Abstract

As health and environmental challenges become more complex, the demand for innovative sensing technologies capable of simultaneously detecting multiple disease indicators and contaminants is critical. This research introduces a wireless dual laser-induced graphene (LIG) aptasensor, utilizing LIG electrodes (LIGEs) for sensitive and selective detection of two significant foodborne pathogens: Salmonella enterica serovar Typhimurium (S. Typhimurium) and Shigella dysenteriae (S. dysenteriae). The aptasensor features a four-electrode configuration, enabling portable and simultaneous measurements. LIGEs outperform traditional screen-printed graphene electrodes (SPGEs), offering enhanced sensitivity, sustainability, and scalability. To further enhance these properties, plasma treatment was applied to address the hydrophobic nature of LIG, improving its surface characteristics prior to functionalization. Silver nanocorals (AgNCs) were electrodeposited, serving as immobilization platforms for specific aptamers and efficient signal tags. Thiolated aptamers were self-assembled onto the modified LIGE, followed by a two-step blocking process with mercaptohexanol (MCH) and skim milk (SM) for effective antifouling. The aptasensor detected electrochemical signal changes from AgNC oxidation using rapid linear sweep voltammetry (LSV). It demonstrated excellent linearity for simultaneous detection of S. Typhimurium and S. dysenteriae at concentrations from 10¹ to 10⁵ CFU/mL, with low detection limits (LODs) of 1.24 and 1.26 CFU/mL, respectively. With good repeatability, high specificity, and stability, this portable aptamer-based sensing platform shows promise for on-site evaluation of disease indicators and environmental contaminants in clinical, food, and environmental samples.