Supercritical Impregnation of Olive Leaf Extract in Poly(L-lactic acid-co-caprolactone) Filaments: An Environmentally Friendly Approach to Obtaining Active Biomedical Materials

The valorization of by-products in the olive sector has increasingly become the focus of business and research in the context of biorefineries. This work evaluates the recovery of bioactive compounds from olive leaves and their subsequent incorporation into poly(L-lactic- acid-co-caprolactone) (PLCL) filaments through supercritical impregnation. Obtaining an olive leaf extract (OLE) using enhanced solvent extraction at a high pressure (ESE with CO₂/ethanol 1:1 <i>v</i>/<i>v</i>) resulted in higher yields and concentrations of bioactives with high antioxidant and anti-inflammatory activity. No significant differences were found between the extracts obtained with different water regimes (irrigated and dry land). The supercritical impregnation of PLCL filaments showed that a low depressurization rate is essential to avoid material deformation, while the impregnation pressure and temperature influenced the OLE loading and antioxidant activity of the filaments. In vitro release studies showed the prolonged release of active compounds over 90 days, and the kinetics best fit the Korsmeyer-Peppas model, suggesting a diffusion mechanism. These results validate supercritical impregnation as a promising strategy for the development of OLE-active PLCL filaments with potential for biomedical applications requiring sustained therapeutic release.