Preparation Of Polymer Films With Different Surface Morphologies And In Vitro Cell Culture

Poly(organophosphazene)s are hybrid polymers with a backbone of alternating phosphorus and nitrogen atoms containing two organic side groups attached to each phosphorus atom, which makes them have the properties of both organic and inorganic compound. Therefore, they can be applied to kinds of fields, such as aerospace, oil, military, biomedical and so on. In biomedical fields, the biodegradable ones of poly(organophosphazene)s have been used the most widely. This is because that hydrolysis of polyphosphazene backbone is greatly affected by different side groups, which makes their degradation speed controllable, and their degradation products are non-toxic phosphate, ammonia salt and side groups, which will not cause aseptic inflammation. As a kind of ideal biomedical polymer materials, poly(organophosphazene)s has been certified by the FDA. Meanwhile, it has been studied and applied widely.On the study of tissue regeneration and repair based on the implant materials, the interaction of surface properties and cells is the key factor, which is because cells can express their functions only when they adhere to the surface of materials. Artificially matrix with specific topolographical structure on its surface has been widely used to control cells adhesion, proliferation and differentiation.To study the interaction with cells,different kinds of surface morphology, such as groove/ridge and micropore, have been constructed on the materials through the methods of coating, etching, grafting, electrospinning, etc. However, such researches mainly focused on the surface of metal, inorganic and non-biodegradable polymer. Seldom were carried out on biodegradable polymers. Accordingly, polyorganophosphazene films with different surface morphologies were prepared by solvent-casting of polymeric solutions of different concentrations in different humidity atmosphere. Then, the effect of surface patterns on cells adhesion, proliferation and differentiation were studied through in vitro.1. PAGP and PLGA7030 were synthesized by ring-opening polymerization and nucleophilic substitution of side groups. The structure, composition and molecular weight of polymers were characterized by 1H-NMR, GPC and viscosity measurement;2. Films of PAGP and PLGA7030 were prepared in different relative humidity atmosphere by the means of solvent casting. The surface properties of the films were characterized by SEM, AFM, XPS and the measurement of water contact angle. It is found that to change solution concentrations or relative humidity surround can significantly make surface morphology and composition of poly(organophosphazene)s films different. It is liable to form patterned surfaces when relative humidity surround is high, and polarity atoms with high affinity with water(P, N)were gathered on the surface;3. The tests of absorption of BSA and the experiments of cells adhesion and proliferation were carried out on the films. Results show that the patterned poly(organophosphazene)s films with higher surface roughness could adsorb more proteins per area, which made mouse osteoblasts OCT-1 adhere more easily, and proliferate more quickly;4. ALP activity, calcium deposition and the collagen typeⅠsynthesis of mouse osteoblasts OCT-1 were tested in vitro to study the effect of poly(organophosphazene)s films on cells proliferation. It is proved that the improvement of surface roughness and the increase of content of P can both promote the proliferation and function express of osteoblasts.