Bioactive antibacterial silica-based nanocomposites hydrogel scaffolds with high angiogenesis for promoting diabetic wound healing and skin repair

Recent Progress on Hyaluronan-Based Products for Wound Healing Applications

Hyaluronic acid (HA) based nanocomposites are considered excellent for improving wound healing. HA is biocompatible, biodegradable, non-toxic, biologically active, has hemostatic ability, and resists bacterial adhesion. HA-based nanocomposites promote wound healing in four different sequential phases hemostasis, inflammation, proliferation, and maturation. The unique biological characteristics of HA enable it to serve as a drug, an antibacterial agent, and a growth factor, which combine to accelerate the healing process. In this review, we focus on the use of HA-based nanocomposites for wound healing applications and we describe the importance of HA for the wound healing process in each sequential phase, such as hemostasis, inflammation, proliferation, and maturation. Metal nanoparticles (MNPs) or metal oxide nanoparticles (MO-NPs) loaded with HA nanocomposite are used for wound healing applications. Insights into important antibacterial mechanisms are described in HA nanocomposites. Furthermore, we explain antibiotics loaded with HA nanocomposite and its combination with the MNPs/MO-NPs used for wound healing applications. In addition, HA derivatives are discussed and used in combination with the other polymers of the composite for the wound healing process, as is the role of the polymer in wound healing applications. Finally, HA-based nanocomposites used for clinical trials in animal models are presented for wound healing applications.

Smart biomaterials and their potential applications in tissue engineering

Smart biomaterials have been rapidly advancing ever since the concept of tissue engineering was proposed. Interacting with human cells, smart biomaterials can play a key role in novel tissue morphogenesis. Various aspects of biomaterials utilized in or being sought for the goal of encouraging bone regeneration, skin graft engineering, and nerve conduits are discussed in this review. Beginning with bone, this study summarizes all the available bioceramics and materials along with their properties used singly or in conjunction with each other to create scaffolds for bone tissue engineering. A quick overview of the skin-based nanocomposite biomaterials possessing antibacterial properties for wound healing is outlined along with skin regeneration therapies using infrared radiation, electrospinning, and piezoelectricity, which aid in wound healing. Furthermore, a brief overview of bioengineered artificial skin grafts made of various natural and synthetic polymers has been presented. Finally, by examining the interactions between natural and synthetic-based biomaterials and the biological environment, their strengths and drawbacks for constructing peripheral nerve conduits are highlighted. The description of the preclinical outcome of nerve regeneration in injury healed with various natural-based conduits receives special attention. The organic and synthetic worlds collide at the interface of nanomaterials and biological systems, producing a new scientific field including nanomaterial design for tissue engineering.

Portable hand-held bioprinters promote in situ tissue regeneration

Three-dimensional bioprinting, as a novel technique of fabricating engineered tissues, is positively correlated with the ultimate goal of regenerative medicine, which is the restoration, reconstruction, and repair of lost and/or damaged tissue function. The progressive trend of this technology resulted in developing the portable hand-held bioprinters, which could be used quite easily by surgeons and physicians. With the advent of portable hand-held bioprinters, the obstacles and challenges of utilizing statistical bioprinters could be resolved. This review attempts to discuss the advantages and challenges of portable hand-held bioprinters via in situ tissue regeneration. All the tissues that have been investigated by this approach were reviewed, including skin, cartilage, bone, dental, and skeletal muscle regeneration, while the tissues that could be regenerated via this approach are targeted in the authors' perspective. The design and applications of hand-held bioprinters were discussed widely, and the marketed printers were introduced. It has been prospected that these facilities could ameliorate translating the regenerative medicine science from the bench to the bedside actively.

Multi-functional wound dressings based on silicate bioactive materials

Most traditional wound dressings passively offer a protective barrier for the wounds, which lacks the initiative in stimulating tissue regeneration. In addition, cutaneous wound healing is usually accompanied by various complicated conditions, including bacterial infection, skin cancer, and damaged skin appendages, bringing further challenges for wound management in clinic. Therefore, an ideal wound dressing should not only actively stimulate wound healing but also hold multi-functions for solving problems associated with different specific wound conditions. Recent studies have demonstrated that silicate bioceramics and bioglasses are one type of promising materials for the development of wound dressings, as they can actively accelerate wound healing by regulating endothelial cells, dermal fibroblasts, macrophages, and epidermal cells. In particular, silicate-based biomaterials can be further functionalized by specific structural design or doping with functional components, which endow materials with enhanced bioactivities or expanded physicochemical properties such as photothermal, photodynamic, chemodynamic, or imaging properties. The functionalized materials can be used to address wound healing with different demands including but not limited to antibacterial, anticancer, skin appendages regeneration, and wound monitoring. In this review, we summarized the current research on the development of silicate-based multi-functional wound dressings and prospected the development of advanced wound dressings in the future.

