Large‐Area Silver‐Coated Silicon Nanowire Arrays for Molecular Sensing Using Surface‐Enhanced Raman Spectroscopy

Abstract

A new and facile method to prepare large‐area silver‐coated silicon nanowire arrays for surface‐enhanced Raman spectroscopy (SERS)‐based sensing is introduced. High‐quality silicon nanowire arrays are prepared by a chemical etching method and used as a template for the generation of SERS‐active silver‐coated silicon nanowire arrays. The morphologies of the silicon nanowire arrays and the type of silver‐plating solution are two key factors determining the magnitude of SERS signal enhancement and the sensitivity of detection; they are investigated in detail for the purpose of optimization. The optimized silver‐coated silicon nanowire arrays exhibit great potential for ultrasensitive molecular sensing in terms of high SERS signal enhancement ability, good stability, and reproducibility. Their further applications in rapidly detecting molecules relating to human health and safety are discussed. A 10 s data acquisition time is capable of achieving a limit of detection of approximately 4 × 10−6 M calcium dipicolinate (CaDPA), a biomarker for anthrax. This value is 1/15 the infectious dose of spores (6 × 10−5 M required), revealing that the optimized silver‐coated silicon nanowire arrays as SERS‐based ultrasensitive sensors are extremely suitable for detecting Bacillus anthracis spores.

Electrochemical Etching Methods for Producing Porous Silicon

“…For these reasons, metal-assisted etching of silicon has become an alternative approach to conventional electrochemical etching methods. Porous silicon structures produced by this approach have demonstrated their applicability in a broad range of fields such as sensing, energy storage and conversion and so on [99][100][101][102][103][104][105][106][107][108][109][110]. Metal-assisted etching of silicon was pioneered by Dimova et al in 1997 when they etched a silicon substrate covered by a thin film of aluminium in a solution composed of HF, HNO 3 and H 2 O 2 [111].…”

Magnetite/reduced graphene oxide nanocomposites: One step solvothermal synthesis and use as a novel platform for removal of dye pollutants

“…To evaluate whether the new adsorbent developed here was suitable for practical applications [58,59], real water samples, including local industrial waste water, and lake water collected from Lake Tai in China, were treated using the as-prepared MRGO. The experiments were conducted by adding dyes to the real water samples and then investigating the removal efficiency by adding 0.7 g/L of MRGO.…”

Silicon-Based Platform for Biosensing Applications

“…In particular, metallic nanoparticles-decorated silicon materials have been extensively studied. Notably, AgNPs/AuNPs aggregation can be efficiently prevented since AgNPs are steadily anchored on the surface of silicon materials [91][92][93][94][95][96][97][98][99][100][101][102][103][104][105][106][107][108][109]. For example, Lee et al employed AgNPs/AuNPs-coated SiNWs as highly active SERS substrate (enhancement factor (EF): 10 11 ) for sensitive detection of a variety of chemical and biological species (e.g., Rhodamine 6G, crystal violet, nicotine and DNA) [97].…”

“…Besides, such AgNPs@SiNWs array was also suitable for ultrasensitive protein analysis and immunoassay, allowing detection of trace amounts (4 ng) of mouse immunoglobulinG and goat-anti-mouse immunoglobulin G [98]. Cheng and coworkers explored SiNWs arrays coated with silver as an efficient SERS substrate, allowing detection of Calcium dipicolinate with a low concentrations of *10-6 M [91]. Boukherroub et al used highly SERS-active (EF: *10 8 ) AgNPs-capped SiNWs for sensitive detection of low-concentration (10-1 4 M) R6G [99].…”