In this paper, we propose a novel "gold on gold" biosensing scheme for absorbance based fiber-optic biosensor. First, a self-assembled monolayer of gold nanoparticles is formed at the sensing region of the fiber-optic probe by incubating an amino-silanized probe in a colloidal gold solution. Thereafter, the receptor moieties, i.e. Human immunoglobulin G (HIgG) were immobilized by using standard alkanethiol and classic carbodiimide coupling chemistry. Finally, biosensing experiments were performed with different concentrations of gold nanoparticle-tagged analyte, i.e. Goat anti- Human immunoglobulin G (Nanogold-GaHIgG). The sensor response was observed to be more than five-fold compared to the control bioassay, in which the sensor matrix was devoid of gold nanoparticle film. Also, the response was found to be ∼10 times higher compared to the FITC-tagged scheme and ∼14.5 times better compared to untagged scheme. This novel scheme also demonstrated the potential in improving the limit of detection for the fiber-optic biosensors. © 2015 SPIE.

Jitendra Satija

Centre for Nanobiotechnology

Vellore Campus

Nirmal Punjabi

J. Satija

Punjabi N

Nirmal s punjabi

Soumyo Mukherji

Satija J

Mukherji S.

Soumyo mukherji

Fiber-optic sensor

Gold Nanoparticles

labeled bioassay

Localized surface plasmon resonance

On-fiber immunoassay

plasmonic biosensor

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

A novel 'Gold on Gold' biosensing scheme for an on-fiber immunoassay

Proceedings of SPIE - The International Society for Optical Engineering

α-Synuclein protein, whose aggregation is associated with Parkinson's disease, is detected using a compact, label-free, localized surface plasmon resonance (LSPR) based optical sensor. U-shaped fiber optic probe immobilized with gold nanoparticles (GNP), and subsequently functionalized using a film of chitosan was used as a sensing platform. The chitosan film acts as a sensitive and selective polysaccharide bioreceptor for detection of α-Synuclein. Binding of amyloid proteins to this film causes a localized change of dielectric constant surrounding the nanoparticles, leading to a change in the spectrum at the output end of the fiber. The combination of binding rate kinetics and intensity change was measured to develop a robust sensing platform. The sensor could detect the presence of monomers & amyloid fibrils independently up to 70 nM and could differentiate them in mixtures having fibril to monomer ratio from 0.1 to 10, within 15 min. The present study introduces a new platform for sensitive detection of amyloid fibrils and monomer of α-Synuclein (independently as well as in mixtures) for potential applications in inhibition and aggregation based studies. © 2017 Elsevier B.V.

Sensors and Actuators, B: Chemical

Detection and differentiation of Α-Synuclein monomer and fibril by chitosan film coated nanogold array on optical sensor platform

Evanescent wave absorption (EWA) based fiber-optic sensors have found widespread applications ranging from environmental sensing to biosensing. In these sensors, optical and geometrical characteristics such as optical fiber type (single-mode or multi-mode), fiber core diameter, fiber probe geometry, fiber probe length, etc., are very important. These parameters affect the penetration depth and fractional power by modulating the ray propagating in the fiber probe that ultimately influences the sensitivity of the EWA sensors. Various geometries of fiber probe designs, like bent, tapered, coiled, etc., have been explored for improving the sensitivity. This chapter describes the design, development and fabrication of a novel bent-tapered fiber-optic sensor. A combination of bending and tapering acts as a mode converter, which results in high penetration depth of the evanescent field. In addition, tapered region of the probe increases the coupling efficiency at the detector end by V-number matching and thus improves the signal-to-noise ratio. EWA sensitivity of the sensor was compared for different taper ratios. Finally, the optimized geometrical design was used to demonstrate biosensing application. © Springer International Publishing Switzerland 2015.

Smart Sensors, Measurement and Instrumentation

Evanescent wave absorption based fiber-optic sensor - Cascading of bend and tapered geometry for enhanced sensitivity

Analytical Chemistry

Enhancing Sensitivity of Surface Plasmon Resonance Biosensors by Functionalized Gold Nanoparticles: Size Matters

The refractive index (RI) sensitivity of a localized surface plasmon resonance (LSPR)-based fiber-optic probes is dependent on surface coverage of gold nanoparticles (GNP), fiber core diameter, and probe geometry. For U-bent LSPR fiber-optic probes, which demonstrated an order higher absorption sensitivity over straight probes, bend diameter and probe length may also have a significant influence on the sensitivity. This study on U-bent fiber-optic LSPR probes is aimed at optimizing these parameters to obtain highest possible RI sensitivity. RI sensitivity increases linearly as a function of surface coverage of GNP in the range of 2–22%. U-bent fiber-optic probes made of 200-, 400-, and 600-μm fiber core diameter show optimum bend diameter value as ∼1.4 mm. In addition, RI sensitivity is almost the same irrespective of fiber core diameter demonstrating flexibility in choice of the fiber and ease in optical coupling. The length of the probe preceding and succeeding the bend region has significantly less influence on RI sensitivity allowing miniaturization of these probes. In addition to these experimental studies, we present a theoretical analysis to understand the relative contribution of evanescent wave absorbance of GNP and refractive losses in the fiber due to GNP, towards the RI sensitivity. © Springer Science+Business Media New York 2013.

Plasmonics

Optimal design for U-bent fiber-optic LSPR sensor probes

Analytica Chimica Acta

A colorimetric probe for online analysis of sulfide based on the red shifts of longitudinal surface plasmon resonance absorption resulting from the stripping of gold nanorods

Sensors and Actuators B: Chemical

Non-aggregation based label free colorimetric sensor for the detection of Cr (VI) based on selective etching of gold nanorods

Journal	Data powered by TypesetProceedings of SPIE - The International Society for Optical Engineering
Publisher	Data powered by TypesetSPIE
ISSN	0277786X
Open Access	No