In Situ Electrospinning of Iodine‑Based Fibrous Meshes for Advanced Antibacterial Wound Dressings

Abstract

We demonstrate the first handheld, in‑situ electrospinning of iodine‑laden poly(vinyl pyrrolidone) (PVP) and poly(vinyl butyral) (PVB) solutions, producing fibrous meshes that combine high porosity, excellent gas permeability, and potent antibacterial activity. Scanning electron microscopy (SEM) confirms smooth, uniform fibers whose diameters decrease with higher iodine content. Energy‑dispersive spectroscopy (EDS) and Fourier‑transform infrared (FTIR) spectroscopy verify the presence of iodine without altering the polymer chemistry. The resulting meshes exhibit low contact angles (<20°) and air permeability up to 324 mm s⁻¹, outperforming conventional wound dressings. Antibacterial tests against E. coli and S. aureus show clear inhibition zones, with the highest activity in 5 % iodine‑doped PVP. Importantly, the handheld device allows direct application onto irregular wound beds, offering a flexible, patient‑friendly dressing solution.

Background

Electrospun nanofibrous membranes are the gold standard for wound care because their nanoscale architecture mimics the extracellular matrix, promoting hemostasis, gas exchange, and scar‑free healing. PVP and PVB are prized for their biocompatibility, solubility, and low toxicity, making them ideal substrates for wound dressings. Iodine, and its complex with PVP (PVPI), has long been used as a broad‑spectrum antiseptic. Traditional PVPI‑based dressings, however, require pre‑fabricated meshes that may need to be trimmed or re‑applied, potentially causing additional trauma. In‑situ electrospinning eliminates this step by depositing the dressing directly onto the wound.

Materials & Methods

• Polymers: PVP (250 kDa, 13 wt % in ethanol) and PVB (100 kDa, 10 wt % in ethyl alcohol).
• Iodine Loading: 1 %, 2 %, and 5 % (wt %) iodine or PVPI dissolved into the polymer solutions. Solutions stirred for ≥24 h before use.
• Device: Hand‑held electrospinning unit (HHE‑1) operating at a fixed 10 kV, nozzle diameter 0.1 mm, with a 8 cm collector distance.
• Characterization: SEM (Phenom ProX, 10 kV) after gold coating; EDS for elemental mapping; FTIR (Thermo Nicolet iN10); contact angle via 2 µL simulated body fluid (SBF); air permeability (Textest FX3300, 200 Pa); pore size (PSM 165); antibacterial zones against E. coli (ATCC 10536) and S. aureus (ATCC 25923).

Results & Discussion

Fiber Morphology

SEM images reveal smooth, defect‑free fibers. Iodine‑only doped PVP fibers show a progressive reduction in mean diameter from 1.2 µm (0 %) to 0.6 µm (5 %), attributed to increased solution conductivity. In contrast, PVPI‑doped PVP and PVB fibers exhibit a slight diameter increase with higher PVPI due to elevated viscosity.

Elemental & Spectroscopic Confirmation

EDS spectra for 5 % iodine/PVPI samples show distinct iodine peaks alongside dominant C and O signals, confirming successful incorporation. FTIR spectra display characteristic PVP/PVB bands (e.g., C=O stretching at ~1720 cm⁻¹) with negligible shifts, indicating that iodine or PVPI does not disrupt the polymer backbone.

Wettability

All meshes are highly hydrophilic; contact angles drop below 20° with increasing iodine/PVPI content. PVB meshes, typically hydrophobic, become nearly fully wettable when PVPI exceeds 2 %, owing to the hydrophilic iodine complex.

Air Permeability & Pore Structure

Air permeability rises from 59.9 mm s⁻¹ (pure PVP) to 324.3 mm s⁻¹ (5 % iodine‑PVP). PVPI‑doped samples maintain values above 200 mm s⁻¹. Pore sizes range from 1.9 µm to 9.1 µm, matching skin cell dimensions and supporting optimal gas exchange. Compared to commercial dressings, the electrospun meshes exhibit 2–4 × higher permeability.

Antibacterial Activity

Clear inhibition zones appear only in iodine/PVPI‑doped meshes. The 5 % iodine‑PVP sample shows the largest zones (~25 mm) against both E. coli and S. aureus, outperforming PVPI‑doped PVP and PVB/PVPI. This trend underscores the dose‑dependent antibacterial efficacy of the incorporated iodine species.

In‑Situ Application

Using the HHE‑1, meshes can be deposited directly onto a model hand wound, forming a conforming, thin film that adheres via electrostatic attraction. The mesh remains flexible, can be peeled off gently, and can be reapplied without additional equipment.

Conclusions

The handheld in‑situ electrospinning platform produces iodine‑loaded PVP/PVB meshes that combine structural fidelity, superior breathability, and robust antibacterial action. The approach eliminates the need for pre‑manufactured dressings and offers a customizable, minimally invasive solution for wound care.