Laser-Emitting Droplet Assay for Enzymatic Evaluation Applications

Accurate analysis of enzymatic activities in complex biological environments is critically important yet remains technically challenging. In this study, we present a laser-emitting droplet assay (LEDA) capable of real-time, label-free monitoring of enzymatic activity. This assay leverages a developed platform based on laser-emitting aqueous droplets, which encapsulate biosamples while simultaneously functioning as whispering-gallery-mode (WGM) microlasers. Enzymatic reactions within the droplets induce measurable shifts in laser signals. Owing to the enhanced light-matter interactions, the LEDA demonstrates a 90-fold increase in sensitivity compared to the conventional polystyrene microlaser configuration. We further applied LEDA for assessing α-amylase activity in saliva and analyzing protein concentration in fresh milk and milk powder. The resulting spectral signatures clearly distinguished the sample differences. By integrating with microfluidic droplet technique, we believe this assay can offer a promising automated and scalable droplet-based analysis and ultrasensitive approach for diverse biochemical analyses.