Colorimetric detection of Staphylococcus aureus based on self-linkable and hollow organic-inorganic nanocomposites as light-driven oxidase-like nanozyme for cascade signal amplification.

Facing increasingly serious bacterial infections and their threat to food safety and human health, exploring specific and sensitive bacterial strategies is indispensable. Nanozyme-based colorimetric biosensors with the superiorities of easy-to-read and catalytic signal amplification have attracted increasing interest. However, few investigations relate to the nanozymes with excellent light-driven oxidase-like activity. In this study, a sensitive colorimetric biosensor for Staphylococcus aureus (S. aureus) detection was constructed based on a light-driven oxidase-like nanozyme (PHCS@CuNcPOP TP) as well as the self-chain linking process. The hollow organic-inorganic nanocomposite (PHCS@CuNcPOP TP) was prepared by a one-step Friedel-Crafts alkylation reaction. The PHCS@CuNcPOP TP exhibited excellent and synergistically enhanced light-driven oxidase-like activity originating from its unique photosensitive properties. Subsequently, PHCS@CuNcPOP TP was served as a scaffold, loading with the rabbit anti- Staphylococcus aureus Rosenbach tropina antibody (bs-4582R, Ab 2), DNA1, and DNA2, respectively, to construct signal probes (PHCS@CuNcPOP TP @Au-Ab 2 /DNA1, PHCS@CuNcPOP TP @Au-DNA1, and PHCS@CuNcPOP TP @Au-DNA2). By the repetitive DNA hybridization among signal probes, a large amount of PHCS@CuNcPOP TP -DNA dendrimers were formed and utilized to trigger the chromogenic reaction without the participation of high-concentration H 2 O 2 , resulting in the cascaded catalytic amplification and the lower background signal. As expected, the suggested sensing platform presented ultrasensitive bacterial detection with a remarkably broad linear range (101 to 108 CFU/mL) and a limit of detection (LOD, 3.40 CFU/mL). • PHCS@CuNcPOP TP demonstrated synergistically enhanced light-driven oxidase-like activity. • CuNcPOP TP possessed excellent light absorption/collection efficiency. • The background signal was effectively reduced by avoiding the direct participation of H 2 O 2. • A sensitive colorimetric biosensor based on the self-chain linking process was fabricated. [ABSTRACT FROM AUTHOR]