A simple, rapid and cost-effective colorimetric assay based on the 4-mercaptophenylboronic acid functionalized silver nanoparticles for bacteria monitoring

Abstract

The rapid and cost- effective detection of bacteria is of great importance in various fields. Herein, a novel colorimetric detection method for Gram-negative bacteria based on the inhibition of the aggregation of 4-mercaptophenylboronic acid functionalized AgNPs (MPBA-AgNPs) was demonstrated. MPBA, one of the boronic acid derivative, which could react with the cis-diol groups contained in saccharides on the bacteria cells, was used as the recognition molecule for bacteria detection. The aggregation of MPBA-AgNPs could be inhibited by bacterial cells, resulting in different color change, which could be distinguished with UV–vis spectrometer and the naked eye. The concentration of E. coli, a model of Gram-negative bacteria, could be determined in a dynamic range from 5 × 104 cfu mL−1 to 1 × 107 cfu mL−1 with a LOD of 0.9 × 104 cfu mL−1 with fast response of 20 min. Meanwhile, a smartphone based measuring analysis was established to make it suitable for routine laboratory applications. Moreover, the concept of the MPBA-AgNPs based colorimetric strategy could be expanded to other Gram-negative bacteria suggesting a universal platform for bacterial assay.