High-Throughput Generation of Size-Tunable Poly(lactic- <i>co</i> -glycolic acid)-Encapsulated DNA Tracers via Controlled-Microfluidics for Environmental Tracing

Synthetic DNA tracers are widely regarded as highly promising tools for sustainable environmental tracing, owing to their high specificity, sensitive detectability, virtually infinite variety, and environmental friendliness; however, the preparation of poly(lactic-co-glycolic acid) (PLGA)-encapsulated DNA tracers is severely constrained by low production efficiency and poor size consistency when using the conventional double-emulsion method. Herein, we established a microfluidic-based platform for the high-throughput production of PLGA-encapsulated DNA tracers, which enables precise size control and excellent batch-to-batch consistency. This platform integrates finely tuned microfluidic channels with precise fluid pressure control to continuously generate PLGA-encapsulated DNA tracers with sizes ranging from tens to hundreds of micrometers and ultrahigh dimensional uniformity. Compared with the conventional double-emulsion method, our approach improves size uniformity (particle dispersion index) by approximately 70%, and enhances DNA encapsulation efficiency by nearly 10-fold, while featuring better flexibility, operational convenience, and reduced labor requirements. Furthermore, column and flume experiments systematically evaluated and validated the tracing performance of the synthesized tracers, confirming their effectiveness in both homogeneous and heterogeneous porous media. This study demonstrates the applicability of microfluidics fabrication as a controllable and scalable platform for standardized PLGA-encapsulated DNA tracers production for environmental tracing applications.