Immunoreaction-based Microfluidic Diagnostic Device for the Detection of Prostate-Specific Antigen

Abstract

This paper addresses an immunoreaction period-independent microfluidic diagnostic method for the detection of prostate-specific antigen. Immunoreaction-based biosensors generally use sandwich binding of a capture antibody, followed by an antigen, and then a detection antibody with a fluorescent label. Fluorescent intensity is proportional not only to the antigen density in a sample but also to the immunoreaction period. Generally, immunoreaction-based sensors are dependent on the immunoreaction period because the amount of antigen bound to fluorescent labels increases as the immunoreaction period increases. A wash-out step is suggested to eliminate dependence on a specific reaction period. Further, the optimal time to start the wash-out step was investigated. For the conventional detection process, fluorescent intensity increases constantly as the immunoreaction period increases, even though the antigen concentration in the sample has not changed. After applying the wash-out process, however, the fluorescent intensity was maintained over a 15-min period. Consequently, even though a user may miss the optimal reading time for the assay, an accurate result can be reported because the wash-out step enables microfluidic diagnostic devices to maintain a constant fluorescent intensity.