This PDF file contains the front matter associated with SPIE Proceedings Volume 8812, including the Title Page, Copyright information, Table of Contents, Invited Panel Discussion, and Conference Committee listing.

We demonstrated the direct and noninvasive imaging of functional neurons by Ionic Contrast Terahertz (ICT) near-field microscopy. This technique provides quantitative measurements of ionic concentrations in both the intracellular and extracellular compartments and opens the way to direct noninvasive imaging of neurons during electrical, toxin, or thermal stresses. Furthermore, neuronal activity results from both a precise control of transient variations in ionic conductance and a much less studied water exchange between the extracellular matrix and the intraaxonal compartment. The developed ICT technique associated with a full three-dimensional simulation of the axon-aperture near-field system allows a precise measurement of the axon geometry and therefore the direct visualization of neuron swelling induced by temperature change or neurotoxin poisoning. We also developed Terahertz Attenuated Total Reflection (ATR) devices perfectly suited for studying cell layers. Inserted in a terahertz time-domain system, and using a high resistivity low loss silicon prism to couple the terahertz wave into the sample, the detection scheme is based on the relative differential spectral phase of two orthogonal polarizations. Biological sample imaging as well as subwavelength (λ/16) longitudinal resolution are demonstrated.

This paper describes the preparation of semiconducting polymer dots (Pdots) and their application for single-molecule imaging and biosensing. The Pdots possessed high fluorescence brightness, with a 16 nm Pdot being ~9 times brighter than 13 nm Quantum Dots (Qdots). The surface of Pdots was successfully conjugated with streptavidin, which made Pdots suitable for specific subcellular labeling and targeting. The interior composition of Pdots was also successfully modified, through which the Pdots obtained additional functionalities. We demonstrated the utility of gold nanoparticle embedded Pdots in dual-modality imaging. We also demonstrated that Rhodamine B embedded Pdots were able to function as ratiometric temperature sensor in live-cell imaging mode.

An electro-active platform based on a single-mode integrated optical waveguide over-coated with a 13-nm indium tin oxide film was developed for highly sensitive investigations on the kinetics of redox reactions from a sub-monolayer of cytochrome-c proteins. Optical impedance spectra (with and without cytochrome-c proteins present in the spectroelectrochemical flow-cell) were measured with the single-mode integrated optical waveguide for a 10-mV ac electric potential modulation. Significant changes in the ac component of the optical baseline response were observed, and a new analysis was developed to factor out the working electrode effects and deliver accurate results for the Faradaic process. Faradaic current density and active surface coverage were reconstructed at several modulation frequencies. As small as 7x10^-14 mole/cm² of cytochrome-c proteins were detected under such electric potential modulation leading to a faradaic current of about 200 nA/cm². Such level of faradaic current is extremely difficult to be isolated by other electrochemical techniques (e.g. electrical impedance measurements) due to the strong background created by an always present electric double layer. We were able to achieve those detection limits because the optical signal is immune to those events and can be tuned solely to the Faradaic process. This highly sensitive and accurate strategy of spectro-electrochemistry is proved powerful for measurements of extreme small amount of electro-active proteins and has the potential to be used in many other important electrochemical processes.

Although bio-detection strategies have significantly evolved in the past decade, they still suffer from many disadvantages. For one, current approaches still require confirmation of pathogen viability by culture, which is the ‘gold-standard’ method, and can take several days to result. Second, current methods typically target protein and nucleic acid signatures and cannot be applied to other biochemical categories of biomarkers (e.g.; lipidated sugars). Lipidated sugars (e.g.; lipopolysaccharide, lipoarabinomannan) are bacterial virulence factors that are significant to pathogenicity. Herein, we present two different optical strategies for biodetection to address these two limitations. We have exploited bacterial iron sequestration mechanisms to develop a simple, specific assay for the selective detection of viable bacteria, without the need for culture. We are currently working on the use of this technology for the differential detection of two different bacteria, using siderophores. Second, we have developed a novel strategy termed ‘membrane insertion’ for the detection of amphiphilic biomarkers (e.g. lipidated glycans) that cannot be detected by conventional approaches. We have extended this technology to the detection of small molecule amphiphilic virulence factors, such as phenolic glycolipid-1 from leprosy, which could not be directly detected before. Together, these strategies address two critical limitations in current biodetection approaches. We are currently working on the optimization of these methods, and their extension to real-world clinical samples.

