Combination of alkaline phosphatase/graphene oxide nanoconjugates and D-glucose-6-phosphate–functionalized gold nanoparticles for the rapid colorimetric assay of pathogenic bacteria

Abstract

Pathogenic bacteria are a major cause of foodborne diseases, which not only seriously threaten human safety but also cause significant losses for the national economy. Therefore, it is very important and urgent to develop a method for the detection of pathogenic bacteria with high accuracy, high sensitivity, and easy interpretation for use in food safety and medical hygiene. Herein, based upon the sensitive color changes induced by the dispersion and aggregation states of gold nanoparticles (AuNPs), a point-of-care (POCT) colorimetric assay was constructed for the rapid and sensitive visual detection of pathogenic bacteria. The POCT visual sensing system is composed of two individual elements: (1) an alkaline phosphatase/graphene oxide (GO@PEI-ALP) nanoconjugate that can release free ALP molecules in the presence of pathogenic bacteria; (2) D-glucose-6-phosphate (pGlu) and 3-aminobenzene boric acid (AMBA)-functionalized AuNPs (pGlu/AMBA-AuNPs) that are cross-linked upon the digestion of pGlu by free ALP molecules, resulting in a significant color change. Under optimized conditions, the detection limit of this sensing system for target bacteria was as low as 24 CFU mL−1 and was successfully applied to complex real samples. This proposed rapid colorimetric assay has high sensitivity, accuracy, and practicability with an intuitive signal and is expected to provide new inspiration for the detection of pathogenic bacteria.