In recent years, tools for the development of new drugs have been dramatically improved. These include genomic and proteomic research, numerous biophysical methods, combinatorial chemistry and screening technologies. In addition, early ADMET studies are employed in order to significantly reduce the failure rate in the development of drug candidates. As a consequence, the lead finding, lead optimization and development process has gained marked enhancement in speed and efficiency. In parallel to this development, major pharma companies are increasingly outsourcing many components of drug discovery research to biotech companies. All these measures are designed to address the need for a faster time to market. New screening methodologies have contributed significantly to the efficiency of the drug discovery process. The conventional screening of single compounds or compound libraries has been dramatically accelerated by high throughput screening methods. In addition, in silico screening methods allow the evaluation of virtual compounds. A wide range of new lead finding and lead optimization opportunities result from novel screening methods by NMR, which are the topic of this review article.

Drug Discovery Today

Noble metal nanoparticle-based localized surface plasmon resonance (LSPR) is an advanced and powerful label-free biosensing technique which is well-known for its high sensitivity to the surrounding refractive index change in the local environment caused by the biomolecular interactions around the sensing area. The characteristics of the LSPR effect in such sensors are highly dependent on the size, shape and nature of the material properties of the metallic nanoparticles considered. Among the various types of metallic nanoparticles used in studies employing the LSPR technique, the use of gold nanorods (GNRs) has attracted particular attention for the development of sensitive LSPR biosensors, this arising from the unique and intriguing optical properties of the material. This paper provides a detailed review of the key underpinning science for such systems and of recent progress in the development of a number of LSPR-based biosensors which use GNR as the active element, including an overview of the sensing principle, the synthesis of GNRs, the fabrication of a number of biosensors, techniques for surface modification of GNRs and finally their performance in several biosensing applications. The review ends with a consideration of key advances in GNR-based LSPR sensing and prospects for future research and advances for the development of the GNR-based LSPR biosensors.

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Gold nanorod-based localized surface plasmon resonance biosensors: A review

This paper presents a brief overview of the technologies used to implement surface plasmon resonance (SPR) effects into fiber-optic sensors for chemical and biochemical applications and a survey of results reported over the last ten years. The performance indicators that are relevant for such systems, such as refractometric sensitivity, operating wavelength, and figure of merit (FOM), are discussed and listed in table form. A list of experimental results with reported limits of detection (LOD) for proteins, toxins, viruses, DNA, bacteria, glucose, and various chemicals is also provided for the same time period. Configurations discussed include fiber-optic analogues of the Kretschmann–Raether prism SPR platforms, made from geometry-modified multimode and single-mode optical fibers (unclad, side-polished, tapered, and U-shaped), long period fiber gratings (LPFG), tilted fiber Bragg gratings (TFBG), and specialty fibers (plastic or polymer, microstructured, and photonic crystal fibers). Configurations involving the excitation of surface plasmon polaritons (SPP) on continuous thin metal layers as well as those involving localized SPR (LSPR) phenomena in nanoparticle metal coatings of gold, silver, and other metals at visible and near-infrared wavelengths are described and compared quantitatively.

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Review of plasmonic fiber optic biochemical sensors: improving the limit of detection.

Recent advances in polyaniline based biosensors

■ CONTENTS Books, Reviews, and Articles of General Interest 488 Sensors for (Dissolved) Gases and Vapors 489 Hydrogen 489 Hydrocarbons 490 Oxygen 491 Ammonia 493 Carbon Dioxide 494 Nitrogen Oxides 494 Vapors of Organic Solvents 495 Sensors for Humidity, Water Fractions, Hydrogen Peroxide, and Hydrazine 495 Humidity 495 Water Fractions 496 Hydrogen Peroxide and Hydrazine 496 Sensors for pH Values, Ions, and Salinity 496 pH Values 496 Ions 497 Salinity and Ionic Strength 499 Sensors for Organic Species 499 Biosensors 500 Immunosensors 500 PNA-Based Biosensors (DNA, Aptamers) 501 Other Affinity Sensors 501 Enzymatic Biosensors 502 Whole Cell Sensors 502 Advanced Optical Sensing Schemes and Materials 503 Author Information 505 Corresponding Author 505 Notes 505 Biographies 505 Acknowledgments 505 References 505

Fiber-Optic Chemical Sensors and Biosensors (2008–2012)

