Development and characterization of PCL membranes incorporated with Zn-doped bioactive glass produced by electrospinning for osteogenesis evaluation

The integration of biomaterials in tissue regeneration has been showing effectiveness in the treatment of diseases related to bone structure and tissue repair. Membranes have aroused interest due to their ease of manufacture, variation in composition, and the structure of the biomaterial. The incorporation of bioactive glass (BG) increases bioactivity, and when doped with therapeutic ions, changes in the physical-chemical composition of the biomaterial are expected to enhance its biological effect. This study aimed to produce polycaprolactone (PCL) membranes incorporated with 58S bioactive glass, doped with Zinc (Zn) by the electrospinning technique, and evaluate the influence of this biomaterial in the activity and differentiation of mesenchymal stem cells. The BG was produced by using the sol-gel process; next, before the PCL preparation, the BG was doped with zinc in a solution. Then, PCL solutions were prepared with 7% by weight of BG and doped with 10% ZnCl₂. Afterward, the electrospinning process was carried out using the fixed parameters: 2mLh-1 flow rate, 10kV voltage, and 12cm distance. Before the biological assays, the chemical elements present in the fibers were evaluated by energy dispersion X-ray spectroscopy (EDS), and the mapping technique. The morphology of the biomaterial and the diameter of fibers were analyzed by scanning electron microscopy (SEM), and the hydrophilicity of the membranes was evaluated by the contact angle technique. The in vitro tests consisted of cell plating with mesenchymal stem cells (MSC’s), previously obtained from rat femurs, at a density of 1x10⁴ per well that contained three different groups: a) P: mesenchymal stem cells plated with PCL; b) PB: mesenchymal stem cells plated with the composite of PCL / BG; c) PBZ: mesenchymal stem cells plated with the Zn doped PCL / BG composite. To evaluate the influence of the biomaterial on osteoblastic activity and differentiation, osteogenic and non-osteogenic media were used in tests of cell viability (MTT assay), total protein content, alkaline phosphatase activity (ALP), and mineralization nodules. The analysis by SEM proved that the electrospinning technique was efficient for producing fibers incorporated with bioactive glass, and EDS and the mapping technique confirmed the chemical components of each group of fibers, including the doped zinc in the bioactive glass. The analysis of fibers diameter showed that P and PBZ had presented fibers with a larger diameter than the PB group, and the contact angle technique showed an increase in the hydrophilicity of the group containing doped Zinc when compared to the other groups analyzed. The MTT assay confirmed that the membranes weren´t cytotoxic and allowed cell viability, total protein content showed that all the groups had cell activity, with a statistically significant difference between the groups (p<0,05). Even with no statistically significant difference, osteogenesis was proved by ALP activity and the formation of mineralization nodules. Based on the results, the PCL membranes incorporated with 58S bioactive glass doped with zinc have shown promise in tissue engineering for use in bone tissue regeneration.