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

7. RFP Loaded PLGA Coated Chitosan Microspheres Obtained by WSD MethodAs can be seen from figure 7.7, the chitosan coating of PLGA particles improuves greatly themucoadhesive properties of the RFP-loaded microspheres. The results confirm those obtainedwith chitosan microspheres and PLGA particles described above (chapters 4 and 6).Moreover, they are also a logical consequence of the zeta potental values measured (table7.2). indeed, it is well known that the main mechanism of mucoadhesion is interactionbetween opposite charged molecules.Therefore, the positive charge of the chitosan coated microspheres increased themucoadhesive properties of the negatively charged uncoated PLGA microspheres.As can be seen from the graph, for chitosan coated particles the percentage of mucin adsorbedincreased as the mucin concentration increased from 0.025 to 0.1 mg/ml reaching a 100%mucoadhesion.100% of mucin adsorbed806040200No chit. 0,1% Chit 0,25% Chit 0,5 % Chit 0,75% ChitFigure 7.7: Mucoadhesive Behaviour of Rfp-Loaded Plga Coated Chitosan Microsferes7.2.8. 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 RFP and RFPentrapped in PLGA coated chitosan microspheres. Cytotoxicity was observed to beconcentration-dependent for free RFP and for all the formulations. The highest cytotoxiceffects were found for free RFP. In fact, as can be seen in figure 7.8, also with the lowestconcentration of RFP the viability is very low and it means that the free drug can cause sideeffects also when it is nebulized directly into the lung, where the infection is. RFPincorporated in PLGA coated chitosan microspheres were less toxic, but toxicity was still afunction of RFP concentration. In fact, empty microspheres were always less toxic than RFP-115