Preparation of quantum dot-embedded polymeric nanoparticles using flash nanoprecipitation
We developed a unique and efficient method to encapsulate quantum dots within amphiphilic polymer micelles using the flash nanoprecipitation technique and various micromixers (multi-inlets vortex mixer, MIVM, and confined impinging-jet mixer, CIJM). Owing to the rapid homogeneous mixing provided by the micromixers, we produced highly stable QD-embedded particles with very narrow size distributions. By adjusting the solvent-to-nonsolvent ratio, homopolymer concentration, and micromixer arrangement, the resulting mean particle diameter was varied from 90 to 800 nm. Additionally, the self-quenching of quantum dots, which is commonly observed in confined systems, was nearly eliminated by adding hydrophobic homopolymer during mixing. This technique results in controllable, rapid synthesis of fluorescent polymeric particles that are stable for many months. Potential applications of this method include the efficient synthesis of fluorescent tracer particles, tags for optical barcoding applications, and biosensors that utilize fluorescence resonance energy transfer (FRET).