| Cobalt-based alloys have been widely used in hip and knee replacement due to their good mechanical properties,corrosion resistance and biocompatibility.However,some problems such as the infection after surgery are still causing complain.For this reason,a new Cu-containing Co-29Cr-6Mo alloys(named Co-Cu alloys)with good antibacterial properties was prepared and a bioabsorbable drug-eluting coating was desighed in this work.The coating consisted of a biodegradable PLGA as drug-loaded material and Clindamycin Hydrochloride as drug.The open circuit potential(OCP),the electrochemical impedance spectroscopy(EIS)and the potentiodynamic polarization curve(Tafel)of Co-Cu alloy were tested by electrochemical workstation in static condition and reciprocating wear condition.The metal ion release was also tested by ICP-MS.The chemical compatibility of clindamycin hydrochloride and PLGA was studied by Fourier transform infrared spectroscopy and the in vitro degradation behavior and drug release of PLGA coating were studied experimentally and the antibacterial activity was assessed by a antibacterial circle method.The results are summaried as follows:The corrosion resistance of the as-cast Co-Cu alloy was similar to that of the aged alloy.However,the corrosion resistance of Co-Cu alloy decreasesd with the increase of copper content.Co-Cu alloy exhibited different corrosion resistances in kinds of simulated body fluids.The fluoride ion had a negative influence on the corrosion resistance,but the influence was limited.The immersion test indicated that the melting ion released from Co-Cu alloy mainly consisted of Co ion and small amount of Cr ion and Cu ion.Compared with the dry friction of Co-Cu alloy,the friction coefficient in solutions was reduced significantly but the wear rate was increased.Co-Cu alloys shows significant tribocorrosion behavior in different solutions,and the wear rate was in the order from low to high:Hank’s,Saliva,Saliva-pH3.5 and Saliva+0.2F.Compared with static corrosion,the corrosion resistance of the alloy was significantly reduced during the friction condition.However,no diffence was found in the triobocorrosion properties between the as-cast alloy and the aged alloy.Clindamycin hydrochloride and PLGA were physically mixed with no obvious chemical reaction.In vitro test indicated that the degradation rate of the drug-eluting PLGA increased with the increase of drug loading and almost completely degraded at 6 weeks.The drug release from the drug-eluting PLGA films can be divided into two stages:burst release and stabilization release.The drug release in the buest release stage was controlled mainly by drug diffusion while the drug release in the stabilization release stage was related to the degradation behaviors of PLGA.In the first 3 weeks of degradation,the drug-eluting PLGA had strong antibacterial activity,but its antibacterial ability decreased slightly with the prolongation of degradation time. |
