钛表面电化学沉积氢氧化镁与氧化镁涂层的抗菌性能与生物活性

Antibacterial Properties and Biological Activities of Magnesium Hydroxide and Magnesium Oxide Coatings by Electrochemical Deposition on Titanium Surface

骨科植入物相关感染已严重影响手术效果及术后康复,因此需研究具备良好抗菌性能及生物活性的涂层。首先确定电化学沉积氢氧化镁[Mg(OH)_(2)]及氧化镁(MgO)涂层的制备条件,在钛表面沉积不同时间的Mg(OH)_(2)及MgO涂层,评价并比较2种涂层的体外抗菌及生物相容性。各组样品表面均匀分布颗粒样物质[Mg(OH)_(2)及Mg O],颗粒密度与覆盖率随沉积时间增加。Mg(OH)2及MgO涂层对金黄色葡萄球菌及大肠杆菌均具良好抗菌性且抗菌率随沉积时间增强。沉积≤3 h,Mg O抑菌率显著高于Mg(OH)_(2);沉积≥6 h,两者`抑菌率均接近100%。Mg(OH)_(2)及MgO涂层细胞毒性随沉积时间上升,其中沉积0.5、1.0 h的2组样品毒性随培养时间下降,其余3组随培养时间上升。沉积0.5 h的Mg(OH)_(2)及MgO样品与细胞共培养5 d时的细胞存活率为152%、90%;沉积12 h的2组样品与细胞共培养5 d时细胞存活率为2%、6%。研究表明电化学沉积法可成功制备Mg(OH)_(2)涂层,且煅烧后可获得Mg O涂层。沉积1h的Mg(OH)_(2)及Mg O涂层样品具备良好抗菌性能的同时细胞毒性较小。

Institute of Tissue Engineering and Stem Cell Research,The Second Clinical College of North Sichuan Medical College,Nanchong Central Hospital;Department of Oral and Maxillofacial Surgery,School of Stomatology and Hospital of Stomatology,Qilu Medical College,Shandong University,Shandong Key Laboratory of Oral Tissue Regeneration,Shandong Engineering Laboratory of Oral Biomaterials and Tissue Regeneration,Shandong Clinical Medical Research Center of Oral Diseases;Sichuan University,Biomaterials Engineering Research Center;Introduction Titanium(Ti)-based implants are one of the most commonly used materials in orthopedic surgery.Although Ti-based implants have good biomechanical properties and biocompatibility,their non-antibacterial shortcomings lead to orthopedic implant-related infections that seriously affect the effect of surgery and postoperative recovery.and serious cases need a second operation and increase the pain and cost of patients.Some studies reported metal or antibiotic antibacterial coatings on Ti-based implants,but they have some disadvantages(i.e.,heavy metal coatings can cause damage to the human body,and excessive use of antibiotic coatings can lead to drug resistance).It is thus necessary to investigate the preparation of coatings with good antibacterial properties and biological activities on the surface of Ti-based implants,so as to provide an effective solution to the problem of bone implant-related infection in clinic.Magnesium(Mg)is a major element in human body.Some studies reported that Mg and its compounds have good antibacterial and biocompatibility.Methods Ti sheets were cleaned and immersed in an electrolyte containing sodium chloride and magnesium chloride(p H=9.5)and applied a DC voltage of 3.0 V for 0-12 h to obtain magnesium hydroxide[Mg(OH)_(2)]coatings.After deposition,Mg(OH)_(2) coatings were calcined in a muffle furnace at a heating rate of 2℃/min at 650℃for 6 h to obtain magnesium oxide(Mg O)coatings.The phases of each group of samples were analyzed by X-ray diffraction(XRD),the surface morphology was analyzed by scanning electron microscopy(SEM)and the composition of surface elements was analyzed by energy dispersive spectroscopy(EDS).The in-vitro antibacterial properties of the samples were evaluated according to the standard ISO22196—2011.The bacterial liquid was resuscitated,diluting it to 1×105 cfu/m L(cfu is colony-forming units).The samples were firstly sterilized by drying,then 300μL bacterial solution(i.e.,Staphylococcus aureus and Escherichia coli)was then dropped onto each sample and incubated in a constant temperature incubator(at 37℃)for 24 h.After diluting the coating plate,the colony number was analyzed and converted to antibacterial rate.The in-vitro cytotoxicity of each sample was evaluated according to the standard ISO10993.5.After dry heat sterilization,the samples were placed in a 24-well plate(no sample cell suspension in the control group and complete culture medium in the blank group).1m L mouse osteoblast suspensions(OB-6;5000 cell/m L)were dropped onto each sample and then incubated in a cell culture box(5%CO_(2) at 37℃)for 1 d,3 d or 5 d.After the completion of culture,the absorbance value was detected by a method named CCK-8 and converted to a cell survival rate.Results and discussion Mg(OH)_(2) coating was prepared on titanium surface by an electrochemical deposition method,and Mg O coating was obtained after calcination.Granular matter[Mg(OH)_(2) and Mg O]are uniformly distributed on the surface of each group,and the particle density and coverage rate increase with deposition time.Mg(OH)_(2) and Mg O coatings all have a good antibacterial activity against Staphylococcus aureus and Escherichia coli.The antibacterial rates increase with deposition time.When deposited for≤3 h,the antibacterial rate of Mg O is higher than that of Mg(OH)_(2).After deposited for≥6 h,the bacteriostatic rate of both is close to 100%.The cytotoxicity of Mg(OH)_(2) and Mg O coatings increases with the deposition time,and the toxicity of the two groups(i.e.,deposited for 0.5 h and 1.0 h)decreases with the culture time,and the toxicity of the other three groups(i.e.,deposited for 3 h,6 h and 12 h)increases with the culture time.At 5 d,the survival rates of Mg(OH)_(2) and Mg O samples deposited for 0.5 h are 152%and 90%,and the survival rates of the two groups of samples deposited for 12 h are 2%and 6%,respectively.Conclusions The surface morphology and thickness of Mg(OH)_(2) and Mg O coatings changed with the deposition time.The cytotoxicity and antibacterial rate of the coatings were enhanced with the deposition time.It was speculated that there was a dose-effect relationship between them and the coating.The results showed that Mg(OH)_(2) coating could be prepared by electrochemical deposition,and the Mg O coating could be obtained after calcination.Mg(OH)_(2) and Mg O coatings deposited for 1 h had good comprehensive properties.