Optoelectrofluidic sandwich immunoassays for detection of human tumor marker using surface-enhanced Raman scattering

A sandwich immunoassay is a powerful tool for identifying a specific substance in a biological sample. However, its heterogeneous strategy always requires repetitive liquid handlings and long processing time. Here an optoelectrofluidic immunoassay platform for simple, fast, and automated detection of human tumor marker based on surface-enhanced Raman scattering (SERS) has been developed. By using a conventional optoelectrofluidic device and a liquid crystal display module, simple and quantitative detection of human tumor marker, alpha-fetoprotein, in a ∼500 nL sample droplet has been automatically conducted with lower detection limit of about 0.1 ng/mL within 5 min. This study depicts the first practical application, for protein detection, of the optoelectrofluidic manipulation technology. This image-driven immunoassay platform opens a new way for simple, fast, automated, and highly sensitive detection of antigens.