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

Surface plasmons (SPs) are coherent oscillations of conduction electrons on a metal surface excited by electromagnetic radiation at a metal -dielectric interface. The growing field of research on such light -metal interactions is known as ‘plasmonics’. 1-3 This branch of research has attracted much attention due to its potential applications in miniaturized optical devices, sensors, and photonic circuits as well as in medical diagnostics and therapeutics. 4-8

Nanostructured plasmonic sensors.

Surface plasmon resonance (SPR) biosensors are optical sensors exploiting special electromagnetic waves—surface plasmon-polaritons—to probe interactions between an analyte in solution and a biomolecular recognition element immobilized on the SPR sensor surface. Major application areas include detection of biological analytes and analysis of biomolecular interactions where SPR biosensors provide benefits of label-free real-time analytical technology. This paper reviews fundamentals of SPR affinity biosensors and discusses recent advances in development and applications of SPR biosensors.

Present and future of surface plasmon resonance biosensors.

Sensitive optical biosensors for unlabeled targets: a review.

In recent years, zwitterionic materials such as poly(carboxybetaine) (pCB) and poly(sulfobetaine) (pSB) have been applied to a broad range of biomedical and engineering materials. Due to electrostatically induced hydration, surfaces coated with zwitterionic groups are highly resistant to nonspecific protein adsorption, bacterial adhesion, and biofilm formation. Among zwitterionic materials, pCB is unique due to its abundant functional groups for the convenient immobilization of biomolecules. pCB can also be prepared in a hydrolyzable form as cationic pCB esters, which can kill bacteria or condense DNA. The hydrolysis of cationic pCB esters into nonfouling zwitterionic groups will lead to the release of killed microbes or the irreversible unpackaging of DNA. Furthermore, mixed-charge materials have been shown to be equivalent to zwitterionic materials in resisting nonspecific protein adsorption when they are uniformly mixed at the molecular scale.

Ultralow-Fouling, Functionalizable, and Hydrolyzable Zwitterionic Materials and Their Derivatives for Biological Applications

We report on a unified theoretical model of the resolution of SPR sensors which makes it possible to predict the ultimate performance of all major configurations of SPR sensors. The theory indicates that the performance of SPR sensors is independent of the method of excitation of surface plasmons (prism or grating coupling) or the method of modulation (amplitude, angular or wavelength) and depends dominantly on the noise properties of the light source and detector. Results of the theoretical analysis are compared with the performance reported for several SPR sensors to illustrate that the best state-of-art SPR sensors are approaching their theoretical limits. Possibilities for further advances in the performance of SPR sensor technology are discussed.

Surface plasmon resonance (SPR) sensors: approaching their limits?

A crucial step in the development of implanted medical devices, in vivo diagnostics, and microarrays is the effective prevention of nonspecific protein adsorption from real-world complex media such as blood plasma or serum. In this work, a zwitterionic poly(carboxybetaine acrylamide) (polyCBAA) biomimetic material was employed to create a unique biorecognition coating with an ultralow fouling background, enabling the sensitive and specific detection of proteins in blood plasma. Conditions for surface activation, protein immobilization, and surface deactivation of the carboxylate groups in the polyCBAA coating were determined. An antibody-functionalized polyCBAA surface platform was used to detect a target protein in blood plasma using a sensitive surface plasmon resonance (SPR) sensor. A selective protein was directly detected from 100% human blood plasma with extraordinary specificity and sensitivity. The total nonspecific protein adsorption on the functionalized polyCBAA surface was very low (<3 ng/cm2 ...

Ultralow Fouling and Functionalizable Surface Chemistry Based on a Zwitterionic Polymer Enabling Sensitive and Specific Protein Detection in Undiluted Blood Plasma

4 Main Performance Characteristics of SPR Sensors . . . . . . . . . . . . . . 49 4.1 Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 4.1.1 Sensitivity of SPR Sensors with Angular Modulation . . . . . . . . . . . . . 52 4.1.2 Sensitivity of SPR Sensors with Wavelength Modulation . . . . . . . . . . . 56 4.1.3 Sensitivity of SPR Sensors with Intensity Modulation . . . . . . . . . . . . 60 4.2 Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Surface Plasmon Resonance (SPR) Sensors

The development of biosensors with improved sensitivity for the detection of biological molecules presents obvious possibilities for improved diagnostic tools in healthcare. Here, the authors present a technique for the label-free detection and super-resolution imaging of single proteins.

/pdf/direct-optical-sensing-of-single-unlabelled-proteins-and-3a1k2kulvd.pdf

Direct optical sensing of single unlabelled proteins and super-resolution imaging of their binding sites.

A novel wavelength modulation-based fiber-optic surface plasmon resonance (SPR) sensor is reported which utilizes both polarization separation and broad band radiation depolarization in polarization-maintaining fibers to enhance sensor stability. Theoretical analysis of the sensing structure with ideally separated polarizations based on the mode of expansion and propagation method is presented. The effect of polarization cross-coupling was also analyzed in the approximation of an equivalent bulk optic structure. A laboratory prototype of the fiber-optic SPR sensor was characterized in terms of sensitivity and resolution. Experimental results indicate that this fiber-optic SPR sensor is able to resolve refractive index changes as low as 4×10−6 under moderate fiber deformations.

Marek Piliarik

Papers

Surface plasmon resonance (SPR) sensors: approaching their limits?

Ultralow Fouling and Functionalizable Surface Chemistry Based on a Zwitterionic Polymer Enabling Sensitive and Specific Protein Detection in Undiluted Blood Plasma

Surface Plasmon Resonance (SPR) Sensors

Direct optical sensing of single unlabelled proteins and super-resolution imaging of their binding sites.

Surface plasmon resonance sensor based on a single-mode polarization-maintaining optical fiber