Metasurface Surface Plasmon Resonance Technology for Affinity and Quantitative Detection of Alpha-fetoprotein

Objective A novel biosensor was developed based on the metasurface plasmon resonance (MetaSPR) technology for the evaluation of the affinity between alpha-fetoprotein (AFP) antigen and antibody, as well as for the rapid quantitative detection of AFP in human serum.Methods The MetaSPR biosensor was fabricated using nanoimprinting technology, in combination with laser interference lithography and ion etching techniques. The unique 3D nanocup metasurface array structure makes up for the deficiencies of traditional Surface Plasmon Resonance (SPR) technology. By integrating with the gold nanoparticles (AuNPs) labeling technology, the detection performance is significantly enhanced.Results The affinity parameters (KD) of this sensor for AFP antigen-antibody are 0.681 nmol/L and 0.225 nmol/L. By using the AuNPs labeling technology as an amplification system, the standard curve established through the double-antibody sandwich method shows a good linear relationship in the range of 0.5-32 ng/mL (R2 = 0.997). The limit of detection (LOD) reaches 0.2 ng/mL, which is 10 times higher than that of the traditional Enzyme-Linked Immunosorbent Assay (ELISA). The detection time is 15 min, which is 16 times shorter than that of the traditional ELISA. The spiked recovery rate is between 82% and 120%, and the specificity verification shows no cross-reaction.Conclusion The AFP antigen detection platform developed in this study, based on MetaSPR technology, is easy to operate, rapid, highly sensitive, and low in cost. It can complete high-throughput and accurate quantitative detection within 15 min. It is expected to provide a new technical solution for the detection of malignant tumor markers, and it has important clinical significance for promoting the early diagnosis of liver cancer and personalized treatment.