Target-induced aptamer release strategy based on electrochemical detection of staphylococcal enterotoxin B using...

A novel electrochemical aptasensor was developed for ultrasensitive detection of staphylococcal enterotoxin B (SEB) by combining signal amplification and target-induced aptamer release strategy. A gold electrode was modified with a nanocomposite made of gold nanoparticles reduced in situ, zirconia nanoparticles, and chitosan. The SEB aptamer was hybridized by anchoring the capture probe on the modified gold electrode surface through AuS binding. In the presence of SEB, the capture probe-aptamer duplex was compelled to open, releasing the aptamer from the electrode. The resulting single-strand capture probe was hybridized with a biotinylated detection probe and labeled with streptavidin-horseradish peroxidase, producing an ultrasensitive enzyme-catalyzed electrochemical signal. Under optimal conditions, the amperometric responses were proportional to the SEB concentrations ranging from 2 to 512ngmL(-1), with a detection limit of as low as 0.24ngmL(-1) (S/N=3). The aptasensor exhibited good stability, outstanding reproducibility, and high selectivity. The as-prepared aptasensor was used to analyze SEB in human serum specimens, and validated through enzyme-linked immunosorbent assay method. Analytical results suggest that the developed assay is a promising alternative approach for detecting SEB in clinical diagnosis.