Dopamine-mediated immunoassay for bacteria detection

Traditional enzyme-linked immunosorbent assay (ELISA) with sufficient sensing specificity is a useful analytical approach for the detection of toxicologically important substances in in vivo systems or complicated biological systems. Increasing worldwide demand for analyses of bacteria by signal amplification and increasing concern regarding their safe development and use require a simple, stable, and sensitive detection assay for target evaluation and clinical diagnosis. A sensitive and selective immunoassay for detection of bacteria is constructed that combines horseradish peroxidase (HRP)-catalyzed signal amplification with the strong linker of the polydopamine-biotin complex on the surface of solid substances or biomolecules. The incorporation of HRP labeling and amplification increases the detection sensitivity by about one to two orders of magnitude compared with conventional ELISA systems. A linear relationship between the response and the logarithm of the bacterial concentration was observed in the range from 1.5 x 10(2) to 1.5 x 10(7) colony-forming units per milliliter. This work demonstrates a new signal-amplification-based dopamine-mediated process for the development of a sensitive method. This dopamine-mediated immunoassay may be broadly applied in clinical diagnoses and for the monitoring of water environmental pollution. The approach proposed is distinct with simple protocols and easy processes, which allow it to be applied in a broad area.