Since the first application of the surface plasmon resonance (SPR) phenomenon for sensing almost two decades ago, this method has made great strides both in terms of instrumentation development and applications. SPR sensor technology has been commercialized and SPR biosensors have become a central tool for characterizing and quantifying biomolecular interactions. This paper attempts to review the major developments in SPR technology. Main application areas are outlined and examples of applications of SPR sensor technology are presented. Future prospects of SPR sensor technology are discussed.

Surface plasmon resonance sensors: review

5.1. Detection Formats 475 5.2. Food Quality and Safety Analysis 477 5.2.1. Pathogens 477 5.2.2. Toxins 479 5.2.3. Veterinary Drugs 479 5.2.4. Vitamins 480 5.2.5. Hormones 480 5.2.6. Diagnostic Antibodies 480 5.2.7. Allergens 481 5.2.8. Proteins 481 5.2.9. Chemical Contaminants 481 5.3. Medical Diagnostics 481 5.3.1. Cancer Markers 481 5.3.2. Antibodies against Viral Pathogens 482 5.3.3. Drugs and Drug-Induced Antibodies 483 5.3.4. Hormones 483 5.3.5. Allergy Markers 483 5.3.6. Heart Attack Markers 484 5.3.7. Other Molecular Biomarkers 484 5.4. Environmental Monitoring 484 5.4.1. Pesticides 484 5.4.2. 2,4,6-Trinitrotoluene (TNT) 485 5.4.3. Aromatic Hydrocarbons 485 5.4.4. Heavy Metals 485 5.4.5. Phenols 485 5.4.6. Polychlorinated Biphenyls 487 5.4.7. Dioxins 487 5.5. Summary 488 6. Conclusions 489 7. Abbreviations 489 8. Acknowledgment 489 9. References 489

Surface Plasmon Resonance Sensors for Detection of Chemical and Biological Species

Sensitive optical biosensors for unlabeled targets: a review.

Graphene is a monolayer of carbon atoms packed into a two-dimensional (2D) honeycomb crystal structure, which is a special material with many excellent properties. In the present study, we will discuss the possibility that graphene can be used as a substrate for enhancing Raman signals of adsorbed molecules. Here, phthalocyanine (Pc), rhodamine 6G (R6G), protoporphyin IX (PPP), and crystal violet (CV), which are popular molecules widely used as a Raman probe, are deposited equally on graphene and a SiO2/Si substrate using vacuum evaporation or solution soaking. By comparing the Raman signals of molecules on monolayer graphene and on a SiO2/Si substrate, we observed that the intensities of the Raman signals on monolayer graphene are much stronger than on a SiO2/Si substrate, indicating a clear Raman enhancement effect on the surface of monolayer graphene. For solution soaking, the Raman signals of the molecules are visible even though the concentration is low to 10(-8) mol/L or less. What's more interesting, the enhanced efficiencies are quite different on monolayer, few-layer, multilayer graphene, graphite, and highly ordered pyrolytic graphite (HOPG). The Raman signals of molecules on multilayer graphene are even weaker than on a SiO2/Si substrate, and the signals are even invisible on graphite and HOPG. Taking the Raman signals on the SiO2/Si substrate as a reference, Raman enhancement factors on the surface of monolayer graphene can be obtained using Raman intensity ratios. The Raman enhancement factors are quite different for different peaks, changing from 2 to 17. Furthermore, we found that the Raman enhancement factors can be distinguished through three classes that correspond to the symmetry of vibrations of the molecule. We attribute this enhancement to the charge transfer between graphene and the molecules, which result in a chemical enhancement. This is a new phenomenon for graphene that will expand the application of graphene to microanalysis and is good for studying the basic properties of both graphene and SERS.

Can graphene be used as a substrate for Raman enhancement

Towards integrated and sensitive surface plasmon resonance biosensors: a review of recent progress.

