A novel NiCoFe LDH-based aptasensor for rapid colorimetric detection of Staphylococcus aureus in milk

Abstract Foodborne pathogens, especially Staphylococcus aureus ( S. aureus ), pose a major risk to public health. The currently employed methods to detect such a microorganism are often time-consuming and require specialized equipment. To overcome these obstacles, we designed a nanozyme-based colorimetric aptasensor that employs a simple platform to facilitate the rapid detection of S. aureus in milk. It utilizes a DNA aptamer functionalized NiCoFe-layered double hydroxide (LDH) nanoparticles that can bind specifically to the S. aureus outer membrane. NiCoFe-LDH nanoparticles are utilized as peroxidase enzyme mimics that can oxidize the TMB substrate leading to a blue color. The DNA aptamers’ binding on the surface of NiCoFe-LDH led to an enhancement of the nanozyme activity. Hence, upon the presence of the S. aureus , the aptamers detached from the NiCoFe-LDH NPs to bind to their targeted molecule resulting in lower color intensity. Under optimal conditions, the aptasensor could detect 10 CFU/mL of S. aureus with high specificity. To our understanding, this is the first report of an aptasensor based on NiCoFe-LDH nanozyme for the detection of S. aureus .