Recent Advances in Nano-Formulations for Skin Wound Repair Applications

Skin injuries caused by accidents and acute or chronic diseases place a heavy burden on patients and health care systems. Current treatments mainly depend on preventing infection, debridement, and hemostasis and on supplementing growth factors, but patients will still have scar tissue proliferation or difficulty healing and other problems after treatment. Conventional treatment usually focuses on a single factor or process of wound repair and often ignores the influence of the wound pathological microenvironment on the final healing effect. Therefore, it is of substantial research value to develop multifunctional therapeutic methods that can actively regulate the wound microenvironment and reduce the oxidative stress level at the wound site to promote the repair of skin wounds. In recent years, various bioactive nanomaterials have shown great potential in tissue repair and regeneration due to their properties, including their unique surface interface effect, small size effect, enzyme activity and quantum effect. This review summarizes the mechanisms underlying skin wound repair and the defects in traditional treatment methods. We focus on analyzing the advantages of different types of nanomaterials and comment on their toxicity and side effects when used for skin wound repair.

Nanobiotechnology: Applications in Chronic Wound Healing

Wounds occur when skin integrity is broken and the skin is damaged. With progressive changes in the disease spectrum, the acute wounds caused by mechanical trauma have been become less common, while chronic wounds triggered with aging, diabetes and infection have become more frequent. Chronic wounds now affect more than 6 million people in the United States, amounting to 10 billion dollars in annual expenditure. However, the treatment of chronic wounds is associated with numerous challenges. Traditional remedies for chronic wounds include skin grafting, flap transplantation, negative-pressure wound therapy, and gauze dressing, all of which can cause tissue damage or activity limitations. Nanobiotechnology — which comprises a diverse array of technologies derived from engineering, chemistry, and biology — is now being applied in biomedical practice. Here, we review the design, application, and clinical trials for nanotechnology-based therapies for chronic wound healing, highlighting the clinical potential of nanobiotechnology in such treatments. By summarizing previous nanobiotechnology studies, we lay the foundation for future wound care via a nanotech-based multifunctional smart system.

Efficiency of Multifunctional Antibacterial Hydrogels for Chronic Wound Healing in Diabetes: A Comprehensive Review

Diabetic chronic wounds or amputation, which are complications of diabetes mellitus (DM), are a cause of great suffering for diabetics. In addition to the lack of oxygen, elevated reactive oxygen species (ROS) and reduced vascularization, microbial invasion is also a critical factor that induces non-healing chronic diabetic wounds, ie, wounds still remaining in the stage of inflammation, after which the wound tissue begins to age and becomes necrotic. To clear up the infection, alleviate the inflammation in the wound and prevent necrosis, many kinds of hydrogel have been fabricated to eliminate infections with pathogens. The unique properties of hydrogels make them ideally suited to wound dressings because they provide a moist environment for wound healing and act as a barrier against bacteria. This review article will mainly cover the recent developments and innovations of antibacterial hydrogels for diabetic chronic wound healing.

Zn2+ Cross-Linked Alginate Carrying Hollow Silica Nanoparticles Loaded with RL-QN15 Peptides Provides Promising Treatment for Chronic Skin Wounds

Chronic and non-healing wounds pose a great challenge to clinical management and patients. Many studies have explored novel interventions against skin wounds, with bioactive peptides, nanoparticles, and hydrogels arousing considerable attention regarding their therapeutic potential. In this study, the prohealing peptide RL-QN15 was loaded into hollow silica nanoparticles (HSNs), with these HSN@RL-QN15 nanocomposites then combined with zinc alginate (ZA) gels to obtain HSN@RL-QN15/ZA hydrogel. The characteristics, biological properties, and safety profiles of the hydrogel composites were then evaluated. Results showed that the hydrogel had good porosity, hemocompatibility, biocompatibility, and broad-spectrum antimicrobial activity, with the slow release of loaded RL-QN15. Further analysis indicated that the hydrogel promoted skin cell proliferation and keratinocyte scratch repair, regulated angiogenesis, reduced inflammation, and accelerated re-epithelialization and granulation tissue formation, resulting in the rapid healing of both full-thickness skin wounds and methicillin-resistant Staphylococcus aureus biofilm-infected chronic wounds in mice. This peptide-based hydrogel provides a novel intervention for the treatment of chronic skin wounds and shows promise as a wound dressing in the field of tissue regeneration.

