Antibacterial Electrospun Membrane with Hierarchical Bead-on-String Structured Fibres for Wound Infections

Abstract

Chronic wounds often result in multiple infections with various kinds of bacteria and uncontrolled wound exudate, resulting in several healthcare issues. Advanced medicated nanofibres prepared by electrospinning have gained much attention for their topical application on infected chronic wounds. The objective of this work is to enhance the critical variables of ciprofloxacin-loaded polycaprolactone-silk sericin (PCL/SS-PVA-CIP) nanofibre production via the process of electrospinning. To examine the antibacterial effectiveness of PCL/SS-PVA-CIP nanocomposites, the material was tested against P. aeruginosa and S. aureus. The combination of PCL/SS-PVA-CIP exhibited potent inhibitory properties, with the most effective concentrations of ciprofloxacin (CIP) being 3 μg/g and 7.0 μg/g for each bacterium, respectively. The biocompatibility was evaluated by conducting cell reduction and proliferation studies using the human epidermal keratinocyte (HaCaT) cells and human gingival fibroblasts (HGFs) in vitro cell lines. The PCL/SS-PVA-CIP showed good cell compatibility with HaCaT and HGF cells, with effective proliferation even at antibiotic doses of up to 7.0 μg/g. The drug release effectiveness of the nanocomposites was assessed at various concentrations of CIP, resulting in a maximum cumulative release of 76.5% and 74.4% after 72 h for CIP concentrations of 3 μg/g and 7 μg/g, respectively. In summary, our study emphasizes the possibility of combining silk sericin (SS) and polycaprolactone (PCL) loading with CIP nanocomposite for wound management.

Keywords: biocompatible; biodegradable; ciprofloxacin; nanofibres; natural polymer; polycaprolactone; silk sericin.

Scheme 1

(A) Schematic of the PCL/SS-PVA-CIP nanofibre fabrication process. (B) The cross-sectional area of the encapsulation of CIP within SS and PVA with Tween 20.

Figure 1

(A) Effect of fast-evaporating solvents on conical-shaped polymeric droplet during electrospinning and stable Taylor cone formation with control of T and RH in the chamber. (B) Conductivity of (a) 10% PCL, (b) 1% PCL/SS-PVA-CIP (3.0 μg/g), (c) PCL/1% SS-PVA-CIP (7.0 μg/g) (d) PCL/2% SS-PVA-CIP (3.0 μg/g), and (e) PCL/2% SS-PVA-CIP (7.0 μg/g). Data illustrates mean ± SD, n = 3.

Figure 2

SEM images (left) and diameter distributions (right) showing morphological features of electrospun PCL scaffolds. The scaffolds were obtained from 10% w/v pure PCL in ethyl acetate, with 2% w/v SS, 0.5% w/v PVA, and (A) 1.5 μg/g, (B) 3.0 μg/g and (C) 7.0 μg/g of CIP. Fiber diameter distribution of (A–C) scaffolds with mean ± SD for 50 nanofibres.

Figure 3

(A) Contact angle drop images and (B) measured contact angle values, (C) viscosity, and (D) conductivity of (a) 10% PCL, (b) 1% PCL/SS-PVA-CIP (3.0 μg/g), (c) PCL/1% SS-PVA-CIP (7.0 μg/g) (d) PCL/2% SS-PVA-CIP (3.0 μg/g), and (e) PCL/2% SS-PVA-CIP (3.0 μg/g). Data illustrate mean ± SD, n = 3. (D) The graph showing the change in dry weight of electrospun scaffolds due to the degradation: (1) PCL/1% SS-PVA-CIP (3.0 μg/g), (2) PCL/1% SS-PVA-CIP (7.0 μg/g), (3) PCL/2% SS-PVA-CIP (3.0 μg/g) and (4) PCL/2% SS-PVA-CIP (7.0 μg/g) over 1 week in PBS (n = 3).

Scheme 2

The process and mechanism of slow drug release of the nanofibre scaffolds and its applications.

Figure 4

Photographic images of (A) ZOI of (a) PCL (negative control), (b) PCL/1% SS-PVA-CIP (3.0 μg/g), (c) PCL/1% SS-PVA-CIP (7.0 μg/g), (d) PCL/2% SS-PVA-CIP (3.0 μg/g), and (e) PCL/2% SS-PVA-CIP (7.0 μg/g) exposed to P. aeruginosa and S. aureus. (B,C) Bar graphs representing ZOI of (a) PCL (negative control), (b) PCL/1% SS-PVA-CIP (3.0 μg/g), (c) PCL/1% SS-PVA-CIP (7.0 μg/g), (d) PCL/2% SS-PVA-CIP (3.0 μg/g), and (e) PCL/2% SS-PVA-CIP (7.0 μg/g) exposed to P. aeruginosa and S. aureus, respectively. Data were analyzed using one-way ANOVA and Tukey analysis; data represent mean ± SD, n = 3, * p ≤ 0.05.

Figure 5

(A) The proliferation of HaCaT and HGF cells under multiple treatments and (B,C) MTT assay results of (a) TCP (vehicle control), (b) 6.4 μg/mL CIP (positive control), (c) PCL (negative control), (d) PCL/1% SS-PVA-CIP (3.0 μg/g), (e) PCL/2% SS-PVA-CIP (3.0 μg/g), (f) PCL/1% SS-PVA-CIP (7.0 μg/g) and (g) PCL/2% SS-PVA-CIP (7.0 μg/g). Data were analysed using one-way ANOVA and Tukey analysis, n = 6; mean ± SD; * p ≤ 0.05.