Ag-Functionalized Si Nanowire Arrays Aligned Vertically for SERS Detection of Captured Heavy Metal Ions by BSA

Ai-Huei Chiou,Jun-Luo Wei,Ssu-Han Chen

doi:10.3390/coatings11060685

Ai-Huei Chiou, Jun-Luo Wei + Show 1 more

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https://doi.org/10.3390/coatings11060685

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Abstract

A novel surface-enhanced Raman scattering (SERS)-based probe to capture heavy metal ion (Zn2+) by bovine serum albumin (BSA) using Si-nanowire (SiNW) arrays with silver nanoparticles (AgNPs) was developed. A layer with AgNPs was deposited on the SiNW surface by RF magnetron sputtering for enhancement of SERS signals. Using a high-resolution transmission electron microscope (HRTEM), the observation reveals that the AgNP layer with depths of 30–75 nm was successfully deposited on SiNW arrays. The Ag peaks in EDS and XRD spectra of SiNW arrays confirmed the presence of Ag particles on SiNW arrays. The WCA observations showed a high affinity of the Ag–SiNW arrays immobilized with BSA (water contact angle (WCA) = 87.1°) and ZnSO4 (WCA = 8.8°). The results of FTIR analysis illustrate that the conjugate bonds exist between zinc sulfate (ZnSO4) and –OH groups/–NH groups of BSA. The resulting SiNWs/Ag NPs composite interfaces showed large Raman scattering enhancement for the capture of heavy metal ions by BSA with a detection of 0.1 μM. BSA and ZnSO4 conjugations, illustrating specific SERS spectra with high sensitivity, which suggests great promise in developing label-free biosensors.

Highlights

Introduction and Marcin PisarekHeavy metal ions (Zn2+, Hg2+, and Cd2+ ), which frequently occur in the environment, medicine, and the food industry, are sources of certain chronic and acute visceral syndromes [1,2]
The Ag nanoparticles (AgNPs), which appear as the brighter area, were uniformly grown onto SiNW arrays (Figure 2b)
The results reveal that the binding of the heavy metal ion Zn2+ onto the bovine serum albumin (BSA)-immobilized Ag

Summary

Introduction

Introduction and Marcin PisarekHeavy metal ions (Zn2+ , Hg2+ , and Cd2+ ), which frequently occur in the environment, medicine, and the food industry, are sources of certain chronic and acute visceral syndromes [1,2]. Despite the fact that these techniques are precise and accurate in identification of toxic metal ions, the major disadvantages associated with them include high cost, longer execution time, and need of technically sound workers. Raman spectroscopy has been widely used for organic and surface analysis. This technique shows high sensitivity to the disorder of the structure based on the optical measurement of the surface. Owing to the development of a large-scale Raman spectroscopy system, surface-enhanced Raman spectroscopy (SERS) can analyze the vibrational signatures of material associated with its chemical information. SERS are capable of nondestructive detection and identification of molecules without exogenous labels due to the inherent vibrational frequency and Raman modes in the surface spectra [7]. The SERS effect is very fast and accurate in the detection of the biomolecules [8], antibiotics [9], Received: 26 April 2021

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