Recent Progress in Development of Dressings Used for Diabetic Wounds with Special Emphasis on Scaffolds

Diabetic wound (DW) is a secondary application of uncontrolled diabetes and affects about 42.2% of diabetics. If the disease is left untreated/uncontrolled, then it may further lead to amputation of organs. In recent years, huge research has been done in the area of wound dressing to have a better maintenance of DW. These include gauze, films, foams or, hydrocolloid-based dressings as well as polysaccharide- and polymer-based dressings. In recent years, scaffolds have played major role as biomaterial for wound dressing due to its tissue regeneration properties as well as fluid absorption capacity. These are three-dimensional polymeric structures formed from polymers that help in tissue rejuvenation. These offer a large surface area to volume ratio to allow cell adhesion and exudate absorbing capacity and antibacterial properties. They also offer a better retention as well as sustained release of drugs that are directly impregnated to the scaffolds or the ones that are loaded in nanocarriers that are impregnated onto scaffolds. The present review comprehensively describes the pathogenesis of DW, various dressings that are used so far for DW, the limitation of currently used wound dressings, role of scaffolds in topical delivery of drugs, materials used for scaffold fabrication, and application of various polymer-based scaffolds for treating DW.

Leveraging the advancements in functional biomaterials and scaffold fabrication technologies for chronic wound healing applications

Exploring new avenues for clinical management of chronic wounds holds the key to eliminating socioeconomic burdens and health-related concerns associated with this silent killer. Engineered biomaterials offer great promise for repair and regeneration of chronic wounds because of their ability to deliver therapeutics, protect the wound environment, and support the skin matrices to facilitate tissue growth. This mini review presents recent advances in biomaterial functionalities for enhancing wound healing and demonstrates a move from sub-optimal methods to multi-functionalized treatment approaches. In this context, we discuss the recently reported biomaterial characteristics such as bioadhesiveness, antimicrobial properties, proangiogenic attributes, and anti-inflammatory properties that promote chronic wound healing. In addition, we highlight the necessary mechanical and mass transport properties of such biomaterials. Then, we discuss the characteristic properties of various biomaterial templates, including hydrogels, cryogels, nanomaterials, and biomolecule-functionalized materials. These biomaterials can be microfabricated into various structures, including smart patches, microneedles, electrospun scaffolds, and 3D-bioprinted structures, to advance the field of biomaterial scaffolds for effective wound healing. Finally, we provide an outlook on the future while emphasizing the need for their detailed functional behaviour and inflammatory response studies in a complex in vivo environment for superior clinical outcomes and reduced regulatory hurdles.

Engineering Biomimetic Extracellular Matrix with Silica Nanofibers: From 1D Material to 3D Network

Biomaterials at nanoscale is a fast-expanding research field with which extensive studies have been conducted on understanding the interactions between cells and their surrounding microenvironments as well as intracellular communications. Among many kinds of nanoscale biomaterials, mesoporous fibrous structures are especially attractive as a promising approach to mimic the natural extracellular matrix (ECM) for cell and tissue research. Silica is a well-studied biocompatible, natural inorganic material that can be synthesized as morpho-genetically active scaffolds by various methods. This review compares silica nanofibers (SNFs) to other ECM materials such as hydrogel, polymers, and decellularized natural ECM, summarizes fabrication techniques for SNFs, and discusses different strategies of constructing ECM using SNFs. In addition, the latest progress on SNFs synthesis and biomimetic ECM substrates fabrication is summarized and highlighted. Lastly, we look at the wide use of SNF-based ECM scaffolds in biological applications, including stem cell regulation, tissue engineering, drug release, and environmental applications.

