Engineering a β-Cyclodextrin-mediated hydrophobic microenvironment within iridium-incorporated porphyrin-MOF nanozyme for enhancing aflatoxin B1 immunoassay

Nanozymes have emerged as promising alternatives to natural enzymes due to their facile synthesis, cost-effectiveness, and exceptional storage stability. However, the catalytic performance—particularly for those derived from metal-organic frameworks (MOFs)—remains suboptimal because of their low substrate affinity. In this study, we developed a β-cyclodextrin-doped iridium-incorporated porphyrin-MOF nanozyme (CD-PCN-224-Ir). The incorporated iridium components serve as highly active catalytic centers, offering robust peroxidase-like activity. Simultaneously, the doped β-cyclodextrin creates localized hydrophobic microenvironments that facilitate the enrichment of hydrophobic substrates such as tetramethylbenzidine. Consequently, the specific activity of CD-PCN-224-Ir (424 U/mg) increases by 2.6-fold compared to its undoped counterpart (161 U/mg). Leveraging the improved catalytic performance, we constructed a CD-PCN-224-Ir nanozyme-based enzyme-linked immunosorbent assay for the ultrasensitive detection of aflatoxin B 1 , achieving a detection limit of 12.6 pg/mL and a half-maximal inhibitory concentration of 60.9 pg/mL. This work not only offers an effective strategy for enhancing MOF nanozyme activity through biomimetic microenvironment modulation but also demonstrates its significant potential in food safety monitoring.