Study On The Properties Of MAO/PA Composite Coatings On The Magnesium Alloy Clip In Cholecystectomy

Background and ObjectiveWith the development of laparoscopic cholecystectomy,surgical ligation clips become a most common method to ligate the cystic duct and artery.Because the non-degradable clip will inevitably produce some side effects such as removing and falling off.Because the magnesium alloy materials can produce the satisfactory biocompatibility and biodegradability,which has attracted widely attention,however,it is a pity that poor corrosion resistance.Therefore,in this study,MAO/PA composite coating were used to cover the surface of Mg-Zn-Y-Nd alloy clip,and the biocompatibility of the clip was explored through in vivo and in vitro experiments,so as to evaluate the feasibility of the application of magnesium alloy clip in cholecystectomyMaterials and methods(1)Mg-Zn-Y-Nd magnesium alloy disks were coated by micro arc oxidation in the electrolyte prepared under suitable parameters,and phytic acid was coated on the surface of micro arc oxidation film by dipping method.Electrochemical experiment was carried out in the electrochemical workstation to observe the instantaneous corrosion state.(2)In vitro was observed cell compatibility by the relative survival rate and cell morphology.The activity and apoptosis of cells were detected by flow cytometric analysis.The morphology and structure were explored by cell adhesion experiment,so as to judge the adhesion of cells on the alloy surface.(3)The gall bladder clips were made of magnesium alloy.After sterilization,the gall bladder duct and artery were closed with gall bladder clips,the gall bladder was cut off,and then the abdomen of surgical rabbits were closed.The liver and kidney of rabbits were taken out at 1,2 and 3 weeks respectively,and using the HE staining to investigate the pathological changes.Blood magnesium ion was detected the changes of magnesium in the body.And the corrosion morphology of the gallbladder clip surface was observed by naked eyes and scanning electron microscopy(SEM)respectively,elemental composition was investigated by energy spectrum analysis(EDS).Results(1)In vitro,the results of electrochemical experiment showed that the MAO/PA coating magnesium alloy samples can reduce the corrosion in the simulated body fluid.In vivo,the degradation experiments also confirmed that the good corrosion performance,but 1-3 weeks after cholecystectomy,the MAO/PA coated magnesium alloy clips have been degraded.(2)In vitro cytotoxicity experiments and cell adhesion experiments showed that the gallbladder clip had no obvious toxic effect on cells,and the relative survival rate of the cells was more than 75%,but the results of cell flow cytometry discovered that the rate of apoptosis went up slightly with the increasing the extract concentration.And the cell adhesion showed that the morphology and structure of the cells were matched with the normal fibroblasts.(3)In vivo experiments,the HE staining results showed that MAO/PA coating of the Mg-Zn-Y-Nd alloys gallbladder clip demonstrated no significant damage to the heart and liver even kidney tissues of New Zealand white rabbits.There was no obvious abnormality in blood magnesium content.X-ray examination showed that the MAO/PA coated Mg-Zn-Y-Nd alloys gallbladder clips did not fall off and remove,and there was no obvious tissue emphysema in the surrounding tissues.Conclusions(1)In vitro,the MAO/PA conversion coated Mg-Zn-Y-Nd alloys,which has a superior corrosion resistance compared to the uncoated group.Thus,micro-arc oxidation and phytic acid double coating can slow down the rapid degradation of Mg alloy,what is more,they also enhance the biocompatibility of Mg-Zn-Y-Nd alloys.(2)In vivo,the MAO/PA coating Mg-Zn-Y-Nd alloy gallbladder clip also showed that good biocompatibility and corrosion resistance,However,1-3 weeks after cholecystectomy,the magnesium alloy gallbladder clips have been degraded before the physical body without recovering fully.Therefore,it is necessary to further explore the corrosion-resistant coatings to improve the corrosion resistance of the magnesium alloy.But this study provides a new idea for the application of degradable magnesium alloy gall bladder clips in laparoscopic cholecystectomy.