Abstract:

Objective Wound infections present a serious threat to human health, frequently causing delayed healing and potentially life-threatening complications. With the rise of antibiotic-resistant pathogens led by antimicrobial overuse, the alternative antibacterial approaches have become crucial. This study developed a biodegradable composite nano electrospun membrane with high antibacterial properties by electrospinning polyvinyl alcohol (PVA) incorporated with peony bark extract (PBE), a natural product known in traditional medicine for its anti-inflammatory and antimicrobial properties, aiming to create an eco-friendly and effective material. Meanwhile, glutaraldehyde (GA) was used as crosslinking agent to enhance the structural stability and water resistance of the membrane in a physiological environment.

Method PVA/PBE composite nanofiber membranes with different mass ratios of PBE were prepared by electrospinning technique, and glutaraldehyde (GA) was used as a crosslinking agent. The applied voltage was 19.5 kV, the feed rate was 0.72 mL/h, and the needle-to-collector distance was 15 cm. The resulting PBE/PVA composite nanofiber membranes were characterized using scanning electron microscopy (SEM) to analyze fiber morphology and diameter distribution, Fourier transform infrared spectroscopy (FTIR) to identify functional groups and investigate molecular interactions, X-ray diffraction (XRD) to assess changes in the crystalline phase, tensile testing to evaluate mechanical strength and flexibility, and water contact angle measurements to determine the surface wettability, which is critical for exudate management in wounds. Their antibacterial performances were evaluated against both Escherichia coli and Staphylococcus aureus.

Results The pure PVA nanofiber membrane had an average diameter of 0.16 μm. When GA was added, the average diameter of PVA/GA nanofiber membrane increased to 0.25 μm due to the enhanced molecular chain entanglement and increased solution viscosity. The incorporation of PBE further led to the slight increase in the average fiber diameter of PVA/PBE composite nanofiber membrane. When the mass fraction of PBE was 2%, the average fiber diameters in PVA/PBE composite membrane reached about 0.26 μm. SEM images confirmed that all membranes consisted of randomly oriented, continuous nanofibers without significant defects, and the incorporation of PBE did not cause bead formation. The results from FTIR spectra confirmed that the combination between PBE and PVA matrix was physical interactions rather than chemical bonding.The crosslinking effect of GA broadened the characteristic diffraction peak of PVA at around 19.5°, indicating the reduced crystallinity, while the addition of PBE hardly impacted on crystalline structure of PVA. This suggests that PBE was well-dispersed within the amorphous regions of the PVA matrix. Compared with the pure PVA membrane, the tensile strength and water contact angle of PBE/PVA composite membrane were obviously increased, indicating enhanced mechanical robustness and improved hydrophobicity, which is beneficial for maintaining integrity in a moist environment and the elongation at break decreased. When the mass fraction of PBE was 2%, the PVA/PBE composite nano electrospun membrane exhibited remarkable antibacterial activity. Its antibacterial efficiency was 99.99% against Escherichia coli (10.52 mm zone) and 99.88% against Staphylococcus aureus (4.58 mm zone).

Conclusion This study successfully developed a PVA/PBE composite nano electrospun membrane with high antibacterial activity. When the mass fraction of PBE was 2%, the antibacterial efficiency of PVA/PBE composite nano electrospun membrane could reach 99% against Escherichia coli and Staphylococcus aureus, and obviously inhibited the growth of these two bacterial colonies. The enhanced mechanical properties and tailored hydrophobicity further support its potential application as a functional wound dressing material. Our research may provide theoretical references for the antibacterial modification of PVA-based nanofibrous electrospun membranes including traditional Chinese medicine extracts, and expands the application of PVA nanofibrous electrospun membrane in the medical and health field.

Key words: polyvinyl alcohol, peony bark extract, glutaraldehyde, electrospinning, antibacterial property, nano fiber membrane, antibacterial agent