Sprayable Multifunctional Black Phosphorus Hydrogel with On-Demand Removability for Joint Skin Wound Healing

Robust Controlled Degradation of Enzyme Loaded PCL-Based Fibrous Scaffolds Toward Scarless Skin Tissue Regeneration

Uncontrolled degradation of wound dressings may result in residues, causing several negative effects on wound healing, such as secondary damage, undesirable inflammation, and scar skin formation. Here, an available strategy associated with the synthesis of enzyme-loaded (Burkholderia cepacia lipase, BCL) polycaprolactone (PCL) nanofiber scaffolds, aligning with wound healing effects is reported. These scaffolds are fabricated via fiber microfluidic electrospinning degradation-control technique. The obtained scaffolds exhibit tunable degradation rates, achieving complete degradation within 12-72-h cycles. The acidic degradation products are further elucidated and reveal the potential degradation mechanism. The acidic degradation products create an optimal microenvironment during the hemostasis and inflammation stages of wound healing. Notably, in vivo experiments demonstrate the enzyme-loaded scaffolds effectively promote angiogenesis, reduce inflammatory responses, mitigate collagen deposition, and regulate fibroblast differentiation. This promotes rapid wound healing with a remarkable scarless rate of over 99% by day 21. New guidelines for scar-free healing dressings are proposed, which carry out faster degradation without microplastics (MPs) and toxic byproducts before scar formation. These principles might provide valuable insights and promise for developing more effective wound dressings.

Black Phosphorus Nanosheet-Based Composite Biomaterials for the Enhanced Repair of Infectious Bone Defects

Infectious bone defects pose significant challenges in orthopedic practice, marked by persistent bacterial infection and ongoing inflammatory responses. Recent advancements in bone tissue engineering have led to the development of biomaterials with both antibacterial properties and the ability to promote bone regeneration, offering new solutions to these complex issues. Black phosphorus nanosheets (BPNS), a unique two-dimensional material, demonstrate exceptional biocompatibility, bioactivity, and antibacterial properties. Their combination of osteogenic, antibacterial, and anti-inflammatory effects positions BPNS as an ideal candidate for addressing bone defects complicated by infection. This Review explores the potential of BPNS-based composite biomaterials in repairing infectious bone defects, discussing their molecular mechanisms for antibacterial activity, including intrinsic antibacterial properties, photothermal therapy (PTT), photodynamic therapy (PDT), and drug delivery. The application of BPNS in treating infectious bone defects, through hydrogels, scaffolds, coatings, and fibers, is also discussed. The Review emphasizes the transformative role of BPNS in bone tissue engineering and advocates for continued research and development in this promising field.

Sprayable, antimicrobial and immunoregulation hydrogel loading exosomes based on oxidized sodium alginate for efficient wound healing at skin graft donor sites and health detection

Skin grafting techniques are widely used for large burns, trauma, and various acute and chronic wounds, contributing greatly to the repair of traumatic tissue. However, donor site repair and regeneration are often neglected, resulting in infection and delayed healing. Therefore, it is crucial to reduce the rate of donor site infection and improve the speed and quality of healing. The low-oxidized sodium alginate (OSA) grafting ε-polylysine (OSA-g-EPL) prepared through the Schiff base reaction was used to load with mesenchymal stem cell exosomes (Exo), and crosslinked by Ca2+ to form a gel film (HAE) on the surface of the wound by spraying. EPL provided the hydrogel with good antimicrobial properties, and Exo promoted the polarization of the M2 macrophage, shortened the inflammatory phase of the wound and rapidly transitioned to the proliferation phase, thus accelerating the wound healing process and avoiding the transition to chronic wounds. The excellent electrical conductivity and sensing properties of the hydrogel could be used to monitor the behavioral activities of mice in real time to determine their wound recovery. Therefore, this strategy will provide a promising prospect for efficient and high-quality treatment of donor site wounds.

