COS-ID-based imprinted polymers with carbohydrate-metal-epitope synergy for selective MMP-9 detection in cancer...

To address the insufficient specificity and lack of glycosylation-dependent recognition of conventional molecularly imprinted polymers (MIPs) for matrix metalloproteinase-9 (MMP-9) pretreatment in complex serum, biomimetic epitope-imprinted polymers were prepared using a novel chitosan oligosaccharide-imine derivative (COS-ID). A "carbohydrate-metal-epitope" synergistic system was constructed via multi-site hydrogen bonding, Zn²⁺ dual-site coordination, and 3D cavity imprinting, enabling highly specific recognition of MMP-9. Under optimized conditions, the COS-ID-based MIPs achieved a maximum adsorption capacity of 48.59 mg g^-1, and an imprinting factor of 4.26, with 94.15% reusability after five cycles. After 36 weeks of storage, the MIPs retained 96.81% of their initial adsorption capacity, with the imprinting factor slightly declining from 4.44 to 4.16, confirming satisfactory long-term stability. The adsorption behavior fitted well to the pseudo-second-order kinetic (R² = 0.9987) and Langmuir isotherm models (R² = 0.9753), with relatively high selectivity toward MMP-9. Recoveries were 90.56-92.13% for spiked human serum (avg.: 91.56%, RSD = 0.95%, n = 3) and 82.35-115.02% for clinical cancer patient serum (avg.: 95.42%, RSD = 0.30-2.53%, n = 3), with most values complying with FDA/EMA acceptance criteria. Benefiting from their polysaccharide backbone and functional groups, the MIPs exhibited satisfactory biocompatibility and anti-matrix interference capacity. This low-cost, selective, and long-term stable MIP platform offers a promising alternative to antibody-based methods for the pretreatment and analysis of MMP-9 in complex clinical serum matrices.