Current treatment of a number of orthopaedic conditions, for example fractures, bone infection, joint replacement and bone cancers, could be improved if mechanical support could be combined with drug delivery. A very challenging example is that of infection following joint replacement, which is very difficult to treat, can require multiple surgeries and compromises both the implant and the patient’s wellbeing. An implant capable of providing appropriate biomechanics and releasing drugs/proteins locally might ensure improved healing of the traumatized bone. We propose fabrication of nanoengineered titanium bone implants using bioinert titanium wires in order to achieve this goal. Titanium in the form of flat foils and wires were modified by fabrication of titania nanotubes (TNTs), which are hollow self-ordered cylindrical tubes capable of accommodating substantial drug amounts and releasing them locally. To further control the release of drug to over a period of months, a thin layer of biodegradable polymer PLGA poly(lactic-coglycolic acid) was coated onto the drug loaded TNTs. This delayed release of drug and additionally the polymer enhanced bone cell adhesion and proliferation.

In reproductive medicine it is important to determine the quality of embryo development without interference in their function and viability. The surface plasmon resonance of silver nanoparticles makes them promising candidates for optical sensing, molecular labeling and imaging applications. Furthermore unique optical properties of silver nanoparticles provide an opportunity to use them as real time analytic tools in living state especially for observation of dynamic processes in gametes and embryos. The main aim of the study was to investigate the physicochemical properties and biological activities of novel silver nanoparticles with prospect of their use for the determining the quality of embryo development. For this purpose, we investigated the optical properties of new silver nanoparticles in biological mediums during cultivation and their influence on rabbit’s embryos development in vitro. The physicochemical and biological properties of novel silver nanoparticles were compared with silver nanoparticles identical in size and shapes but with different chemical surfaces modifications by polyvinylpyrrolidone and bovine serum albumin. The results suggest that silver nanoparticles with hyaluronic acid were disintegrated with the formation of new complexes with proteins in biological mediums. This property with strong optical surface plasmon resonance of novel silver nanoparticles with hyaluronan makes them promising candidates in diagnostic area and gives reasons to explore them as biomarkers of target molecules. Nevertheless novel silver nanoparticles with hyaluronan at the concentrations of 0.1-1 μg/ml have no toxic effect on rabbit’s embryos development and can be successfully applied in reproductive medicine.

Ultra small scale implants have gained lots of importance for both acute and chronic applications. Optical techniques hold the key to miniaturizing these devices to long sought sub-mm scale. This will lead towards long term use of these devices for medically relevant applications. It can also allow using multiple of these devices at the same time and forming a true body area network of sensors. In this paper, we present optical power transfer to such devices and the techniques to harness this power for different applications, for example high voltage or high current applications. We also present methods for wireless data transfer from such implants.

Up/down regulation of microRNA panels has been correlated to cardiovascular diseases and cancer. Frequent miRNA profiling at home can hence allow early cancer diagnosis and home-use chronic disease monitoring, thus reducing both mortality rate and healthcare cost. However, lifetime of miRNAs is less than 1 hour without preservation and their concentrations range from pM to mM. Despite rapid progress in the last decade, modern nucleic acid analysis methods still do not allow personalized miRNA profiling---Real-time PCR and DNA micro-array both require elaborate miRNA preservation steps and expensive equipment and nano pore sensors cannot selectively quantify a large panel with a large dynamic range. We report a novel and low-cost optical fiber sensing platform, which has the potential to profile a panel of miRNA with simple LED light sources and detectors. The individual tips of an optical imaging fiber bundle (mm in diameter with 7000 fiber cores) were etched into cones with 10 nm radius of curvature and coated with Au. FRET (Forster Resonant Energy Transfer) hairpin oligo probes, with the loop complementary to a specific miRNA that can release the hairpin, were functionalized onto the conic tips. Exciting light in the optical fiber waveguide is optimally coupled to surface plasmonics on the gold surface, which then converges to the conic tips with two orders of magnitude enhancement in intensity. Unlike nanoparticle plasmonics, tip plasmonics can be excited over a large band width and hence the plasmonic enhanced fluorescence signal of the FRET reporter is also focused towards the tip--- and is further enhanced with the periodic resonant grid of the fiber array which gives rise to pronounced standing wave interference patterns. Multiplexing is realized by functionalizing different probes onto one fiber bundle using a photoactivation process.

