Multifunctional Self-Signaling nanoMIP and Its Application for a Washing-Free Assay of Human Angiotensin-Converting Enzyme 2

Molecular imprinting techniques have attracted a lot of attention as a potential biomimetic technology, but there are still challenges in protein imprinting. Herein, multifunctional nanosized molecularly imprinted polymers (nanoMIPs) for human angiotensin-converting enzyme 2 (ACE2) were prepared by epitope imprinting of magnetic nanoparticles-anchored peptide (magNP-P) templates, which were further applied to construct a competitive displacement fluorescence assay toward ACE2. A cysteine-flanked dodecapeptide sequence was elaborately selected as an epitope for ACE2, which was immobilized onto the surface of magnetic nanoparticles and served as a magNP-P template for imprinting. During polymerization, fluorescent monomers were introduced to endow fluorescence responsiveness to the prepared self-signaling nanoMIPs. A competitive displacement fluorescence assay based on the nanoMIPs was established and operated in a washing-free manner, yielding a wide range for ACE2 (0.1–6.0 pg/mL) and a low detection limit (0.081 pg/mL). This approach offers a promising avenue in the preparation of nanoMIPs for macromolecule recognition and expands potential application of an MIP in the detection of proteins as well as peptides.