Double-Dynamic-Bond Cross-Linked Hydrogel Adhesive with Cohesion-Adhesion Enhancement for Emergency Tissue Closure and Infected Wound Healing

The hydrogel adhesives with strong tissue adhesion and biological characteristics are urgently needed for injury sealing and tissue repair. However, the negative correlation between tissue adhesion and the mechanical strength poses a challenge for their practical application. Herein, a bio-inspired cohesive enhancement strategy is developed to prepare the hydrogel adhesive with simultaneously enhanced mechanical strength and tissue adhesion. The double cross-linked network is achieved through the cooperation between polyacrylic acid grafted with N-hydroxy succinimide crosslinked by tannic acid and cohesion-enhanced ion crosslinking of sodium alginate and Ca2+. Such a unique structure endows the resultant hydrogel adhesive with excellent tissue adhesion strength and mechanical strength. The hydrogel adhesive is capable of sealing various organs in vitro, and exhibits satisfactory on-demand removability, antibacterial, and antioxidant properties. As a proof of concept, the hydrogel adhesive not only effectively halts non-compressible hemorrhages of beating heart and femoral artery injury models in rats, but also accelerates the healing of infected wound by inhibiting bacteria and reducing inflammation. Overall, this advanced hydrogel adhesive is promising as an emergency rescue adhesive that enables robust tissue closure, timely controlling bleeding, and promoting damaged tissue healing.

Multi-Functional Responsive Microcapsules with Sequential Release Capacity for Wound Healing

The development of biomaterials capable of on-demand delivery holds significant promise for wound therapy. Current research is centered on refining design precision and enhancing structural functionality to achieve effective controlled release of active agents, thereby facilitating wound healing. In this study, a coaxial microfluidic electrospray technique is employed to fabricate microcapsules comprising a black phosphorus (BP)-laden alginate shell and a gelatin methacrylate (GelMA) core. Curcumin nanoparticles (CNPs) and vascular endothelial growth factor (VEGF) are respectively incorporated into the shell and core of the microcapsules. The photothermal performance of the microcapsules contributed to superior sterilization efficacy in the early stages of wound healing, while the growth factors in the core provided robust angiogenic effects during the later stages. These attributes enabled the microcapsules to significantly accelerate wound healing, enhance collagen deposition, and modulate inflammatory responses in a rat wound model, underscoring their potential for clinical application.

Prospects of black phosphorus nanosheets in the treatment of peri-implantitis

Peri-implantitis represents an inflammatory condition characterized by the presence of plaque-related soft and hard tissue damage surrounding dental implants, often resulting in progressive alveolar bone loss and, ultimately, implant failure. Black phosphorus (BP), a novel two-dimensional (2D) material that has recently emerged in the biomedical field, has attracted increasing attention due to its unique osteogenic properties and exceptional antibacterial and antioxidant characteristics. Additionally, its outstanding biomedical attributes enhance angiogenesis and nerve regeneration. Compared to other biomaterials, its high specific surface area, high photothermal conversion efficiency, and complete biodegradability make BP a promising candidate for treating infection-related bone defects. This article reviews the biological properties of BP nanosheets (BPNSs) and discusses their potential applications in the context of peri-implantitis, aiming to provide fresh insights for future research and applications of BPNS.

Micro-Electro Nanofibrous Dressings Based on PVDF-AgNPs as Wound Healing Materials to Promote Healing in Active Areas

Purpose

The purpose of this study is to develop an innovative solution for chronic wounds in high-mobility areas, such as joints, where conventional treatments are hindered by passive healing mechanisms and the need for immobilization. By designing a micro-electro-Nanofiber dressing composed of piezoelectric polyvinylidene fluoride (PVDF) integrated with antimicrobial silver nanoparticles (AgNPs), this research aims to address the dual challenges of promoting effective wound healing and maintaining joint mobility.

Methods

Herein, we developed a novel micro-electro-Nanofiber dressing using electrospinning technology, incorporating polyvinylidene fluoride (PVDF) with silver nanoparticles (AgNPs). The optimized PVDF-AgNPs Nanofiber dressings exhibited strong piezoelectric effects suitable for joint wounds.

Results

In vitro experiments demonstrated that the dressing effectively promoted fibroblast migration and collagen synthesis. In vivo, the dressing exhibited a trend of rapid healing in infected wounds within 12 days while modulating macrophage differentiation toward the anti-inflammatory M2 phenotype. Additionally, the incorporation of antimicrobial nanosilver effectively controlled local infections, further facilitating the healing process.

