This PDF file contains the front matter associated with SPIE Proceedings Volume 10891, including the Title Page, Copyright Information, Table of Contents, Author and Conference Committee lists.

Motor proteins, including kinesin, can serve as biological components in engineered nanosystems. A proof-of-principle application is a "smart dust" biosensor for the remote detection of biological and chemical agents. The development of this system requires the integration of a diverse set of technologies, illustrates the complexity of biophysical mechanisms, and enables the formulation of general principles for nanoscale engineering. For example, our most recent work created a molecular system that is capable of dynamically assembling and disassembling its building blocks while retaining its functionality, and demonstrates the possibility of self-healing and adaptation. Optical techniques are a key tool to interrogate and interact with these nanosystems as they enable non-destructive measurements with nanometer precision as well as the control of chemical events at the nanoscale. The presentation will highlight the important contributions of photonics to the study of active nanosystems.

In vivo physiological sensing is typically done either by imaging thin tissues or by examining changes in the attenuation coefficient. One known technique for thin tissue in vivo applications is the optical coherence tomography (OCT). However, deep tissue methods are usually based on diffusion reflection (DR), which correlates the optical properties to the reflected light intensity. The attenuation coefficient is composed of tissue absorption and scattering. We present a noninvasive nanophotonics technique, the iterative multi-plane optical property extraction (IMOPE) for extracting the scattering properties from a turbid medium. The reflectance-based IMOPE is most relevant for in vivo applications, hence, in this research we suggest a new theoretical description of phase accumulation in deep tissue, which is rarely mentioned in the literature, using a modified DR theory that represents the phase based on the effective pathlength. The IMOPE records multiple intensity images, reconstructs the phase using Gerchberg-Saxton (GS) algorithm. This algorithm is usually being used for beam shaping or phase reconstruction. We propose to calculate the phase second order moment to estimate the scattering. IMOPE experiments were conducted with tissue-like phantoms for calibration purposes, as well as ex vivo and in vivo measurement. The suggested technique was applied both in transmission and reflection mode. The transmission based IMOPE detected organic nanoparticles within tissues and the quantitative signature of milk components. The reflectance-based IMOPE was applied for tissue viability test and in vivo gold nanorods and blood flow detection.

Almost all known nanoscopy methods rely upon the contrast created by fluorescent labels attached to the object of interest. This causes limitations on their applicability to in vivo imaging. A new label-free spectral encoding of spatial frequency (SESF) approach to nanoscale probing of three-dimensional structures has been developed. It has been demonstrated that spatial frequencies, encoded with optical wavelengths, can be passed though the optical system independent of the resolution of the imaging system. As a result information about small size structures can be detected even using a low resolution imaging system. Different versions of the SESF imaging have been published [1-7], including a novel contrast mechanism for high resolution imaging [1], real time nano-sensitive imaging [2], reconstruction the axial (along depth) spatial frequency profiles for each point with nano-sensitivity to structural changes [3], and the adaptation of the SESF approach to depth resolving imaging [4,5]. Recently the SESF approach has been applied to break the diffraction limit and dramatically improve resolution [6,7]. Here we present further development of the SESF approach including correlation mapping SESF imaging. Both results of numerical simulation and preliminary experimental results, including biological objects, will be presented. [1] Alexandrov, et.al., Opt. Lett. 36 3323 (2011). [2] Alexandrov, et.al., Opt. Express 20 (8) 9203 (2012). [3] Alexandrov, et.al., Appl. Phys. Let., 101 033702 (2012). [4] Uttam, et.al., Opt. Express, 21, 7488 (2013). [5] Alexandrov, et.al., Nanoscale, 6, 3545 (2014). [6] Alexandrov, et.al., Sci. Rep., 5, doi: 10.1038/srep13274 (2015). [7] Alexandrov, et.al., J. Biophotonics, https://doi.org/10.1002/jbio.201700385 (2018).

In this paper we present a new method for shaping of a pulsed IR (λ=1550 nm) laser beam in silicon. The shaping is based on plasma dispersion effect (PDE). The shaping is done by a second pulsed pump laser beam at 532 nm which simultaneously and collinearly illuminates the silicon’s surface with the IR beam. Following the PDE, and in proportion to its spatial intensity distribution, the 532 nm laser beam shapes the point spread function (PSF) by controlling the lateral transmission of the IR probe beam. The use of this probe in laser scanning microscope allows imaging and wide range of contactless electrical measurements in silicon integrated circuits (IC) being under operation e.g. for failure analysis purposes. We propose this shaping method to overcome the diffraction resolution limit in silicon microscopy on and deep under the silicon surface depending on the wavelength of the pump laser and its temporal pulse width. This approach is similar to the stimulated emission depletion (STED) concept previously introduced in scanning fluorescence microscopy.

Atomic Force Microscopy – Infrared spectroscopy (AFM-IR) is a powerful technique for mapping material composition at sub micrometer length scales. Unlike related technologies such as scanning near-field optical microscopy (SNOM), the detected signal can be equally sensitive to both chemical and mechanical sample properties due to variations in the cantilever’s response (or responsivity) to a sample perturbation local to the tip. Understanding cantilever responsivity has led to new approaches for correcting this effect, which show improved chemical specificity and imaging fidelity for heterogeneous samples. Here, we present implications of correcting the cantilever responsivity effect in AFM-IR images for studying biological samples at nanometer length scales and discuss the future of this emerging technology.

