Functionalization Of PLLA Surfaces And The Interaction Between The Functionalized Surfaces And Proteins, Cell And Tissue

Interaction between biomaterials and tissues occurs via a layer of proteins adsorbed at the surface of biomaterials, which is the immediate event occurring on its first contact with biological fluids and tissues. The nature and amount of the protein or polysaccharide adsorption layer depends on material surface properties, such as wettability, polar or ionic interactions, chemical structures and topography of the surface. The surface determines essentially the biocompatibility whereas the bulk decides the physical, mechanical properties required of an implant. In this study, the surface of poly(L-lactic acid) (PLLA) was functionalized to improve its biocompatibility. The effects of the functional surfaces on the absorption/desorption property of proteins and on cell/tissue compatibility were investigated.Three kinds of functional PLLA surfaces were gained by alkaline hydrolysis and ammonia plasma treatments, entrapment method and biomineralization principle. The active carboxy and amido, six kinds of biomacromolecules (i.e., chitosan, carboxymethyl chitosan, methylene phosphochitosan, herapin, hyaluronic acid and chondroitin sulfate), and calcium-phosphorus coatings were introduced to functionalize PLLA surfaces. Many techniques were used to character the functional surfaces, and the results showed that the hydrophilicity, the density of active groups and the roughness of PLLA functional surfaces could be controlled by adjusting the modification conditions, such as the NaOH concentrations, the hydrolysis times and the plasma treatment powers and times. The x-ray photoelectron spectroscopy (XPS) analysis results showed that it was successful to get the biomacromolecules modified surfaces by means of the entrapment method. The SEM and AFM observation results showed that carboxylated PLLA surface could improve the building rate of the calcium-phosphorus coatings, which included matrix and granule with nano-scale structure. The component of the calcium-phosphorus coatings was apatite with rather loosing crystal by means of X-ray diffraction (XRD) analysis.In the research of the effect of functional surfaces on the adsorption/desorption...