Electrospun Fibers and Sorbents as a Possible Basis for Effective Composite Wound Dressings

Abstract

Skin burns and ulcers are considered hard-to-heal wounds due to their high infection risk. For this reason, designing new options for wound dressings is a growing need. The objective of this work is to investigate the properties of poly (ε-caprolactone)/poly (vinyl-pyrrolidone) (PCL/PVP) microfibers produced via electrospinning along with sorbents loaded with Argovit™ silver nanoparticles (Ag-Si/Al₂O₃) as constituent components for composite wound dressings. The physicochemical properties of the fibers and sorbents were characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The mechanical properties of the fibers were also evaluated. The results of this work showed that the tested fibrous scaffolds have melting temperatures suitable for wound dressings design (58-60 °C). In addition, they demonstrated to be stable even after seven days in physiological solution, showing no macroscopic damage due to PVP release at the microscopic scale. Pelletized sorbents with the higher particle size demonstrated to have the best water uptake capabilities. Both, fibers and sorbents showed antimicrobial activity against Gram-negative bacteria Pseudomona aeruginosa and Escherichia coli, Gram-positive Staphylococcus aureus and the fungus Candida albicans. The best physicochemical properties were obtained with a scaffold produced with a PCL/PVP ratio of 85:15, this polymeric scaffold demonstrated the most antimicrobial activity without affecting the cell viability of human fibroblast. Pelletized Ag/Si-Al₂O₃-3 sorbent possessed the best water uptake capability and the higher antimicrobial activity, over time between all the sorbents tested. The combination of PCL/PVP 85:15 microfibers with the chosen Ag/Si-Al₂O₃-3 sorbent will be used in the following work for creation of wound dressings possessing exudate retention, biocompatibility and antimicrobial activity.

Keywords: Electrospinning; poly (vinyl pyrrolidone); poly (ε-caprolactone); silver sorbents; wound dressings.

Figure 1

SEM images of (A) poly (ε-caprolactone) (PCL), (B) poly (vinyl pyrrolidone) (PVP), (C) PCL/PVP 85:15 and (D) PCL/PVP 95:5 microfibers scaffold. All micrographs are in 5000× amplification (scale bar = 1 µm).

Figure 2

FTIR spectra of PCL, PVP and PCL/PVP fibers.

Figure 3

SEM images of (A) PCL, (B) PCL/PVP 85:15 and (C) PCL/PVP 95:5 microfibers scaffold after 7 days of physiological solution contact. All micrographs are 10,000× amplification (scale bar = 2 µm; scale bar = 1 µm for B and C).

Figure 4

HFF-1 cell viability of electrospun fibers and controls (DMEM as the positive control and DMSO as the negative control).

Figure 5

Typical stress–strain curves of electrospun pure PCL, PVP, PCL/PVP composite fiber mats (a selected replicate for each sample was chosen for this graph).

Figure 6

(A) Water absorption properties of compressed (pelletized) Ag-Si/Al₂O₃ sorbents. (B) Water absorption properties of powdered Ag-Si/Al₂O₃ sorbents.

Figure 7

Percentage of microbial growth of exposed Pseudomona aeruginosa to PCL/PVP fibers and sorbents, at 24, 48 and 72 h.