A controllable glycosyl molecularly imprinted strategy on MOF nanozyme for high-specificity colorimetric detection of...

Molecularly imprinted nanozymes (MINs) offer a compelling alternative to antibody-based assays by integrating specific molecular recognition with enzyme-like catalytic activity. Nevertheless, conventional molecular imprinting of glycoproteins remains technically challenging. In this work, employing CA19-9 as a model glycoprotein biomarker, we develop a surface-directed glycan imprinting strategy by integrating molecular imprinting technology with iron-based metal-organic framework (MIL-88B-NH₂) nanozymes. The characteristic glycan of CA19-9 (sialyl Lewis A, SLe^a) is pre-adsorbed onto the amino-rich MIL-88B-NH₂ surface via hydrogen bonding and boronic acid affinity, followed by sol-gel polymerization to grow an imprinted shell. After template removal, the recognition cavities are automatically positioned within nanometers of the intrinsic Fe catalytic sites. Upon specific binding of CA19-9, steric hindrance exerted by the protein backbone impedes diffusion of the chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) to the surface of MOF, resulting in quantifiable suppression of color development. The developed sensor demonstrates sensitive detection of CA19-9 across a wide linear range from 0.001 to 50 U mL^-1, with a detection limit of 1.01 × 10^-4 U mL^-1 (3σ/slope), and shows excellent selectivity in serum samples. This work provides a stable, cost-effective, and visual biosensing platform with significant potential for point-of-care biomarker testing.