Near infrared light has been used for the determination of blood oxygenation in the brain but little attention has been paid to the fact that the states of blood oxygenation in arteries, veins, and capillaries differ substantially. In this study, Monte Carlo simulations for a heterogeneous system were conducted, and near infrared time-resolved reflectance measurements were performed on a heterogeneous tissue phantom model. The model was made of a solid polyester resin, which simulates the tissue background. A network of tubes was distributed uniformly through the resin to simulate the blood vessels. The time-resolved reflectance spectra were taken with different absorbing solutions filled in the network. Based on the simulation and experimental results, we investigated the dependence of the absorption coefficient obtained from the heterogeneous system on the absorption of the actual absorbing solution filled in the tubes. We show that light absorption by the brain should result from the combination of blood and blood-free tissue background.

The possibility of measuring the blood oxygenation in the brain with near infrared light has been studied. The goal of this study was to quantify the influence of different brain layers on brain blood oxygenation measurements. Experimental results obtained from time resolved reflectance measurements on layered tissue phantoms were compared to Monte Carlo simulations of layered models, diffusion theory, and in vivo measurements on the human head. Both the experimental results and simulations show that the absorption coefficient (mu) _a, which is closely related to the blood oxygenation, of deeper layers can be accessed in the time domain. Thus fitting analytical expressions found from diffusion theory only to the late part of the time resolved reflectance allows us to determine (mu) _a and subsequently the blood oxygenation of the deepest medium (e.g. brain tissue).

The problem of spatial localization of a near-infrared (NIR) light absorber in turbid media is approached using continuous wave (CW) laser diode sources. The excitation and backscattered light are fiber optic guided. It is a preliminary study for the development of simple and portable optical instrumentation concerning quantitative non invasive oxymetry. A stable, not expensive, well defined and reproducibile phantom to test the performances of NIR spectroscopy instrumentation is presented. lntralipid solution is used as turbid medium. The concentration of Intralipid is chosen to match the "in-vivo" optical coefficients. The size distribution of scattering particle are actually determined by a laser light-scattering analyzer. A moving absorber driven by a micrometer positioning system is placed inside the turbid medium. A NIR CW laser diode oxymeter with fiber optic probe is tested with the system. Several measurements are presented at differem source-detector distances, absorber positions and lntralipid concentrations. The maximum inspection depth (MID) is defined and measured for the instrument under test.

A new method for morphodensitometric analysis of blood cells was applied for medically screening some ecological influence and infection pathologies. A complex algorithm of computational image processing was created for supra molecular restructurings of interphase chromatin of lymphocytes research. It includes specific methods of staining and unifies different quantitative analysis methods. Our experience with the use of a television image analyzer in cytological and immunological studies made it possible to carry out some research in morphometric analysis of chromatin structure in interphase lymphocyte nuclei in genetic and virus pathologies. In our study to characterize lymphocytes as an image-forming system by a rigorous mathematical description we used an approach involving contaminant evaluation of the topography of chromatin network intact and victims' lymphocytes. It is also possible to digitize data, which revealed significant distinctions between control and experiment. The method allows us to observe the minute structural changes in chromatin, especially eu- and hetero-chromatin that were previously studied by genetics only in chromosomes.

A novel biodosimetry method based on red blood cell analysis by means of laser flow cytometry and specially designed monoclonal antibodies is used for reconstructing ionizing radiation doses for Chernobyl accident victims. In addition to analysis of the patient's blood samples, we are evaluating both spectroscopy procedures and laser-based flow techniques. It was shown that resonance energy transfer processes can take place among the two different dyes links to the spherical cell surface. This can affect the accuracy of rare mutant cell scoring. Also a new technique providing conventional flow cytometric analysis and kinetic measurements of the elementary stages of biochemical reactions is described.

