New true direct methods of sensitive real-time recording of molecular reactions on a surface and detection of bio- and chemical agents have been developed. The methods are based on measuring changes of thickness of a sensor layer due to binding reactions. A transparent plate or a gap between two surfaces of optical materials is used as the sensor layer. The methods allow employment as biochips of microscopic glass slips without deposition of any metal or dielectric films. Alternatively, direct pumping of liquid samples through the sensing gap with deposited recognition layers can be used. For label-free biosensing, different optical schemes were realized to record thickness changes due to receptor-ligand bindings with picometer-scale resolution. Biosensors named one-dimensional PicoscopeTM and AffinoscopeTM have been developed for real-time detection of several biological agents by different recognition spots or wells with specific receptors on the biochip surface. The devices have been successfully employed for detection of food pathogens, for investigation of pharmaceutical substances, for epitope mapping of different monoclonal antibodies and immunotherapy research, for monitoring of bacteriocin production, etc. Application of the devices can be as wide as that of optical microscopes as they provide standard lateral resolution and, in addition, offer much more comprehensive information with outstanding real-time resolution in depth, e.g., for measuring molecular binding kinetics, monitoring of assembling in molecular structures, etc. The Picoscope technology significantly increases power of research instruments for bio-, nano- and pico-technologies.
An optical method has been proposed and successfully tested for direct detection of biochemical reactions on a surface, which is insensitive to variations of the radiation intensity and refractive index of a solution. The method is based on detection of the spectrum of the reflected or transmitted radiation modulated by the interference in a sensitive layer of large thickness (several tens and hundreds of microns), which can be a microscope cover glass with a deposited receptor layer. A change in the phase of the interference pattern in this spectrum is used as an information signal about a change in the thickness of the sensitive layer caused by a biochemical reaction. Single- and multichannel (up to 96 channels) devices have been designed to study reactions of binding and detachment of proteins in real time. The root-mean-square noise of the prototypes expressed in the layer thickness was 3 pm.
A novel synthetic peptide spacer designed on a gold film is introduced for use in surface plasmon resonance (SPR) sensing. The peptide was a specially designed sequence of amino acids, synthesized by the Fmoc-solid-phase chemistry. The peptide was adsorbed on the gold film from an aqueous solution via its four thiol groups, forming a self-assembled negatively charged monolayer. The monolayer contained carboxyl groups, which were activated by the EDC/NHS technique. It was successfully used as a matrix (2 - 4 nm thick) for covalent immobilization of fusion protein, which included C-terminal fragment of human 5-hydroxytryptamine transporter (molecular weight approximately 21 kDa). The reaction between the immobilized protein and antibodies was monitored by SPR means. The matrix did not cause degradation of immobilized components and steric hindrances to mass transport, and also demonstrated low nonspecific binding to antibodies. Besides, the matrix could be regenerated without decreasing SPR response to the reaction. Along with the ability to immobilize high weight molecules, which are unable to enter a conventional CM-dextran matrix due to steric hindrances to mass transport, the peptide matrix has a number of advantages over the CM-dextran matrix, namely, simplicity in preparation, low cost, and much shorter time needed for preparation. The peptide spacer matrix can be widely used not only in SPR, but also in other analytical techniques that require immobilization of proteins on metal surfaces, such as interferometry, piezoelectric detection, scanning tunneling microscopy.
Interferometry that detects phase jumps of a beam reflected under surface plasmon resonance (SPR) has been developed for bio- and chemical sensing and microscopy. In our approach the near-field of surface plasmon is used to detect monolayer reactions on a metal surface or to visualize ultra-thin films. Comprehensive theoretical model and its experimental verification are presented. A number of prospective device schemes has been developed that provide sensitivity much higher as compared to the traditional SPR sensors and equally wide dynamic range. The proposed technique has been used for a `phase jump' SPR microscopy. It can also be used for Gene Chips and High Throughput Screening analyses.
The concept of surface plasmon resonance chemical sensors based on Si substrate is developed which combines a number of advantages of both optical and microelectronical approaches to investigate gaseous media. This type of the gas sensor has been made and tested for the first time. A reversible response to ntirogen dioxide at the level of ppm concentrations has been recorded.
An optical biosensor has been developed for detection of pesticides, based on surface plasmon resonance (SPR) technique. Concentration of the pesticides was measured in liquid or gas. We specially originated organic film on a disposable element. A setup on the base of Kretschmann arrangement was improved by using a computer-controlled angular scanning system. The detection concentration limit of dinitrophenole (DNP) was 10-9 M. Some samples exhibited effect down to 10-11 M of DNP. The results obtained provide reason for further development of SPR sensor as applied to pesticides monitoring.
The problem of chemical and biological sensing, i.e., identification of components of various media and measuring their concentrations, is of extreme importance in science, technology, medicine, environmental monitoring, etc. Principally, the problem could be solved by means of purely optical methods, particularly, tunable diode laser spectroscopy [1]. Due to the spectral resolution by an order or two of magnitude higher than Doppler width of spectral lines, it provides ideal selectivity and suitable sensitivity in gas sensing. However, such techniques require bulk, expensive laboratory equipment and qualified personnel. This results in a very high cost of analysis and makes the method unsuitable from the commercial standpoint
The pulsed photothermal radiometry of biological objects is used for controlling and investigation of tissue damage by YAG:Er ((lambda) equals 2,94 mkm), YAG:Nd ((lambda) equals 1,06 mkm), CO2 ((lambda) equals 10,6 mkm) laser radiation thermal action, study of optical and thermophysical properties of tissue (tooth) in vivo.
Magnetic materials with high Faraday effect were studied for fiber—optic
magnetic fields and electric currents sensors design. Different compositions of
semimagnetic semiconductors were grown to measure high frequency magnetic fields (up
to several GHz). For moderate frequency sensors < 50 MHz the most perspective
material was found to be Bi-substituted yttrium—iron gamete . Several ways to
achieve high sensitivity and wide frequency band are discussed. Sensors on the basis
of the investigated materials for various spheres of applications were constructed.
Significant electric potentials have been observed along thin metallic films deposited on rippled or randomly rough dielectric substrates, under pulsed laser irradiation [1,2]. Experimental work investigating this effect with an eye toward developing pulsed laser detectors will be discussed.
The effects of electric current generation under laser irradiation of thin metallic films on randomlyrough and rippled dielectric substrates are discussed. Regular surface microrelief of substrate was produced by pulse laser processing of a polished dielectric. The determined laws of the current generation along the films their possible mechanisms and applications for varios types of pulse radiation detectors are described.
Investigations of currents in close-to surface plasma, produced by CO2- laser radiation of different temporal structure have been carried out. The character of evolution of registered currents temporal structure at growing energy density was different when the target was irradiated in air and in vacuum by the train of short (τ= 2.5 ns ) pulses. Experiments in vacuum have revealed that the transit from smooth single mode pulse to the nanosecond pulse train of the same total energy was followed by a considerable decrease in plasma formation energy thresholds and by the increase of amplitudes of currents induced by plasma. The current pulses from the target were registered after finishing the laser irradiation; their appearance was probably connected with cumulation effects, caused by the ring form of the irradiated area.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.