Multi-layered liposomes, comprising a concentric series of lipid bilayers – separated at fixed distances and compartmentalizing aqueous solutions of alternating refractive indices – are proposed as optical Bragg resonators.
Seminal work focuses on the feasibility of successive encapsulations coupled with size-control via extrusion. Synthesis
criteria for realization of these liposomes were subsequently discussed based on experimental observations. Numerical
studies of the proposed structure showed discernible band gaps, qualifying their potential application in biological lasing.
Butterflies are one of the most colorful creatures in animal Kingdom. Wings of the male butterfly are brilliantly colored to
attract females. Color of the wings plays an important role in camouflage. Study of structural colors in case of insects and
butterflies are important for their biomimic and biophotonic applications. Structural color is the color which is produced by
physical structures and their interaction with light.
Paris Peacock or Papilio paris butterfly belongs to the family Papilionidae. The basis of structural color of this butterfly is
investigated in the present study. The upper surface of the wings in this butterfly is covered with blue, green and brown
colored scales. Nano-architecture of these scales was investigated with scanning electron microscope (SEM) and
environmental scanning electron microscope (ESEM). Photomicrographs were analyzed using image analysis software.
Goniometric color or iridescence in blue and green colored scales of this butterfly was observed and studied with the help of
gonio spectrophotometer in the visible range. No iridescence was observed in brown colored scales of the butterfly. Hues of
the blue and green color were measured with spectrophotometer and were correlated with nano-architecture of the wing.
Results of electron microscopy and reflection spectroscopy are used to explain the iridescent nature of blue and green scales.
Sinusoidal grating like structures of these scales were prominently seen in the blue scales. It is possible that the structure of
these wings can act as a template for the fabrication of sinusoidal gratings using nano-imprint technology.
Optical detection and imaging have wide applications in biomedicine and biological and chemical analyses. With
continuing miniaturization effort to realize integrated microsystems, micro-scale optical components become more and
more important. For any optical system, lenses are critical elements. In this paper, I will present our work on liquid
microlenses. I will first introduce a few types of microlenses and microlens arrays, including tunable liquid microlenses
actuated by temperature-, pH- and infrared light-responsive hydrogels. Then, I will discuss about potential applications
of these lenses in medical instruments. I will describe miniaturized cameras capable of multiple viewpoints, and
prototype flexible endoscopes implementing infrared-light responsive liquid microlenses at their distal ends.
A biomimetic polydopamine (PD)-based strategy was employed for presenting antibodies on gold nanorods (NRs) to target cancer cells for photothermal therapy. PD was polymerized onto NRs, and epidermal growth factor receptor antibodies (anti-EGFR) were immobilized onto the layer. Anti-EGFR-PD-NRs specifically bound to EGFRoverexpressing cells as quantified by optical coherence tomography, and illumination enhanced cell death compared to non-irradiated or antibody-free controls.
Enzyme-linked immunosorbent assays (ELISA) are the most popular immunoassay techniques performed every day in
hospitals and laboratories and they are used as a diagnostic tool in medicine and plant pathology, as well as a qualitycontrol check in various industries. However, complex labeling techniques are required to be able to perform the assay and non-specific binding and endpoint timing are difficult to optimize. These issues could be solved by label-free techniques such as silicon nanophotonic microring resonator sensors, but this platform requires complex microfluidics, which is very much removed from the daily practice in e.g. hospital labs, which still relies to a large degree on platforms like 96-well microtiter plates or reaction tubes. To address these issues, here, we propose the combination of a simple and compatible reaction tube platform with label free silicon-on-insulator (SOI) photonic biosensors, where the flow is through the sensor chip as opposed to over the chip as in more conventional approaches. This device allows real time detection and analysis. Its great flexibility and small footprint make it ideal for an easy handling in any laboratory.