Conclusion

To sum up, by harnessing the piezoelectric effect to stimulate endogenous healing mechanisms without restricting joint mobility, the developed PVDF-AgNPs Nanofiber dressings represent a transformative approach for the treatment of wounds in highly mobile body areas.

Sprayable Nanocomposites Hydrogel for Wound Healing and Skin Regeneration

Wound management remains a critical challenge worldwide and imposes a huge financial burden on every nation. Hydrogels are promising for biomedical applications because of their extracellular matrix (ECM) like structure, good biocompatibility and multifunctional bioactivity. However, the poor mechanical properties and inconvenient operation of traditional hydrogels make it difficult to meet the complex and multifaceted needs of clinical practice. In recent years, the multifunctional nanocomposites hydrogel with especially sprayable feature have shown enhanced mechanical properties and facile operation, which enable their huge clinical applications value. A unique and powerful nanocomposite hydrogels (NCH) platform is developed by combining the many advantages of nanomaterials and hydrogels, which can achieve efficient trauma repair. This work reviews important advances on the preparation, functions and applications of sprayable NCH platforms. The challenges and future trends in the field with the aim of providing researchers with clarity on the past, present, and future of the emerging field of sprayable NCH are also proposed in detail.

Enhancing Wound Healing With Sprayable Hydrogel Releasing Multi Metallic Ions: Inspired by the Body's Endogenous Healing Mechanism

In the pursuit of new wound care products, researchers are exploring methods to improve wound healing through exogenous wound healing products. However, diverging from this conventional approach, this work has developed an endogenous support system for wound healing, drawing inspiration from the body's innate healing mechanisms governed by the sequential release of metal ions by body at wound site to promote different stages of wound healing. This work engineers a multi-ion-releasing sprayable hydrogel system, to mimic this intricate process, representing the next evolutionary step in wound care products. It comprises Alginate (Alg) and Fibrin (Fib) hydrogel infused with Polylactic acid (PLA) polymeric microcarriers encapsulating multi (calcium, copper, and zinc) nanoparticles (Alg-Fib-PLA-nCMB). Developed sprayable Alg-Fib-PLA-nCMB hydrogel show sustained release of beneficial multi metallic ions at wound site, offering a range of advantages including enhanced cellular function, antibacterial properties, and promotion of crucial wound healing processes like cell migration, ROS mitigation, macrophage polarization, collagen deposition, and vascular regeneration. In a comparative study with a commercial product (Midstress spray), developed Alg-Fib-PLA-nCMB hydrogel demonstrates superior wound healing outcomes in a rat model, indicating its potential for next generation wound care product, addressing critical challenges and offering a promising avenue for future advancements in the wound management.

Glucose and pH dual-responsive hydrogels with antibacterial, reactive oxygen species scavenging, and angiogenesis properties for promoting the healing of infected diabetic foot ulcers

The healing process of diabetic foot ulcers is challenging due to the presence of a complex and severe inflammatory microenvironment, characterized by hyperglycemia, low pH, susceptibility to infection, vascular dysfunction, and over-expression of reactive oxygen species (ROS), which can potentially lead to amputation or even mortality. Herein, a glucose and pH dual-responsive hydrogel was designed and prepared by crosslinking phenylboronic acid-grafted quaternary chitosan (QF, 4 wt%) with dopamine-grafted oxidized hyaluronic acid (OD, 5 wt%) through phenylboronation, schiff-base reaction, and other techniques. The multifunctional QO/@PV@AB7 hydrogel was prepared by incorporating pravastatin-loaded chitosan nanoparticles (CSNPs@PV, 2 mg/mL) and antimicrobial peptide AMP-AB7 loaded silica nanoparticles (SiO2NPs@AB7, 0.5 mg/mL). The results demonstrate that the QO/@PV@AB7 hydrogel exhibits good responsiveness to acidic conditions and high glucose levels, while effectively scavenging various types of ROS. Moreover, it exerted protective effects against oxidative stress on cells, enhanced HUVECs viability, and promoted angiogenesis. Notably, the QO/@PV@AB7 hydrogel displayed potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Additionally, in an MRSA-infected rat model of diabetic foot wounds, administration of the QO/@PV@AB7 hydrogel led to increased secretion of pro-angiogenic factors such as vascular endothelial nitric oxide synthase (eNOS), vascular endothelial-generating factor (VEGF), and endothelial cell adhesion molecule (CD31). Furthermore, the hydrogel significantly reduced the levels of inflammatory factors such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), while simultaneously increasing the levels of anti-inflammatory cytokines such as interleukin-10 (IL-10). The findings suggest that multifunctional hydrogels incorporating PV@CSNPs and SiO2NPs@AB7 demonstrate promising potential as a therapeutic approach for the treatment of diabetic foot. STATEMENT OF SIGNIFICANCE: Here, a glucose and pH dual-responsive QO/@PV@AB7 hydrogel with antimicrobial and angiogenesis-promoting properties was developed for the treatment of infected wounds in diabetic feet. Our findings demonstrate that the proposed hydrogel exhibits good responsiveness, effectively scavenges various types of reactive oxygen species (DPPH, O2-, -OH, and ABTS+), provides protection against oxidative stress, enhances HUVECs cell viability, and promotes angiogenesis. Notably, it also demonstrates potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and E. coli. Additionally, in vivo experiments demonstrated that the hydrogel exhibited accelerated wound healing in MRSA-infected diabetic foot ulcers, with a reduction of four days compared to the control group.