Chromium is a toxic metal can do severe damage to public health, plants, and aquatic animals due to its high carcinogenicity. Cr(VI) is about 1000 times more toxic than Cr(III). As a result, exploring methods for differentiation between Cr(III) and Cr(VI) and quantification of these species with high selectivity are essential in aquatic analysis. In this paper, carbon-dots (C-dots) were successfully synthesized with high quantum yield and applied for the determination of the concentration of Cr(VI). It was found that C-dots and Cr (VI) were effective fluorophore and quencher pair for the fluorescence sensor based on inner filter effect. The fluorescence intensity of the C-dots was highly sensitive to the change of concentration of Cr (VI) with good analytical performance. Since ascorbic acid (AA) has been advocated as a treatment of systemic chromium poisoning by converting Cr(VI) to Cr(III), the determination of AA was also investigated. A standard addition methodology was used to determine the Cr(VI) concentration in water samples and the concentration of AA in human serum samples with good results. In summary, compared to traditional methods, the method using C–dots as fluorescence probe is sensitive, selective, cheap and eco-friendly for the determination of the concentration of Cr(VI) and ascorbic acid.

While numerous multifunctional antifouling nanostructures on insect wings have been previously studied and replicated, their potential incorporation into implantable medical devices remains unexplored. We have demonstrated the use of multifunctional bioinspired nanostructured membrane inspired by transparent butterfly wings for intraocular pressure (IOP) sensing in vivo. [1]. We investigated the multifunctional properties of the biophotonic nanostructures found on the wings of the longtail glasswing (C. faunus) butterfly. The AFM, SEM, optical, and biological characterizations have revealed that two groups of dome-shaped nanostructures with different periodicity co-exist on the transparent wings of the C. faunus: (1) angle-independent anti-reflective nanostructures with periods of 140-180 nm in the postdiscal areas; (2) angle- independent transmissive light-scattering nanostructures with periods of 200-300 nm in the basal areas. In vitro testing has revealed both regions displayed antifouling properties based on physically-induced cell lysis. We have (1) adapted the coherence-preserving angle-independent transmissive light-scattering property of the basal nanostructures that could make optical sensors such as Fabry Perot (FP) resonators more angle-independent; and (2) by further engineering the basal nanostructures, created bioinspired nanostructures (BINS) that would prevent biofouling without inducing cell lysis and suppress inflammation. To produce BINS with periods of 385-505 nm on a Si3N4-membrane, we used a polymer-phase separation process following the nature’s way of forming nanostructures [2,3]. Angle- resolved transmission spectroscopy showed that the light transmission of the BINS-integrated membrane was twice more angle-independent than a flat Si3N4-membrane. In a series of in vitro studies the BINS-integrated Si3N4 surface displayed remarkable anti-biofouling properties against proteins (albumin and streptavidin, ***P ≤ 0.001), prokaryotes (E. coli, **P ≤ 0.01), and eukaryotes (HeLa cells, ***P ≤ 0.001) when compared to flat Si3N4 and control (glass) surfaces. Finally, we integrated BINS onto the FP-resonator-based IOP sensor that was recently developed in our lab [4]. However, its practical applications were limited by its narrow readout angle inherent to FP-resonators and infrequent but severe biofouling observed after long-term implantation. The BINS integration onto the IOP sensor led to a 2.5-fold improvement in readout angle allowing easy handheld monitoring and in a one-month in vivo study conducted in rabbits, showed a 3-fold reduction in IOP error and 12-fold reduction in tissue encapsulation and inflammation, compared to an IOP sensor without BINS. References [1] V. Narasimhan, R. H. Siddique, et al. Nature Nanotechnology 13, 512–519 (2018) [2] V. Saranathan et al. Nano Letters 15(6), 3735-3742 (2015) [3] R. H. Siddique, et al. Science Advances 3 (10), e1700232 (2017) [4] J. O.Lee at al. Microsystems & Nanoengineering 3, 17057 (2017)

Electrochemistry shows great potential for biosensing due to its easy-operation (typically with a three-electrode system) and rapid measuring, particularly for portable substrates so they can be integrated as electrode conveniently with the system. The electrical and physical properties make metallic nanoparticles suitable materials for electrochemical biosensors. Metallic nanoparticles can not only facilitate electron transfer with high conductivity but also immobilize molecules of interest. Among metals, silver is the best conductor and silver nanoparticles (AgNPs) can be easily obtained through chemical synthesis. Conductive carbon tapes are a good candidate for deposition of metallic nanoparticles. They can not only make the substrates flexible and portable but also provide good conductivity during electrochemical measurements. They can be self-assembled with metallic nanoparticles. Therefore, in this work, double-sided adhesive carbon tapes coated with AgNPs are fabricated in a simple way. With the prepared conductive substrate as working electrode in a three-electrode system, urea and other proteins at low concentration were measured with cyclic voltammetry (CV). The results showed that carbon tapes coated with AgNPs were able to detect urea with strong signals and that different proteins on the substrates can also be identified. Moreover, urea can be distinguished from proteins or other samples such as plasma including several components on this substrate via EC biosensing.

