Colorimetric quantification of sodium benzoate in food by using d-amino acid oxidase and 2D metal organic framework nanosheets mediated cascade enzyme reactions

A rapid colorimetric method for detecting sodium benzoate in food products was established based on the d-amino acid oxidase (DAAO) and 2D metal organic framework (2D MOF) nanosheets mediated cascade enzyme reactions. Firstly, the synthesized 2D MOF nanosheets served as high efficient nanozyme with outstanding peroxidase-like catalytic activity and catalyzed the color reaction between H2O2 and 3, 3’, 5, 5′- tetramethylbenzidine. Secondly, sodium benzoate as a competitive inhibitor of DAAO, could influence the production of H2O2 in DAAO mediated oxidation reaction. After a combination of those two reactions, this colorimetric quantitative method was constructed and validated for sodium benzoate determination with wide linear range (2.0–200.0 μM), low limit of detection (2.0 μM), high accuracy (recovery rate in 95.80–108.00%) and satisfied selectivity. Lastly, this method was utilized to analyze sodium benzoate concentration in juice, wine and vinegar by naked eyes. [Display omitted] •The structure and peroxidase-like catalytic activity of 2D MOF were fully characterized.•The effect of pH value and temperature on DAAO mediated H2O2 production were studied.•A colorimetric method for SB detection was established based on its inhibitory effect on DAAO.•This colorimetric mehtod was validated and applied for SB detection in different food.