Tannic acid-reinforced zwitterionic hydrogels with multi-functionalities for diabetic wound treatment

Diabetic wounds remain one of the most prevalent hard-to-heal wounds in the clinic. The causative factors impeding the wound healing process include not only the elevated oxidative stress and bacterial infections but also the high and repetitive plantar stress (including compressive pressure and shear stress). Conventional hydrogel dressings are mechanically weak and fragile, limiting their applications in the high stress-loading conditions of diabetic foot ulcers. As such, mechanically tough hydrogel dressings with appropriate bioactivities are highly desirable for diabetic wound treatment. In this study, a mechanically reinforced hydrogel with multiple biofunctionalities was developed via a facile and straightforward strategy of incorporation of tannic acid (TA) in zwitterionic poly(sulfobetaine methacrylate) (polySBMA) hydrogel. The polySBMA hydrogel reinforced by TA showed excellent mechanical property, with the tensile stress and compressive stress up to 93.7 kPa and 18.4 MPa, respectively, and it could resist cyclic compressive stress at ∼200 kPa (maximum in-shoe plantar pressure) for up to 3500 cycles. The TA-reinforced zwitterionic hydrogel exhibited strong adhesion to skin tissue (20.2 kPa), which was expected to reduce the shear stress on the foot. The plantar pressure on the foot was significantly reduced by the application of the resilient hydrogel. Attributed to the antioxidant and antibacterial properties of TA, the hydrogel showed rapid radical scavenging capability and strong bactericidal efficacy against Gram-positive and Gram-negative bacteria. In vitro and in vivo studies confirmed that the hydrogel has good cytocompatibility and negligible skin irritation, and promoted healing of diabetic wounds in mice. Such tough and effective hydrogel with a straightforward preparation strategy holds great promise as wound dressings for diabetic wound treatment.

Tough complex hydrogels transformed from highly swollen polyelectrolyte hydrogels based on Cu2+ coordination with anti-bacterial properties

The development of broad-spectrum anti-bacterial tough hydrogels without antibiotics remains a challenge in biomedical applications. In this study, we have synthesized a novel tough anti-bacterial complex hydrogel based on Cu²⁺ coordination. A swollen and weak poly(acrylamide-co-4-vinylbenzyl-(trihydroxymethyl-phosphonium)chloride) (P(AAm-co-VBzTHPC)) hydrogel was prepared by the radical copolymerization of AAm and VBzTHPC monomer solutions, followed by immersion in CuSO₄ solution to coordinate with Cu²⁺ to form a strong and tough hydrogel. Fourier transform infrared (FTIR) spectra and X-ray photoelectron spectra (XPS) were used to characterize the coordination structure between phosphorus and oxygen atoms in the VBzTHPC monomer and copper ions. The water content and mechanical properties of the obtained hydrogel varied with gel composition. The prepared toughened hydrogel exhibited excellent anti-bacterial performance because of the introduction of copper ion coordination and the slow release of copper ions, with bacterial viability of 5.1% when the mole fraction of VBzTHPC was 10 mol%. Cell viability when cocultured with the toughened hydrogel was above 85% using the Cell Counting Kit-8 (CCK-8) method, indicating the good biocompatibility of the hydrogel. Compared with the control group experiment in vivo, this tough hydrogel can also promote wound healing, making it a promising candidate for wound dressing.

Biomimetic Hydrogel Scaffolds with Copper Peptide-Functionalized RADA16 Nanofiber Improve Wound Healing in Diabetes

Wound healing in diabetes is retarded by the dysfunctional local microenvironment. Although there are many studies using hydrogels as substitutes for natural extracellular matrices (ECMs), hydrogels that can mimic both the structure and functions of natural ECM remain a challenge. Self-assembling peptide RADA16 nanofiber has distinct advantageous to provide a biomimetic extracellular matrix nanofiber structure. However, it is still lack of biological cues to promote angiogenesis that is of vital significance for diabetic wounds healing. With a customized copper peptide GHK functionalized RADA16, an integrated approach using functionalized RADA16 nanofiber to chelate copper ion, has been innovatively proposed in this present study. The acquired composite hydrogel held the biomimetic nanofiber architecture, and exhibited promoting angiogenesis by both enhancing adhesion and proliferation of endothelial cells (EC) in vitro and neovascularization in vivo. It showed that the functionalized nanofiber scaffolds significantly accelerated wound closure, collagen deposition, and tissue remodeling both in healthy and diabetic mice. Furthermore, immunohistochemical analysis gave evidence that an upregulated expression of eNOS and CD31 in the copper peptide-functionalized RADA16 treated group. It can be envisioned that this scaffold can serve as a promising dressing for diabetic wound healing. This article is protected by copyright. All rights reserved.

