Ascorbyl palmitate–PCL fiber mats loaded with strontium polyphosphate nanoparticles for guided bone regeneration

Abstract

AbstractMultifunctional fiber mats are explored as potential bioactive matrices for the development of the next generation of guided bone regeneration membranes with tunable microstructure, strength and therapeutic activity. In the present study, polycaprolactone (PCL) nanofibers with different concentrations of ascorbic acid derivatives (ascorbyl palmitate) and strontium polyphosphate nanoparticles (Sr-polyP NPs) were fabricated. The obtained PCL mats scaffolds were assessed not only for microstructure structure features, including morphological observation, hydrophilicity and tensile strength, but also in vitro water uptake, biodegradation (under enzymatic and hydrolytic conditions), bioactivity using SBF, as well as ascorbic acid release study. The observed results showed that the mean fiber diameter of the PCL fibers (388 ± 340 nm) increased with the increase in the concentration of the ASP and Sr-polyP NPs. The addition of ascorbyl palmitate caused an increase in viscosity from 40.6 ± 2.5 to 66.6 ± 2.0 cP in the case of 20% AsP/PCL; however, it caused a decrease in conductivity from 7.3 ± 0.4 to 6.38 µs, while there was an obvious increase in the viscosity and conductivity by Sr-polyP Nps addition from 40.6 ± 2.5 cP in the case of PCL only to 88.3 ± 2.5 cP in the case of PA1/SP15. The contact angle decreases from 125.9 ± 2.5° in the case of PCL only to 112 ± 4 and 102 ± 2.4° in the case of 20% loaded ascorbyl palmitate-PCL mats and 15% Sr/PCL, respectively. Moreover, the assessment of the antioxidant activity of PCL fiber mats containing 10% and 20% ascorbyl palmitate demonstrated that the 20% ascorbyl palmitate-PCL fiber mats have a higher antioxidant effectiveness compared to the 10% mats. This could be attributed to the controlled release of ascorbic acid from PCL, which occurs after 7 days. However, the highest tensile strength was observed for 5% Sr-polyP NPs-loaded PCL/AsP mats at 1.52 ± 0.51 MPa. Further increase of Sr-polyP NPs content resulted in a clear decrease of tensile strength to 1.13 ± 0.13and 0.93 ± 0.71 for 10% and 20% ascorbyl palmitate-PCL mats, respectively. Importantly, the fabricated AsP and Sr-polyP NPs-loaded PCL fiber mats showed induction of calcium phosphate deposition in SBF and the ability to sustain release of ascorbic acid over a time period of 28 d, in addition to the enhancement in cell proliferation compared to PCL only suggesting their application as a favorable synthetic matrix to amplify guided bone regeneration process. Graphical abstract