A close-packed imprinted colloidal array for naked-eye detection of glycoproteins under physiological pH

According to the combination of colloidal crystals and molecular imprinting techniques, a novel close-packed imprinted colloidal array (CPICA) for naked-eye horseradish peroxidase (HRP) detection at physiological pH was proposed. The CPICA was fabricated by self-assemble of monodispersed HRP imprinted particles. The HRP imprinted particles were prepared based on surface imprinting technique and immobilized template strategy using 2,4-difluoro-3-formylphenylboronic acid (DFFPBA) as functional monomer which allowed the material binding of HRP at physiological pH (denoted as SiO₂@DFFPBA/MIPs). The adsorption capacity of the SiO₂@DFFPBA/MIPs for HRP was 1.16 μmol/g, and reached saturated adsorption within 25 min. The limit of detection (LOD) of the CPICA was 3.0 × 10^-13 mol/mL. In addition, the adsorption of HRP on the CPICA could be directly transferred into visible color changes and readable optical signals through the reflection peak shifts. The structure color of the CPICA changed from brilliant blue to dark red with an maximum red shift of 87 nm when the HRP concentration increased from 2.5 to 20.0 μmol/L. Moreover, the CPICA could be used to detect HRP from human serum sample, which demonstrated the promising application prospects in colorimetric sensors.