Microdroplet-Facilitated Assembly of Thermally Activated Delayed Fluorescence-Encoded Microparticles with Non-interfering Color Signals

Encoded microparticles (EMPs) have shown demonstrative value for multiplexed high-throughput bioassays such as drug discovery and diagnostics. Herein, we propose for the first time the incorporation of thermally activated delayed fluorescence (TADF) dyes with low-cost, heavy metal-free, and long-lived luminescence properties into polymer matrices via a microfluidic droplet-facilitated assembly technique. Benefiting from the uniform droplet template sizes and polymer-encapsulated structures, the resulting composite EMPs are highly monodispersed, efficiently shield TADF dyes from singlet oxygen, well preserve TADF emission, and greatly increase the delayed fluorescence lifetime. Furthermore, by combining with phase separation of polymer blends in the drying droplets, TADF dyes with distinct luminescent colors can be spatially separated within each EMP. It eliminates optical signal interference and generates multiple fluorescence colors in a compact system. Additionally, in vitro studies reveal that the resulting EMPs show good biocompatibility and allow cells to adhere and grow on the surface, thereby making them promising optically EMPs for biolabeling.

Automated summary

This research proposes a method for incorporating thermally activated delayed fluorescence (TADF) dyes with low-cost, heavy metal-free, and long-lived luminescence properties into polymer matrices using a microfluidic droplet-facilitated assembly technique. The resulting composite encoded microparticles (EMPs) are highly monodispersed and efficiently shield TADF dyes from singlet oxygen, preserving TADF emission and increasing the delayed fluorescence lifetime. Additionally, phase separation of polymer blends in the drying droplets allows for spatial separation of TADF dyes with distinct colors, eliminating optical signal interference and generating multiple fluorescence colors. Furthermore, the resulting EMPs show good biocompatibility and allow cells to adhere and grow on the surface, making them promising for biolabeling applications.