COCu: A Robust Self-Regenerative Hydrogel with Applicability as Both Hydrated Gel Dressing and Dry Suture for Seamless Tissue Fixation and Repair

Self-regenerative hydrogels have recently been developed, and represent a special type of self-healing hydrogels with the ability to restore a dehydrated hydrogel with physical damage. In this study, a self-regenerative hydrogel (COCu) based on two chitosan polymers assembled by slow-released Cu²⁺ is developed. The COCu hydrogel displays an excellent regeneration ability after being dehydrated and fractured. By simple hydration at room temperature, the fragments of the dehydrated gel fuse into one seamless whole, thereby preserving the mechanical properties and functionalities of the original hydrogel. The regeneration process can be conducted repeatedly after different methods of dehydration (natural volatilization, heat drying, lyophilization) and various modes of deconstruction (flakes, powder, lumpy sponge, etc.). Furthermore, the COCu hydrogel provides ultra-stretchability, and it can be stretched into thin (0.01-0.1 mm) filaments, which, when dried (dtCOCu), can be used as suture lines. Moreover, when used as a dry suture, it regenerates into the hydrogel in the presence of the tissue fluid, forming an excellent sealant to immobilize tissues and seamlessly seal wounds. The fast self-regeneration allows for its facile application as both a hydrated gel dressing and dry suture, and offers customized strategies for fixing and repair of different wounds in soft tissues.

Wound closure, angiogenesis and antibacterial behaviors of tetracalcium phosphate/hydroxyethyl cellulose/hyaluronic acid/gelatin composite dermal scaffolds

Polymeric and tetracalcium phosphate (TTCP)-containing polymeric scaffolds were fabricated using a freeze-drying technique, with a homogenous solution of hydroxyethyl cellulose (HEC)/hyaluronic acid (HA)/gelatin (G) or suspension of 15 or 20% TTCP) particles in HEC/HA/G solution. The morphology, phase composition, chemical bands, and swelling behavior of the scaffold were determined. In vitro fibroblast cell viability and migration potential of the scaffolds were determined by MTT, live/dead staining, and scratch assay for wound healing. The in vivo chick embryo angiogenesis test was also carried out. Finally, the initial antibacterial activity of the scaffolds was determined using Staphylococcus aureus. The scaffolds exhibited an enormous porous structure in which the size of pores increased by the presence of TTCP particles. While the polymeric scaffold was amorphous, the formation of low crystalline hydroxyapatite phase and the initial TTCP particles was determined in the composition of TTCP-added scaffolds. TTCP increased swelling behavior of the polymeric scaffold in PBS. The results demonstrated that the amount of TTCP was a crucial factor in cell life. A high concentration of TTCP could restrict cell viability, although all the scaffolds were nontoxic. The scratch assessments determined better cell migration and wound closure in treating with TTCP-containing scaffolds so that after 24 h, a wound closure of 100% was observed. Furthermore, TTCP-incorporated scaffolds significantly improved the angiogenesis, in the chick embryo test. The presence of TTCP had a significant effect on reducing the bacterial activity and 20% TTCP-containing scaffold exhibited better antibacterial activity than the others.

Bioactive anti-inflammatory antibacterial metformin-contained hydrogel dressing accelerating wound healing

Highly efficient wound healing and skin regeneration remain a challenge. Long-term inflammation and bacterial infection can inhibit the healing process and lead to the scar formation. Here, we report a hydrogel (FEM) formed by self-assembly of ε-poly-l-lysine-F127-ε-poly-l-lysine (EPL-F127-EPL) and metformin for wound repair. Especially, the role of metformin-based antibacterial hydrogel in wound healing and repair was investigated for the first time. FEM has inherent multifunctional properties, including controlled metformin release, anti-inflammatory and antibacterial activity, temperature responsiveness, injectable and self-healing capabilities. The in vivo results showed that FEM dressings accelerated the wound healing by stimulating the angiogenesis process of the wound tissue and anti-inflammation. This study shows that the multifunctional metformin-contained hydrogel scaffolds could enhance the wound repair through the anti-inflammation and accelerated angiogenesis, which could also expand the biomedical applications of metformin-based biomaterials.