Bioinspired Wearable Hydrogel Composite with Sustained Drug-Release for Wound Healing and Naked-Eye Visual Early Warning of Wound Dehiscence

Wound healing is critical to the structural and functional restoration of damaged tissue. However, effective wound closure and healing are always great challenges in regenerative engineering. This study provided bioinspired wearable hydrogel composites with drug-releasing hydrogel and nonclose-packed photonic crystals (NPCs) for wound therapy and naked-eye visual early warning of wound dehiscence. Molecular dynamics models and drug-releasing results illustrated the sustained drug release of ibuprofen, and the mechanical properties of the drug-releasing hydrogel were optimized with 1410% tensile strain by introducing fish collagen; their biocompatibility and adhesion were also improved. The structural color of the NPCs blue-shifted from 630 to 500 nm with 15.0% strain, and the original color was customized with poly(methyl methacrylate) (PMMA) concentration and acrylamide content. Compared with the gauze and the traditional hydrogels, the composite provided a moist environment and an effectively closed wound; the debridement and released drug avoided inflammation, and the rat wound was healed 40.5% on the third day and essentially 100% on the 14th day. The work provided a novel strategy for wound healing and naked-eye visual early warning when a wound deforms, which is expected to promote the synergistic development of clinical treatment and visualized early warning.

A Dopamine-Modified Hyaluronic Acid-Based Mucus Carrying Phytoestrogen and Urinary Exosome for Thin Endometrium Repair

Thin endometrium (TE) is closely associated with infertility in reproductive medicine. Estrogen therapy gains unsatisfactory outcomes. In this study, an artificial mucus based on dopamine (L-DOPA)-modified hyaluronic acid combining phytoestrogen cajaninstilbene acid and rat urinary exosomes (CUEHD) is constructed for TE treatment using a rat TE model. In the rat TE model, the dominant elastic behavior and adhesive properties of CUEHD guarantee adequate retention, rendering superior synergistic treatment efficacy and favorable biosafety characteristics. CUEHD treatment significantly increases endometrial thickness and promotes receptivity and fertility. Mechanistically, estrogen homeostasis, inflammation inhibition, and endometrial regeneration are achieved through the crosstalk between ER-NLRP3-IL1β and Wnt-β catenin-TGFβ-smad signaling pathways. Moreover, the therapeutic potential of exosomes from human urine and adipose tissue-derived stem cells (ADSCs) and rat ADSCs are also demonstrated, indicating extensive use of the artificial mucus system. Thus, this study illustrates a platform combining phytoestrogen and exosomes with promising implications for TE treatment.