Surface-enhanced Raman Scattering (SERS) is a promising technique for biosensing due to its high sensitivity at low concentration of analytes of interest. Via this technique, Raman signals of detected molecules are significantly enhanced on the surface of metal or metallic nanostructures. Metallic nanoparticles are widely used for biosensors based on SERS due to their optical and physical properties, generating high enhancement factor. The enhancement factor of SERS is not only dependent on the materials but also dependent on the size, shape and architecture of the substrates. Biosilica diatoms make good candidates that are attractive for plasmonic composite since they show natural nanostructures with a great diversity, which lead to their unique mechanical and optical properties. Therefore, in this work, diatoms and metallic nanoparticles are combined as a novel biocomposite material for potential applications as biosensors. Silver nanoparticles (AgNPs) were self-assembled with diatoms and then deposited on adhesive office tapes. With the prepared substrate, bacteria and proteins at low concentration were measured with Raman spectroscopy. The results indicated although the substrate based the nanocomposite consisting of AgNPs, diatoms and office tapes is particularly suitable for biological particles at nano- to micro-meter scale, showing better performance on identifying different types or strains of bacteria from each other compared to protein identification due to their larger sizes.

Over the last years, we developed advanced microfiber devices including fiber microknots and long period fiber gratings on tapered fibers. In this proceeding, we present our try out to create a twisted fiber for manipulating the state of polarization of the light and specifically to rotate the state of polarization. This attempt did not succeed due to the fact that we tapered the fiber during the twisting by heating it which relieved all the tension in the fiber and prevented from creating twisted birefringence.

Cytokines play critical roles in homeostatic control of health and they are integral for the creation and maintenance of a myriad of disease states. Their ultra-low concentration, often in the picomolar range, and extremely dynamic transient secretion process place stringent demands on cytokine quantification. We developed a nanoparticle-based strategy to detect trace cytokine secretion from individual, single live cells, for which we coined the term “OnCELISA”. Using a capture surface on the cell membrane and fluorescent magnetic nanoparticles as assay reporters, our universal OnCELISA assay achieved the sensitivity 0.1 pg mL-1, an over 10-fold enhancement, compared to state-of-the-art. The sensitive OnCELISA cell labelling made it possible to select and sort different cell types to determine highly cytokine - secreting cell subpopulations . The capture surfaces on cell membranes did not show noticeable effect on cell viability and their subsequent proliferation. The capability to specifically select such highly cytokine-secreting cells and purify their populations is pivotal for their use in multicellular pathologies such as atherosclerosis. Accordingly, we used this new approach to label cytokine secretion from vascular tissues of apolipoprotein E-/- mice; an in vivo model of atherosclerosis. In response to lipopolysaccharide, we observed increased capture of cytokine using this model. With the capacity of monitoring multiple cytokine secretions (IL-6 and IL-1β)), our OnCELISA method is able to probe how the individual cells and tissues secrete cytokines as they respond in real time to the surrounding signals.

Subwavelength systems such as optical nanoantennas are widely used for optical sensing due to their ultrahigh field localization. Compared to isolated nanoantennas, hybrid sensor systems composed of optical nanocavities and microcavities enjoy higher quality factor (Q) plasmonic-cavity modes, as well as larger resonance shifts for any given sensing target. We have shown that rational engineering of the coupling between nanoantennas can maximize the system’s sensitivity. This can be achieved through near-field optimization of the system to maximize the field enhancement and suppression of the far-field radiation to maintain the highest possible Q. Finite element eigenvalue analysis shows that a trimer plasmonic nanoantenna coupled to a whispering gallery mode (WGM) of a microtoroid cavity supports higher Q and field enhancement than single nanorods that are randomly scattered on the surface of microcavity. We have studied the robustness of this system against any possible perturbation in geometry of trimers such as length, angle or gap between the nanoantennas. On the basis of this study, a general design approach is introduced, which helps engineers to enhance the efficacy of plasmonic-photonics based biosensors.

The latest tendencies in individual diagnostics show high interest in development of optical methods. We have used a dynamic light scattering technique to study the size composition of proteins in blood serum of donors with different diseases. In this work, we focused our attention on demonstration of differences between size compositions of blood serum of donors with different types of diseases. It had been found that the proteins' size composition for sick donors differs in a certain way from the size map of healthy donors. Specifically, the relative concentrations of albumins, globulins and circulating immune complex can be used as a diagnostic parameter as it changes significantly on the disease. This result shows the possibilities of application of dynamic light scattering technique to analyze progress and stage of different diseases, in particular, immune diseases and oncology. We declare that the proposed dynamic light scattering technique can be used in medical practice for early fast and simple diagnostics.