Engineering Robust Ag-Decorated Polydopamine Nano-Photothermal Platforms to Combat Bacterial Infection and Prompt Wound Healing

Polydopamine (PDA) nanoparticles have emerged as an attractive biomimetic photothermal agent in photothermal antibacterial therapy due to their ease of synthesis, good biodegradability, long-term safety, and excellent photostability. However, the therapeutic effects of PDA nanoparticles are generally limited by the low photothermal conversion efficiency (PCE). Herein, PDA@Ag nanoparticles are synthesized via growing Ag on the surface of PDA nanoparticles and then encapsulated into a cationic guar gum (CG) hydrogel network. The optimized CG/PDA@Ag platform exhibits a high PCE (38.2%), which is more than two times higher than that of pure PDA (16.6%). More importantly, the formulated CG/PDA@Ag hydrogel with many active groups can capture and kill bacteria through effective interactions between hydrogel and bacteria, thereby benefiting the antibacterial effect. As anticipated, the designed CG/PDA@Ag system combined the advantages of PDA@Ag nanoparticles (high PCE) and hydrogel (preventing aggregation of PDA@Ag nanoparticles and possessing inherent antibacterial ability) is demonstrated to have superior antibacterial efficacy both in vitro and in vivo. This study develops a facile approach to boost the PCE of PDA for photothermal antibacterial therapy, providing a significant step forward in advancing the application of PDA nano-photothermal agents.

Inorganic Nanoparticles in Bone Healing Applications

Modern biomedicine aims to develop integrated solutions that use medical, biotechnological, materials science, and engineering concepts to create functional alternatives for the specific, selective, and accurate management of medical conditions. In the particular case of tissue engineering, designing a model that simulates all tissue qualities and fulfills all tissue requirements is a continuous challenge in the field of bone regeneration. The therapeutic protocols used for bone healing applications are limited by the hierarchical nature and extensive vascularization of osseous tissue, especially in large bone lesions. In this regard, nanotechnology paves the way for a new era in bone treatment, repair and regeneration, by enabling the fabrication of complex nanostructures that are similar to those found in the natural bone and which exhibit multifunctional bioactivity. This review aims to lay out the tremendous outcomes of using inorganic nanoparticles in bone healing applications, including bone repair and regeneration, and modern therapeutic strategies for bone-related pathologies.

Bacillus subtilis WB800N alleviates diabetic wounds in mice by regulating gut microbiota homeostasis and TLR2

OBJECTIVE

This study aims to investigate the effect of Bacillus subtilis WB800N on diabetic wounds.

METHODS

Hematoxylin & eosin (H&E) staining was used to observe the healing of skin wounds. Collagen deposition was assessed by Masson staining. Western blotting and qRT-PCR were used to detect vascular endothelial-related factors (VWF), CD31, TLR2, NLRP3, ASC, and Caspase-1 expression. 16S rDNA sequencing detected microbiota distribution. The concentrations of IL-1β and IL-37 were measured by ELISA. Apoptosis was measured by the TUNEL assay.

RESULTS

Compared with the control group, the wound healing was delayed in diabetic mice. The wound area in the Bacillus subtilis group decreased more significantly than the diabetic wounds group. H&E staining showed that Bacillus subtilis WB800N promoted wound healing and increased re-epithelialization. Masson staining showed that Bacillus subtilis WB800N increased collagen deposition in diabetic wounds mice. Bacillus subtilis WB800N upregulated VWF and CD31 protein expression in diabetic wounds mice. The 16S rDNA results showed that Bacillus subtilis WB800N reduced the diversity of the gut microbiota of diabetic wounds mice and regulated the microbial composition. At the genus level, Bacillus subtilis WB800N reduced the relative abundance of Muribaculaceae and CG-005 in diabetic wounds mice, while increasing the relative abundance of Lactobacillus. Bacillus subtilis WB800N increased the expression of TLR2, NLRP3, ASC, and Caspase-1. Bacillus subtilis WB800N increased the concentrations of IL-1β and IL-37 in serum. Bacillus subtilis WB800N upregulated cell apoptosis. The TLR2 antagonist Sparstolonin B (SsnB) reduced the expression of TLR2, NLRP3, ASC, Caspase-1, IL-1β, and IL-37 and the apoptosis in diabetic wounds mice, while the combined intervention of Bacillus subtilis and SsnB reversed the effect of SsnB treatment alone.

