Analysis of surface microtopography of biodegradable polymer matrices using confocal reflection microscopy

Currently, synthetic degradable polymers are frequently employed as culture substrates prior to cell transplantation and as implantable scaffolds for cellular infiltration during soft and hard tissue repair. The surface microstructure of matrices based on such polymers may be important in controlling cellular anchorage, spreading, and growth on the external surface, as well as infiltration into the voids of porous polymer scaffolds. While the chemistry, bulk structure, and mechanical properties of such polymers have been extensively studied, the surface microstructure has not yet been systematically examined, particularly following polymer degradation. In this study, we present the first account of the use of confocal laser-scanning reflection microscopy (CLSM) to visualize and quantitate the microtopography of the surface of porous matrices of poly(lactic acid)/poly(glycolic acid) (PLAGA) copolymers following polymer degradation. Utilizing this technique, we report that the surface morphology of PLAGA matrices changes significantly upon degradation, with increased local clustering of textured regions. Our quantitative analysis suggests that polymer degradation results in a lower spatially-averaged surface roughness, with significant cyclical variations observed at later time points. The computed surface correlation function was observed to increase upon degradation, confirming the results from our morphological studies. Finally, we demonstrate the efficacy of CLSM to concomitantly image both the polymer surface and locally attached cells, in real time.