X-ray mammography is the current gold standard for breast cancer screening. Microcalcifications and other features
which are helpful to the radiologist for early diagnostics are often buried in the noise generated by the surrounding
dense tissue. So image processing techniques are required to enhance these important features to improve the
sensitivity of detection. An innovative technique is demonstrated for recording a hologram of the mammogram. It is
recorded on a thin polymer film of Bacteriorhodopsin (bR) as photo induced isomerization grating containing the
interference pattern between the object beam containing the Fourier spatial frequency components of the
mammogram and a reference beam. The hologram contains all the enhanced features of the mammogram. A significant innovation of the technique is that the enhanced components in the processed image can be viewed by the
radiologist in time scale. A technician can record the movie and when the radiologist looks at the movie at his
convenience, freezing the frame as and when desired, he would see the microcalcifications as the brightest and last
long in time. He would also observe lesions with intensity decreasing as their size increases. The same bR film can
be used repeatedly for recording holograms with different mammograms. The technique is versatile and a different
frequency band can be chosen to be optimized by changing the reference beam intensity. The experimental
arrangement can be used for mammograms in screen film or digital format.
Continuous glucose detection has a great significance for diabetics. On the one hand, it can fully reflect the patient blood glucose change level. On the other hand, it can better guide the insulin dosage, and achieve closed-loop control of insulin pump. A continuous detection method of glucose concentration by borate polymer fluorescent indicator is proposed in the paper. The principle of this method is based on the competing reaction between alizarin, glucose and borate polymer. The borate polymer has high specific reaction with glucose, meanwhile reacts with non fluorescent alizarin. The product of the reaction between borate polymer and alizarin is fluorescent, called as fluorescent indicator. When glucose was introduced, the glucose molecules could react with the borate polymer in fluorescent indicator because of the high specificity. This competing process leads to the decomposition of fluorescent indicator into the non-fluorescent alizarin, and the fluorescent intensity gets loss. Therefore, the change of fluorescent intensity can reflect the glucose concentration level. In this method, the fluorescent indicator can well identify the glucose molecules. According to the experiment, we know that there is a high specific and good linear reaction between glucose and borate polymer. The linear fitting is up to 0.97 and the detection limitation can reach to 10 mg/dL. The fluorescent intensity reaches strongest with the optimal proportion of alizarin: borate polymer as 1:3. The reaction of the fluorescent indicator identifying glucose molecules has a good linear relationship, the linear fitting of which can reach to 0.98. The detection limitation can reach to 30 mg/dL, which fulfills the detection
requirements of glucose concentration in vivo.
Diatoms are a group of single-celled photosynthetic algae that make skeletal shells of hydrated amorphous silica, called
frustules, which possess hierarchical nanoscale photonic crystal features made by a bottom-up approach at ambient
temperature and pressure. In this paper, we theoretically investigate electric field enhancements of plasmonic
nanoparticles coated on the surface of diatom skeletal shells. Surface-Enhanced Raman Scattering substrates are
prepared by evaporating 10 nm thick silver film and self-assembling silver nanoparticles on diatom surfaces, which show
significantly better SERS signals than silver nanoparticles on flat glass substrates.
In this paper we report a novel hydrogel functionalized optical Fiber Bragg Grating (FBG) sensor based on chemo-mechanical-
optical sensing, and demonstrate its specific application in pH activated process monitoring. The sensing
mechanism is based on the stress due to ion diffusion and polymer phase transition which produce strain in the FBG.
This results in shift in the Bragg wavelength which is detected by an interrogator system. A simple dip coating method to
coat a thin layer of hydrogel on the FBG has been established. The gel consists of sodium alginate and calcium chloride.
Gel formation is observed in real-time by continuously monitoring the Bragg wavelength shift. We have demonstrated
pH sensing in the range of pH of 2 to 10. Another interesting phenomenon is observed by swelling and deswelling of
FBG functionalized with hydrogel by a sequence of alternate dipping between acidic and base solutions. It is observed
that the Bragg wavelength undergoes reversible and repeatable pH dependent switching.