Investigation of coumarin functionality on the formation of polymeric nanoparticles.

The effect of coumarin molecules on the formation of polymeric nanoparticles is examined using a model polymer, poly(methyl methacrylate) (PMMA), functionalized with varying amounts of coumarin pendant groups (PCM). PCM nanoparticles are prepared in a continuous manner by Flash NanoPrecipitation (FNP). PCM forms spherical nanoparticles in water, while the PMMA without coumarin functionality fails to form nanoparticles. As the amount of coumarin functionality increases, the nanoparticle size and size polydispersity are decreased and the nanoparticle stability in water is enhanced. In particular, well-isolated spherical nanoparticles are generated from PCM with 20 mol% coumarin side chain functionality. These results can be explained by an observed increase in the negative surface charge with increasing coumarin content in the polymer.

Photoresponsive coumarin-stabilized polymeric nanoparticles as a detectable drug carrier.

The ability to create aqueous suspended stable nanoparticles of the hydrophobic homopolymer poly(ϵ-caprolactone) end-functionalized with coumarin moieties (CPCL) is demonstrated. Nanoparticles of CPCL are prepared in a continuous manner using nanoprecipitation. The resulting nanoparticles are spherical in morphology, about 40 nm in diameter, and possess a narrow size distribution and excellent stability over 4 months by repulsive surface charge. Nanoparticle size can be easily controlled by manipulating the concentration of CPCL in the solution. The interparticle assembly between the nanoparticles can be reversibly adjusted with photoirradiation due to photoinduced [2 + 2] cyclodimerization and cleavage between the coumarin molecules. In addition, the CPCL nanoparticles show significant cellular uptake without cytotoxicity, and the intrinsic fluorescence of the coumarin functional group permits the direct detection of cellular internalization.