Miscibility, interactions and antimicrobial activity of poly(ε-caprolactone)/chloramphenicol blends

Poly(ε-caprolactone) (PCL) has been blended with Chloramphenicol (CAM), a well-known bacteriostatic antibiotic, in order to obtain new biomaterials with antibacterial properties. The resulting samples have been thoroughly characterized regarding both their physicochemical behavior and antimicrobial efficacy by means of very diverse techniques. Hence, PCL/CAM blend miscibility has been analyzed by Differential Scanning Calorimetry (DSC) using the single glass transition temperature (T_g) criterion, intermediate between those corresponding to the two components in the blend. In turn, the interaction parameter has been obtained from the analysis of the melting point depression in both PCL-rich and CAM-rich blends. Fourier-Transform Infra-Red (FTIR) spectroscopy and X-Ray Diffraction (XRD) analysis have been used -in the pure components and in the blends- to analyze both the specific interactions and the crystallization behavior, respectively. The morphology of PCL/CAM blends obtained by spin-coating has been also studied by means of Atomic Force Microscopy (AFM). Finally, drug release kinetics of different PCL/CAM systems as well as their antibacterial efficacy against Escherichia Coli have been investigated, indicating that CAM can be released from the PCL/CAM blends in a controlled way while keeping intact the antibacterial efficiency.