Synthesis and characterization of novel positively charged gold nanoparticle for the detection of food contaminants

The suggested work emphasizes the benefits of employing positively charged gold nanoparticles to detect negatively charged E.coli cells by electrostatic attraction without the need of any identification elements. As a result, a simple, label-free colorimetric biosensor for detecting E.coli, a well-known food contaminant, was developed. Initially, the Taguchi approach was used to synthesis small, stable, and positively charged Au NPs in orthogonal array L8 by optimizing 5 critical parameters such as pH, capping agents, temperature, Sonication duration, and Au/LE ratio. Based on the Maximum wavelength (λ max) values and ANOVA, Trail 3 (T3) a Polyallyl amine hydrochloride capped Au NPs (PAH-Au NPs) along with D-Mannose was chosen to be employed in detecting E.coli. It functions as a colorimetric sensor in both sol and paper coated forms. Based on the sensing technique, we discovered that the LOD in sol is (1*105CFU/mL), which is significantly higher than the sensor based on paper (1*102 CFU/mL).