Fluorescent, thermo-responsive biotin-P(NIPAAm-co-NDAPM)-b-PCL micelles for cell-tracking and drug delivery

An amphiphilic, biotinylated poly(N-isopropylacrylamide-co-N-(3-dimethylamino propyl)methacrylamide)-block- poly(?-caprolactone) (biotin-P(NIPAAm-co-NDAPM)- b-PCL) block copolymer was synthesized. The cytotoxicity study showed that the copolymer exhibited no apparent cytotoxicity. In aqueous solution, biotin-P(NIPAAm-co-NDAPM)- b-PCL copolymer was able to self-assemble into micelles of around 60?nm in diameter with a critical micellar concentration (CMC) of 36?mg?l?1. Biotin-P(NIPAAm- co-NDAPM)-b-PCL micelles were thermo-responsive and the cloud point temperature was at 36.5??C. The fluorescent group, fluorescein isothiocyanate (FITC) was further introduced to label the biotin-P(NIPAAm-co-NDAPM)- b-PCL copolymer. A cell internalization experiment was conducted and it was found that the fluorescent micelles could be internalized into the cells. The drug release behavior of drug-loading micelles was also examined and the drug-loaded biotin-P(NIPAAm-co-NDAPM)- b-PCL micelles showed slow drug release at 27??C and fast drug release at 37??C.