The use of nanoantennas to enhance molecular fingerprinting has an important application in the field of biomolecular reaction sensing. Nanoantennas, which are plasmonic metastructures that manipulate light to generate a localized electric field, or hotspot, can be scaled and coupled with Raman spectroscopy and surface enhancement also known as surface enhanced Raman spectroscopy (SERS) to achieve single molecule structural changes, such as signal transduction mechanisms in eukaryotic cells. In this work, we explore an optimal design of nanoantennas in the bowtie configuration using computer simulation technology (CST) microwave studio and simulate gold-contact bowtie nanoantennas with varying fabrication parameters. Simulated gold-contact bowtie nanoantennas are designed with varying tip-to-tip gap distances ranging from 20-100 nm, contact thicknesses ranging from 15-45 nm, and side lengths ranging from 20-300 nm based on the protein chain lengths involved in post translational modifications within eukaryotic cells. Based on our current Jobin Yvon BX41 Confocal Raman microscope configuration, the bowtie antennas are modeled using a one-micron diameter spot and a 532 nm light source to achieve an optimized design. The nanoantenna is fabricated using electron beam lithography (EBL), electron beam evaporation and deposition (EBED), and metal lift-off process. In comparison with other demonstrations of nanoantenna-enhanced Raman spectroscopy, our design is unique for measuring protein phosphorylated events in eukaryotic cells. Based on the optimized design, electric field intensities in the gap were estimated at 7.30 V/m.

Using surface-enhanced Raman spectroscopy (SERS), an electric field can be manipulated to map biochemical reactions in real time. The goal of this lab study will impact bio-photonics, material science, and electrical engineering fields by providing methods of Raman signal enhancement. This work involves use of nanoantennas, a nanoscale antenna like structures used for sending and transmitting electromagnetic waves. This project will present the optimization steps within the nanoantenna’s design. The team used computer simulation technology (CST) studio to perform electromagnetic simulations by modeling various bowtie nanoantenna geometries to obtain an optimized structure based on varying gap distances, side lengths, and layer thicknesses. These findings are then used to optimize bowtie nanoantenna designs. The presented CST simulations display trends producing a model of an optimized design. The design parameters that were varied are the side lengths of the nanoantennas ranging from 80-110 nanometers (nm), the gap distances between the nanoantenna pairs ranging from 20-40 nm, and the gold thickness layer ranging from 15-45 nm. We have chosen to use fixed wavelength input for our model that matches our own Raman instrument, a Jobin Yvon BX41 Confocal Raman microscope, which is equipped with a 532 nm excitation source. Results are displayed in a maximum volts/meter (V/m) calculation which is shown numerically and on a 3D phase plot. Using this data, the optimized design was found and is used to aid in biochemical reaction detection. In a brief description of our final design from CST simulation our lab found a 90nm side dimension followed by a 20nm gap distance with a 15nm gold thickness was the most optimized design.

The healthcare industry is moving towards personalized medicine and patients seek greater role in their care. In this paper we describe a proof of concept of versatile optical sensor that potentially can be used for in vivo detection of biological events. The developed sensor comprises of a silver thin film glass slide and gold nanoparticles (GNPs) and allows detection of chemical changes using surface plasmon resonance (SPR), local surface plasmon resonance (LSPR) and fluorescence lifetime detection modalities. A change in spectrum was observed after removal of GNPs by 2-mercaptoethanol. Moreover, GNP conjugated to fluorescein were tested using fluorescence lifetime microscopy (FLIM) to enhance sensing capabilities and provide additional dimension for detection. The sensor has the potential to provide real-time analyses of different biological molecules, such as antibody and antigen, receptor and ligand, and complementary DNA fragments.

We have investigated the excitation of fluoresce molecules using nanoscale light confinement on the plasmonic nanostructures. We have fabricated gold nano-dimer arrays whose diameter and height were 100 and 20 nm respectively on 20-nm gold film with BK7 substrate with a period of 746 nm. We have calculated the field distribution by three dimensional finite-difference time-domain (FDTD) method and confirmed the field localization on the dimer’s gap whose size was 18 nm. The field confinement was induced by a light source at 671 nm and experimentally measured by near-field scanning optical microscopy (NSOM) under same incident condition given at FDTD calculation. The angle of surface plasmon resonance (SPR) was chosen to enable both fluorescence microscopy and SPR microscopy simultaneously. Given a resonance angle, a dimer could provide a subdiffraction-limited observation volume to study the dynamics of fluorescence molecules and a highly sensitive light scattering probe as a nanoantenna. By employing dual microscopic images, we could separate the fluorescence excitations within a subdiffracion-limited volume from those outside the volume. We calculated scattering intensities of fluorescence nanobeads on the dimer nanoantenna to assure the presence within an observation volume when they diffuse near the dimer nanoantenna with Brownian motion. We have applied the subdiffraction-limited volume to fluorescence correlation spectroscopy (FCS) to measure the dynamics of fluorescence molecules with high signal-to-noise ratio, with additional spatial analysis from SPR microscopy. The result of imaging FCS using gold nano-dimer with SPR microscopy shows novel applications for nanoscale sensing and imaging methods.

Please see the full paper at: https://www.biorxiv.org/content/early/2018/04/11/261917 It's under review in Nat. Com.

