A SERS biosensor regulated by tilt angle: an immunochip for α-fetoprotein

Hepatocellular carcinoma (HCC) has attracted worldwide attention due to its extremely high mortality rate. Early diagnosis is conducive to the remission and recovery of patients' symptoms and has become one of the effective methods to reduce the mortality rate. Surface-enhanced Raman scattering (SERS) participating in immune analysis has become a popular research method for early diagnosis of HCC in recent years. In this article, a large amount of Ag deposited on one side of the rod top causes it to be constructed into a bent rod array structure. Finite-difference time-domain simulation of the bent rod arrays proves the variation of the flatness at the top of the rods and the gap caused by the bending of the rod are the main reasons for the changes of the SERS signal intensity. The Raman shift in the characterization results of antigen-captured immunochip has become the important information to quantify the α-fetoprotein content of HCC marker. The bent rod array can be considered as an excellent immunochip in SERS spectroscopy and has a good application prospect as a biosensor.