Thermoresponsive On-Demand Adhesion and Detachment of a Polyurethane-Urea Bioadhesive

The development of bioadhesives with strong adhesion and on-demand adhesion-detachment behavior is still critically important and challenging for facilitating painless and damage-free removal in clinical applications. In this work, for the first time, we report the easy fabrication of novel polyurethane-urea (PUU)-based bioadhesives with thermoresponsive on-demand adhesion and detachment behavior. The PUU copolymer was synthesized by a simple copolymerization of low-molecular-weight, hydrophilic, and biocompatible poly(ethylene glycol), glyceryl monolaurate (GML, a special chain extender with a long side hydrophobic alkyl group), and isophorone diisocyanate (IPDI). Here, GML was expected to not only adjust the temperature-dependent adhesion behavior but also act as an internal plasticizer. By simple adjustment of the water content, the adhesion strength of the 15 wt % water-containing PUU film toward porcine skin is as high as 55 kPa with an adhesion energy of 128 J/m2 at 37 °C. The adhesion strength dramatically decreases to only 3 kPa at 10 °C, exhibiting switching efficiency as high as 0.95. Furthermore, the present PUU-based adhesive also shows good on-demand underwater adhesion and detachment with a cell viability close to 100%. We propose that biomaterial research fields, especially novel PUU/polyurethane (PU)-based functional materials and bioadhesives, could benefit from such a novel thermoresponsive copolymer with outstanding mechanical and functional performances and an easy synthesis and scaled-up process as described in this article.

Proangiogenic effect and underlying mechanism of holmium oxide nanoparticles: a new biomaterial for tissue engineering

BACKGROUND

Early angiogenesis provides nutrient supply for bone tissue repair, and insufficient angiogenesis will lead tissue engineering failure. Lanthanide metal nanoparticles (LM NPs) are the preferred materials for tissue engineering and can effectively promote angiogenesis. Holmium oxide nanoparticles (HNPs) are LM NPs with the function of bone tissue "tracking" labelling. Preliminary studies have shown that HNPs has potential of promote angiogenesis, but the specific role and mechanism remain unclear. This limits the biological application of HNPs.

RESULTS

In this study, we confirmed that HNPs promoted early vessel formation, especially that of H-type vessels in vivo, thereby accelerating bone tissue repair. Moreover, HNPs promoted angiogenesis by increasing cell migration, which was mediated by filopodia extension in vitro. At the molecular level, HNPs interact with the membrane protein EphrinB2 in human umbilical vein endothelial cells (HUVECs), and phosphorylated EphrinB2 can bind and activate VAV2, which is an activator of the filopodia regulatory protein CDC42. When these three molecules were inhibited separately, angiogenesis was reduced.

CONCLUSION

Overall, our study confirmed that HNPs increased cell migration to promote angiogenesis for the first time, which is beneficial for bone repair. The EphrinB2/VAV2/CDC42 signalling pathway regulates cell migration, which is an important target of angiogenesis. Thus, HNPs are a new candidate biomaterial for tissue engineering, providing new insights into their biological application.

Photoresponsive Hydrogels for Tissue Engineering

Hydrophilic and biocompatible hydrogels are widely applied as ideal scaffolds in tissue engineering. The "smart" gelation material can alter its structural, physiochemical, and functional features in answer to various endo/exogenous stimuli to better biomimic the endogenous extracellular matrix for the engineering of cells and tissues. Light irradiation owns a high spatial-temporal resolution, complete biorthogonal reactivity, and fine-tunability and can thus induce physiochemical reactions within the matrix of photoresponsive hydrogels with good precision, efficiency, and safety. Both gel structure (e.g., geometry, porosity, and dimension) and performance (like conductivity and thermogenic or mechanical properties) can hence be programmed on-demand to yield the biochemical and biophysical signals regulating the morphology, growth, motility, and phenotype of engineered cells and tissues. Here we summarize the strategies and mechanisms for encoding light-reactivity into a hydrogel and demonstrate how fantastically such responsive gels change their structure and properties with light irradiation as desired and thus improve their applications in tissue engineering including cargo delivery, dynamic three-dimensional cell culture, and tissue repair and regeneration, aiming to provide a basis for more and better translation of photoresponsive hydrogels in the clinic.