Laser Doppler perfusion monitoring is a method of assessing tissue perfusion based on measurements performed using Doppler broadening of monochromatic light scattered in moving blood cells. Ever since laser Doppler perfusion monitors became available about 15 years ago they have been used in numerous applications in both clinical and laboratory settings. The high spatial resolution has in practice manifested itself as one of the main limitations of the method. The reason for this is the difficulty in attaining reproducible values at successive measurement sites because most skin tissue possesses a substantial variation in blood flow even at adjacent measurement sites. In order to overcome this difficulty the laser Doppler perfusion imager was developed. In this camera-like device, the laser beam successively scans the tissue and the Doppler components of the backscattered light are detected by a remote photodiode. After a scanning procedure is complete, a color-coded perfusion map showing the spatial variation of skin blood flow is displayed on a monitor. The operating principle and early applications of this emerging technology are addressed in further detail.

Laser Doppler measurements of blood flow velocities in the vessels of rat mesentery have been performed to study the effect of the drag-reducing agent polyethylene oxide Polyox WSR-301 on microcirculation. These agents are capable of increasing the cardiac output and decreasing the arterial pressure. Measurements performed on spontaneously hypertensive rats anesthetized by Nembutal showed that the mean blood velocities in all groups of studied vessels are higher (by nearly two to three times) as compared to those in controls. Most likely these results reflect the effects of hypertensive raising pressure drop and the `rarefaction' phenomenon.

Theoretical investigations into the processes of focused Gaussian beam diffraction in blood capillaries with a diameter about erythrocyte size have been carried out. A correlation function of dynamic speckles formed in this case has been analyzed.

A new bioanalytical concept that uses the characteristic fluorescence lifetimes of new multiplex dyes as an identification parameter is presented. Several dyes can be distinguished at the same wavelength by recognition of the fluorescence lifetimes. It is shown that the identification can be achieved in a capillary gel electrophoresis system in a few milliseconds with a misclassification rate of 10^-4. As an example the simultaneous detection of two antibodies at one wavelength is presented.

A light scattering technique is presented which investigates the backscattered and transmitted flux of He-Ne laser light illuminating a concentrated suspension of red blood cells (RBC) submitted to a simple shear flow. Our experiments show that the angular distributions of scattered light are closely related to the state of the suspension (at rest, or submitted to a simple shear flow) and the rheological parameters of the suspension such as viscosity and volume concentration. Transmitted and reflected light measurements demonstrated reproducible and predictable changes in scattering cross sections of oriented and deformed RBCs by shear flow. Additionally, it is shown that the scattering cross-section of aggregated RBCs is different from disaggregated RBCs. A theoretical model, substantiated by Monte- Carlo simulations, is proposed which relates the changes in shape of the angular distribution of scattered light to the rate of aggregation and the gradients of deformation of RBCs.

Changes in aggregability and/or deformability of red blood cells (RBC) can cause severe complications in blood circulation. We use a laser light scattering technique, which can distinguish between normal and pathological RBCs by studying the angular distributions of backscattered and transmitted light of concentrated suspensions of RBCs submitted to a simple shear flow. In order to study the deformation, we induced partial rigidity in the RBC membrane, and showed that the gradients of deformation and the relaxation times of normal and partially rigidified RBC membranes can be quantified using a non-Newtonian rheological model. We observe that blood aggregation of patients with `microcirculatory' diseases, such as diabetes, differs from that of healthy individuals.

The elongation curve of RBC as determined by rheoscopy or ektacytometry (laser diffraction) resembles a rectangular hyperbola. The experimental data obtained so far included too large errors of measurement to allow precise mathematical description. The combination of laser diffraction with image analysis has improved ektacytometry considerably, such that the error of measurement is reduced to less than 0.5%. In laminar flow RBC of healthy donors are elongated elliptically (p <EQ 0.001). Using the precise data of elliptical deformation, the elongation curve can be described to be hyperbolic. Hence, the double reciprocal plot gives a linear curve which -- over a wide range of shear stress (15 to 500 dyn/cm²) -- fits well the experimental data (r >= 0.99: p <EQ 0.001). The stress strain characteristics (i.e. elongation curve) can be described by two parameters: maximum elongation (E_max) and the shear stress needed for half-maximum elongation (K_E).

