Ozonation has been proved as a viable surface modification technique providing certain properties to the scaffolds that are essential in tissue engineering. However, the ozone (O₃) treatment of PCL scaffolds in aqueous environments has not yet been presented. O₃ treatment performed in aqueous environments is more effective compared with traditional, executed in ambient air treatment due to more abundant production of hydroxyl radicals (•OH) within the O₃ reaction with water molecules. During interaction with •OH, the scaffold acquires functional groups which improve wettability properties and encapsulate growth factors. In this study, a poly(ε)caprolactone (PCL) scaffold was fabricated using solution electrospinning and was subsequently ozonated in a water reactor. The O₃ treatment resulted in the expected occurrence of oxygen-containing functional groups, which improved scaffold wettability by almost 27% and enhanced cell proliferation for up to 14 days. The PCL scaffold was able to withhold 120 min of O₃ treatment, maintaining fibrous morphology and mechanical properties.

Polycaprolactone (PCL) is a non-cytotoxic, completely biodegradable biomaterial, ideal for cartilage tissue engineering. Despite drawbacks such as low hydrophilicity and lack of functional groups necessary for incorporating growth factors, it provides a proper environment for different cells, including stem cells. In our study, we aimed to improve properties of scaffolds for better cell adherence and cartilage regeneration. Thus, electrospun PCL–scaffolds were functionalized with ozone and loaded with TGF-β3. Together, human-muscle-derived stem cells (hMDSCs) were isolated and assessed for their phenotype and potential to differentiate into specific lineages. Then, hMDSCs were seeded on ozonated (O) and non-ozonated (“naïve” (NO)) scaffolds with or without protein and submitted for in vitro and in vivo experiments. In vitro studies showed that hMDSC and control cells (human chondrocyte) could be tracked for at least 14 days. We observed better proliferation of hMDSCs in O scaffolds compared to NO scaffolds from day 7 to day 28. Protein analysis revealed slightly higher expression of type II collagen (Coll2) on O scaffolds compared to NO on days 21 and 28. We detected more pronounced formation of glycosaminoglycans in the O scaffolds containing TGF-β3 and hMDSC compared to NO and scaffolds without TGF-β3 in in vivo animal experiments. Coll2-positive extracellular matrix was observed within O and NO scaffolds containing TGF-β3 and hMDSC for up to 8 weeks after implantation. These findings suggest that ozone-treated, TGF-β3-loaded scaffold with hMDSC is a promising tool in neocartilage formation.

Melt electrospinning is a fast-emerging technique for fibre formation. While the process is similar to solution electrospinning, the absence of solvents broadens the applications, avoiding the potential toxicity of solvent residues and enables the usage of non-dissolvable polymers. In this article, the influence of selected melt electrospinning process parameters (tip-to-collector distance, voltage, and melt temperature) on fibre diameter and diameter distribution was investigated. The screening experiments indicated that the lowest fibre diameter median was 2.19 μm. Based on the dependencies between each process parameter and median fibre diameter, the authors used response-surface plots to determine the optimal conditions to produce fibres with the desired fibre diameters. The lowest fibre diameters were obtained with the following process parameter input values: temperature, 348°C; voltage, 19 kV; and tip-to-collector distance, 3 cm. The obtained fibres indicated that the average value of fibre diameter medians decreased in comparison to the screening experiment and the median fibre diameter for the sample “Optim.” was 1.27 μm.