Study On Design And Cytocompatibility Of Functional Particles Modified Poly (Lactic Acid) Surface

Poly(lactic acid)(PLA) used widely as a tissue engineering material has excellent physical and mechanical properties and good biodegradability. However, its cytocompatibility isn't satisfied for many applications. Polymeric particles have been used widely in many different fields, since they can be prepared easily and have controlled particles' sizes and good surface characters. Consideration of the poor cytocompatibility of PLA materials and excellent properties of polymeric particles, PLA materials were modified by embedding with polymeric particles and the cytocompatibility of modified PLA materials was studied in this work.Polymeric microspheres or nanospheres with a core-shell structure and different surface characters were prepared by using different materials as the surfactants and low-molecular-weight PLA as the core materials via o/w solvent evaporation. The results of confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) proved that the microspheres or nanospheres with different surface characters were obtained successfully. The CLSM investigation of FITC labeled particles showed that polymeric microspheres have a core-shell structure in which the surfactants existed in the shell of particles.Polymeric microspheres with different surface characters were embedded onto the surface of PLA membranes via surface entrapment. The obtained microspheres modified PLA membranes with different surface characters were proved by scanning electronic microscopy (SEM), CLSM and stability tests. Cytocompatibility tests of the microspheres modified PLA membranes showed that the cytocompatibility of modified PLA membranes with positive charges was better than that of modified PLA membranes with negative charges or neutral surface. There was an optimal density of positive charges for the cytocompatibility of the modified PLA membranes. The PLA membranes modified by polymeric microspheres with amino acids or RGD had better cytocompatibility than virgin PLA membrane. Polymeric microspheres with lysine or RGD could improve the cytocompatibility of PLA membranes better than polymeric microspheres with other amino acids.PLA membranes were modified by embedding with gelatin nanospheres or chitosan nanospheres via electrostatic assembly (ESA). The AFM results showed that nanospheres modified PLA membranes via electrostatic assembly were obtained successfully. The cytocompatibility test results showed that the gelatin nanospheres and chitosan nanospheres that embedded on the PLA membranes could obvious promote the attachment, growth and activity of chondrocytes. The higher density of gelatin nanospheres could lead to the better cytocompatibility of the nanospheres modified PLA membrane.Microspheres or nanospheres could be designed to modify the PLA membrane via surface entrapment or electrostatic assembly in this dissertation, which provided the surface modification of tissue engineering materials with a novel way.