It is well known that the hemorheological disturbances play an important role in the pathogenesis of many diseases. Rheological methods, aggregometry in particular, are efficient in the study of the role of the erythrocytes in the hemorheological disturbances. Wide application of aggregometry is limited because of the absence of the standard methods and devices. It should be noted that the generally accepted correlation between the aggregation state of blood and the variation of the light scattering intensity is not at all clear. We have worked out a system of informative parameters which can be distinguished when registering the backscattered light and use it for the microrheological diagnostics. In this paper we report on the application of the aggregometry method for the diagnostics of many diseases and present the statistically treated parameters of the erythrocytes aggregation.

Laser cytodiffractometry which allows to analyse the shape of erythrocytes being in the nontensed conditions was used to objectivise the results of the technique application in treatment. Quantitative parameters of the physiological solution motion in cytodiffractometer pipeline are giv~n in this paper. The reasons of erythrocyte cytoplasm spiral mode motion are discussed. The oscillations of diffraction minimum formed by the spinning erythrocytes are explained. The results of the experiment with an air bubble, attached to the cuvette walls, are represented. The investigations of erythrocytes concentration increase and the possibility of the erythrocytes magnetic moment analysis as well as its clinical significance are discussed. It is proved that the diffraction ellipse eccentricity reflect the erythrocyte membrane deformation not by shear stress, as the inventors of the device said, but by intracellular osmotic pressure (increased as a cause of an acute decease). The investigation of the wattertunneling through the erythrocyte membrane kinetics is proposed. The results of the low energy laser treatment fundamental mechanismes investigations are given. Detecting of threshold dose of treating physical influence on blood is given. The information about the measuring the amplitude-frequency characteristics of erythrocytes is represented. The fundamental investigations, using this device, are proposed.

A novel D-glucose 6-phosphate (G6P) assay is described that exploits the technique of substrate induced quenching. In a reaction between G6P and glucose 6-phosphate dehydrogenase (G6P-DH) the cofactor nicotinamide adenine dinucleotide (NAD⁺) is reduced to NADH. The latter being a quencher of thionine allows an indirect determination of the G6P concentration. A Stern-Volmer type analysis of the data for the investigated range of 0 - 1 mM G6P results in a quenching constant of 439 (+/- 37) M^-1, with a detection limit of 9 (mu) M. A simple empirical model based on enzyme kinetics is presented for the overall G6P assay. Excellent correlation exists between the results predicted by the model and those obtained experimentally. Possibilities of employing the proposed G6P SIQ assay in multi-enzyme assays and in the construction of immunoassays is discussed.

Glycerol concentrations are measured using a novel photo reaction between an excited fluorophore and NADH, the latter being generated due to the reduction of NAD⁺ in an enzymatic reaction between glycerol dehydrogenase (GlDH) and glycerol. The results are treated using a modified Stern-Volmer type relation and at equilibrium, a SIQ quenching constant of 9.78 (+/- 2.05) M^-1 is obtained for the substrate induced quenching of thionine by glycerol. The reported method was investigated over the glycerol concentration range of 0 - 100 mM and offers a detection limit of 0.4 mM.

In the course of experimental examination of the blood circulation in the eye retina with use of laser Doppler anemometers (LDA) laser radiation is scattered both by the blood flow and optically inhomogeneous tissues. In this paper we consider the effect of the extra scattering on the LDA signal in terms of broken spatial coherence of the radiation in the retina. An explicit formula for the correlation function of the signal is obtained for a practical optical scheme that includes a crystalline lens, a pupil, and a concave retina as elements. The correlation function shows narrowing with spatial coherence of the radiation degrading. Most favorable configuration of the optics for the blood circulation intensity measurements and mapping in the retina are discussed.

