate scattering events by different particles, total scattering properties can be equivalent to as scattering sum of particles with different diameters. The results suggest that scattering coefficient of the cancerous tissue is significantly higher than that of normal tissue. The scattering phase function is different especially in the backscattering area. Those are significant clinical benefits to diagnosis cancerous tissue

The multi-axis differential optical absorption spectroscopy (MAX-DOAS) technique is being widely used in the monitoring of trace gases column density. In this paper, a retrieval method of visibility from O₄ slant column density measured with MAX-DOAS is present. O₄ slant column density is sensitive to the change of aerosol properties, and aerosol properties determine the atmospheric visibility. The relationship of atmospheric visibility and O₄ slant column density is analyzed, and a retrieval algorithm to convert the O₄ differential slant column density into visibility is described. MAX-DOAS observation is carried out, and atmospheric visibility is retrieved successfully. The visibility measured with MAX-DOAS shows good agreement with the result obtained with visibility meter, proving the feasibility of the retrieval method. This research presents a simple and effective monitoring method of visibility with MAX-DOAS, expands the application of MAX-DOAS technique.

Monte Carlo simulation procedure is accelerated by scaling method based on baseline data from standard Monte Carlo calculation in turbid medium. Gaussian beam is modeled by hyperboloid of one sheet for actual condition to obtain distribution of photons on sample surface. Depth dependence coherent signal and photons distribution are calculated in this way, which is important to reconstruction of optical parameters by inverse Monte Carlo. Numerical results have verified this method in turbid medium of different optical parameters with acceptable relative errors.

A method for noninvasive simultaneously detecting hemoglobin oxygen saturation (SO₂) and carboxyhemoglobin saturation (SCO) in subcutaneous microvasculature with multi-wavelength photoacoustic microscopy (PAM) is presented. In vitro blood samples mixed with different concentration of carboxyhemoglobin were used to testify the feasibility and accuracy of the PAM. Moreover, fixed-point detection of SO₂ and SCO of the vessel in mouse ear were obtained. And the changes of SO₂ and SCO from normoxia to carbon monoxia hypoxia were dynamically recorded in vivo. Experimental results demonstrate that the PAM has the capability to detect SO₂ and SCO, which has potential application in clinic.

Prostate cancer is one of diseases with high mortality in man. Many clinical imaging modalities are utilized for the detection, grading and staging of prostate cancer, such as ultrasound, CT, MRI, etc. But they lacked adequate sensitivity and specificity for finding cancer in transition or central zone of prostate. To overcome these problems, we propose a photoacoustic imaging modality based on cylinder diffuse radiation through urethra for prostate cancer detection. We measure the related parameters about this system like lateral resolution (~2mm) and axial resolution(~333μm). Finally, simulated sample was imaged by our system. The results demonstrate the feasibility for detecting prostate cancer by our system.

The principles of ergonomics design in fundus cameras should be extending the agreeableness by automatic control. Firstly, a 3D positional numerical control system is designed for positioning the eye pupils of the patients who are doing fundus examinations. This system consists of a electronically controlled chin bracket for moving up and down, a lateral movement of binocular with the detector and the automatic refocusing of the edges of the eye pupils. Secondly, an auto-focusing device for the object plane of patient’s fundus is designed, which collects the patient’s fundus images automatically whether their eyes is ametropic or not. Finally, a moving visual target is developed for expanding the fields of the fundus images.

The effect of temperature on the optical properties of biological tissue has been studied by using milk as an example. Optical properties of milk were measured by using optical coherence tomography(OCT) technology in the temperature range of 20-35°C, and we get the logarithm of the OCT signal, then the rules of change of optical properties with temperature were analyzed. The results show that obvious increase can be observed with increasing temperature in the increase attenuation coefficient. It is a novel method to study the effect of temperature on optical properties of biological tissue.

