Oxygen-Releasing Antibacterial Nanofibrous Scaffolds for Tissue Engineering Applications

Abstract

Lack of suitable auto/allografts has been delaying surgical interventions for the treatment of numerous disorders and has also caused a serious threat to public health. Tissue engineering could be one of the best alternatives to solve this issue. However, deficiency of oxygen supply in the wounded and implanted engineered tissues, caused by circulatory problems and insufficient angiogenesis, has been a rate-limiting step in translation of tissue-engineered grafts. To address this issue, we designed oxygen-releasing electrospun composite scaffolds, based on a previously developed hybrid polymeric matrix composed of poly(glycerol sebacate) (PGS) and poly(ε-caprolactone) (PCL). By performing ball-milling, we were able to embed a large percent of calcium peroxide (CP) nanoparticles into the PGS/PCL nanofibers able to generate oxygen. The composite scaffold exhibited a smooth fiber structure, while providing sustainable oxygen release for several days to a week, and significantly improved cell metabolic activity due to alleviation of hypoxic environment around primary bone-marrow-derived mesenchymal stem cells (BM-MSCs). Moreover, the composite scaffolds also showed good antibacterial performance. In conjunction to other improved features, such as degradation behavior, the developed scaffolds are promising biomaterials for various tissue-engineering and wound-healing applications.

Keywords: PGS/PCL; antibacterial properties; biocompatibility; biodegradability; calcium peroxide; electrospinning; oxygen-releasing scaffold.

Figure 1

Schematic illustration describing the fabrication process of oxygen-releasing scaffolds by electrospinning.

Figure 2

(a) Alizarin red S staining of the electrospun sheet with different concentration of CP, confirms incorporation of CP in PGS/PCL polymer network. (b) XRD spectra of CP nanoparticles, PCL/PGS scaffold and composite scaffold. (c) TEM image of the electrospun composite nanofiber demonstrates embedding of CP nanoparticles within the fiber. (d,e) DSC curve of PGS/PCL scaffold with different concentration of CP scaffold during heating (d) and cooling (e).

Figure 3

SEM images and size distributions of ball-milled CP particles (a), PCL/PGS scaffold without CP (b) and PCL/PGS scaffold with 1% (c), 2.5% (d), 5% (e) and 10% (f) CP. Scale bars = 1 µm (a) and 10 µm (b–f).

Figure 4

(a) Degradation profiles in PBS buffer, and (b) oxygen-releasing kinetics of the composite PGS/PCL scaffolds at various CP concentrations.

Figure 5

(a) Antibacterial activity of the scaffolds against S. aureus presented by zone of inhibition. (b) Cell viability results for the scaffold-free 3D-printed ring (control), presented by the optical density (OD) value for the MTT assays. (c) Cell metabolic activity of BM-MSCs in the scaffold. The data were normalized according to Equation (4) and represented as mean ± SD (n = 3).