Average membrane potential (MP) of T-lymphocytes in different physiological states of mice were measured with the help of fluorescent probe anilinonaphtalin-8-sulphonate (ANS). We investigated thymocytes of healthy animals and animals in whose organisms inflammatory process (IP) or cancer (IC) was developed. It was shown that MP is different in different physiological states of mice and is 61 mV, 96 mV, and 112 mV in control, IP, and IC respectively. Kinetics of regulation of volume and MP of T-lymphocytes in different physiological states in hypotonic medium were also investigated. It was shown that the kinetics have different quasiperiodic characters in the case of healthy organism and in the case of IP. During development of IC T-lymphocytes lost their adaptability to hypotension. The disappearance of adaptability of T-lymphocytes beginning from the third day of development of IC represents an early test of cancer. The relationship between MP and surface potential of plasmatic membrane was also investigated.

This study was carried out as part of the state program Children Affected by the Chernobyl Accident and used materials and results of the medical examinations of children living in radio-contaminated areas of the Bryansk region. The health status of children and adolescents exposed to low-dose radiation is causing increasing concern. Our attention was focused on assessing chromatin disorders in interphase lymphocyte nuclei and determining diagnostic criteria for lymphocytes and erythrocytes through measurement of their morphodensitometric parameters using a system of our own design called DIAMORF. Blood cells from children and adolescents exposed to low-dose radiation were examined after processing images of DNA- stained lymphocytes and unstained erythrocytes in a computer analyzer. The new method was used to study the fine supromolecular structure of the chromatin network. An optoelectronic image analyzer can differentiate between different areas of the erythrocytes surface and determine their curvatures. Parameters of cellular changes in response to low-dose radiation were evaluated quantitatively by measuring the optical density index and a number of other optical and geometric parameters.

Time-resolved fluorescence spectroscopy is presently regarded as a research tool in biochemistry, biophysics, and chemical physics. Advances in laser technology, the development of long-wavelength probes, and the use of lifetime-based methods are resulting in the rapid migration of time-resolved fluorescence to the clinical chemistry lab, to the patient's bedside, to flow cytometers, to the doctor's office, and even to home health care. Additionally, time-resolved imaging is now a reality in fluorescence microscopy, and will provide chemical imaging of a variety of intracellular analytes and/or cellular phenomena. In this overview paper we attempt to describe some of the opportunities available using chemical sensing based on fluorescence lifetimes, and to predict those applications of lifetime-based sensing which are most likely in the near future.

The development of automated interferometry for the ultracentrifuge is presented briefly, along with a short description of our current `real-time' acquisition system for equilibrium studies. Use of this system and of the associated data analyses techniques for both conventional and short solution column experiments of various types are discusses with emphasis on the application of nonlinear least squares fitting procedures. A brief summary is presented of the use of these approaches to detect and measure heterogeneity of various types.

This paper describes a new diagnostic instrument which uses magnetic modulation of an optical signal to rapidly measure whole blood Prothrombin time. The new instrument improves diagnosing and level monitoring by allowing accurate, rapid, low cost near patient testing. The measurement system consists of five major components: a control system; a user interface, a disposable-strip laminate architecture with proprietary chemistry which interacts with a time-varying magnetic field and accelerates the coagulation reaction; an optical measurement module -- the optics assembly of the instrument contains a heater, electromagnet, dc magnet, and numerous reflective/transmissive radiometric sensor systems; and a calibration-instrument using a custom developed test device which accurately simulates the coagulation reaction's induced optical properties. The theory of operation of the coagulation assay system and optical measurement module is describe and typical data and performance metrics are presented. 6

Biomedical diagnostic systems perform as combinations of assay chemistry, sample handling, reagent addition, detection and data processing components. Modeling the response of an instrument's photonic detection subassembly provides a quantitative estimate of the minimum relative uncertainty in analyte concentration. Limits on the operating range for which the relative uncertainty falls within specified uncertainty boundaries also follow from this analysis. The present study examines the optimal uncertainty in spectrophotometric measurements for different models of detector response. For the constant uncertainty model the operating range which corresponds to relative uncertainty no greater than twice the minimum value extends from A approximately equals 0.07 to A approximately equals 0.79. A PMT-like response results in the limits A approximately equals 0.2 to A approximately equals 2.3.

