The field of wound care has long faced an "impossible triangle": it is difficult for a single dressing to simultaneously provide comprehensive protection, comfortable wear, and highly effective antibacterial properties. Now, this challenge has been overcome by an innovative achievement that integrates materials bionics and photocatalysis technology.

A research team led by Professors Wang Xun'ai, Shi Shuo, Zhou Huiqun, and Yang Ming from Hong Kong Polytechnic University, in collaboration with City University of Hong Kong, Jiangnan University, and Zhejiang Sci-Tech University, has successfully developed a novel wound dressing called "biomimetic cooling skin." It does not simply cover the wound; rather, it functions like a highly intelligent life support system, actively participating in and accelerating the entire healing process.

Traditional dressings have their drawbacks: gauze tends to stick to wounds, causing secondary pain during dressing changes; foam dressings are expensive; and hydrocolloids are ineffective against infected wounds. This newly launched biomimetic cooling skin fundamentally changes this situation. It ingeniously constructs a hierarchical "Janus" nanofiber structure and loads visible-light-responsive metal-organic frameworks (MOFs), unprecedentedly integrating passive thermal management, on-demand antibacterial properties, and skin-like mechanical properties.

The brilliance of this "skin" lies in its duality. Its outer layer is a hydrophobic "protective armor," where polyvinylidene fluoride (PVDF) nanofibers are firmly bonded together using solvent welding technology. This not only endows the material with a tensile strength of approximately 21.6 MPa and a fracture strain of approximately 54%, closely matching natural skin, but also efficiently reflects sunlight and radiates heat outward, achieving passive cooling. Its hydrophilic inner layer, on the other hand, is a "healing chamber," responsible for absorbing wound exudate and firmly anchoring the key to its antibacterial function—iron-modified zeolite imidazole framework-8 (Fe-ZIF8) nanoparticles.

It was on this particle that the research team achieved a key breakthrough. Through DFT simulations and UPS measurements, they discovered that the incorporation of iron atoms acted like a key, significantly reducing the band gap of ZIF8 from 5.15 eV to 2.56 eV, making it activatable by visible light. Under illumination, Fe-ZIF8 can generate reactive oxygen species with twice the intensity of the original material, triggering a redox chain reaction with potent bactericidal effects.

The performance data of this dressing is impressive. It breathes like skin, exhibiting excellent breathability, moisture permeability, and particle filtration efficiency. Under simulated sunlight, its Janus structure cools the surface by approximately 4°C; in real outdoor environments, it also achieved an average cooling of 1.7°C on the wound surface in rat models. This ability to proactively create a cooling environment on hot, infected wounds is itself crucial for reducing early inflammation.

In terms of combating infection, under white light irradiation, the dressing achieved an antibacterial rate of up to 97.1% against Staphylococcus aureus, even surpassing the antibiotic control group, while maintaining good biocompatibility with cells. Its efficacy was definitively validated in a rat model of infected wounds: wounds treated with the biomimetic skin healed almost completely within 11 days, more than twice the healing speed of the untreated group or the conventional material group.

To ensure wounds not only heal quickly but also heal well, the research team, through comprehensive RNA sequencing analysis, revealed for the first time the deep mechanism by which this dressing actively regulates repair at the gene level. Like a master conductor, it upregulates genes that promote angiogenesis and cell migration, while activating the expression of antimicrobial peptides and downregulating key inflammatory factors. This means the wound microenvironment is comprehensively optimized, creating a harmonious symphony of healing through antibacterial, angiogenesis, anti-inflammation, and antioxidant effects. Final tissue sections confirmed this: the newly formed collagen deposits were uniform and dense, and the regenerated epidermis was almost twice the thickness of normal skin, exhibiting a robust healing state without excessive scarring.

This research, published in a renowned international academic journal, transcends the traditional definition of "a new material." It groundbreakingly demonstrates that through the seamless integration of structural biomimicry and functional materials, inanimate dressings can actively respond to the wound environment and provide precise treatment. It combines thermal comfort, active infection control, and accelerated tissue regeneration, setting an ideal benchmark for next-generation biomedical materials and bringing new hope to patients suffering from chronic or infected wounds.