Design of multifunctional nanoparticles for multimodal in-vivo imaging and advanced targeting to diseased single cells for massive parallel processing nanomedicine approaches requires careful overall design, including particle shape, and a multilayered approach to match the multi-step targeting required. In addition to thermodynamically driven self-assembly, complex patterns can be produced by micro-palette and 3D printing approaches. Initial core materials can include nanomaterials that simultaneously serve as x-ray contrast agents for CAT scan imaging as well as T1 or T2 contrast agents for MRI imaging. Use of superparamagnetic iron oxide allows for convenient magnetic manipulation during manufacturing re-positioning inside the body as well as single-cell hyperthermia therapies. To permit real-time fluorescence-image-guided surgery, fluorescence molecules can also be included. Advanced cell targeting can be achieved by attaching antibodies, peptides, aptamers, or other targeting molecules to the nanoparticle in a multilayered approach mimicking the multi-step targeting required. Addition of “stealth” molecules (e.g. PEG or chitosan) to the outer surfaces of the nanoparticles can permit greatly enhanced circulation times. Nanoscale imaging of these manufactured, multifunctional nanoparticles can be achieved either directly through superresolution microscopy or indirectly through single nanoparticle zeta-sizing or x-ray correlation microscopy. Since these multifunctional nanoparticles are best analyzed by technologies permitting analysis in aqueous environments, superresolution microscopy is, in most cases, the preferred method. This review paper will discuss the importance of specific design criteria as well as advantages and disadvantages of each approach. The overall design required a system engineering approach to the problem.

Bright and photo-stable luminescent nanoparticles held great potential for bioimaging, long-term molecular tracking. Rare-earth-doped upconversion nanoparticles (UCNPs) have been recently discovered with unique properties for Stimulated Emission Depletion (STED) super-resolution microscopy imaging. However, this system strictly requires optical alignment of concentric excitation and depletion beams, resulting in cost, stability, and complicity of the system. Taking the advantage of intermediate state saturation in UCNPs, emission saturation nanoscopy has been developed as a simplified modality by using a single doughnut excitation beam. In this work, we report that the emission saturation curve of fluorescence probes can modulate the performance of multi-photon emission saturation nanoscopy. With the precise synthesis of UCNPs, we demonstrate the resolution of this new imaging approach can be improved with five parameters, including emission band, activator doping, excitation power, sensitizer doping, core-shell. This approach opens a new strategy to a simple solution for super-resolution imaging and single molecule tracking at low cost, suggesting a large scope for materials science community to improve the performance of emission saturation nanoscopy.

Three major challenges in biological sensing and imaging systems are to improve sensitivity, resolution, and throughput. In this talk, I present results on using structures seeded or constructed by nanoparticles to provide enhancements in these three areas. We present our work in two parts. First, we have used vapor-deposited liquid nanoscale polyethylene glycol lenses to aid in sensing nanoscale particles that serve as seeds for these nanolenses. This approach is combined with lensfree holographic microscopy to image a transparent sample slide with adsorbed nanoparticles. Lensfree holographic microscopy provides an ultra-large field of view >20 mm^2 together with submicron resolution, however its sensitivity to nanoparticles is limited and particles smaller than ~300 nm cannot be inherently distinguished from background noise. The liquid nanolenses we deposit significantly enhance the sensitivity of this system such that >10^5 particles as small as 40 nm can be individually detected, localized, and sized. The second part of this talk focuses on using optical tweezers to assemble nanophotonic structures out of heterogeneous colloidal nanoparticles. The resulting structures can provide superresolution based on transmission line and metamaterial physical principles. Optically-positioned nanoparticles can also be attached to whispering gallery mode microresonators to enhance their sensitivity and facilitate free-space coupling. Finally, we have investigated the speed with which we can position nanoparticles using optical tweezers, and have measured maximum manipulation rates in excess of 150 um/s, which makes optical tweezers a viable approach for rapid prototyping additive manufacturing of nanophotonic structures.

By using virtual imaging through dielectric microspheres as well as through coverslips with embedded high-index microspheres, point-like nanoscale objects are imaged in two different configurations - without and with nanoplasmonic arrays. The nanoplasmonic arrays with various periods are used to provide structured illumination of fluorescent nanospheres and/or F-actin protein filaments. To study the nanoplasmonic contributions to the resolution of nanoscale structures, we investigated several combinations of spectral emission bands (blue, green fluorescent nanospheres) with various spectral positions of localized surface plasmonic resonances (LSPRs) in the Au and Al arrays located in close proximity to nanospheres. It is demonstrated that the resolution about λ/7, where λ is the emission wavelength, can be obtained under conditions of spectral overlap between the emission and LSPRs. We show that the microsphere-based imaging has a solid immersion lens-limited resolution, however use of short-period nanoplasmonic arrays allows reaching ~λ/7 resolution. The mechanism of the observed superresolution effects is related to efficient coupling of the object’s emission to diffraction orders of the nanoplasmonic array, resembling the basic physics of localized plasmonic structured illumination microscopy and far-field superlens. However, we show that neither postimaging processing nor all-optical hardware after superlens such as additional layers of metal with surface gratings are required in our approach.

