A rapid and label-free SERS detection method for biomarkers in clinical biofluids

Most approaches in clinical diagnostics are accomplished using laboratory-based sandwich-type immunoassays which are, however, tedious, time-consuming and require experienced personnel, making them unsuitable as a rapid, high-throughput clinical diagnostic method. Similarly, current detection methods that are based on fluorescence and surface plasmon resonance (SPR) face the challenges of interference from sample matrix background, and long analysis time. The poor sensitivity can be circumvented through the use of protein-induced aggregation of silver colloids, but silver nanoparticles are known to induce protein conformational changes readily. This approach is also unsuitable with clinical samples that have high ionic strength as silver nanoparticle aggregation, and hence signal fluctuation, is enhanced.