A new highly sensitive method of detection of the Browns or bio-particles in liquids, based on the fluctuations intensity spectroscopy, is described. A special scheme of disposition of photodetectors has made it possible to significantly reduce noise due to intensity fluctuations of probe laser radiation. As a result the detection sensitivity increases and is mainly restricted by electronical noise. We demonstrate the high sensitivity of the method allowed to detect the presence of viable micro-organisms in natural water reservoirs. The optical scheme of the device and preliminary experimental data are presented.

Capillary zone electrophoresis (CZE) is a powerful new separation technique which possesses the ability to separate small and large molecules. Due to the small volume of material that is typically loaded onto the column, ultrasensitive detection is often required. We have constructed a laser-induced fluorescence detector appropriate for CZE applications using near- IR fluorescence excitation and detection. Separations of native NIR fluorescent dyes in nonaqueous running buffer systems have been performed with detection sensitivities in the low zeptomole range, comparable to state-of-the-art detection limits reported for visible fluorescence detection in CZE. Using our NIR fluorescence detector and NIR labeling dyes synthesized in our laboratory, we present electropherograms of peptides and proteins separated by CZE and detected with NIR fluorescence. We also discuss the basic operating principles of CZE as well as the instrumental components necessary to perform CZE separations.

The need to detect increasingly low levels of antigens or polynucleotides in cells requires improvements in both the preparation and the staining of samples. The combination of centrifugal cytology with the use of glyoxal as cross-linking fixative produces monolayers of cells having minimum background fluorescence. Detection can be further improved by the use of a recently developed type of luminescent tag containing a lanthanide(III) ion as the light- emitting center. These novel tags are macrocyclic complexes functionalized with an isothiocyanate group to allow covalent coupling to a biosubstrate. The Eu(III) complex possesses a set of properties -- water solubility, inertness to metal release over a wide pH range, ligand-sensitized narrow-band luminescence, large Stoke's shift, and long excited-state lifetime -- that provides ease of staining as well as maximum signal with minimum interference from background autofluorescence. Luminescence efficiency studies indicate significant solvent effects.

Charge is a fundamental property of macromolecules. However, new instruments and new methods have been needed to explore the role of charge in determining the structure, stability, and interactions of macromolecules. An apparatus is described here that is capable of performing equilibrium electrophoresis, electrophoretic mobility or diffusion measurements. This instrument acquires absorbance data from up to 512 positions along a quartz cell. The cell permits the establishment of an electric field along its length, while retaining macroions in the field of view. The prospects and limitations of using equilibrium electrophoresis for clinical applications are explored, particularly for characterizing macromolecular reagents. Applications are described for detecting charge heterogeneity, monitoring sample stability, and for determining the role of charge in molecular structure, stability and interactions. Because equilibrium electrophoresis provides little sample fractionation, the analysis of complex fluids requires the use of specific optical labels for discriminating components.

Fourteen serum specimens from patients with early Leptospirosis proven by blood culture and serological test were detected by PCR with the oligonucleotide primers obtained from a genomic library of leptospira interrogans. The amplified DNA were hybridized with the homologous DNA probe labeling with Digoxingenin-AMPPD. All of the samples revealed the presence of leptospira and the strong signals were visualized with homologous DNA probes hybridization. Negative and positive controls appeared correctly. The DNA fragment generated from PCR amplification homologically hybridized with the DNA of 16 strains of leptospira. The single recognized band (about 400 bps) from 6 out of the 16 strains has come out which are representative of the principal strains in Sichuan, China. The results demonstrated that PCR is an advanced diagnostic technique for early Leptospirosis. The treatment of samples is easy and has little risk of DNA loss and contamination. This is a considerable advantage over other detective techniques and can be available especially in China and other developing countries.

