The use of nanoparticles in sensing is attracting the interest of many researchers. The aim of this work was to fabricate Acacia gum-stabilised silver nanoparticles (SNPs) using green chemistry to use them as a highly sensitive and cost-effective localised surface plasmon resonance (LSPR) colorimeter sensor for the determination of reactive oxygen species, such as hydrogen peroxide (H2O2). Silver nanoparticles were fabricated by the reduction of an inorganic precursor silver nitrate solution (AgNO3) using white sugar as the reducing reagent and Acacia gum as the stabilising reagent and a sonication bath to form uniform silver nanoparticles. The fabricated nanoparticles were characterised by visual observation, ultraviolet-visible (UV-Vis) spectrophotometry, transmission electron microscopy (TEM) analysis, energy-dispersive X-ray spectroscopy (EDAX), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR). The TEM micrographs of the synthesised nanoparticles showed the presence of spherical nanoparticles with sizes of approximately 10 nm. The EDAX spectrum result confirmed the presence of silver (58%), carbon (30%), and oxygen (12%). Plasmon colorimetric sensing of H2O2 solution was investigated by introducing H2O2 solution into Acacia gum-capped SNP dispersion, and the change in the LSPR band in the UV-Vis region of spectra was monitored. In this study, it was found that the yellow colour of Acacia gum-stabilised SNPs gradually changed to transparent, and moreover, a remarkable change in the LSPR absorbance strength was observed. The calibration curve was linear over 0.1-0.00001 M H2O2, with a correlation estimation (R2) of .953. This was due to the aggregation of SNPs following introduction of the H2O2 solution. Furthermore, the fabricated SNPs were successfully used to detect H2O2 solution in a liquid milk sample, thereby demonstrating the ability of the fabricated SNPs to detect H2O2 solution in liquid milk samples. This work showed that Acacia gum-stabilised SNPs may have the potential as a colour indicator in medical and environmental applications.
Keywords: Acacia gum; Silver nanoparticles; hydrogen peroxide; localised surface plasmon resonance; white sugar.