chitosan and plga microspheres as drug delivery ... - UniCA Eprints

4. RFP Loaded Chitosan Microspheres Prepared by Precipitation Method% of Mucin Adsorbed100806040200Form.1 Form.2 Form.3 Form.4 Form.5 Form.60,025 mg/ml Mucin Solution 0,1 mg/ml Mucin Solution0,5 mg/ml Mucin SolutionFigure 4.10: Mucoadhesive Studies of Chitosan Microspheres4.2.8. Viability Studies with A549 CellsThe cytotoxic effects of RFP against A549 cells were examined by MTT assay. In theexperiments, the cytotoxicity was evaluated by varying the concentration of free andmicrosphere-encapsulated RFP. This study was carried out only on Formulation 1 (uncrosslinked)and Formulation 4 (cross-linked), which had been prepared with 0.25% of chitosan.Cytotoxicity was observed to be RFP concentration-dependent for all the tested samples(Figure 4.11). The highest cytotoxic effects were found for free RFP, which even in thelowest concentration (0.1%) showed only a 55% cell viability that further decreased to 12%when the free drug was used in the highest concentration (0.5%). These results show the hightoxicity of RFP that can cause side effects also when it is nebulized directly into the lung,where is the site of infection. The viability assay also showed that RFP toxicity can bereduced by encapsulating the drug in chitosan microspheres. Cell viability was generally notaffected by chitosan concentration, in fact empty particles showed always the best results interm of viability. As can be seen in figure 4.11 the presence of GA decreased the viability ofcells probably because same cross-linking agent was in the particles also after the purificationsteps.68