Biodegradable materials for biomedical applications should not only have appropriate Volasertib PLK mechanical and biodegradation properties, but also good interactions with the surrounding tissues of the implantation site. Indeed, the biological response is mainly influenced by the surface properties of the biomaterial. Therefore, incorporation of biologically active molecules, such as proteins or peptides, on the surface of biomaterials is recognized as a promising strategy to improve the bioactivity of the materials employed in the medical field.11,12 In order to obtain a stable protein layer, the biomolecule should be covalently bonded on the surface of the material. However, PLCL copolymers do not have any reactive groups in their chemical structure for further covalent attachment of proteins.
Thus, they should be functionalized, which is a major challenge for this kind of material. Indeed, special care has to be taken when trying to modify the surface of biodegradable polymers showing glass transition temperatures similar to room or body temperatures such as the PLCL used in this work. Moreover, the functionalization should not affect the copolymer structural composition in order to keep all its initial properties. Among the numerous techniques described in literature for the introduction of reactive groups,13,14 surface modification by plasma treatment is the most adequate15,16 since it allows the efficient incorporation of functional groups onto the biomaterial surface without affecting their bulk properties (chain reorganization, crystallinity, faster degradation).
17,18 Regarding plasma treatments applied on biodegradable polymers, to our knowledge, no study on PLCL has been reported whereas such treatments have already been done on PLLA, poly(glycolide) (PGA), PLGA or PCL.19-22 In this work a terpolymer composed of ��-caprolactone (CL), D-lactide (D-LA) and L-lactide (L-LA) was used as base material and fully characterized in terms of molecular weight, molecular organization, chemical structure and mechanical properties before surface modification. The terpolymer functionalization was done under N2 and H2 atmospheric pressure plasma discharge. The amino groups created were used as the anchoring point for the covalent grafting of albumin by using a heterobifunctional crosslinker.
X-ray photoelectron spectroscopy (XPS), contact angle and atomic force microscopy (AFM) were used to characterize the surface modifications of the material. Finally, a hydrolytic degradation study of untreated terpolymer (PLCL), plasma modified PLCL (P-PLCL) and albumin grafted PLCL (BSA-PLCL) Carfilzomib in phosphate-buffered saline (PBS) at 37 ��C was performed for a period up to 63 d. The changes in crystallinity, molecular weight and chemical composition of the samples were followed by using differential scanning calorimetry (DSC), gel permeation chromatography (GPC), Fourier Transform Infrared spectroscopy (FTIR) and XPS.