Ultra-small fluorescent bile acid conjugated PHB–PEG block copolymeric nanoparticles: synthesis, characterization and cellular uptake

A novel method based on solvent-diffusion and solvent evaporation is reported for the first time to prepare ultra-small (10 nm) nanoparticles (NPs) of deoxycholic acid conjugated polyhydroxybutyrate–polyethylene glycol block copolymer (DOCA–PHB–PEG). Cellular uptake of the NPs after attachment of a fluorophore is demonstrated with an aim to enable better understanding of the effect of such a small size on the NPs transport in the cells. The novel DOCA–PHB–PEG copolymer showed low cytotoxic profile and the FITC–insulin labeled ultra-small NPs showed a higher time-dependant cellular uptake. These NPs exhibit an excellent potential in delivering intra-cellular therapeutics.