The Research Of Cell’s Regulation Growth In The Micropattern Bioactive Surface Of Biomaterials

The study of bone defect and its repairation is still a great problem inorthopaedics,the desired biomaterials in orthopaedics should in the nature ofosteoconduction and osteoinductivity,surface modification is a important approach tocreate biocompatibility in the surface of biomaterials.The main purpose of this paper isto fabricate different shape and size bioactive molecule micropatterns on the surface ofbiomaterials to regulate the growth and the function of osteoblast,and create a surfacewhich have good biocompatibility。For this purpose,we create different types ofbioactive micropatterns through microcontact printing in biomaterials（titanium andPolystyrene），and study the effects of micropatterns in the regulation of osteoblastadhesion, spread and protein expression.The main component and result is as follows：1.We modify the surface of titanium and obtain a aldehyde functionlizationsurface，then use albumin from bovine serum（BSA） and human fibronectin（FN）as model protein，to create different size and shape of micropatterns in the aldehydemodified titanium surface through microcontact printing.The analysis of XPS、contactangle and AFM show we success in each steps of modification，then we observe BSAmicropatterns and FN micropatterns in the surface of titanium through Confocal LaserScanning Microscope（CLSM）.We use the same methed to analyse the proteinmicropatterns in the polystyrene（PS）,and take compare of micropatterns in twodifferent materials,we find the stability of the micropattern covalent bonding in titaniumis higher than the micropattern physical adsorp in PS,but the accuracy of the PS sampleis higher than the titanium sample;In the analysis of different sizes of micropatterns,wefind both positive stamp and negative stamp were deformed when the value of a wasless than or equal to5μm, which resulted in replication errors,and the patternsfabricated by the negative stamp were better than those of prepared by the positivestamp.2.Newborn rat osteoblast cells are seeded on these proteinmicropattern-functionalized PS and use microscope to observe the effection of themicropattern in osteoblast cell adhesion,spreading and proliferation;As the same timewe dye the cytoskeleton,nucleolus,collagenⅠ and osteocalcin throughimmunofluorescence method,then take images with CLSM. The results demonstrate thatosteoblast cells preferentially adhere and grow on the protein-functionalized patterns areas. The pattern sizes have significant influence on cell behaviour, including adhesion,spreading, distribution, and proliferation.The surface which have micropattern canpromote the proliferation of osteoblast and encourage the expression of collagenⅠ andosteocalcin.3.The single-walled carbon nanotubes (SWCNTs) were covalently grafted on thesurface after graft Poly ethylene imine（PEI） in3-Aminopropyltrimethoxysilane（APTMS） modified titanium. Water contact angle, X-ray photoelectronspectroscopy (XPS),atomic force microscopy (AFM) and scanning electron microscope（SEM） results revealed that the PEG-functionalized SWCNTs were successfullygrafted on the titanium surface.As the same time we obtain the CNT micropatterns inthe surface.Newborn rat osteoblast cells are seeded on CNT-functionalizedsurface,3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide（MTT） assayand cell adhesion were used for biocompatibility tests. When compared with theunmodified titanium substrate, the results showed that the CNT modified titaniumpresented lower cell viability but higher cell differentiation,the CNT have no obviouscytotoxicity However, for both titanium and CNT modified titanium samples, thenumber of survived cells in culture medium increased with the increase of incubationtime. Cell adhesion observations suggested that there were no obvious differencesbetween the titanium and the CNT modified titanium, and the number of adhered cellsincreased with the increase of culture time.