In an attempt to increase the interaction of a nanocarrier system with gastrointestinal epithelial cells,a transferrin-receptor(TfR) specific 7peptide was conjugated to PEG-b-PCL copolymer and the functional nanocarriers were constructed and characterized.The endocytosis, intracellular trafficking and transcytosis of such nanocarriers loaded with coumarin 6(7pep-M-C6) in a human colon carcinoma cell fine(Caco-2) were investigated,followed by the in vivo intestine distribution study The real-time imaging of five cell,three dimensional reconstruction of confocal image,quantitative colocafization analysis and other techniques were applied.First,the TfR expression was confirmed in Caco-2.Then,7pep-M-C6exhibited higher intracellular uptake compared with unmodified nanocarriers.In a five cell study,7pep-M-C6 demonstrated faster uptake kinetics especially in the surface ofcells.Together with a competition study using TfR antibody,it was proved that the increased cellular uptake was due to a receptor-mediated mechanism.Besides the unspecific endocytosis pathway,7pep-M-C6 was found to enter the cells through aspecific clathrin-mediated mechanism,related to the expression of TfR on Caco-2cells.Possibly for this reason,7pep-M-C6 tended to colocalize more with late endosomes and lysosomes than the control micelles. Also for the same mechanism,the increased transport of 7pep-M-C6 across Caco-2 monolayer was found,through atranscellular but not a paracellular pathway,while an increased in vivo intestinal distribution of 7pep-M-C6 was observed.In conclusion,the functional nanocarriers could specifically interact with gastrointestinal endothelial cells,increase their transport and alter their pathway as a result.
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