Colorimetric Detection Based on Localised Surface Plasmon Resonance Optical Characteristics for the Detection of Hydrogen Peroxide Using Acacia Gum–Stabilised Silver Nanoparticles

Abstract

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.

Colorimetric Detection Based on Localized Surface Plasmon Resonance Optical Characteristics for Sensing of Mercury Using Green-Synthesized Silver Nanoparticles

“…ere is correspondence between polysaccharideoriented aromatic C − C stretching vibrational modes and anionic carboxylate group and the absorption band at 1660 cm − 1 [81]. is is in good agreement with the report done by Alzahrani et al [52,82]. e nanoparticles gain further stability when functionalization of silver nanoparticles that herbal extracts synthesized is undertaken using polysaccharides and aromatic compounds as documented within the FT-IR analysis.…”

“…Formation of Green AgNPs. For use in analytical applications, stable silver nanoparticles should be synthesized against the dilution, over ionic strength, different pH ranges, and long storage period [28,48,52]. In this study, wetchemical green synthesis was used for preparing the green silver nanoparticles because it constituted the most prevalent procedure for fabricating uniform nanoparticles with regulated sizes and strong silver nanoparticles alongside their colloidal dispersions in organic solvents or water [54][55][56].…”

“…ere was a change in colour from yellow, light yellow, and light salmon to clear/transparent after different volumes of mercury II solution was introduced incrementally from 0 to 1400 µL, as illustrated in the photograph for silver nanoparticle solution in Figure 10(a). Notably, the trend is significantly attributed to silver nanoparticle oxidation by mercury II ions caused by greater mercury/mercury ion potential (0.851 V), as opposed to silver/silver ions (0.799 V) [52,87]. e reduction of silver nanoparticle LSPR band intensity was visible with mercury II ions.…”

“…Indeed, the linear correlation involving the unreacted silver nanoparticles after loading mercury ions followed by the conventional galvanic reaction and the measured intensity of absorption constitutes the premise for the quantitative feedback titration approach. For construction of the calibration curve (A str vs Hg 2+ volume), the change in conventional absorbance strength at optimum absorption wavelength was measured in form of absorption ratio A str denoted by the following equation [51,52]:…”

Citrate-silver nanoparticles and their impact on some environmental beneficial fungi

“…This could be caused by the complex composition of the citrate-AgNP suspension, involving dynamical electric phenomena at the AgNP surface, for example due to silver and sodium ions available for electron acceptance, ( Mogensen and Kneipp, 2014 ). However according to Alzahrani (2017) up to date it was not established any general rule for the LSPR band shift because of numerous factors that could influence that spectral behavior: particle size, shape, dimensional distribution, particle association, but also molecular vicinity – mainly coating shell properties, and suspension composition, reflected especially the pH and the refractive index ( Pillai and Kamat, 2004 ), Badawy et al, 2010 ). Thus, because of combined actions of such factors there is rather difficult to explain the LSPR band position; according to Campos et al (2019) , in some cases, in citrate coated AgNPs suspension, compared to naked particles in water suspension, there could be observed a blue-shift, while in other, apparently similar cases, there is a red-shift or no band shifting at all.…”