CONCLUSION

Bacillus subtilis WB800N alleviated diabetic wounds healing by regulating gut microbiota homeostasis and TLR2.

SIGNIFICANCE AND IMPACT OF RESEARCH

Our findings might provide potential therapeutic targets for diabetic wounds.

Leveraging Potential of Nanotherapeutics in Management of Diabetic Foot Ulcer

Diabetic foot ulcers (DFUs) are the most common complications associated with diabetes mellitus. DFUs are displayed as open sores or wounds located on the bottom of the foot as a secondary complication of diabetes mellitus (DM). DFUs are associated with significant morbidity and mortality and can subsequently lead to hospitalization and lower limb amputation if not recognized and treated on time. An immense challenge to conventional treatments is caused by the chronic nature of diabetic foot syndrome and it has led to the emergence of nanotechnology-based therapeutics. The greatest advantages of these nanotherapeutics are their unique biological, chemical, and physical properties. The present review highlights the augmentation of bacterial infections relating to delayed healing of DFUs and the potential of nanotherapeutics such as polymeric nanoparticles, metallic nanoparticles, siRNA-based nanoparticles, lipid nanoparticles, and nanofibers in accelerating wound healing in diabetic foot ulcers.

Recent Advances in Bioengineered Scaffolds for Cutaneous Wound Healing

Wound healing is an evolved dynamic biological process. Though many research and clinical approaches have been explored to restore damaged or diseased skin, the current treatment for deep cutaneous injuries is far from being perfect, and the ideal regenerative therapy remains a significant challenge. Of all treatments, bioengineered scaffolds play a key role and represent great progress in wound repair and skin regeneration. In this review, we focus on the latest advancement in biomaterial scaffolds for wound healing. We discuss the emerging philosophy of designing biomaterial scaffolds, followed by precursor development. We pay particular attention to the therapeutic interventions of bioengineered scaffolds for cutaneous wound healing, and their dual effects while conjugating with bioactive molecules, stem cells, and even immunomodulation. As we review the advancement and the challenges of the current strategies, we also discuss the prospects of scaffold development for wound healing.

Diverse nanocomposites as a potential dressing for diabetic wound healing

Wound healing is a programmed process of continuous events which is impaired in the case of diabetic patients. This impaired process of healing in diabetics leads to amputation, longer hospitalisation, immobilisation, low self-esteem, and mortality in some patients. This problem has paved the way for several innovative strategies like the use of nanotechnology for the treatment of wounds in diabetic patients. The use of biomaterials, nanomaterials have advanced approaches in tissue engineering by designing multi-functional nanocomposite scaffolds. Stimuli-responsive scaffolds that interact with the wound microenvironment and controlled release of bioactive molecules have helped in overcoming barriers in healing. The use of different types of nanocomposite scaffolds for faster healing of diabetic wounds is constantly being studied. Nanocomposites have helped in addressing specific issues with respect to healing and improving angiogenesis. Method: A literature search was followed to retrieve the articles on strategies for wound healing in diabetes across several databases like PubMed, EMBASE, Scopus and Cochrane database. The search was performed in May 2022 by two researchers independently. They keywords used were "diabetic wounds, nanotechnology, nanocomposites, nanoparticles, chronic diabetic wounds, diabetic foot ulcer, hydrogel". Exclusion criteria included insulin resistance, burn wound, dressing material.

Multifarious applications of bioactive glasses in soft tissue engineering

Tissue engineering (TE), a new paradigm in regenerative medicine, repairs and restores the diseased or damaged tissues and eliminates drawbacks associated with autografts and allografts. In this context, many biomaterials have been developed for regenerating tissues and are considered revolutionary in TE due to their flexibility, biocompatibility, and biodegradability. One such well-documented biomaterial is bioactive glasses (BGs), known for their osteoconductive and osteogenic potential and their abundant orthopedic and dental clinical applications. However, in the last few decades, the soft tissue regenerative potential of BGs has demonstrated great promise. Therefore, this review comprehensively covers the biological application of BGs in the repair and regeneration of tissues outside the skeleton system. BGs promote neovascularization, which is crucial to encourage host tissue integration with the implanted construct, making them suitable biomaterial scaffolds for TE. Moreover, they heal acute and chronic wounds and also have been reported to restore the injured superficial intestinal mucosa, aiding in gastroduodenal regeneration. In addition, BGs promote regeneration of the tissues with minimal renewal capacity like the heart and lungs. Besides, the peripheral nerve and musculoskeletal reparative properties of BGs are also reported. These results show promising soft tissue regenerative potential of BGs under preclinical settings without posing significant adverse effects. Albeit, there is limited bench-to-bedside clinical translation of elucidative research on BGs as they require rigorous pharmacological evaluations using standardized animal models for assessing biomolecular downstream pathways.

