The cell viability of the insulin solution group still remained above 95%, and two liposomes had negligible difference in cell viability relative to insulin solution under various lipid concentrations. Besides, the cytotoxicity Tamoxifen research buy of BLPs was on close level in comparison with CLPs, indicating that the biotinylation of liposomes did not bring

extra toxicity. Furthermore, the desirable biocompatibility could also be judged from the result of apoptosis of Caco-2 cells (Figure 9). The effects of BLPs and CLPs at three lipid concentrations on the apoptosis were relatively insignificant relative to the negative control. In quadrant 4 (Q4) betokening the early apoptotic cells, there were no positive signals detected either for BLPs or CLPs, declaring that liposomes, whether being biotinylated or not, did not significantly cause the apoptosis of cells. Although some late apoptotic cells were observed in Q2, they may

come from the necrotic cells as a result of natural mortality of cells rather than the apoptosis induced by liposomes. The results indicated that biotin-modified liposomes had a good oral safety for insulin delivery. Alvelestat Figure 8 Cell viability of Caco-2. Incubated with BLPs or CLPs at different lipid concentrations as well as insulin saline for 4 h. (n = 3). Figure 9 Distribution of cells in different apoptotic stages treated with liposomes at different lipid concentrations for 4 h. Collection of annexin V signals as FL1 and propidium iodide (PI) signals as FL2. Conclusion This research provided insight into the potential

of biotinylated liposomes as novel nanocarriers for oral insulin delivery. Liposomes prepared under optimal conditions can effectively entrap insulin into the inner aqueous cavity and improve the stability of transportation through the GI tract. By biotinylation, the GI absorptive feature of liposomes was notably enhanced. Significant hypoglycemic effect was observed in rats in comparison with CLPs after oral administration of BLPs, especially using liposomes with a particle size about 150 nm. The enhanced oral delivery of insulin was mainly ascribed to ligand-mediated endocytosis by targeting to biotin receptor on enterocytes. Authors’ information XZ, XH, and WH are Ph.D students at Fudan University. JQ holds a lecturer position at Fudan Baricitinib University. YL and WW hold associate professor and professor position at Fudan University, respectively. Acknowledgements This work was supported by the National Key Basic Research Program of China (2009CB930300) and the Ministry of Education (NCET-11-0114). The authors should also be thankful for the financial assistance from the Shanghai Commission of Education (10SG05). References 1. Philip S, Howat I, Carson M, Booth A, Campbell K, Grant D, Patterson C, Schofield C, Bevan J, Patrick A, Leese G, Connell J: An audit of growth hormone replacement for GH-deficient adults in Scotland. Clin Endocrinol (Oxf) 2013, 78:571–576.CrossRef 2.