Poly(L-DOPA)-mediated bimetallic core−shell nanostructures of gold and silver and their employment in SERS, catalytic activity, and cell viability

Abstract

Core–shell gold nanorod (AuNR)@silver (Ag) nanostructures with their unique properties have gained enormous interest and are widely utilized in various applications including sensor systems, catalytic reactions, diagnosis, and therapy. Despite the recent progress, simple, effective, low-cost, and easy-to-tune strategies are heavily required to fabricate these nanoparticles (NP) systems. For this, we propose the employment of the polymer of 3,4-dihydroxyphenyl-L-alanine (L-DOPA) as a ligand molecule. A conformal thin layer of polymer of L-DOPA (PLDOPA) with its various functional groups enabled the reduction of silver ions onto the AuNRs and stabilization of the resultant NPs without using any surfactant, reducing agent, and seed material. The shape and growth model of the AuNR@Ag nanostructures was manipulated by simply tuning the amount of silver ions. This procedure created different NP morphologies ranging from concentric to acentric/island shape core–shell nanostructures. Also, even at the highest Ag deposition, the PLDOPA layer is still conformally present onto the Au@Ag core–shell NRs. The unique properties of NP systems provided remarkable characteristics in surface-enhanced Raman spectroscopy, catalytic activity, and cell viability tests.

Electrochemical aspects of coinage metal nanoparticles for catalysis and spectroscopy

“…113 Subsequently, the manipulation of gold and silver particles has found innumerable applications in surface-enhanced Raman scattering (SERS) studies. 114,115 Recently, copper nanoparticles have been exploited as an SERS substrate. 116 Currently, SERS is considered the most sensitive and selective analytical detection method.…”

Catalytic and SERS activities of WO3-based nanowires: the effect of oxygen vacancies, silver nanoparticle doping, and the type of organic dye

“…40 Shortly, the SERS effect is created through two mechanisms: electromagnetic enhancement (EE) which depends on the enhancement of the electromagnetic fields, and chemical enhancement (CE) which originates from the emergence of charge-transfer complexes between the analyte molecule and the SERS substrate. [40][41][42][43][44] WO 3Àx nanosystems provide opportunities in terms of stability and low cost. Also, due to the oxygen vacancies, WO 3Àx exhibits noble metal-comparable SERS activity through the CE.…”