Wound dressing from polyvinyl alcohol/chitosan electrospun fiber membrane loaded with OH-CATH30 nanoparticles

Highlights

• Antimicrobial analysis revealed antibacterial activity against Escherichia coli and Staphylococcus aureus.

• The nanofibers could effectively maintain OH-30 biological activity, keep from degradating and improve bioavailability.

• The nano-system had dual antibacterial and promoting wound healing function.

Abstract

Novel nanomaterials have been developed for antimicrobial and wound healing applications. Here, we report the preparation of a polyvinyl alcohol/chitosan (PVA/CS) nanofiber with carboxymethyl chitosan nanoparticles (CMCS-OH30 NPs) encapsulating the antibacterial peptide OH-CATH30 (OH-30). The PVA/CS nanofibers containing OH-30 NPs (NP-30-NFs) obtained via electrospinning could achieve a secondary embedded OH-30. The effect of NP-30-NFs on the release of OH-30 was investigated through high-performance liquid chromatography. The antibacterial activities of NP-30-NFs against Escherichia coli and Staphylococcus aureus were studied by bacterial plate counting. NP-30-NFs containing different concentrations of NPs were applied to mouse skin wounds to determine their effectiveness in promoting wound healing. Results showed that NP-30-NFs exhibited antibacterial properties and promoted skin wound healing.

Introduction

Surgery, burns, abrasions, and chronic ulcers are among the key factors that cause skin trauma (Sun, Siprashvili, & Khavari, 2014). Skin damage is often accompanied with self-repair of the skin. These repair processes are essential for organismal homeostasis and survival (Rankin & Artis, 2018). Skin tissue repair is a dynamic and complex process that involves inflammation, angiogenesis, granulation tissue growth, foreign body reaction, and re-epithelialization (Gao et al., 2018; Zhou et al., 2016). Unfortunately, wound infections can easily occur during wound healing, thereby delaying the healing process. Therefore, bacterial infection is a major concern in the treatment of open wounds and burns (Akia, Rodriguez, Materon, Gilkerson, & Lozano, 2019).

Antibacterial peptides (AMPs) of natural origin may be clinical candidates because of their broad-spectrum antibacterial activity, difficulty in causing drug resistance, and regulatory effect on the body’s immune system. As a possible candidate drug against clinical drug-resistant isolates (Li, Lee, & Zhang, 2012, 2013), cathelicidin OH-CATH30 (OH-30) derived from king cobra selectively upregulates chemokine and cytokine production without eliciting harmful immune responses to induce a regulatory effect on inflammatory responses and to treat various bacterial infections (Li et al., 2014; Zhang et al., 2010; Zhao et al., 2018). Notably, the dynamic balance of inflammatory response and reduced inflammation is an important guarantee for tissue repair (Eming, Krieg, & Davidson, 2007; Rankin & Artis, 2018). AMPs, as antibacterial agents, have great potential for wound dressing applications (Gomes, Mano, Queiroz, & Gouveia, 2015). However, limited stability and bioavailability restrict their applications because AMPs are easily hydrolyzed by proteases (Silva et al., 2015). Therefore, effectively avoiding the enzyme degradation of AMPs and accurately controlling their release are desired for active peptide nanomaterials (Silva et al., 2015). A drug delivery carrier should be developed to protect active peptides from proteases and release these peptides. We reported that our prepared biodegradable drug nanoparticle (NP) CMCS-OH-30 delivery system can promote OH-30 sustained release. Our results also demonstrated that the prepared CMCS-OH-30 NPs accelerate the healing of skin lesions and reduce scars on mice (Sun et al., 2018).

The application of occlusive wound dressings is a routine external intervention that helps accelerate re-epithelialization and alters the inflammatory milieu to favor healing (Sun et al., 2014). Traditional wound dressings, such as gauze, bandages, and sponges, are used to prevent bacterial invasion, but limited swelling capacity restricts their applications (Fu et al., 2016). Modern wound dressings, such as hydrogels and nanofibers produced by electrospinning active components derived from natural sources, have been widely explored to overcome this issue in regenerative medicine and trauma (Zhou, Sui, Mo, & Sun, 2017). However, biological dressing that creates a moist environment to promote wound healing is also an ideal place for the colonization and reproduction of pathogenic microbes (Pei, Sun, Sun, Wang, & Zhao, 2015). Therefore, effectively reducing bacterial infection and creating a relatively sterile microenvironment are important prerequisites for developing an effective wound dressing. Stimulus-responsive CS and poly (N-vinyl-2-pyrrolidone) (PVP) hydrogels for wound healing application exhibit antibacterial activity (Rasool, Ata, & Islam, 2019), and injectable hydrogels (Xan-CHO and NOCC) accelerate the reconstruction of the abdominal wall in rats (Huang et al., 2018). In addition, wound dressings containing antibiotics (Garcia et al., 2017), nonsteroidal anti-inflammatory drugs, such as ibuprofen (Morgado, Miguel, Correia, & Aguiar-Ricardo, 2017), titanium dioxide (El-Aassar, El Fawal, El-Deeb, Hassan, & Mo, 2016), and silver nanoparticles (Ag-NPs) (Das, Kumar, Patil, Viswanathan, & Ghosh, 2015; Kohsari, Shariatinia, & Pourmortazavi, 2016; Lee et al., 2014; Mokhena & Luyt, 2017), have shown good results against bacteria and are beneficial to wound healing.

Electrospun nanofibers have been considered as applicable materials for wound dressing applications because of their intrinsic properties, such as high surface-area-to-volume ratio and swelling (Miguel et al., 2019). Nanofibers in these membranes can act as drug delivery systems (Gao et al., 2016), which prompt the incorporation of biomolecules within the fiber structure to prevent skin infections and improve healing (El-Aassar et al., 2016; Miguel et al., 2019). CS is a biodegradable natural polysaccharide that promotes blood clotting and pain relief (Charensriwilaiwat et al., 2012). PVA is a water-soluble polymer widely used in wound dressings because of its excellent film-forming and mechanical properties (Fu et al., 2016; Zhao, Chen, Yao, & Li, 2017). Besides, blended fiber membranes composed of PVA and CS are extensively used in various fields, such as tissue engineering scaffolds, drug delivery (Miguel et al., 2019; Zarandi et al., 2015), new wound dressings (Zhao et al., 2017; Zhou et al., 2013), heavy metal adsorption (Habiba, Afifi, Salleh, & Ang, 2017), and air filtration sterilization (Wang et al., 2018). Therefore, a PVA/CS system is expected to be a good carrier of OH-30 and beneficial to the sustained release of reagents.

In this study, NP-30-NFs were used as dressing for mouse skin wound to test the applicability of PVA/CS nanofibers as a drug delivery carrier of OH-30 and wound dressing material via FTIR, SEM and LSCM. We envisaged that NP-30-NFs could further enhance the bioavailability and stability of OH-30. The release behaviour of OH-30 in NP-30-NFs was evaluated compared with CMCS−OH-30 NPs. In addition, antibacterial tests and mouse wound healing experiments were also evaluated. These characteristics showed the advantage of using the nanofibers as wound dressing.