Investigation of glucose biosensors by non-enzymatic photoluminescent detection using oleic acid treated Ag2S nanoparticles

Abstract

The immobilization of carboxylic acid moieties on the surface of nanoparticles to promote the development of non-enzymatic detection of target molecules (sensors) with better feasibility and selectivity has been investigated. This work is focused on treating Ag2S nanoparticles with Oleic acid, a potential carboxylic acid moiety with good stereochemical compatibility, photochemical responses, photoluminescence (PL) quantum yield, and biocompatibility. The hydrothermally synthesized Ag2S was crystalline in nature with a monoclinic crystal system, as inferred from X-ray diffractograms. The surface morphology of Ag2S studied using the SEM micrographs showed nearly spherical and fused particles. ATR-FTIR was recorded by the compensation method in the wavenumber range 600–4000 cm−1 and the changes in the chemical composition of pristine Ag2S and Oleic acid-treated Ag2S (with or without glucose molecules) were investigated. UV–Vis analysis was carried out to establish the absorption region of the respective nanoparticles, and the corresponding inferred excitation wavelength (396 nm) was fixed for the PL analysis. Photoluminescence spectra (PL) of Ag2S with oleic acid and glucose at various concentrations showed a reduction in PL intensity as glucose concentration increased. This PL reduction arises due to various oxidation processes that take place on the large surface of Oleic acid-treated Ag2S. Chronoamperometric studies were used to analyze the electrocatalytic glucose oxidation that occurs in Ag2S nanoparticles with Oleic acid with a low-cost procedure. The concentration of glucose was varied from 0.25 to 30 mM, and the significant sensing abilities of the oleic acid-treated Ag2S were demonstrated.