Preparation,Characterization And In Vitro Release Study On A Novel Drug-eluting Electrode Of Cochlear Implant

Objective:To prepare and characterize a new drug-eluting electrode of cochlear implant using poly-lacticco-glycolic acid(PLGA)by which the drug could be sustained release.Methods:At 30°C,PLGA(50:50,Mw=1-3k)was dissolved in trichloromethane with a mass fraction of 5% in an incubator.Dexamethasone sodium phosphate was also added to the solution.The solution casting protocol was applied to prepare the polymer drug-eluting on the surface of a cochlear implant electrode.Scanning electron microscopy was used to observe the surface.Electrode impedance,water contact angle and Shore hardness were also measured before and after coating.The drug release kinetics from drug-eluting electrodes was investigated in artificial perilymph.Results:The coating was smooth and uniform.The thickness of drug-eluting was about 1μm.The water contact angle of electrode decreased significantly after coating.There is no change in the impedance of electrode before and after the coating.While,a slight increase in Shore hardness was noticed(about 1%).Drug release experiments in vitro showed that there was a sudden release of drug in the first 24 hours and a sustained release within 30 days which was not affected by the thickness of the PLGA coating.Conclusion:The new PLGA based drug-eluting electrode can maintain the original morphology and electrical conductivity.At the same time,its hydrophilicity is improved significantly.The drug sustained to release for almost 30 days and the loading dose could be easily controlled.The research offered a new way for high concentration and targeted delivery of drugs to the inner ear.