Colorimetric Detection and Killing of Bacteria by Enzyme-Instructed Self-Aggregation of Peptide-Modified Gold Nanoparticles

Bacterial infections seriously threaten human safety. Therefore, it is very important to develop a method for bacterial detection and treatment with rapid response, high sensitivity, and simple operation. A peptide CF₄KY^P (C, cysteine; F₄, phenylalanine tetrapeptide; K, lysine; Y^P, phosphorylated tyrosine) functionalized gold nanoparticle (AuNPs-CF₄KY^P) was synthesized for simultaneous detection and treatment of bacteria based on bacterial alkaline phosphatase (ALP). In solution, ALP can induce AuNPs-CF₄KY^P aggregation and produce significant color changes. After encountering bacteria, monodisperse AuNPs-CF₄KY^P can aggregate/assemble in situ on the surface of the bacterial membrane, change the color of the solution from wine red to grey, destroy the bacterial membrane structure, and induce the production of a large number of reactive oxygen species within the bacteria. The absorption change of AuNPs-CF₄KY^P solution has a good linear relationship with the number of bacteria. Furthermore, the aggregation of AuNPs-CF₄KY^P kills approximately 80% of <i>Salmonella typhimurium</i>. By combining enzyme-instructed peptide self-assembly technology and colorimetric analysis technology, we achieve rapid and sensitive colorimetric detection and killing of bacteria.