Ultrasensitive Detection of Prostate-Specific Antigen Using a SERS-Based Magnetic Immunosensor

Concentrations of disease biomarkers and their changes are crucial for the diagnosis and monitoring of diseases, so detecting and capturing small changes in biomarkers is especially important. This study demonstrates a surface-enhanced Raman scattering (SERS)-active magnetic immunosensor using a signal amplification strategy for the ultrasensitive detection of prostate-specific antigen (PSA). The sensor consists of a biotin-modified aptamer (B-Apt) and a PSA antibody (Ab) labeled on magnetic beads (MBs), which can immobilize and anchor the target PSA when it is present. After sequential addition of streptavidin and a signal probe, the generated streptavidin-biotin complex reacts to form a three-dimensional network, thereby increasing the number of signal molecules to achieve signal amplification, with the detection limit of 0.87 pg/mL. In addition, this method was also performed to detect PSA in human serum samples. It is believed that this method provides a more sensitive tool for detecting PSA or other biomarkers in clinical samples.