Boron-Doped Mesoporous Bioactive Glass Nanoparticles (B-MBGNs) in Poly(ε-caprolactone)/Poly(propylene succinate- co-glycerol succinate) Nanofiber Mats for Tissue Engineering

Abstract

Increased demand for advanced biomaterials in tissue engineering has driven research to develop innovative solutions based on smart material combinations. Mesoporous bioactive glass nanoparticles (MBGNs) have emerged as attractive materials because of their angiogenic and regenerative properties. This study explores the incorporation of boron-doped mesoporous bioactive glass nanoparticles (B-MBGNs) into poly(ε-caprolactone) (PCL) and poly(propylene succinate-co-glycerol succinate) (PPSG) fibers to enhance their biodegradation and bioactivity. B-MBGNs were synthesized via a microemulsion-assisted sol-gel method and characterized through morphology, pore size distribution, composition, and surface area. PCL/PPSG nanofibers were fabricated using an alternative combination of solvents, formic acid, and acetic acid. B-MBGNs were incorporated into PCL/PPSG solutions at concentrations of 5, 10, and 15 wt % and electrospun into nanofiber mats under a flow rate of 0.2 mL/h at 22 °C and 40% relative humidity, while the voltage applied at the needle tip was 18 kV and -2 kV at the rotating drum. The addition of 10 wt % of B-MBGNs resulted in nanofibers that exhibited a high degradation rate in PBS with a weight loss of 44% in 30 days, significant hydrophilicity with a contact angle of 33°, and improvements in cell viability tested with normal human dermal fibroblasts (NHDF). In addition, the study highlights the effect of the concentration of B-MBGNs on the morphology of the fibers, which can agglomerate and form undesired beads. Although the particles improved cellular activity, the changes in morphology caused tension points that reduced the elasticity of the fibers. Overall, this work contributes to the innovative use of green polyesters combined with boron ions in electrospun fibrous scaffolds, expanding the opportunities for applications in tissue regeneration, for example, to treat chronic wounds in diabetic patients.

Keywords: benign solvents; biodegradable polymers; electrospinning; mesoporous bioactive glass nanoparticles; scaffolds.

1

SEM image and corresponding EDX analysis of B-MBGNs (a), XRD pattern (b), and FTIR spectrum (c) of the B-MBGNs.

2

SEM micrographs of the electrospun samples and their respective size diameter distribution, without B-MBGNs (a) PCL/PPSG, and with 5 wt % (b) PCL/PPSG/5B-MBGNs; with 10 wt % (c) PCL/PPSG/10B-MBGNs; and 15 wt % (d) PCL/PPSG/15B-MBGNs.

3

EDS mapping of electrospun nanocomposite scaffold PCL/PPSG/5B-MBGNs showing distribution of Ca and Si elements on the surface.

4

FTIR spectra of fiber mats in the 400 to 3500 cm^–1 wavenumber range.

5

Weight loss during immersion of the fiber mats in PBS at 37 °C for 30 days (a), contact angle of electrospun mats with varying amounts of B-MBGNs (b), and SEM images of samples after 30 days of immersion in PBS: PCL/PPSG (c); PCL/PPSG/5B-MBGNs (d); PCL/PPSG/10B-MBGNs (e); PCL/PPSG/15B-MBGNs (f).

6

XRD patterns of B-MBGNs electrospun fibers incubated in SBF solution over 14 days. The peaks at 21.4° and 23.8° indicate the crystal structure of PCL (●), and the peak at 32.2° indicates the presence of hydroxyapatite (⧫).

7

FTIR analysis of electrospun PCL/PPSG fiber mats containing 5% of B-MBGNs (a), 10% of B-MBGNs (b), and 15% of B-MBGNs (c) immersed in SBF solution over 7 days and their respective SEM images.

8

Metabolic activity measured by WST-8 analysis at 450 nm for all seedings (*p < 0.05). Fluorescence images of fibroblasts on fibers after 1 day: PSC/PPSG/5B-MBGNs (a); PSC/PPSG/10B-MBGNs (b); PSC/PPSG/15B-MBGNs (c); PSC/PPSG (d).