(409f) Preparation of Quantum Dot-Embedded Polymeric Nanoparticles in a Micromixer

We describe a process for stabilizing luminescent quantum dots within a block co-polymer particle. The method uses a staged micromixer which initially forms nanocrystal-homopolymer aggregates in the first mixer, which are then fed into the second mixer where they are stabilized by a suitable block co-polymer. The precipitation is controlled by the nanocrystal and polymer concentrations, flow rate, resident time, and solvent ratio. Under turbulent mixing conditions, the generated particles have a low polydispersity index and relatively small size (~100-500 nm diameter). Below the turbulence threshold, polydispersity increases dramatically. The loading of quantum dots and ultimate composite particle size depends strongly on the efficiency of aggregation obtained within the first mixer and can be controlled by adjusting the homopolymer concentration as well as the capping ligands present on the nanocrystal surface. Careful selection of the block co-polymer introduced in the second mixer provides long-term colloidal stability in aqueous solutions and preserves the luminescence properties of the quantum dots. This method is a rapid (< 1 minute) and effective means for stabilizing quantum dots within a polymeric particle for applications including cell labeling, drug delivery, and particle image velocimetry.