| 316LSS stainless steel（316LSS）is widely used in the medical field of orthopedic implant,dental implant and coronary stents due to its good biocompatibility,mechanical properties and corrosion resistance.However,it still has some disadvantages,such as bio-inert and non-antibacterial properties.It is general recognize that infection is unavoidable after transplantation,which would result in failure of surgery.Therefore,the surface of 316LSS needs to be modified to improve its biological properties.Nano-pits arrays could be prepared by anodization method on 316LSS.In our previous study,different sized（40-200）nm nano-pits surfaces on 316LSS were prepared by an anodization procedure and this special nano-structure（nano-pits arrays）has been proven to effectively regulate the behaviors of cells.It can take advantage of nano-pits arrays to load bioactivity materials in order to improve the biological properties of 316LSS.Firstly,Se is an essential trace element for human being,which possess antioxidant and anticancer properties.Secondly,Si bioactive materials have excellent bioactivity,which can rapidly inducethe bone-like apatite deposition and promote the bone cell proliferation and differentiation.MSNs possess high drug loading capability due to their high specific surface area and large pore volume.Lastly,TiO2 has broad-spectrum resistance and suppress or kill common pathogen to some extent.Therefore,the main purpose of this study is to introduce nano-particles(Se,MSNs and TiO2 into the 316LSS nano-pits array as functional units.The repeated arrangement of the dot units is expected to obtain an ordered array of functional dots on the 316LSS surface.Firstly,nano-pits arrays with large size were prepared on 316LSS（N-316LSS）by anodization method and the related physical parameters were characterized.Secondly,Se,MSNs,TiO2 was introduced into appropriate nano-pits arrays in order to obtain the corresponding nano-dots array.The conclusions are as follows:Nano-Se/316LSS（NSA/316LSS）were prepared by redox-melting method.FESEM results show that nano-Se with an average size of（45±5）nm was well distributed into the nano-pit arrays XRD indicated that the crystal form of Se is hexagonal form.The cellular compatibility experiment exhibits that the NSA/316LSS shows higher OD value than the others after 1,3 and 5 days of culture,and The result of proliferation of MSCs showed that NSA/316LSS demonstrated great potential for promoting the proliferation of MSCs.ALP expression of MSCs cultured on samples for 14 and 21 days was tested,which results showed that the ALP activity of the NSA/316LSS was significantly higher than 316LSS（p<0.01）.ICP-AES results showed that the nano-Se on the NSA/316LSS surface has a sustained release effect in PBS.Furthermore,the NSA/316LSS suggest a higher level of the abilities above,resulting from up-regulated proliferation,gene expression and bone generation.MSNs/316LSS was prepared by coating-template method.FESEM results show that ordered nano-pits array of MSNs（4515）nm and（9015）nm can be assembled in the 316LSS pits-array.TEM results showed that MSNs had worm-like pore structure.The BET measurements indicated a high surface area ≈626 m2/g,and pore diameter =（2.7=10.3）nm.The drug loading and the entrapment efficiency of MSNs/316LSS was（16.3±2.8）%and（29.7±3.2）%.At pH=7.4,the accumulated release amount of 24h was about 18.9%;at pH= 5.5,the accumulated release amount of 24h was about 44.6%.NTA/316LSS was prepared by sol-gel-one step in situ method.FESEM results show that nano-TiO2 well distributed into the surface of the nano-pits array.The diameter of nano-TiO2 on 316LSS surface was was about（45±4）nm.The results of antibacterial activities show that the inhibition rates of NTA/316LSS to E.coli and S.aureus were（93.1±1.3）%and（96.3±2.4）%after 24 h incubation.In addition,the cellular compatibility in vitro shows that the OD value of MSCs on NTA/316LSS was dramatically higher than that control group（p<0.01）.In summary,the ordered nano-pits array constructed by electrochemical anodization on the 316LSS surface can be used as a template to obtain the nano-dots array of various bioactive substances.NSA/316LSS were prepared by redox-melting method,which can promote the adhesion and extension of MSCs and have the effect of releasing ions in PBS.MSNsA/316LSS was prepared by coating-template method.The results show that the sizes of MSNs can be adjusted,and mesoporous structure of MSNs can be further loaded with drugs for drug delivery.NTA/316LSS was prepared by sol-gel-one step in situ method.NTA/316LSS possess excellent antibacterial activity and compatibility to MSCs.Thoes modifications of 316LSS are expected to provide experimental and theoretical evidences for the study of functionalization surface of biomaterials. |
