Protein-directed hydrogen-bonded organic framework with enhanced enzyme stability and catalytic efficiency for sensitive colorimetric/ fluorometric immunoassays

The fragility inherent in enzymes can be overcome by immobilizing them within nano-carriers, which offer designability and controllability and serve as a promising strategy for overcoming the inherent fragility of enzymes. While enzyme immobilization enhances enzyme stability and reusability, it can potentially hinder their bioactivity and catalytic efficiency. In this study, we present an enzyme-directed biomimetic mineralization approach for the in situ encapsulation of horseradish peroxidase (HRP) within hydrogen-bonded organic frameworks (HOFs) to obtain HOF@HRP nanocomposites. Remarkably, the HOF@HRP nanocomposites exhibit an ultrahigh protein content and demonstrate comparable catalytic activity to that of the free enzyme. Moreover, the HOFs act as protective shields, safeguarding the internal enzymes against various environmental disturbances. Leveraging the unique properties of HOF@HRP, we propose a dual-modal enzyme-linked immunosorbent assay for the sensitive detection of prostate-specific antigen in human serum. The resultant biosensor exhibits a good linear range, excellent sensitivity, and selectivity, showcasing its promising potential and clinical application in the field of diagnostic medicine.