Turning Polysaccharides into Injectable and Rapid Self-Healing Antibacterial Hydrogels for Antibacterial Treatment and Bacterial-Infected Wound Healing

Great efforts have been devoted to the development of novel and multifunctional wound dressing materials to meet the different needs of wound healing. Herein, we covalently grafted quaternary ammonium groups (QAGs) containing 12-carbon straight-chain alkanes to the dextran polymer skeleton. We then oxidized the resulting product into oxidized quaternized dextran (OQD). The obtained OQD polymer is rich in antibacterial QAGs and aldehyde groups. It can react with glycol chitosan (GC) via the Schiff-base reaction to form a multifunctional GC@OQD hydrogel with good self-healing behavior, hemostasis, injectability, inherent superior antibacterial activity, biocompatibility, and excellent promotion of healing of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds. The biosafe and nontoxic GC@OQD hydrogel with a three-dimensional porous network structure possesses an excellent swelling rate and water retention capacity. It can be used for hemostasis and treating irregular wounds. The designed GC@OQD hydrogel with inherent antibacterial activity possesses good antibacterial efficacy on both S. aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria), as well as MRSA bacteria, with antibacterial activity greater than 99%. It can be used for the treatment of wounds infected by MRSA and significantly promotes the healing of wounds. Thus, the multifunctional antibacterial GC@OQD hydrogel has the potential to be applied in clinical practice as a wound dressing.

Sprayable Zwitterionic Antibacterial Hydrogel With High Mechanical Resilience and Robust Adhesion for Joint Wound Treatment

Wound healing in movable parts, including the joints and neck, remains a critical challenge due to frequent motions and poor flexibility of dressings, which may lead to mismatching of mechanical properties and poor fitting between dressings and wounds; thus, increasing the risk of bacterial infection. This study proposes a sprayable zwitterionic antibacterial hydrogel with outstanding flexibility and desirable adhesion. This hydrogel precursor is fabricated by combining zwitterionic sulfobetaine methacrylate (SBMA) with poly(sulfobetaine methacrylate-co-dopamine methacrylamide)-modified silver nanoparticles (PSBDA@AgNPs) through robust electrostatic interactions. About 150 s of exposure to UV light, the SBMA monomer polymerizes to form PSB chains entangled with PSBDA@AgNPs, transformed into a stable and adhesion PSB-PSB@Ag hydrogel at the wound site. The resulting hydrogel has adhesive strength (15-38 kPa), large tensile strain (>400%), suitable shape adaptation, and excellent mechanical resilience. Moreover, the hydrogel displays pH-responsive behavior; the acidic microenvironment at the infected wound sites prompts the hydrogel to rapidly release AgNPs and kill bacteria. Further, the healing effect of the hydrogel is demonstrated on the rat neck skin wound, showing improved wound closing rate due to reduced inflammation and enhanced angiogenesis. Overall, the sprayable zwitterionic antibacterial hydrogel has significant potential to promote joint skin wound healing.

Two-Dimensional Biodegradable Black Phosphorus Nanosheets Promote Large Full-Thickness Wound Healing through In Situ Regeneration Therapy

Large full-thickness skin lesions have been one of the most challenging clinical problems in plastic surgery repair and reconstruction. To achieve in situ skin regeneration and perfect clinical outcomes, we must address two significant obstacles: angiogenesis deficiency and inflammatory dysfunction. Recently, black phosphorus has shown great promise in wound healing. However, few studies have explored the bio-effects of BP to promote in situ skin regeneration based on its nanoproperties. Here, to investigate whether black phosphorus nanosheets have positive bio-effects on in situ skin repair, we verified black phosphorus nanosheets' positive effects on angiogenic and anti-inflammatory abilities in vitro. Next, the in vivo evaluation performed on the rat large full-thickness excisional wound splinting model more comprehensively showed that the positive bio-effects of black phosphorus nanosheets are multilevel in wound healing, which can effectively enhance anti-inflammatory ability, angiogenesis, collagen deposition, and skin re-epithelialization. Then, multiomics analysis was performed to explore further the mechanism of black phosphorus nanosheets' regulation of endothelial cells in depth. Molecular mechanistically, black phosphorus nanosheets activated the JAK-STAT-OAS signaling pathway to promote cellular function and mitochondrial energy metabolism in endothelial cells. This study can provide a theoretical basis for applying two-dimensional black phosphorus nanosheets as nanomedicine to achieve in situ tissue regeneration in complex human pathological microenvironments, guiding the subsequent optimization of black phosphorus.