A novel biodegradable brain drug delivery system, the lactoferrin (Lf) conjugated polyethylene glycol-polylactide-polyglycolide (PEG-PLGA) nanoparticle (Lf-NP) was constructed in this paper with its in vitro and in vivo delivery properties evaluated by a fluorescent probe coumarin-6. Lf was thiolated and conjugated to the distal maleimide function surrounding on the pegylated nanoparticle to form Lf-NP. TEM observation and ELISA analysis confirmed the existence of active Lf on the surface of Lf-NP. The results of qualitative and quantitative uptake studies of coumarin-6 incorporated Lf-NP showed a more pronounced accumulation of Lf-NP in bEnd.3 cells than that of unconjugated nanoparticle (NP). Further uptake inhibition study indicated that the increased uptake of Lf-NP was via an additional clathrin mediated endocytosis processes. Following intravenous administration, a near 3 fold of coumarin-6 was found in the mice brain carried by Lf-NP compared to that carried by NP. Intravenous injection of urocortin loaded Lf-NP effectively attenuated the striatum lesion caused by 6-hydroxydopamine in rats as indicated by the behavioral test, the immunohistochemistry test and striatal transmitter content detection results. The cell viability test and CD68 immunohistochemistry demonstrated the acceptable toxicity of the system. All these results demonstrated that Lf-NP was a promising brain drug delivery system with reasonable toxicity.
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