Ultrasensitive electrochemiluminescence sensor based on nitrogen-decorated carbon dots for Listeria monocytogenes...

Current method for identification of foodborne pathogens suffers from its relatively poor performance, consequently limiting its use. Herein, we first describe an ultrasensitive electrochemiluminescence (ECL) sensor based on nitrogen-decorated carbon dots (NCDs) for Listeria monocytogenes (L. monocytogenes) determination using a screen-printed carbon electrode (SPCE). Citric acid serves as carbon source, and ethylenediamine, a molecule containing nitrogen atom, is employed to synthesize CDs. Approximately 4 nm NCD with homogenous size distribution can be produced via a single step green microwave-assisted methodology. The construction of ECL sensor is initiated by the immobilization of capture antibody (Ab1) onto the carboxyl graphene (GOOH)-modified SPCE, where immunocomplexes (antigen and the NCD-labelled secondary antibody (Ab2-NCD)) are formed, resulting in a substantial increment in the ECL signal response in the presence of K₂S₂O₈. The GOOH allows direct formation of the capture antibodies and enhances the electrochemical properties. Under optimal parameters, this sensor exhibits wide linearity (2 to 1.0 × 10⁶ CFU mL^-1), high sensitivity (0.104 or 1.0 × 10^-1 CFU mL^-1) and specificity over the nontargeting studied pathogens and is successfully applied to determine L. monocytogenes in food products. These promising results together with its performance suggest that this proposed platform may serve as an alternative device to effectively control the spread of foodborne diseases.