The design and development of the miniaturized interferometer for measurement of the refractive index or concentration of sub-microliter volume aqueous solution in microfludic chip is presented. It is manifested by a successful measurement of the refractive index of sugar-water solution, by utilizing a laser diode for light source and the small robust instrumentation for practical implementation. Theoretically, the measurement principle and the feasibility of the system are analyzed. Experimental device is constructed with a diode laser, lens, two optical plate and a complementary metal oxide semiconductor (CMOS). Through measuring the positional changes of the interference fringes, the refractive index change are retrieved. A refractive index change of 10^-4 is inferred from the measured image data. The entire system is approximately the size of half and a deck of cards and can operate on battery power for long time.

The optical characteristics of absorption and scattering of irradiated tissue determine light spatial distribution and the subsequent biological effects, which could decide the dosimetry for laser medical applications. Studys have shown that the optical properties of bio-tissue could be determined through some fitting algorithms with spatially resolved diffuse reflectance theory based on the measurement of diffuse reflectance. The regression of reflectance data with by diffusion theory model was important for optical properties estimation. In the paper, the reflectance versus distance data acquired from Monte Carlo method was by fit to diffusion theory model by the nonliear least-squares fitting algorithm to study the produre and mothod of determination of optical properties. And attention was especially paid to the influence of the radial step width Δr, length of radial distance r_L and start value of radial distance r₀ on the regression results. Preliminary results indicated that the radial step width and length of radial distance r_L both have little influence on the fitting. Nevertheless, the start value of radial distance r₀ of reflectance data has great influence on the fitting. Fitting deviation would become little while the start value of radial distance r₀ grow greater. and an appropriate r₀ was important for data fitting. Study also showd a more accurate light diffuse reflectance theoretical model was need for estimate the optical parameters by fitting the diffuse reflectance data accurately. Our work maybe be helpful to the experiment measurement of light diffuse reflectance data for noninvasive optical properties determination.

Rotaviruses are double-stranded RNA viruses belonging to the family of enteric pathogens. It is a major cause of diarrhoeal disease in infants and young children worldwide. Consequently, rapid and accurate detection of rotaviruses is of great importance in controlling and preventing food- and waterborne diseases and outbreaks. Reverse transcription-polymerase chain reaction (RT-PCR) is a reliable method that possesses high specificity and sensitivity. It has been widely used to detection of viruses. Electrochemiluminescence (ECL) can be considered as an important and powerful tool in analytical and clinical application with high sensitivity, excellent specificity, and low cost. Here we have developed a method for the detection of rotavirus by combining in situ magnetic beads (MBs) based RT-PCR with ECL. RT of rotavirus RNA was carried out in a traditional way and the resulting cDNA was directly amplified on MBs. Forward primers were covalently bounded to MBs and reverse primers were labeled with tris-(2, 2’-bipyridyl) ruthenium (TBR). During the PCR cycling, the TBR labeled products were directly loaded and enriched on the surface of MBs. Then the MBs–TBR complexes could be analyzed by a magnetic ECL platform without any post-modification or post-incubation，which avoid some laborious manual operations and achieve rapid yet sensitive detection. In this study, rotavirus from fecal specimens was successfully detected within 2 h, and the limit of detection was estimated to be 10⁴copies/μL. This novel in situ MBs based RT-PCR with ECL detection method can be used for pathogen detection in food safety field and clinical diagnosis.

Here, we report that low-power laser irradiation (LPLI) activates ERK/Sp1 pathway to upregulate VEGF expression and promote vascular endothelial cell proliferation. We demonstrate for the first time that LPLI enhances DNA-binding activity and transactivation activity of Sp1 on VEGF promoter. Additionally, ERK translocates from cytoplasm to nucleus following LPLI. Moreover, activated ERK phosphorylates Sp1 and results in increased EKR-Sp1 interaction. Selective inhibition of Sp1 or ERK suppresses the effect of LPLI on the promotion of cell cycle progression and proliferation. These findings provide a novel link between LPLI and angiogenesis, supplying potential therapy strategies for angiogenesis with LPLI.