A novel type of highly efficient phosphorescent labels is proposed for time-resolved phosphorescent immunoassay (TR-PIA). The phosphorescent properties of palladium and platinum coproporphyrins and different derivatives of tetraphenylporphyrin were studied in deoxygenated micellar solution and at the dry surface in the presence of oxygen. Lifetime, quantum yield, and quantum efficiency in time-resolved mode of phosphorescence measurements for more than 20 compounds were determined. At the optimum condition the detection limit of Pd- or Pt-coproporphyrin of 10^-13M may be achieved. The labels are thermodynamically and kinetically stable and insensitive to contamination of solutions and samples with ions of heavy metals. The measurement of room temperature phosphorescence of metalloporphyrin in micellar solution are rather simple and highly reproducible, the phosphorescent signal is stable for several hours and microtiter plates are suitable for micellar and dry surface measurements. Techniques have been developed for covalent and non-covalent labeling of proteins and oligonucletides with the phosphorescent label. The labeling proteins can be stored in the lyophilized state rather long and retain their immunological properties.

Intracavity laser spectroscopy (ILS) presents itself as a highly effective technique that allows one to detect the change of light signal from absorbing molecules at a level of radiation quantum noise. Thus high sensitivity of ICLS allows one to determine the absorbing molecules concentrations in gases and liquids in the range between 10^-6 to 10^-10. The potential of ICLS technique employment for establishing interrelations between small changes in the breathed air caused by diseases in the early stage, as well as a mass screening of patients with diseases of the liver and kidneys by acetone and urea detection in breathed air, and with heart diseases by measurement of CO₂ concentration is discussed. Usage of gas, dye and solid-state lasers for such measurements is analyzed, optimum spectral ranges are presented.

The features and the behavior of a modular ultra-fast time correlated single photon counting (TCSPC) system are analyzed. Using a Ti-Sapphire laser as excitation source an instrumental response function (IRF) of less than 17 ps for the total system was achieved. Despite this excellent IRF time there are at present some problems in analyzing fluorescence decay curves with such an ultra-fast IRF because of increased influence of color shift, time-spatial relationship, and electronic noise. Furthermore, we developed a new compact experimental set-up for TCSPC measurements consisting of laserdiodes including generator DL 4000 with pulse width less than 15 ps and the PC plug-in electronic card SPC 300. Thus the financial and spatial expense for TCSPC systems can be extremely reduced. Besides the traditional single channel data acquisition the new electronics allow parallel detection and acquisition of up to 128 channels simultaneously. This offers a lot of new applications for the highly sensitive TCSPC technique.

The schlieren optical system detects dn/dr which is the gradient of the refractive index n with the location r in dependence on the location r. A simple optical modification is presented which increases the sensitivity of a schlieren optical system extensively. This improvement is achieved by means of two cylindrical lenses in front of the phase plate which are arranged in a way that their focal points fall together. The phase plate remains in the focus of the lens system. The combination of the two cylindrical lenses is a beam expander which amplifies the measuring effect. Therefore it is possible to investigate solutions with a much lower polymer concentration than before. Furthermore the detected schlieren curve will be much sharper because the phase plate angle can be increased. The principal function and apparative aspects of the ultrasensitive schlieren optical system are discussed. Furthermore some potential applications for the example of analytical ultracentrifugation are presented.

We describe the fabrication and testing of an optical pH sensor based on fluorescence lifetime measurements and sol-gel technology. The sensor is based on the phenomenon of fluorescence resonance energy transfer (FRET), from a pH-insensitive donor to a pH-sensitive acceptor. The pH-dependent increase in the bromothymol blue acceptor absorbance results in increased energy transfer, reducing the lifetime of the Texas red hydrazide donor. The lifetimes were measured by the phase and modulation of the emission, relative to the modulated incident light, and were found to be insensitive to the total signal level and fluctuations in light intensity. However, the present sensors are sensitive to salt concentration and/or ionic strength. Importantly, this sol-gel sensor is not fragile, providing stable readings for days and can be repeatedly autoclaved without loss of sensitivity to pH. The use of FRET as the pH transduction mechanism can be reliably extended to longer wavelengths, and allows the future use of laser diode excitation sources.