In recent years, many quantum lights-based applications were suggested, ranging from encrypted communication and precision metrology to fluorescent biomolecules detection and advanced spectroscopy schemes. Such applications mostly rely on entanglement, the property of correlations between particles which cannot be explained by classical mechanisms, to overcome classical light limitations. Some of these applications, e.g. nonlinear spectroscopy, require the use of entangled-photon-pair interaction (EPPI) with the matter. However, such entangled pairs, generated through spontaneous parametric down-conversion (SPDC), are scarce, and multi-photon interaction with matter is usually very weak and barely detectable. Therefore, an enhancement of this interaction is needed. In our research, we investigate a novel way to achieve such enhanced EPPI using metallic nanoparticles (MNPs), which are known for their exceptional capability of light-matter coupling at their localized surface plasmon resonance (LSPR). We present a novel way of theoretically estimating the rate of EPPI with MNPs, based on a simple method of classical light second-harmonic generation (SHG) measurements. The theory is supported with experimental results, obtained for a solution of silver NPs (SNPs). These results show an estimated six orders-of-magnitude EPPI enhancement, relative to the best organic molecules, and indicate that the use of SNPs can be advantageous for realization of advanced quantum light applications.

Optical Feedback Imaging is the most recent advancement of the traditional Laser Self-Mixing. It is a coherent scanning imaging technique with the unique feature of having the light source acting also as the signal detector. Optical Feedback Imaging is being increasingly applied to both inorganic and organic samples, especially in the infrared and Terahertz spectral region. The technique relies on the analysis of the back-scattered (or reflected) radiation, thus it is contactless, detectorless and suited to be applied also in-vivo. As a coherent technique in reflection, it is sensitive to both phase (index) contrast and amplitude (absorption) contrast. We demonstrate selective contrast imaging of different organic pigments at three different visible wavelengths allowing for unambiguous identification of absorption features in back-scattering geometry. However, a wealth of information about the chemical composition of tissues is more readily available at mid-infrared wavelengths, where molecular bonds have their spectral signatures. We also present Optical Feedback images collected in organic (agar-agar) tissue phantoms at mid infrared wavelengths. 1% sensitivity to potato starch concentration included in the agar-agar matrix was detected at 6.26 μm, in resonance to the amide-I band.

Frequency domain analysis of time-resolved fluorescence measurements (TRFM) is an extremely rapid technique for medical diagnostics thanks to its unique sensitivity to a wide variety of physical and chemical features. Nevertheless, the determination of the underlying fluorescence lifetime (FLT) data of samples by their frequency response data (FRD), demands fitting algorithms. Therefore, the interpretation of the precise changes in the FLT of complex environments in term of biochemical processes is a challenge as it involves uncertainties associated with the chosen fitting algorithm. This research suggests a novel characterization procedure based on the squared distance (D²) between the FRD of the samples that avoid the inherent blurring caused by the transformation of the FRD into FLT data. The D² approach was validated through simulated data of 6 classes with similar FLT characteristics, where the accuracy of D² classification was about 96%. In addition, this approach was tested on experimental FRD from 43 individual samples that their preliminary physician diagnosis divided them into 4 groups: 5 healthy samples served as controls, 9 samples diagnosed with diverse types of bacteria, 16 samples diagnosed with diverse types of viruses and 13 samples were negatives to any bacterial or viral infection, although presenting related symptoms. Using the D² analysis, the classification of 28/30 matched the physician diagnosis and the classification of 41/43 samples matched earlier report. In conclusion, this work demonstrated that the D² model can aid in disease identification and increase the specificity and sensitivity of conventional medical procedures or TRFM-based diagnosis.

Prostate cancer is a heterogenous disease that has a varied range from indolent to highly aggressiveness. The routinely used biomarker, Prostate Specific Antigen (PSA), is controversial due to over-diagnosis. A new approach is urgently needed to discriminate the indolent and lethal prostate cancer. We report the measurements of patient urine using surface-enhancement Raman scattering (SERS) as a potential means of differentiating aggressive and indolent prostate cancer types. To this end, urine samples from twenty prostate cancer patients with known clinical outcome are investigated in this study, with ten in each of the two groups: aggressive and indolent. SERS measurements, ten for each sample, are carried out in blind without revealing any clinical details to the investigators. Principal component analysis (PCA) and linear discriminant analysis (LDA) are used to statistically analyze the large number of Raman spectra to identify and classify the specific Raman features potentially associated with aggressive and indolent prostate cancer types. The experimental classifications are compared with the clinical outcome of the prostate cancer patients to demonstration the potential of SERS as an alternative method for patient screening and decision-making for the optimal treatment strategy.

Porous silicon (PSi) has been recognized as an advantageous material for use in optical biosensors due to its large internal surface area, ability to form multilayer optical structures, and compatibility with standard silicon lithographic techniques. We demonstrate an order of magnitude improvement in small molecule detection sensitivity for on-chip PSi ring resonators and photonic crystal nanobeams compared to the same structures fabricated on silicon-on-insulator wafers. Moreover, we demonstrate that PSi optical structures can be exploited for mobile diagnostics by using a smartphone with no additional functional accessories to detect color changes in the PSi that result from molecule capture.