Bioluminescence tomography(BLT) is an instrumental molecular imaging modality designed for the 3D location and quantification of bioluminescent sources distribution in vivo. In our context, the diffusion approximation(DA) to radiative transfer equation(RTE) is utilized to model the forward process of light propagation. Mathematically, the solution uniqueness does not hold for DA-based BLT which is an inverse source problem of partial differential equations and hence is highly ill-posed. In the current work, we concentrate on a general regularization framework for BLT with Bregman distance as data fidelity and total variation(TV) as regularization. Two specializations of the Bregman distance, the least squares(LS) distance and Kullback-Leibler(KL) divergence, which correspond to the Gaussian and Poisson environments respectively, are demonstrated and the resulting regularization problems are denoted as LS+TV and KL+TV. Based on the constrained Landweber(CL) scheme and expectation maximization(EM) algorithm for BLT, iterative algorithms for the LS+TV and KL+TV problems in the context of BLT are developed, which are denoted as CL-TV and EM-TV respectively. They are both essentially gradient-based algorithms alternatingly performing the standard CL or EM iteration step and the TV correction step which requires the solution of a weighted ROF model. Chambolle’s duality-based approach is adapted and extended to solving the weighted ROF subproblem. Numerical experiments for a 3D heterogeneous mouse phantom are carried out and preliminary results are reported to verify and evaluate the proposed algorithms. It is found that for piecewise-constant sources both CL-TV and EM-TV outperform the conventional CL and EM algorithms for BLT.

Esophageal cancer is a common malignancy with a very poor prognosis. Successful strategies for primary prevention and early detection are critically needed to control this disease. Multiphoton microscopy (MPM) is becoming a novel optical tool of choice for imaging tissue architecture and cellular morphology by two-photon excited fluorescence. In this study, we used MPM to image microstructure of human normal esophagus, carcinoma in situ (CIS), and early invasive carcinoma in order to establish the morphological features to differentiate these tissues. The diagnostic features such as the appearance of cancerous cells, the significant loss of stroma, the absence of the basement membrane were extracted to distinguish between normal and cancerous esophagus tissue. These results correlated well with the paired histological findings. With the advancement of clinically miniaturized MPM and the multi-photon probe, combining MPM with standard endoscopy will therefore allow us to make a real-time in vivo diagnosis of early esophageal cancer at the cellular level.

MicroRNAs (miRNAs) play pivotal roles in many fundamental aspects of life, such as tissue differentiation, metabolic modulation and cell proliferation control. As miRNA has the characteristics of small size, easy degradation and low abundance, a simple, rapid and specificity method to measure the concentration of miRNA is required. Herein, we present an Electrochemiluminescent Chips system for rapid miRNA detection based on the base stacking hybridization and magnetic beads (MB) enrichment technology. In this design, integrating the microfluidic system with Electrochemiluminescent detection makes it easy to assemble the multiple assay steps (e.g., sample preparation, incubation, washing and detection) and let the device convenient to carry. This method is very fast, we can detect miRNA in 19 min with a 10 uL sample volume. Moreover, in this experiment the detection limit was 1 fmol of the pure synthetic miRNA, and the linear range was from 5 fmol to 1 pmol. It also exhibited excellent selectivity over a series of interference miRNA, which display a high level of expression in cancer cell. These results suggest that this method might have potential for cancer diagnosis at the point of care.

A new label-free isothermal fluorescence amplification detection for nucleic acid has been developed. In this paper, we first developed a novel sensitive and specific detection platform with an unmodified hairpin probe (HP) combination of the graphene oxid (GO)/ SYBR green I dye (SG), which was relied on the selective principle of adsorption and the high quenching efficiency of GO. Then for the application of this new strategy, we used Mirco RNA-21 (Mir-21) as the target to evaluate this working principle of our design. When the target was hybridizing with the HP and inducing its conformation of change, an efficient isothermal circular strand-displacement polymerization reaction was activating to assist the first signal amplification. In this format, the formed complex conformation of DNA would interact with its high affinity dye, then detached from the surface of GO after incubating with the platform of GO/intercalating dye. This reaction would accompany with obvious fluorescence recovery, and accomplish farther signal enhancement by a mass of intercalating dye inserting into the minor groove of the long duplex replication product. By taking advantage of the multiple amplification of signal, this method exerted substantial enhancement in sensitivity and could be used for rapid and selective detection of Mir-21 with attomole range. It is expected that this cost-effective GO based sensor might hold considerable potential to apply in bioanalysis studies.