This study shows development of highly sensitive and stable localized surface plasmon resonance (LSPR)-active U-bent glass and polymeric optical fiber (GOF and POF) sensor probes by a seed-mediated in situ growth technique. Here, the nickel/nickel oxide seeds (Ni/NiO, 3 to 5 nm size) were formed on the U-region of the fiber probe by sputter coating nickel under a low vacuum (3 Pa), and then, gold nanostructures (AuNSs) were grown over the Ni/NiO seeds. The evanescent wave absorbance (EWA) phenomenon in the U-bent fiber probe was exploited to monitor the growth kinetics of AuNSs in real-time. Experimental observations point to a potential galvanic replacement of Ni by Au. The newly formed AuNSs on U-bent GOF and POF probes gave rise to a LSPR-based refractive index sensitivity of 27.66 and 25.65 ΔA/ΔRIU with plasmonic peak at 600 and 570 nm, respectively. These plasmonic probes show an excellent chemical and mechanical stability, in addition to high surface enhanced Raman scattering (SERS) activity. This quick and facile technique is highly suitable for large-scale manufacture of reliable plasmonic fiber optic sensor probes for chemical and bio sensing applications.

Highly Stable Plasmonic Nanostructures on a Nickel-Sputtered Glass and Polymeric Optical Fiber Sensors

This study demonstrates a novel fiber optic sensing strategy for selective adsorption and rapid detection of Cr(VI) ions by exploiting a suitable metal-organic framework matrix and the characteristic spectral absorption of Cr(VI) at 395 nm wavelength, respectively. U-bent fiber optic sensor (U-FOS) probes that exhibit remarkably high evanescent wave-based absorbance sensitivity were employed to efficiently detect the Cr(VI) ions that are adsorbed to a stable zeolitic imidazolate framework (ZIF-67) matrix immobilized on the probe surface. A facile technique was developed for the fabrication of ZIF-67-coated U-FOS probes (FOS/ZIF-67) involving an in situ deposition process followed by heat treatment. Selectivity of the FOS/ZIF-67 probes to Cr(VI) was confirmed by optical absorption spectral investigations with 14 other heavy metals and interfering ions. The sensor performance was evaluated with a compact light-emitting diode-photodetector-based setup. FOS/ZIF-67 probes demonstrate an ability to detect Cr(VI) ions with a limit of detection of 1 ppb and a wide linear dynamic range from 0.005 to 100 ppm within a short response time of 5 to 10 min. These sensors show good recovery rates with real water samples and a shelf-life of at least 4 weeks under ambient conditions, thereby demonstrating their viability for real-world application.

Metal-Organic Framework-Based Fiber Optic Sensor for Chromium(VI) Detection.

This study demonstrates a rapid, wash-free dip-type fiber optic plasmonic sandwich (DiP) assay capable of zeptomole analyte detection and 6-orders of wide dynamic range. The DiP assay is realized on a compact U-bent fiber optic probe surface by dipping the antibody functionalized probe into a mixture of sample solution and AuNP labeled reagent. U-bent fiberoptic probes with a high evanescent wave absorbance sensitivity allow detection of the high extinction gold nanoparticle (AuNP) labels in terms of a drop in the light intensity, which is measured with the help of a pair of LED and photodetector (PD). This simple and low-cost DiP assay gave rise to unprecedented detection limit down to 0.17 zeptomole of human immunoglobulin G (HIgG) in 0.025 ml buffer solution within an assay time of 25 min. Further, silver enhancement of AuNP labels over 5 min resulted in a limit of quantitation (LoQ) down to 0.17 zeptomole (~100 molecules in 0.025 ml). The DiP assay with high sensitivity and low detection limits within an assay time of 30 min demonstrated here could facilitate low cost point-of-care diagnostics as well as high-throughput systems.

A wash-free, dip-type fiber optic plasmonic (DiP) assay for sub-zeptomole analyte detection

A U-Bent Fiberoptic Absorbance Biosensor Array (Arfab) for Multiplexed Analyte Detection

We report a novel one-step polyamidoamine (PAMAM) dendrimer based polymethyl methacrylate (PMMA) surface functionalization strategy for the development of polymeric optical fiber (POF) based plasmo ...

V. V. R. Sai

Papers

Highly Stable Plasmonic Nanostructures on a Nickel-Sputtered Glass and Polymeric Optical Fiber Sensors

Metal-Organic Framework-Based Fiber Optic Sensor for Chromium(VI) Detection.

A wash-free, dip-type fiber optic plasmonic (DiP) assay for sub-zeptomole analyte detection

A U-Bent Fiberoptic Absorbance Biosensor Array (Arfab) for Multiplexed Analyte Detection

Self-assembled polyamidoamine dendrimer on poly (methyl methacrylate) for plasmonic fiber optic sensors