Poly-ε-Caprolactone/Gelatin Hybrid Electrospun Composite Nanofibrous Mats Containing Ultrasound Assisted Herbal Extract: Antimicrobial and Cell Proliferation Study

Abstract

Electrospun fibers have emerged as promising materials in the field of biomedicine, due to their superior physical and cell supportive properties. In particular, electrospun mats are being developed for advanced wound dressing applications. Such applications require the firers to possess excellent antimicrobial properties in order to inhibit potential microbial colonization from resident and non-resident bacteria. In this study, we have developed Poly-ε-Caprolactone /gelatin hybrid composite mats loaded with natural herbal extract (Gymnema sylvestre) to prevent bacterial colonization. As-spun scaffolds exhibited good wettability and desirable mechanical properties retaining their fibrous structure after immersing them in phosphate buffered saline (pH 7.2) for up to 30 days. The initial burst release of Gymnema sylvestre prevented the colonization of bacteria as confirmed by the radial disc diffusion assay. Furthermore, the electrospun mats promoted cellular attachment, spreading and proliferation of human primary dermal fibroblasts and cultured keratinocytes, which are crucial parenchymal cell-types involved in the skin recovery process. Overall these results demonstrated the utility of Gymnema sylvestre impregnated electrospun PCL/Gelatin nanofibrous mats as an effective antimicrobial wound dressing.

Keywords: anti-infective wound dressing; electrospun hybrid mats; gelatin; poly-ε-caprolactone; ultrasound assisted extraction.

Scheme 1

Electrospinning setup used to prepare hybrid mats.

Figure 1

SEM images of electrospun (a) Poly-ε-Caprolactone (PCL); (b) PCL/Gelatin (Gel); (c) PCL/Gel+Ultrasound Assisted Extracts (USE); (d) PCL/Gel+Cold Macerated Extracts (CME); and (e) PCL/Gel+Gymnemagenin (GYM). Scale bar = 1 µm.

Figure 2

(A) FTIR spectrum of PCL/Gel, PCL/Gel+USE, PCL/Gel+CME and PCL/Gel+GYM nanofiber mats. (B) Stress-strain curve of PCL, PCL/Gel, PCL/Gel+USE, PCL/Gel+CME and PCL/Gel+GYM nanofibrous mats. For mechanical studies, 4 samples were tested for each mat type (n = 4) and the representative data was shown.

Figure 3

Photographs showing the water contact angle on (a) PCL; (b) PCL/Gel; (c) PCL/Gel+USE; (d) PCL/Gel+CME; and (e) PCL/Gel+GYM.

Figure 4

(A) Drug release profile of USE/CME from PCL/Gel nanofibrous mats. (B) In vitro degradation of electrospun nanofibers.

Figure 5

Cell proliferation on electrospun PCL/Gel based mats via MTS assay. (A) DFs and (B) HaCaT. Statistical significance of cell viability was determined by 1-way ANOVA ** p < 0.01; *** p < 0.001; **** p < 0.0001 and ns p > 0.05. SEM images of cells on different electrospun mats. (C) DFs and (D) HaCaT. Scale bar = 100 µm. Red dotted lines indicate the initial seeding density of cells (8000 cells per well). Insets represent the magnified image (500×).

Figure 6

Laser confocal microscopy images on various electrospun mats. (A) DFs and (B) HaCaT cells. F-Actin stained green for DFs, red for HaCaT and the nuclei were stained blue. Scale bar = 20 µm.

Figure 7

Bactericidal activity of electrospun mats against microorganisms. Statistical significance compared against positive control determined by 1-way ANOVA **** p < 0.0001 and ns p > 0.05.