Binding of p-mercaptobenzoic acid and adenine to gold-coated electroless etched silicon nanowires studied by surface-enhanced Raman scattering

Vlasta Mohaček-Grošev; Hrvoje Gebavi; Alois Bonifacio; Valter Sergo; Marko Daković; Danica Bajuk-Bogdanović

doi:10.1016/j.saa.2018.04.016

Binding of p-mercaptobenzoic acid and adenine to gold-coated electroless etched silicon nanowires studied by surface-enhanced Raman scattering

Spectrochim Acta A Mol Biomol Spectrosc. 2018 Jul 5:200:102-109. doi: 10.1016/j.saa.2018.04.016. Epub 2018 Apr 10.

Authors

Vlasta Mohaček-Grošev¹, Hrvoje Gebavi², Alois Bonifacio³, Valter Sergo³, Marko Daković⁴, Danica Bajuk-Bogdanović⁴

Affiliations

¹ Centre of Excellence for Advanced Materials and Sensing Devices, Ruđer Bošković Institute, Bijenička cesta 54, 10002 Zagreb, Croatia. Electronic address: Vlasta.Mohacek.Grosev@irb.hr.
² Centre of Excellence for Advanced Materials and Sensing Devices, Ruđer Bošković Institute, Bijenička cesta 54, 10002 Zagreb, Croatia.
³ University of Trieste, Via Valerio 6/A, Trieste, Italy.
⁴ Faculty of Physical Chemistry, University of Belgrade, Studentski trg 15-16, 11000 Belgrade, Serbia.

PMID: 29677496
DOI: 10.1016/j.saa.2018.04.016

Abstract

Modern diagnostic tools ever aim to reduce the amount of analyte and the time needed for obtaining the result. Surface-enhanced Raman spectroscopy is a method that could satisfy both of these requirements, provided that for each analyte an adequate substrate is found. Here we demonstrate the ability of gold-sputtered silicon nanowires (SiNW) to bind p-mercaptobenzoic acid in 10^-3, 10^-4 and 10^-5M and adenine in 30 and 100μM concentrations. Based on the normal mode analysis, presented here for the first time, the binding of p-mercaptobenzoic acid is deduced. The intensity enhancement of the 1106cm^-1 band is explained by involvement of the CS stretching deformation, and the appearance of the broad 300cm^-1 band attributed to SAu stretching mode. Adenine SERS spectra demonstrate the existence of the 7H tautomer since the strongest band observed is at 736cm^-1. The adenine binding is likely to occur in several ways, because the number of observed bands in the 1200-1600cm^-1 interval exceeds the number of observed bands in the normal Raman spectrum of the free molecule.

Keywords: Biosensors; Hot spots mapping; Mercaptobenzoic acid; Normal mode analysis; SERS; Silicon nanowires; Substrate binding.