Immunoassay of Tumor Markers Based on Graphene Surface-Enhanced Raman Spectroscopy.

With a unique chemical enhancement capability, graphene oxide is exceptionally suitable to serve as an alternative surface-enhanced Raman scattering (SERS) substrate, which is usually defined as GERS. However, such a GERS matrix with both promising uniformity and molecule enrichment ability has not been applied in the quantitative detection of tumor markers. Herein, an ultrasensitive and specific immunoassay of carcinoembryonic antigens mediated by the GERS matrix was demonstrated. With the assistance of Au NRs as immunoprobes, a reliable limit of detection as low as 3.01 pg/mL was finally achieved because of the collective effect of chemical and electromagnetic enhancements. Meanwhile, a calibration curve with a high R 2 value of 0.996 was obtained in the range from 1 μg/mL to 10 pg/mL. These results exhibit that the GERS matrix has a great promise for participating in immunoassay, which may pave a potential avenue for the real utilization of the SERS technique in clinical biomedicine.