Rapid and ultrasensitive activity detection of β-amylase based on cross-linked metal-organic framework nanozyme

Rapid quantitative detection of β-amylase is important for food quality, production efficiency, and food safety. However, current detection methods are time-consuming with low sensitivity. Fast, sensitive, and simple detection of β-amylase remains a challenge in practice. In the present work, we constructed a colorimetric β-amylase assay based on cross-linked nanozyme. The assay utilized the interaction between β-amylase and its specific substrate, p-nitrophenyl-β-maltopentaoside (PNPG3), which cross-links with the FeCo-BDC-NH₂ metal-organic framework nanozyme. The detection mechanism is based on β-amylase hydrolyzing the crosslinking agent PNPG3 on the surface of FeCo-BDC-NH₂, leading to enhanced peroxidase-mimicking biological activity of the nanozyme in free state. The detection limit was 2.77 U L^-1, with a broad linear range (5-160 U L^-1) and remarkable specificity. In addition, the assay was used in fermentation samples to validate the analytical performance. This assay offers an accessible and efficient method of determining β-amylase activity in the actual production.