Tailor-made porous striped gold-silver nanowires for surface enhanced Raman scattering based trace detection of β-hydroxybutyric acid

This paper presents a novel fabrication of series of striped (S) and porous striped (PS) gold-silver alloy nanowires (Au-Ag alloy NWs). First, S-Au-Ag alloy NWs were fabricated using anodic aluminum oxide (AAO) template-based electrodeposition technique. The length of the Au-Ag alloy segments was easily tailored by adjusting the deposition pulse time. The surface roughening of Au-Ag alloy nanowires was controlled via dealloying method, resulting in formation of periodic nanogaps between Au alloy nanodisks. This structure was called PS-Au-Ag alloy NWs. The structure of the gap between Au alloy nanodisks was proved to be the key parameter to influence the SERS enhancement ability of nanomaterials. The SERS performance was performed using 4-mercaptobenzoic acid (4-MBA) as a Raman probe molecule. The remarkable SERS enhancement factor of a wire was about 10(5). The uniformity of NWs was in an acceptable value of relative standard deviation and the NWs showed good stability during 3 months storage time. Moreover, this work was the first demonstration of beta-hydroxybutyric acid (BHB) detection using SERS as signal readout with low detection limit about 11 nM. It has been shown that a single PS-Au-Ag alloy NWs exhibited great promise in highly sensitive SERS substrates.