Silver-Based SERS Pico-Molar Adenine Sensor

Abstract

Adenine is an important molecule for biomedical and agricultural research and applications. The detection of low concentration adenine molecules is thus desirable. Surface-enhanced Raman scattering (SERS) is a promising label-free detection and fingerprinting technique for molecules of significance. A novel SERS sensor made of clusters of silver nanostructures deposited on copper bumps in valleys of an etched silicon substrate was previously reported to exhibit a low and reproducible detection limit for a 10−11 M neutral adenine aqueous solution. Reflection of laser illumination from the silicon surface surrounding a valley provides additional directions of laser excitation to adenine molecules adsorbing on a silver surface for the generation of enhanced SERS signal strength leading to a low detection limit. This paper further reports a concentration dependent shift of the ring-breathing mode SERS adenine peak towards 760 cm−1 with decreasing concentration and its pH-dependent SERS signal strength. For applications, where the pH value can vary, reproducible detection of 10−12 M adenine in a pH 9 aqueous solution is feasible, making the novel SERS structure a desirable pico-molar adenine sensor.

A simple and reliable approach for the fabrication of nanoporous silver patterns for surface-enhanced Raman spectroscopy applications

“…It is worth noticing that, according to Ref. 45 ,an increase of the measured EF (up to almost an order of magnitude) can be obtained by increasing the buffer pH value from 7 to 9.…”

Wafer-scale silver nanodendrites with homogeneous distribution of gold nanoparticles for biomolecules detection

“…Surface-enhanced Raman spectroscopy/scattering (SERS) is one of the most fascinating analytic techniques for rapid, in-field, single-shot detection of analyte molecules finding impending applications in biomedicine, clinical, environmental detection, food safety, and so forth. ( Vendamani et al, 2022 ; Verma and Soni, 2022 ; Tzeng and Lin, 2020 ; Zhang et al., 2013 ; Powell et al., 2017 ; Ouyang et al., 2018 ; Xu et al., 2018 ; Zhu et al., 2021 ). This technique has also been favored in food inspection via examining antibiotic deposits in animal products ( Lirio et al., 2016 ; Li et al., 2015 ).…”

Trends in Application of SERS Substrates beyond Ag and Au, and Their Role in Bioanalysis

“…Numerous SERS studies have been conducted to detect this molecule and one of the best reported LOD was achieved by Tzeng and Lin who could detect down to 10 picomolar neutral adenine solutions with good reproducibility by using Ag@Cu@Si substrate. Further, 1 picomolar detection was achieved with the same substrate by taking SERS measurements of the aqueous adenine solution at a pH of 9 [ 266 ]. Other silicon-based substrates such as AgNC@SiO 2 on a polymethylhydrosiloxane modified filter paper and AuNP@FePt@SiO 2 demonstrated the enhancement by 6–7 orders of magnitude and LOD of about 1 nM [ 101 , 231 ].…”