Natural tissue recapitulation biomaterials provide an appropriate microenvironment to direct cell behaviors and fates. In addition, natural skin mimicking asymmetric dressing is an efficient approach to improve wound healing, especially in the case of severe burns.
Study: Asymmetric biomimetic composite dressing by electrospinning with aligned nanofibrous and micropatterned structures for the healing of severe burn wounds. Image credit: Roman Zaiets/Shutterstock.com
In a paper recently published in the journal ACS Applied Materials and Interfaces, an asymmetric composite dressing was fabricated by preparing asymmetric surfaces and modifying the sponge on both sides for wettability using electrospinning.
The collagen and quaternized chitosan composite sponge (Col/QCS) was fabricated by freeze-drying, in which the modification of the inner layer with hydrophilicity of poly(ε-caprolactone) (PCL)/gelatin (Gel) nanofibers. On the other hand, by modifying the outer layers of the sponge with micronanostructure, the PCL/polystyrene microsphere imparted hydrophobicity on each side.
The morphology and properties of the fabricated asymmetric composite dressings synergistically contributed to the antibacterial activity promoting wound healing in severe burns by managing cell behavior. Experimental results obtained from in vitro studies revealed that the inner layer of the sponge lined with nanofibers promoted all stages from cell adhesion to cell proliferation. The outer layer showed resistance to bacterial adhesion and presented good mechanical properties.
On the other hand, the in vivo results showed that the fabricated composite dressing reduced the inflammatory response, accelerated angiogenesis, prevented infection and epithelial regeneration, and accelerated the healing of severe burns. Therefore, the proposed asymmetric composite dressing was expected to serve as a potential candidate for wound healing in severe burns.
Efficient dressing for wound healing in severe burns
According to tissue engineering studies, the composition, topography and surface structure of biomaterials influence cell behavior and fate. Therefore, significant effects on stem cells guided their differentiation, promoting neuroregeneration and bone regrowth.
Although several dressings based on hydrogels, sponges and membranes with loaded bioactive agents were used for wound healing in severe burns, the efficiency of these dressings was limited to their dressing composition without considering account for the influence of structure and topography. Different novel dressings with wettability were prepared by bioprinting, electrostatic spinning and phase conversion (dry/wet).
In asymmetric wound dressings, a hydrophobic outer layer mimics an epidermal layer in terms of tensile strength, preventing excessive dehydration, resisting bacterial adhesion, maintaining infiltration, and creating a moisturizing environment. On the other hand, the hydrophilic inner layer can mimic the dermis and allow gas exchange, providing space for cell growth, proliferation and migration. However, building an antibacterial hydrophobic outer layer into a composite dressing for severe burns is challenging.
The natural superhydrophobic surface structure of lotus leaves has inspired the development of various micronanostructures. These micronanostructures mimicked natural superhydrophobic surfaces and had enhanced surface roughness that reduced their contact with water to improve the hydrophobicity of the material. Thus, preparing asymmetric dressings based on biomimetic hydrophobic principles with an antibacterial outer layer may help to achieve an efficient dressing for wound healing in severe burns.
Asymmetric biomimetic composite dressing for wound healing in severe burns
In the present study, electrospinning technology was used to create a composite dressing for severe burns with asymmetric structures and surface wettability. The composite dressing prevented bacterial infection and accelerated wound healing in severe burns. To this end, the composite dressing material mimicked the structure and properties of natural skin.
Initially, a Col/QCS sponge was created by freeze-drying, followed by its alignment with PCL/gelatin-loaded curcumin nanofiber (Cur) to obtain a hydrophilic inner layer. Additionally, a PCL/PS hierarchical micronanostructure in the outer layer imparted hydrophobicity to both sides of the sponge.
Between the two layers, the inner hydrophilic layer was predicted to promote the adhesion, growth, and migration of endothelial cells and fibroblasts through topographic guidance, to achieve radical scavenging ability and a shortened inflammatory phase due to the controlled release of cur, to heal severe burns. .
In addition, the porous structure of the Col/QCS sponge prevented the accumulation of exudates, excess water dehydration in severe burns, and showed antibacterial activity. The superhydrophobic structure of the lotus leaf mimicking the outer layer of PCL/PS provided good mechanical support and prevented bacterial adhesion and colonization in severe burns.
Thus, the fabricated asymmetric composite dressing structurally mimicked the dermis and epidermis of natural skin and exhibited good physical properties, osmotic fluid absorption, biocompatibility, antibacterial ability, and reactive oxygen species (ROS) scavenging. In addition, re-epithelialization, healing rate, angiogenesis, collagen deposition and anti-inflammatory effects were investigated for asymmetric composite dressings used for wound healing in severe burns.
conclusion
A composite dressing mimicking natural skin with wettability and asymmetric structure was developed to facilitate wound healing in severe burns. The outer layer had a hierarchical micronanostructure, inspired by the lotus leaf effect, and prevented contamination by bacterial adhesion.
In addition, the nanofiber-lined inner layer mimicked the structure of the dermis, which enhanced the biological process from cell adhesion to macrophage polarization. In addition, cur loaded in the inner layer showed antioxidant and antibacterial properties that were synthesized with the morphological structure, reduced inflammatory reactions and accelerated wound healing in severe burns.
reference
He, C., Yu, B., Lv, Y., Huang, Y., Guo, J., Li, L., Chen, M et al. (2022). Asymmetric biomimetic composite dressing by electrospinning with aligned nanofibrous and micropatterned structures for healing severe burn wounds. ACS applied materials and interfaces. https://pubs.acs.org/doi/10.1021/acsami.2c04323
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