Diabetic foot ulcer (DFU) is a common complication in patients with diabetic hyperglycemia, which leaves patients at increased high risk of morbidity, infection, nontraumatic limb amputations, and even early death. [1-5] Among various efforts to address this urgent issue, wound dressings are effective strategies to provide an optimal environment for wound repair. [6,7] Traditional wound dressings for DFU treatment typically cover rubber, electrospun nanofiber, cotton wool, natural or synthetic bandages, and gauzes. [8,9] Although these dry dressings are convenient to control the initial state of wound healing, they tend to adhere to the wound area once the absorbed blood and exudate dry out. [7] Besides, the dry dressings still suffer from limitations of maintaining a moisture environment, allowing gaseous exchange, and preventing infection. [6,7] In this context, a wound dressing that can deal with the above shortcomings would be ideal to speed up diabetic foot wounds healing and improve treatment outcomes. In recent years, hydrogels have generated tremendous interest in wound healing applications. [10-16] As water-based soft materials, hydrogels can facilitate wound healing by absorbing wound exudate, preventing wound desiccation, and isolating the wound from the environment, which makes them the best choice for wound healing. [17,18] However, the currently available hydrogel dressings still require to be changed frequently, which is a laborious process and inevitably cause reinjury of the wounds, wound infection, delayed healing time, and personal suffering. [19] To this end, on-demand dissolvable hydrogels represent a new class of emerging "smart" wound dressings that can be readily operated and painlessly removed. [19-24] Generally, this type of hydrogels can form in situ and dissolve on-demand via physical crosslinking cases and chemical crosslinking cases. The dissolution of physically crosslinked hydrogels is based on physical interactions, such as molecular entanglements and/or secondary forces (e.g., ionic, H-bonding, and hydrophobic associations). [19,20,22,23] Diabetic foot ulcers (DFU) remain a very considerable health care burden, and their treatment is difficult. Hydrogel-based wound dressings are appealing to provide an optimal environment for wound repair. However, the currently available hydrogel dressings still need surgical or mechanical debridement from the wound, causing reinjury of the newly formed tissues, wound infection, delayed healing time, and personal suffering. Additionally, to meet people's increasing demand, hydrogel wound dressings with improved performance and multifunctionality are urgently required. Here, a new multifunctional supramolecular hydrogel for on-demand dissolvable diabetic foot wound dressings is designed and constructed. Based on multihydrogen bonds between hydrophilic polymers, the resultant supramolecular hydrogels present controlled and excellent properties, such as good transparency, antibacterial ability, conductive, and self-healing properties. Thus, the sup...
Wound infections are serious medical complications that can endanger human health. Latest researches show that conductive composite materials may make endogenous/exogenous electrical stimulation more effective, guide/comb cell migration to the wound, and subsequently promote wound healing. To accelerate infected wound healing, a novel medical silver nanoparticle-doped conductive polymer-based hydrogel system (Ag NPs/CPH) dressing with good conductivity, biocompatibility, and mechanical and antibacterial properties was fabricated. For the hydrogel dressing, Ag NPs/CPH, polyvinyl alcohol (PVA), and gelatin were used as the host matrix materials, and phytic acid (PA) was used as the cross-linking agent to introduce conductive polyaniline into the matrix, with antibacterial Ag NPs loaded via impregnation. After a series of analyses, the material containing 5 wt% of PVA by concentration, 1.5 wt% gelatin, 600 μL of AN reactive volume, and 600 μL of PA reactive volume was chosen for Ag NPs/CPH preparation. XPS and FTIR analysis had been further used to characterize the composition of the prepared Ag NPs/CPH. The test on the swelling property showed that the hydrogels had abundant pores with good water absorption (≈140% within 12 h). They can be loaded and continuously release Ag NPs. Thus, the prepared Ag NPs/CPH showed excellent antibacterial property with increasing duration of immersion of Ag NPs. Additionally, to evaluate in vivo safety, CCK-8 experiments of HaCat, LO2 and 293T cells were treated with different concentrations of the Ag NPs/CPH hydrogel soaking solution. The experimental results showed the Ag NPs/CPH had no significant inhibitory effect on any of the cells. Finally, an innovative infection and inflammation model was designed to evaluate the prepared Ag NPs/CPH hydrogel dressing for the treatment of severely infected wounds. The results showed that even when infected with bacteria for long periods of time (more than 20 h), the proposed conductive antibacterial hydrogel could treat severely infected wounds.
In recent years, carbon‐based fluorescent nanomaterials have been developed rapidly in biology and biomedicine due to their high optical absorptivity, adjustable fluorescent emission, chemical stability, well biocompatibility, and low toxicity. Their applications in temperature sensing have become one of the research hotspots. In this review, the authors summarize and sort out the carbon‐based fluorescent nanothermometers in the following work: 1) the types and temperature‐response mechanism of carbon‐based fluorescent nanomaterials are discussed; 2) the preparation methods of colorimetric fluorescent carbon‐based thermometers are introduced; 3) the applications of single/double emission carbon‐based fluorescent nanothermometers have been focused on. Finally, the authors give their own views on the future development direction of carbon‐based fluorescent nanothermometers. This review can provide guidance for the design and application of novel carbon‐based fluorescent nanothermometers.
As a kind of temperature‐responsive hydrogel, polystyrene‐co‐poly(N‐isopropylacrylamide)/poly(N‐isopropylacrylamide) (PS‐co‐PNIPAM/PNIPAM) core–shell nanoparticles prepared by two‐step copolymerization are widely studied and used because of their specific structures and properties. Unlike most reports about the steady stability of PS‐co‐PNIPAM/PNIPAM core–shell nanoparticle hydrogel emulsion, in this work, the PS‐co‐PNIPAM/PNIPAM core–shell nanoparticle hydrogel emulsion (symbolized as PS/PNIPAM hydrogel emulsion), which is prepared after the second step of synthesis and without washing out a large number of PNIPAM polymer segments, shows a reversible temperature‐dependent sol–gel transition characteristic during the temperature range of 34–80 °C. The PS/PNIPAM hydrogel emulsion is a normal solution at room temperature, and it changes from a sol to a gel statue when the temperature approaches up to low critical solution temperature (LCST). As the temperature continues to increase, the gel (core–shell nanoparticles as the crosslinkers and the linear PNIPAM chain as the 3D gel network) of the PS/PNIPAM hydrogel emulsion gradually shrinks and drains linearly. Compared with most crosslinked hydrogels, the hydrogel here can be arbitrarily changed in shape according to use needs, which is convenient for use, transportation, and storage. Here a new route is provided for the preparation of a PS/PNIPAM core–shell hydrogel nanoparticle system, as well as a new supramolecular crosslinking sol–gel system for application in biomedical materials, sensors, biological separation, drug release, macromolecular adsorption, and purification.
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