Design of portable biosensor assay using multifunctional carbon nanosheets for on-site monitoring of Staphylococcus Aureus in water and food samples

Abstract: Recently, there has been an urgent need to develop portable and wearable analytical devices for applications in healthcare and environmental monitoring. These devices can assist in the on-site detection of waterborne and foodborne pathogens, allowing epidemic prevention. Staphylococcus aureus (S. Aureus), a drug-resistant bacterium, is known to cause various diseases and could exist in food and water samples. To address this, we have developed a label-free portable electrochemical immunosensor for the rapid and on-site detection of S. Aureus with high sensitivity and selectivity in food and water samples. This sensor features a nanoengineered design utilizing 3D nitrogen-, phosphorus-, and sulfur-doped carbon nanosheets (3D-NPS-doped CNSs). The 3D-NPS-doped CNSs show a three-dimensional structure with abundant and multiple vacant sites, a hierarchical framework, a large surface area, and rough nanosheet surfaces. These nanosheets are 50 to 60 nm thick and contain heteroatoms (N, P, and S) on their outer surfaces and within the graphitic carbon network, facilitating surface functionalization and creating multiple active centers for the creation of numerous active centers and high loading of monoclonal antibodies (anti-S. Aureus). The portable immunosensor based on 3D-NPS-doped CNSs offers high sensitivity, a low detection limit of 24 CFU/mL, and selectivity, providing accurate and precise detection of S. Aureus. This sensor offers a fast, user-friendly, and precise method for on-site screening and rapid detection of S. Aureus in food and water samples. Highlights: • A controlled synthesis process was developed for three-dimensional carbon-based materials with novel properties. • Nitrogen, phosphorus, and sulfur were actively doped into carbon materials (3D-NPS-doped CNSs). • A portable electrochemical immunosensor assay was created to detect Staphylococcus aureus. • A sensitive and selective bioassay was achieved for detecting Staphylococcus aureus in food and water samples.