Characterization and Properties of PCL / PDIPF Matrices for Biomedical Applications

FERNÁNDEZ JM ; CORTIZO SM,; CORTIZO AM; ABRAHAM GA

Granada

Congreso; European Polymer Congress EPF 2011; 2011

Introduction: Currently there is a high interest in the study of synthetic biodegradable polymers for use as biocompatible scaffolds in different areas of tissue engineering and regenerative medicine. Poly(epsilon-caprolactone) (PCL) and poly(diisopropilfumarato) (PDIPF) have proven to be good substrates for adhesion, growth and differentiation of two osteoblastic cell lines, mouse calvaria derived MC3T3E1 and rat osteosarcoma UMR106, suggesting that these polymers can be useful in bone tissue regeneration. A blend material with better mechanical properties, intermediate degradation rate between the two homopolymers and demostrated biocompatibility was prepared and compatibilized by high intensity ultrasound starting from PCL and PDIPF(1). The aim of this study was to characterize and to evaluate the activity of MC3T3E1 cells compared to porous and non porous matrices of PCL/PFIP compatibilized.   Materials and Methods: The compatibilized sample was obtained according to previously described method (1). Non-porous films were obtained by casting of 4%w/v solutions on Petri dishes (5.5 cm diameter). Solvent was evaporate at ambient conditions in a fume hood and finally dried under vacuum until constant weight. Porous films were obtaining by electrospraying (flow rate = 1.5 ml / h, applied voltage = 0.7 kV / cm) and collected on glass slides (2.6 cm x 1.8 cm). The morphology of both kind of films was evaluated by scanning electron microscopy (SEM) and optical microscopy (OM). The hydrophobicity of films was determined by contact angle measurement. Adhesion and proliferation test: MC3T3E1 cells cultured on the films for 1 or 24 h, washed with PBS, fixed with methanol and stained with Giemsa. The number of cells was evaluated by counting the cells in 10 fields/films using an inverted microscope. Alkaline phosphatase activity (ALP), a markers of osteoblastic phenotype associated with bone-forming capacity was evaluated as previously reported (2). The control experiments were performed on plastic petri dishes for cell culture. The results are expressed as mean ± SEM obtained from experiments. Differences between groups were evaluated by a linear model with Tukey post-hoc using GraphPad in Stat version 3.00. A p value <0.05 was considered significant for all statistical analysis.   Results and Discussion: SEM images (Fig. 1 A,B) shows the morphology of the membranes obtained by electrospraying consist of a highly porous structure with interconnected pores, formed by polymer droplets of a size 6.7 mm ± 0.1 mm. In contrast, the films obtained by casting display a smooth surface, only few pores can be observed. Figure 1: SEM micrographs of PCL/PDIPF matrices obtained by electrospraying (left), and solvent casting (right). Biocompatibility studies showed that both adhesion and cell proliferation as well as ALP  increased significantly in cells cultured on theporous matrix with respect to non-porous scaffold ones (Fig.2). Figure 2: Celladhesion and proliferation (upper graph) and Alkaline phosphatase specific activity (lower graph).   Conclusions: Matrices obtained by deposition of droplets by the method of electrospraying allow us to obtain polymeric matrices with structures of interest in the field of bone tissue engineering.   References 1) J.M. Fernadez, M.S. Molinuevo, A.M. Cortizo, A.D. McCarthy, M.S. Cortizo. J. Biomater. Sci. Polym. Ed. 21, 1297-1312 (2010). 2) A.M. Cortizo, M.S. Molinuevo, D.A. Barrio and L. Bruzzone, Int. J. Biochem. Cell Biol. 38, 1171-1180 (2006).