One-pot facile synthesis of enzyme-encapsulated Zn/Co-infinite coordination polymer nanospheres as a biocatalytic cascade platform for colorimetric monitoring of bacteria viability.

Abstract

Arapid method for colorimetric monitoring of bacterial viabilityis described. The colorimetric method was carried out based on glucose oxidase-encapsulated Zn/Co-infinite coordination polymer (Zn/Co-ICP@GOx), which was prepared in aqueous solution free of toxic organic solvents at room temperature. The Zn/Co-ICP@GOx was confirmed to be a robust sphere structure with an average diameter of 147.53 ± 20.40nm. It integrated the catalytic activity of natural enzyme (GOx) and mimetic peroxidase (Co (П)) all in one, efficiently acting as a biocatalytic cascade platform for glucose catalytic reaction. Exhibiting good multi-enzyme catalytic activity, stability, and selectivity, Zn/Co-ICP@GOx can be used for colorimetric glucose detection. The linear range was 0.01-1.0mmol/L, and the limit of detection (LOD) was 0.005mmol/L. As the glucose metabolism is a common expression of bacteria, the remainingglucose can indirectly represent the bacterial viability. Hence, a Zn/Co-ICP@GOx-based colorimetric method was developed for monitoring of bacterial viability. The color was intuitively observed with the naked eye, and the bacterial viability was accurately quantified by measurement of the absorbance at 510nm. The method was applied to determination of bacterial viability in water and milk samples with recoveries of 99.0-103% and RSD of 0.43-7.5%. The method was rapid (lessthan 40min) and applicable to different bacterial species irrespective of Gram-positive and Gram-negative bacteria, providing a universal and promising strategy for real-time monitoring ofbacterial viability.