Design of host-guest interaction based molecularly imprinted polymers: Targeting recognition of the epitope of neuron-specific enolase via a SERS assay

Molecularly imprinted polymers (MIPs) are a kind of synthetic receptors possessing wide application prospects in proteins recognition. However, there are still great challenges in proteins imprinting due to their large size and easy conformation change. In this study, we explored epitope-oriented MIP based on host-guest interaction (hg-MIP) and constructed a novel hg-MIP-SERS (surface-enhanced Raman scatting) approach for efficiently recognizing the terminal epitopes of neuron-specific enolase (NSE), a well-known disease biomarker for small cell lung cancer, neuroblstom, and Alzheimer's disease. The C- and N-terminal epitopes of NSE were modified with 4-(phenylazo) benzoic acid, then they were used as the templates and immobilized on β-cyclodextrin-functionalized substrates. The imprinted layer was formed by polymerization of various functional monomers. Combined with SERS detection, an antibody-free sandwich assay based on hg-MIP was successfully used to detect the concentration of NSE in human serums, with the advantages of simple operation, small sample volume (5 μL), wide linear range (1–10⁴ ng/mL) and a limit of detection as low as 0.01 ng/mL. The developed epitope-oriented hg-MIP-SERS approach can also be extended to other proteins, expanding the imprinting method of proteins, and has a broad development space in the field of protein separation and detection.