An ultrasensitive, rapid and low-cost immuno-detection platform for bacteria and protein biomarkers using field-effect enzymatic detection

A novel immuno-detection system has been constructed by incorporating the newly invented field-effect enzymatic detection (FEED) technique with the immunosensing technique to demonstrate a novel detection platform. The demonstration consists of the detections of three biomarkers and two bacteria. The detected biomarkers include CA125, PSA in serum and AMACR (a novel marker for prostate cancer) in serum and urine. The PSA and AMACR detections were performed on the femto gram/mL level. The two detected bacteria are E. coli and Shigella. E. coli was detected in milk and meat juice with detection limits on the order of 10 CFU/mL. Because of the intrinsic amplification provided by FEED, the detection was performed without the culture-based amplification, resulting in a significantly shortened assay time of 1 hr. The detection system was realized on screen printed electrodes (SPE). This method, compared with current detection methods, provides three distinctive advantages: (1) ultrasensitive detection of bacteria (10 CFU/mL) and biomarkers (fg/mL) in complex matrices, (2) real-time/rapid detection (1 hour) of bacteria without the culture process, and (3) low-cost detection (<$5/SPE). The patented method can be used as an ultrasensitive, rapid detection platform for point-of-care, disposable and low-cost applications.