The thyroid is one of the main endocrine glands of human body, which plays a crucial role in the body's metabolism. Thyroid cancer mortality ranks only second to ovarian cancer in endocrine cancer. Routine diagnostic methods of thyroid diseases in present clinic exist misdiagnosis and missed diagnosis to varying degrees. Those lead to miss the best period of cancer treatment--early. Photoacoustic spectroscopy technology is a new tool, which provides an effective and noninvasive way for biomedical materials research, being highly sensitive and without sample pretreatment. In this paper, we use photoacoustic spectroscopy technology (PAST) to detect the absorption spectrum between normal and malignant thyroid tissues. The result shows that the photoacoustic spectroscopy technology (PAST) could differentiate malignant thyroid tissue from normal thyroid tissue very well. This technique combined with routine diagnostic methods has the potential to increase the diagnostic accuracy in clinical thyroid cancer diagnosis.

Larynx cancer is one of the most common primary head and neck cancers. For early-stage laryngeal cancer, both surgery and radiotherapy are effective treatment modalities, offering a high rate of local control and cure. Optical coherence tomography (OCT) is an established non-invasive optical biopsy method, capable of imaging ranges of 2- 3 mm into tissue. By using the principles of low coherence light interferometry, OCT can be used to distinguish normal from unhealthy laryngeal mucosa in patients. Two forward-looking endoscope OCT probes of different sizes in a sweeping frequency OCT (SS-OCT) configuration were compared in terms of their performances for ex-vivo laryngeal cancer imaging. The setup configuration of the first OCT probe unit was designed and constructed at the Institute of Applied Physics RAS, Russia (diameter of 1.9 mm and the rigid part at the distal end is 13 mm long). The second OCT endoscope probe was constructed at the Department of Biomedical Engineering at Johns Hopkins University, USA, using a tubular piezoelectric actuator with quartered electrodes in combination with a resonant fiber cantilever (diameter of 2.4 mm, and rigid part of 45 mm). Cross-sectional images of laryngeal lesions using the two OCT configurations were aquired and compared with OCT images obtained in a 1310 nm SS-OCT classical non-endoscopic system. The work presented here is an intermediate step in our research towards in-vivo endoscopic laryngeal cancer imaging.

The effect of glucose on fluorescence characteristics of synthesized ZnCdS nanoparticles in glucose oxidase solution has been investigated. It has been shown that, on addition of glucose, the nanoparticle fluorescence is quenched. Dynamics of fluorescence quenching with increasing glucose concentration was observed. Threshold sensitivity of recording of glucose concentration has been 0,25 mg/ml. So the presented effect opens the facilities for application of synthesized ZnCdS nanoparticles for the glucose control in bodyfluids.

In this paper, we study muscle elastic drawing and damage using our lab’s polarization-sensitive optical coherence tomography (PS-OCT) instrument and polarization sensitive Monte Carlo program. First, we acquire two-dimensional PS-OCT images of elastically drawn and injured muscle, injury processes including dehydration and hydrolysis, we extract some characteristics from experimental results including extinction coefficient, integral reflectivity and birefringence and so on, which will change during muscle is being elastically drawn or injured. In order to further understand and evaluate the degree of muscle elastic drawing or damage according to the measurements parameters mentioned above, we do some corresponding simulations using our lab’s Monte Carlo program, which is based on a sphere cylinder birefringence model and can simulate complicated tissue containing anisotropic microstructures and various polarization imaging and measurement systems. For muscle elastic drawing, we find that integral reflectivity sometimes increases and decreases as muscle’s elastic drawing continues, and through simulation we are unable to find the relationship between extinction coefficients and muscle elastic drawing. As for muscle damage, we simulate two processes: dehydration and hydrolysis. We find that as dehydration deepens, the birefringence of muscle is increasing but getting slowly and the integral reflectivity is decreasing, and as hydrolysis deepens, the birefringence decreases and the integral reflectivity decreases almost linearly. Through the analysis above, we demonstrate the validity of those parameters to characterize muscle elasticity and fiber structure and explain its potential for assessment of muscle damage.