Affinity capture of escherichia coli pathotypes using poly-L-lysine functionalized silver nanoparticles

Abstract

Abstract In this study, optical detection of different pathotypes of diarrhoeagenic Escherichia coli (E. coli) was exploited using biosynthesized silver nanoparticles (AgNPs) poly-coated with Poly-L-lysine hydrobromide (PLL) and monitored at 540 nm wavelength. A colour change from reddish-brown to colourless (with brown precipitates) with different absorbance values was obtained for each pathotype within two hours of interaction. The bio-affinity sensing and selective adhesion of poly-coated AgNPs (PLL-AgNPs) and E. coli strains were best observed in Enteroaggregative E. coli (0.067 ± 0.004) and Shiga toxin E. coli (0.070 ± 0.002). Slight differences in the negatively charged O-antigen present in E. coli pathotypes informed their varying binding affinity with PLL-AgNPs. Diarrhoeagenic E. coli monitoring using PLL-AgNPs and optical sensing method is a promising approach toward preventing the use of unsafe water and improving public health.