A new efficient fiber optic absorbance sensor is described. The sensor can be configured with optical pathlengths from a few millimeters to 10 cm while maintaining high throughput. The sensor contains a graded index (GRIN) microlens which is ground for a specific sensor optical configuration. The sensor is able to be configured in several diameters ranging from sizes that fit within clinically acceptable gauge hypodermic needles to several millimeter diameter sizes. The sensor has currently been tested for the near-UV-VIS and near-IR spectral regions. Optical test results for several sensor sizes are presented and compared to sensor configurations described previously in the literature. A brief analysis of the sensor design is given in terms of the physical optics of the graded-index lens/multimode fiber optic couples which lead to high optical efficiencies. Example numerical simulations of the sensor optical efficiency are presented and compared with experimental results. Sample spectra and performance results also are presented.

Radiopharmaceuticals containing ^99mTc, a gamma emitting radionuclide, are commonly used in nuclear medicine to image specific organs for the purpose of diagnosis. Following injection of a chemical complex of this isotope and concentration of the activity within the organ of interest, scanning with a gamma ray camera provides an image from which diagnostic information can be obtained. Although, in most instances the composition of the injected radiopharmaceutical is known, the chemical form of the agent that is actually responsible for the image has not been identified and may represent an altered form due to in vivo reaction. Sensors that could be implanted in specific organs in order to specify the chemical form of the radioactive complex that is imaging an organ would be especially useful. In order to accomplish this goal, sensors for in vivo monitoring of imaging agents that are used in nuclear medicine are being developed. Such sensors must be multiwavelength since chemical information is contained in the spectrum of agents. A brief outline of the results of our efforts to make highly efficient catheter-sized absorbance sensors is presented.

A highly sensitive fluoroimmunoassay optical waveguide for the monitoring of biological agents was developed. The scope and versatility of this method was enhanced by combining the principle of fluoroimmunoassay with latex-based waveguide evanescent wave sensing technology. A novel waveguide probe was successfully demonstrated as an antibody-based biosensor. Based on a designed biological model, human immunoglobulin G (h-IgG) were sensitively (0.3 ng/ml, 2 X 10^-12 M) and rapidly (2 minutes assay time) identified and quantified using a diode laser (635 nm). The latex-based thin film has excellent optical quality and an established immunochemistry, making it stable and reliable for sensing applications. Because polymer-matrix waveguide is inexpensive and disposable, the probe cartridge is suitable for one time assay. Very fast and highly sensitive biosensors are potentially useful for many medical and clinical diagnostics, especially for intensive or emergency care patients.

The theory of dielectro-deformational spectroscopy (DDS) of erythrocytes is considered. DDS utilizes the deformation of a cell by high frequency (HF) electric field registered by optical diffractometry or by microphotometering for the monitoring of mechanical and (or) electric properties of erythrocyte. The general dynamic equation of dielectro-deformations of erythrocyte is presented and used to consider the registering of (1) the stationary elongation of a cell as a function of HF amplitude; (2) the elongation-relaxation curves for a step-like variation of HF amplitude; and (3) the oscillatory elongation of a cell due to harmonic modulation of HF amplitude. The determination of erythrocyte electric properties from the frequency dispersion of its dielectro-deformational response is considered also. The connection of the registered curves is elucidated with three main groups of erythrocyte's parameters: mechanical (shear modulus and viscosity of a membrane), geometric (surface area and volume), and electric (conductivities and dielectric constants inside and outside of a cell).

The maximum likelihood criterion is shown to be a powerful method for analyzing fluorescence detection data with small signal to noise ratios. Probability studies of the maximum likelihood criterion for supposed detection experiments of very small amounts of fluorescing molecules, down to a single molecule, are presented. In these studies the photokinetics of the molecules, their flow and diffusion, and the laser-beam geometry are taken into account. The efficiency of time-integrated and time-correlated single-photon counting methods are studied and compared.