Surface plasmon resonance (SPR) interferometry is reported as a novel technique for biological and chemical sensing, which employs not only the amplitude of a resonantly reflected light wave, but its phase as well. In this connection, the phase behavior under SPR has been comprehensively described by theoretical analysis, numerical simulations, and a number of experiments. Near optimum SPR conditions, a resonant phase dependence is step-like, the ‘step’ being at the reflectivity minimum. For SPR-based sensors, the slope of the ‘step’ can always be made by several orders steeper than that of the resonant reflectivity contour. The ‘step’ has been imaged by the fringe of a 2-dimensional interference pattern where one coordinate was the incidence angle, and the other was the phase. The inversion of the ‘step’ has been observed for the first time during antigen–antibody binding, when the system passes through the optimum SPR conditions. Monitoring the inversion provides for ultra-high sensitivity to an analyte while recording angular position of the ‘step’, does for dynamic range as wide as that of traditional SPR sensors. The SPR interferometry technique has confirmed theoretical findings and opened up new possibilities for (bio)chemical sensing.

Surface plasmon resonance interferometry for biological and chemical sensing

Interferometry that detects the phase of a beam reflected under surface plasmon resonance (SPR) has been developed for bio and chemical sensing. The conditions have been found, under which the phase reveals abrupt jumps in response to a minute increase in the effective thickness of a receptor layer that binds analyte particles on the sensor surface. This forms the basis for biosensing with sensitivity much higher as compared to traditional SPR sensors. Besides, SPR interferometry (SPRI) provides spatial resolution at the micron scale. The enhanced sensitivity attributed to the phase jump and interferometric imaging of variations of the phase over the surface are demonstrated, which open up new avenues for micro-array biosensing.

Surface plasmon resonance interferometry for micro-array biosensing

A new label-free optical biosensing method has been developed, which can be called Spectral Correlation Method (SCM). The method is based on measurements of a correlation signal of two interferometers in an original optical scheme. The first interferometer is a scanned Fabry–Perot interferometer, in which the distance between two mirrors is periodically changed by a peizoelectric driver. The second interferometer is formed by a biochip, which is a simple glass plate with thickness of several tens or hundreds microns with different recognition spots or wells, or flow channels. In our experiments, a microscope cover glass was successfully used as a biochip to detect reactions of binding or detachment of different biological agents in real time. Two- and 96-channel SCM devices have been designed to register bio- and chemical-components in real time. The sensogram drifts for these devices expressed in terms of layer thickness were 20 and 40 pm/h, respectively.

New direct optical biosensors for multi-analyte detection

The physical picture of the behaviour of the phase of a light wave, reflected from a metal film under surface-plasmon resonance conditions, was determined theoretically and experimentally for various values of a whole series of parameters. It was found in particular that for a p-polarised wave the dependence of the phase on the angle of incidence and on the radiation wavelength, and also on the refractive index of a medium or on the thickness of a (bio)chemical receptor layer on the metal surface, had a section with an abrupt jump-like change. The steepness of this section, i.e. the sensitivity of the phase to a change in the relevant parameter, can exceed by several orders of magnitude the steepness of the intensity resonance profile and in theory it can tend to infinity as the intensity at the reflection minimum approaches zero. This is the basis of a discussion of promising (bio)chemical sensor methods ensuring a significantly higher sensitivity and yet the same wide dynamic range as the traditional detection of an intensity minimum.

https://iopscience.iop.org/article/10.1070/QE1998v028n05ABEH001245/pdf

Phase properties of a surface-plasmon resonance from the viewpoint of sensor applications

A simple optical method is proposed for the direct detection of biochemical reactions on a surface, which is insensitive to variations in the emission intensity and refractive index of a solution. The method is based on the detection of the spectrum of reflected or transmitted emission modulated by the interference in a sensitive layer of a 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. The method was tested in studies of the reactions of binding and detachment of proteins in real time. The root-mean-square noise of the method expressed in the layer thickness is 3 pm.

M. V. Valeiko

Papers

Surface plasmon resonance interferometry for biological and chemical sensing

Surface plasmon resonance interferometry for micro-array biosensing

New direct optical biosensors for multi-analyte detection

Phase properties of a surface-plasmon resonance from the viewpoint of sensor applications

Spectral-phase interference method for detecting biochemical reactions on a surface