The development of new types of sensing platforms with excellent performance is always appealing. In this report, we demonstrate a low-cost and user-friendly sensing platform based on drying of the aqueous droplet on the surface. The principle relies on the transduction of the surfactant concentration into the area of the dried droplet on the surface. The screening of a lipase inhibitor is demonstrated as an example. When triacylglycerols (GT) and lipase are mixed, the aqueous droplet produces a large dried area on the surface. This phenomenon is attributed to the production of sodium oleate due to the enzymatic digestion of GT by lipase. It results in reduction of the surface tension and causes wetting and spreading of the droplet, leaving a large dried area on the surface. However, in the presence of orlistat, a lipase inhibitor, a small dried area is obtained due to the inhibition of lipase activity by orlistat. Using this method, the lipase inhibitor can be readily and effectively screened. Compared to previous studies, this method is simple, rapid, low-cost and avoids the use of labelled molecules and complex instrumentation, with an IC 50 value of 0.59 ± 0.09 μM for orlistat. In addition, it also works well with a portable microscope and a smartphone interface for data analysis. Overall, this study provides a new method for rapid and cost-effective screening of lipase inhibitors.
Rui Li,Tong Bu,Yijian Zhao,Xinyu Sun,Qinzhi Wang,Yongming Tian,Feier Bai,Li Wang
Conventional immunochromatographic assays (ICAs) based on gold nanoparticles (GNPs) suffer from the disadvantage of low sensitivity. In this work, a highly sensitive ICA based on polydopamine coated zirconium metal-organic frameworks labeled antibodies (ZrPA-Ab) as a novel probe was developed for visual determination of deoxynivalenol (DON). The ZrPA was synthesized via an oxidative self-polymerized assembly (OPMA) strategy using porphyrin functionalized zirconium metal-organic frameworks (Zr-MOFs, MOF-525) and polydopamine (PDA). The Abs could directly attach to the ZrPA surface owing to the large specific surface area, excellent water-stability and bio-compatibility of the ZrPA, on this basis, a sensitive, precise and reliable immunoassay method can be developed for rapid and selective detection of DON. Under optimized conditions, a non-linear calibration curve was obtained in the range of 0–50 ng/mL DON concentration with an IC 50 of 1.22 ng/mL, and the visual detection limit was 0.18 ng/mL, which was about 8-times more sensitive than that of the conventional GNPs-based ICA. Finally, the proposed ZrPA-ICA was successfully applied for the detection of DON in pig hind legs meat, green bean, maize and millet samples, revealing the feasible and reliable application of this biosensor in different food matrices. Thus, this work broadens the possibilities for the use of MOFs as a novel labeling carrier in immunoassays.
危险品化学品经营许可证（带存储）