An integrated hybrid waveguide coupled long range surface plasmon polaritons (LRSPPs) biosensor is proposed and analyzed by the Finite Element Method (FEM). The influence of the structural parameters on the coupling between the dielectric waveguide (DWG) and LRSPPs modes are numerically investigated. Simulation results show that the resonant coupling wavelength between the DWG and LRSPPs modes is very sensitive to small refractive index changes i.e. the estimated sensitivity is as high as 4180 nm/RIU (refractive index unit). Furthermore, when operating in intensity interrogation, its detection of limit has been shown as small as 3.7 x 10^-7 RIU.

Using silicon based microfabrication and materials we have developed a photonic platform capable of single bioparticle analysis. This platform combines liquid and hollow core waveguides on the micron-scale (5 μm x 12 μm) to isolate femtoliter sized sample volumes. Fluorescence excitation and signals in the visible range are directed into and out of the sample volume at an orthogonal angle to maximize signal-to-noise. This paper reveals the development path of these structures over several device generations including innovations in material, geometries, and fabrication techniques to increase detection sensitivity.

The study of carbon nanostructures is a highly topical branch of bionanotechnology because of their potential application in biomedicine. Carbon nanotubes (CNTs) are known for their ability to kill tumor cells causing hyperthermia shock and can be used in photothermal therapy respectively. Also chemically modified CNTs can be used for drug delivery. The needle-like shape of CNTs allows them to penetrate into the cell plasma membrane without killing the cell. C60 fullerenes are regarded as valuable nanocarriers for different hydrophobic molecules as well as potential antiviral agents or photosensitizers. In our previous studies we have demonstrated that all types of carbon nanoparticles cause externalization of phosphatidylserine (PS) from the inner to the outer layer of the cell membrane in the small local patches (points of contact), leaving the other parts of plasma membrane PS-negative. In the current work there were studied the interactions of pristine C60 fullerenes and different types of CNTs with human blood cells (erythrocytes and Jurkat T-cells). We have shown, that carbon nanoparticles do not have any hemolytic effects, if judged by the dynamics of acidic hemolysis, although they are capable of permeabilizating the cells and facilitating the internalization of propidium iodide into the nuclei.

The optical model of polycrystalline networks of blood plasma proteins is suggested. The results of investigating the interrelation between the values of correlation (correlation area, asymmetry coefficient and autocorrelation function excess) and fractal (dispersion of logarithmic dependencies of power spectra) parameters are presented. They characterize the coordinate distributions of Mueller-matrixes elements of blood plasma smears and pathological state of the organism. The diagnostic criteria of breast cancer nascency are determined.

The model of laser polarization fluorescence of biological tissues considering the mechanisms of optically anisotropic absorption – linear and circular dichroism of protein networks was suggested.Muellermatrix rotation invariants characterizing polarization manifestations of laser fluorescence are determined.The interconnections between the statistical, correlation and fractal parameters characterizing the Mueller-matrix images of laser polarization fluorescence and the peculiarities of the mechanisms of optically anisotropic absorption of histological sections of uterus wall biopsy were found. Effectiveness of the method of azimuthinvariant Mueller-matrix mapping of laser polarization fluorescence of protein networks in the task of differentiation of benign and malignant tumors of uterus wall was demonstrated.

An extremely sensitive fluorescent sensor based on a phenylboronic acid monolayer was developed for detecting saccharide molecules. The fluorescent sensor was prepared by assembling a monolayer of 4-mercaptophenylboronic acid (4-MPBA) onto a gold-coated compact disk. The change in the fluorescence of the 4-MPBA monolayer was extremely obvious in basic methanolic buffer containing monosaccharides down to the picomolar level. The fluorescence spectra demonstrated that the 4-MPBA monolayer was sensitive to monosaccharides and disaccharides, and the affinity of the monolayer toward saccharides was in the order of glucose < fructose < mannose < galactose < maltose > lactose > sucrose. Additionally, the fluorescence intensity of 4-MPBA monolayer was restorable after cleaning with weak acid, indicating that the reported fluorescent sensor with the detection limit of glucose down to the picomolar level is reusable for sensing saccharides.