Novel Highly Sensitive Protein Sensors Based on Tapered Optical Fibres Modified with Au-Based Nanocoatings

Abstract

Novel protein sensors based on tapered optical fibres modified with Au coatings deposited using two different procedures are proposed. Au-based coatings are deposited onto a nonadiabatic tapered optical fibre using (i) a novel facile method composed of layer-by-layer deposition consisting of polycation (poly(allylamine hydrochloride), PAH) and negatively charged SiO 2 nanoparticles (NPs) followed by the deposition of the charged Au NPs and (ii) the sputtering technique. The Au NPs and Au thin film surfaces are then modified with biotin in order to bind streptavidin (SV) molecules and detect them. The sensing principle is based on the sensitivity of the transmission spectrum of the device to changes in the refractive index of the coatings induced by the SV binding to the biotin. Both sensors showed high sensitivity to SV, with the lowest measured concentration levels below 2.5 nM. The calculated binding constant for the biotin-SV pair was 2.2 × 10 −11 M −1 when a tapered fibre modified with the LbL method was used, with a limit of detection (LoD) of 271 pM. The sensor formed using sputtering had a binding constant of 1.01 × 10with a LoD of 806 pM. These new structures and their simple fabrication technique could be used to develop other biosensors.

A graphene/Si Schottky diode for the highly sensitive detection of protein

“…4, the detection limit for the BSA protein is about 0.25 nM, which is the same order of magnitude or even better than that of the reported sensors. 30,31 Note that we did not use any conjugated nanoparticles or markers for sensing; moreover, the sample was not manipulated and could be reused aer testing. The rectifying current-voltage characteristics of the Schottky diode can be expressed by the thermionic emission model in which the diode current can be written as follows: 24…”

Preparation and Application of Metal Nanoparticals Elaborated Fiber Sensors

“…Micro/nanofiber provides a stronger optical field, called the evanescent field, to improve the intensity of the optical signal involved in the SPR effect, and enhance the interaction between the optical field and the environment to be measured [ 100 ]. In similar fiber structures, the penetration depth of the evanescent field and the optical scattering loss of NPs or structures need to be considered.…”

Layer-by-Layer Nano-assembly: A Powerful Tool for Optical Fiber Sensing Applications

“…In [149] a novel highly sensitive protein sensor on a tapered optical fiber modified with a Au-based nanocoating is presented. In this work it is remarked that the LbL coating morphology with the AuNPs provides a higher specific surface area for the adhesion of more biotin molecules which is a key factor for a further streptavidin (SV) absorption capacity in these LbL coatings.…”