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

Abstract

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@CuNcPOPTP) as well as the self-chain linking process. The hollow organic-inorganic nanocomposite (PHCS@CuNcPOPTP) was prepared by a one-step Friedel-Crafts alkylation reaction. The PHCS@CuNcPOPTP exhibited excellent and synergistically enhanced light-driven oxidase-like activity originating from its unique photosensitive properties. Subsequently, PHCS@CuNcPOPTP was served as a scaffold, loading with the rabbit anti-Staphylococcus aureus Rosenbach tropina antibody (bs-4582R, Ab2), DNA1, and DNA2, respectively, to construct signal probes (PHCS@CuNcPOPTP@Au-Ab2/DNA1, PHCS@CuNcPOPTP@Au-DNA1, and PHCS@CuNcPOPTP@Au-DNA2). By the repetitive DNA hybridization among signal probes, a large amount of PHCS@CuNcPOPTP-DNA dendrimers were formed and utilized to trigger the chromogenic reaction without the participation of high-concentration H2O2, 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).