β-Amylase (BMY) is a linchpin in food production and the pharmaceutical industry because the enzyme efficiently controls the ratio of diverse saccharides in fermentation and the manufacture of high-quality maltose. However, existing BMY detection tactics suffer from inadequate selectivity/sensitivity and cumbersome operation and do not meet the needs of precise quantification. Consequently, there is an urgent need to develop an ultrasensitive sensing platform to achieve precise BMY analysis with a low detection limit and simpler workflow. In this work, we establish an encapsulated-enzyme-based BMY biosensing platform in which α-glucosidase is embedded in magnetic layered double hydroxide using a self-sacrificing template. The encapsulated enzyme has increased activity, robustness, and recyclability and was utilized for BMY detection via a cascade chromatic process. We found a detection limit for the quantification of BMY activity of 2.67 U/L with a broad range (5–400 U/L), fast response speed (10 min), and satisfactory specificity. We applied the biosensing platform to liquor starters to verify the capability of the assay in complicated fermentation samples. The proposed platform holds great promise as an efficient and simple method for enzymatic bioactivity monitoring in food manufacturing, biopharmaceutical processing, and clinical laboratory tests.
Yue Zhang,Tingting Ren,Hua Tian,Binbin Jin,Junhui He
Conventional analysis of heavy metal ions in water requires highly skilled staff and sophisticated equipment. These limitations make conventional approaches difficult to perform analysis on-site without delay. Herein, we report a facile colorimetric sensing system developed for acute toxicity assessment of heavy metal ions. A bioactive enzyme, β-galactosidase, was used as sensing agent rather than bacteria or other higher organisms to improve selectivity and response time. The developed bioassay is capable of assessing the toxicity of heavy metal ions such as Hg(II), Cd(II), Pb(II), and Cu(II). The effects of enzyme concentration on the assessing performances (i.e., sensitivity and response time) of bioassay were explored and illustrated. Generally, low enzyme concentration facilitates sensitivity enhancement, achieving a 50% inhibiting concentration (IC50) of 0.76 μM (=152 ppb) Hg(II), and high enzyme concentration ensures quick response, enabling a response time down to 9 min. Moreover, the enzyme and substrate were respectively encapsulated by hydrogel to further simplify the assay procedure and enhance the stability of the enzyme. The hydrogel-encapsulated enzyme worked well even when heated up to 60 °C and retained ca. 90% activity after storage for 5 months. Moreover, the developed toxicity-assessing system is feasible for assessing toxicity of actual water samples. This assay approach is low cost and time effective and has no potential ethic issues. In addition, this work paves the way for the development of toxicity assessment kits for on-site analysis based on functional bioactive molecules.
Various methods have been made to achieve sensitive detection (10 CFU/mL) of Escherichia coli O157:H7 ( E. coli ) in real samples, however, they are complex, time-consuming, or instrument-dependent. Enzyme-catalyzed reactions are one of the most efficient methods to amplify signals for sensitive detection. ZIF-8 owning stability, porosity, and high specific area are suitable for embedding enzymes which can effectively protect enzyme activity and thus improve detection sensitivity. Herein, a simple visual assay of E. coli with the limits of detection of 1 CFU/mL was developed based on this stable enzyme-catalyzed amplified system. A microbial safety test of milk, orange juice, seawater , cosmetic, and hydrolyzed yeast protein, was successfully performed with the limits of detection of 10 CFU/mL by the naked eye. And this bioassay possessed high selectivity and stability making the developed detection method practically promising.
危险品化学品经营许可证（带存储）