The development of multifunctional organic nanomaterials is extremely essential for their in vivo cancer theranostic applications. In this study, we report a new BDT-IID based conjugated polymer dots (Pdots) platform that can serve as multifunctional nanoprobes for photoacoustic (PA) imaging-guided photothermal therapy (PTT). The novel BDT-IID Pdots are readily fabricated though nanoreprecipitation and can absorb strongly in the near-infrared region (NIR, 650-700 nm). Furthermore, BDT-IID Pdots possess the stable nanostructure and extremely low biotoxicity. In particular, its photothermal conversion efficiency can be up to 45%. More importantly, our in vivo results exhibit that the BDT-IID Pdots are able to offer concurrently enhanced PA imaging signals and sufficient photothermal effect. Consequently, the BDT-IID Pdots can be exploited as a unique theranostic nanoplatform for PA imaging-guided PTT of tumors, holding great promise for their clinical translational development.

Photodynamic therapy (PDT) is a promising therapeutic modality for cancer treatment. It considered to be minimallyinvasive and nontoxic. Clinical PDT involves systemic administration of photosensitizer drugs, which accumulate at the tumor area and are light sensitive. When laser illuminates the tumor area in the presence of molecular oxygen, highly reactive singlet oxygen is generated, causing to direct killing of the tumor. Despite the advantages of the classical PDT, it suffers from several limitations, impeding its clinical outcome. Thus, developing targeted delivery systems for photosensitizer drugs that will enhance the selectivity is urgently needed. We develop functionalized metal nanoparticles (NPs) as carriers of mTHPC photosensitizer drug. Herein we use NPs composed of either gold or magnetically responsive carries like Ce-doped and Yb-doped -γ-Fe₂O₃ maghemite NPs (MNPs). All nanocomposites form a stable, soluble compound with improved penetration to cancerous tissues. Gold NPs are effective as contrast agents, and hence the AuNP-mTHPC complex can be used as a biomarker for imaging in vivo. MNPs are superparamagnetic, biocompatible and the resulting hybrid mTHPC-Ce-doped and mTHPC-Yb-doped MNPs can be magnetically attracted to the desired area. We examine all complexes efficiency in MDA-MB231 human breast cancer cells after inducing PDT irradiation for 1 hour and show a high death rate. We demonstrate that magnetic targeting with the use of magnetic based NPs enhance the accumulation of the therapeutic PDT drug in the tumor site. Currently, we develop methods to efficiently and selectively deliver drug complexes in vivo. Our approach is presenting an improved PDT therapy for treating cancer.

Isopathlength (IPL) point refers to a point on the surface of an air-bounding tissue where the intensity of diffuse reflectance light does not depend upon the reduced scattering coefficient of the tissue. IPL phenomenon serves as a self-calibration point because the intensity there is influenced by absorption regardless of the scattering and thus improves the accuracy of the optical property extraction. Using novel analytics for photon diffusion in small cylindrical domain, we assess the steady-state IPL points in three tissue geometries, including semi-infinite, concave-infinite-cylindrical, and convex-infinite-cylindrical for medical applications. The cylindrical geometries are assessed along the azimuthal and longitudinal directions.

Currently, gold nanorods (GNRs), with versatile optical behaviors, are in the immense study to achieve a variety of applications in the fields of diagnostics and therapy. Macrophages, the proficient phagocytic immune cells, mainly differentiated from monocytes, play a major role in our innate immunity. Depending on the state of a disease, an enhancement of local macrophage population occurs as a normal protective measure of our body. We want to monitor this increased level and use it as a prediction index of a disease. The advantage of working with macrophages is that they willingly internalize GNRs by phagocytosis. Now, the macrophages with GNRs can be identified by Flow Cytometric technique through the high scattering of GNRs. Moreover, the surface charge of GNRs can significantly change the uptake and cytotoxicity pattern of GNRs. Here we compared the uptake of GNRs, with different zeta potentials, among three different types of macrophages –macrophages isolated from the blood of a healthy donor; macrophages differentiated from THP1 human monocyte cell lines and RAW 264.7 murine macrophage cell line. GNRs with positive zeta i.e. cetyl trimethylammonium bromide (CTAB), poly allylamine hydrochloride (PAH) higher uptake than the GNRs with null zeta i.e. polyethylene glycol (PEG) or negatively charged surface i.e., poly sodium 4-styrenesulfonate (PSS) and citrate. Overall, this study showed an application of the scattering property of GNRs as a tool to identify macrophages and how modifications of the GNR surface monitor their uptake by macrophages.

We developed a time lens which is able to measure the full state of polarization as a function of time for single shot input signals. This is done by splitting the input signal into three copies and projecting each one on a different Stoke vector. In this proceeding, we present the experimental setup in details for measuring the different Stokes vectors.

