Development of surface droplet evaporation-based sensing platform for screening lipase inhibitors

Abstract

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 IC50 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.