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

5. RFP Loaded Chitosan Microspheres Prepared by Spray-Drying Methodexperiments were carried out at 37 ± 0.3°C at a rotation speed of 100 ± 2 rpm. A measure of 1ml samples were withdrawn at appropriate time intervals and centrifuged at 10000 rpm.Supernatants were diluted suitably with acetonitrile and absorbance of the resulting solutionwas measured at 485 nm. The residue (after centrifugation) was redispersed in 1 ml of thefresh dissolution medium and replaced back into the dissolution apparatus. The cumulativeamount of RFP was obtained from the calibration curves of RFP in acetonitrile. The stockstandard solution of RFP (2 mg/ml) was prepared by dissolving the drug in acetonitrile andstoring at 4°C. A standard calibration curve was built up by using standard solutions preparedby dilution of the stock standard solution with acetonitrile.5.1.5. Mucoadhesive Studies5.1.5.1. Adsorption of Mucin on Chitosan MicrospheresStandard calibration curves were prepared from 2 mL of mucin standard solutions (0.25, 0.5,0.75, and 1 mg/2 mL) and then, the absorbance of the solutions was recorded at 500 nm in aUV spectrophotometer. Triplicate samples were run.Mucin aqueous solution with different concentrations (0.025, 0.05, 0.1, 0.2, and 0.5 mg/mL)were prepared. Chitosan microspheres (20 mg) prepared by spray-drying method weredispersed in the above mucin solutions, vortexed, and shaken at room temperature. Then, thedispersions were centrifuged at 4000 rpm for 2 minutes, and the supernatant was used for themeasurement of the free mucin content. The mucin content was calculated from the standardcalibration curve.5.1.6. Statistical AnalysesAll experiments were repeated at least three times. Results are expressed as means ± standarddeviation. A difference between means was considered significant if the p value was less thanor equal to 0.05.5.2. Result And Discussion5.2.1. Preparation of RFP-Loaded Chitosan MicrospheresIn order to find the best microsphere formulations for the delivery of effective doses of RFPto macrophages after aerosol therapy, we also prepared and characterized chitosanmicrospheres of by using an alternative preparation method that is spray drying.Also in this case uncross- and crosslinked (GA) microparticles were prepared and theinfluence of different parameters was studied..75