Phase retrieval is an important field in communication systems, since detectors are generally able to measure intensity while the phase is lost. One of the most common phase retrieval methods is the Gerchberg-Saxton (GS). This algorithm uses two intensity images, while imposing the amplitudes known from the intensities and keeping the phase, the algorithm iteratively reconstructs the lost phase. It was demonstrated that by adding more intensity images, one increase the probability to converge to the correct reconstruction. Space time duality states that since spatial diffraction and temporal dispersion are described by similar equations, the same methodologies developed in space are applicable in time. Following this principle, temporal lenses where developed. Since temporal imaging systems suffer from the same phase loss, phase retrieval methods were applied in this field as well. However, as in space, accurate phase retrieval requires multiple intensity images. In this work, we propose a temporal phase retrieval methods based on Gerchberg-Saxton, where the multiple planes are measured by a timelens array. The temporal lens array is achieved using four-wave mixing interaction between a signal and a chirped pump wave, resulting in high temporal magnification. The proposed iterative phase reconstruction algorithm takes advantage of the overlap between nearby lenses, which improves the convergence. We demonstrate how increasing the number of planes improves the reconstruction. Furthermore, the use of shifted lenses, as opposed to several defocused images, has a practical advantage in regards to additional errors in the system.

Light-tissue interactions are commonly studied for near infra-red (NIR) spectroscopy for imaging and diagnosis. While imaging is bound to the surface due to the high tissue scattering, many diagnosis methods, such as the photoplethysmograph (PPG) and pulse oximeter, focus on sensing instead of imaging.

There are two approaches for the investigation of light-tissue interactions: one numerical and the other analytical. The most common numerical method is the Monte Carlo (MC) simulation, which is a statistical study of photon migration from the optical properties of the different tissue regions. However, the yield of such statistical approaches is limited. Analytical methods are commonly based on the diffusion theory, yet they are inaccurate near the light source. There are several solution methods, where extrapolated boundary conditions lead to a more accurate solution.

Previously, we proposed measuring the full scattering profile (FSP), which is the angular intensity distribution, of cylindrical tissues. MC simulations revealed that the FSP has a fixed intensity point, named the iso-pathlength (IPL) point, which does not depend on the reduced scattering coefficient. The location of this point depends solely on the geometry. In this study, we derived the FSP from the steady state diffusion theory based on the extrapolated zeroboundary condition. A comparison of different reduced scattering coefficients revealed the IPL point, where the intensity remains constant. Furthermore, a MC simulation was performed under the same geometry and optical properties. We show that the position of the IPL according to the diffusion theory is in agreement with the MC simulation.

Nanomaterials functionalized with glucose have shown a great potential in cancer diagnosis and treatment. We have recently demonstrated that gold nanoparticles (GNP), functionalized with glucose, can be used for specific and sensitive tumor detection when combined with computed tomography (CT) - GNP functionalized with glucose in the second carbon position were used as a metabolically targeted contrast agents, and were able to discriminate between cancer and inflammation, which is a superior ability when comparing the FDG-PET which is not tumor specific. Here we aim to understand the uptake mechanisms of the glucose functionalized GNP using a comprehensive in vitro study in several cell types with different metabolic features, and examining the glucose transporter-1 (GLUT1) involvement in the uptake process. We found that the glucose functionalized GNP are not toxic to the cells in the tested concentrations and we demonstrate that the cellular uptake of GNP, when functionalized with glucose in the second carbon position, strongly depends on GLUT1 expression in the cells, which triggers clathrin-mediated endocytosis of the nanoparticles. This study can promote control and development of glucose-functionalized nanoparticles for many biological applications.

A major challenge for treatment of neurodegenerative disorders is the need to overcome the restrictive mechanism of the blood-brain-barrier (BBB) for delivery of therapeutic agents into the brain. Our goal was to develop an efficient nanoparticle-based system with the ability to bypass the BBB by targeting insulin receptors. We demonstrate that insulincoated gold-nanoparticles (INS-GNPs) can serve as an effective endogenous BBB transport system for delivering therapeutics into the brain. We further conducted a quantitative in-vivo investigation of the effect of nanoparticle size (20, 50 and 70nm) on the ability of INS-GNPs to cross the BBB. The most widespread bio-distribution and highest accumulation within the brain (5% of the injected dose) was observed using 20nm INS-GNPs, two hours post-injection. In-vivo CT imaging revealed that particles migrated to specific brain regions, rich in insulin receptors, which are important targets for the treatment of various neurodegenerative disorders. The findings described herein suggest the potential beneficial use of INS-GNPs as nano-vehicles for the transport of drugs through the BBB.

We developed novel fiber microknots which are designed for high order mode beams traveling in the fiber. The device is based on long period fiber gratings which excite high order modes in tapered fiber and a microknot which is fabricated on the tapered fiber. Thus, the light that resonates in the microknot is propagating in the tapered fiber in high order modes which have higher coupling to the environment. The light which exits the microknot and continue to propagate in the fiber is then exited back to the Gaussian mode by another long period fiber grating before the fiber returns to be a single mode fiber. We found that the spectral response of these microknots have deeper resonances and improved Q-factor.

In this work, we exploited time-resolved fluorescence polarization anisotropy (TRFA) to characterize un-doped and doped carbon dots (CDs). The rotational correlation time related to the size of the particle through classical Stokes-Einstein -Debye equation. The TRFA technique applied in this study achieves picoseconds time resolution, which approximately corresponds to the particle size determination at sub-nanometer precision. The calculated diameter of the CDs from the measured depolarization time constants in aqueous solution is well matches with the actual size of the CDs within the precision. This study proves that the TRFA method is highly complementary with other size determination techniques.