Strong Improvements of Localized Surface Plasmon Resonance Sensitivity by Using Au/Ag Bimetallic Nanostructures Modified with Polydopamine Films

Abstract

In the present work, the standard monometallic localized surface plasmon resonance (LSPR) biosensing sensitivity is highly improved when using a new system based on glass substrates modified with high-temperature annealed gold/silver bimetallic nanoparticles (Au/Ag bimetallic NPs) coated with polydopamine films before biomolecule specific immobilization. Thus, different zones of bimetallic NPs are spatially created onto a glass support thanks to a commercial transmission electron microscopy (TEM) grid marker in combination with two sequential evaporations of continuous films of gold (4 nm) and silver (2 nm) and followed by annealing at 500 °C for 8 h. By using the scanning electron microscopy (SEM), it is found that annealed Au/Ag bimetallic NPs have uniform size and shape distribution that exhibited a sharper well-defined LSPR resonant peak when compared with that of monometallic Au NPs and thereby contributing to an improved sensitivity in LSPR biosensor application. The controlled micropatterns consisting of bimetallic particles are used in the construction of LSPR biochips for high-throughput detection of different concentrations of a model antigen named bovine serum albumin (BSA) on a single glass sample, with a lower limit of detection of 0.01 ng/mL under the optimized conditions.

Amplifying the signal of localized surface plasmon resonance sensing for the sensitive detection of Escherichia coli O157:H7

“…5C. It was found that plasmon absorption shifts linearly to longer wavelength with increasing the refractive index 22, 47, 48 . In addition, only absorption is considered here and the influence of scattering are neglected due to higher absorption than scattering of nanorods 49 .…”

Compositional effect on the fabrication of AgxPd1−x alloy nanoparticles on c-plane sapphire at distinctive stages of the solid-state-dewetting of bimetallic thin films

“…9,10 In addition, owing to the structure and element dependent localized surface plasmon resonance (LSPR), the BMNPs can be applied in various optoelectronic devices to improve the optical output, conversion efficiency and detection sensitivity. [11][12][13][14][15] At the same time, the monometallic Ag and Pd NPs individually have been important materials in optical, plasmonic and catalytic applications. 16,17 At this stage, the idea of combining both Ag and Pd atoms in a single nanostructure can further extend their applicability and thus the fabrication of bimetallic Ag x Pd 1Àx nanostructures by controlling their morphology and elemental composition can be promising approach to explore the functionality and usability for the related and novel applications.…”

Sub-monolayer silver loss from large gold nanospheres detected by surface plasmon resonance in the sigmoidal region

“…Both theoretical and experimental results in the literature have shown that SPR peak position depends on particle diameter, aspect ratio, shape, surface coating, surfactants, surface morphology, volume, coating of other nanoparticles, and aggregates of gold substrates. [45][46][47][48][49][50][51][52][53][54] Sigmoidal responses were observed as a function of the coverage of proteins (in log scale) on gold particles deposited on flat substrates. 55 This is similar to the Langmuir-Freundlich isotherm curve, 47 which is not an intrinsic response of silver layer on gold substrate.…”