Injectable and self-healing chitosan-based hydrogel with MOF-loaded α-lipoic acid promotes diabetic wound healing

The difficulty of wound healing in patients with diabetes mellitus remains a considerable challenge for clinical and scientific research. To address the problem of poor healing that affects chronic wounds in patients with diabetes, we developed an injectable self-healing hydrogel based on chitosan (CS), hyaluronic acid (HA), and kalium γ-cyclodextrin metal organic frameworks (K-γ-CD-MOFs) loaded α-lipoic acid (α-LA) with antibacterial activity and antioxidant performance. In vitro analysis showed that the hydrogel could promote cell proliferation and migration on the basis of Cell Counting Kit-8 (CCK-8) assay and Transwell experiments. Moreover, the addition of α-LA allowed the reversal of oxidative stress-induced cell damage. In vivo analyses were performed involving a full-thickness wound model in diabetic Sprague-Dawley (SD) rats. The hydrogel dressing significantly promoted the wound healing process with better granulation tissue formation and more collagen deposition because of its multifunctional traits, suggesting that it can be an excellent treatment for chronic full-thickness skin wound healing.

Advances in bioactive glass-containing injectable hydrogel biomaterials for tissue regeneration

Successful tissue regeneration requires a scaffold with tailorable biodegradability, tissue-like mechanical properties, structural similarity to extracellular matrix (ECM), relevant bioactivity, and cytocompatibility. In recent years, injectable hydrogels have spurred increasing attention in translational medicine as a result of their tunable physicochemical properties in response to the surrounding environment. Furthermore, they have the potential to be implanted via minimally invasive procedures while enabling deep penetration, which is considered a feasible alternative to traditional open surgical procedures. However, polymeric hydrogels may lack sufficient stability and bioactivity in physiological environments. Composite hydrogels containing bioactive glass (BG) particulates, synergistically combining the advantages of their constituents, have emerged as multifunctional biomaterials with tailored mechanical properties and biological functionalities. This review paper highlights the recent advances in injectable composite hydrogel systems based on biodegradable polymers and BGs. The influence of BG particle geometry, composition, and concentration on gel formation, rheological and mechanical behavior as well as hydration and biodegradation of injectable hydrogels have been discussed. The applications of these composite hydrogels in tissue engineering are additionally described, with particular attention to bone and skin. Finally, the prospects and current challenges in the development of desirable injectable bioactive hydrogels for tissue regeneration are discussed to outline a roadmap for future research. STATEMENT OF SIGNIFICANCE: Developing a biomaterial that can be readily available for surgery, implantable via minimally invasive procedures, and be able to effectively stimulate tissue regeneration is one of the grand challenges in modern biomedicine. This review summarizes the state-of-the-art of injectable bioactive glass-polymer composite hydrogels to address several challenges in bone and soft tissue repair. The current limitations and the latest evolutions of these composite biomaterials are critically examined, and the roles of design parameters, such as composition, concentration, and size of the bioactive phase, and polymer-glass interactions on the rheological, mechanical, biological, and overall functional performance of hydrogels are detailed. Existing results and new horizons are discussed to provide a state-of-the-art review that may be useful for both experienced and early-stage researchers in the biomaterials community.

Engineering nanoparticle therapeutics for impaired wound healing in diabetes

Diabetes mellitus is a chronic disease characterized by increased blood glucose levels, leading to damage of the nerves blood vessels, subsequently manifesting as organ failures, wounds, or ulcerations. Wounds in patients with diabetes are further complicated because of reduced cytokine responses, infection, poor vascularization, and delayed healing processes. Surface-functionalized and bioengineered nanoparticles (NPs) have recently gained attention as emerging treatment modalities for wound healing in diabetes. Here, we review emerging therapeutic NPs to treat diabetic wounds and highlight their discrete delivery mechanisms and sites of action. We further critically assess the current challenges of these nanoengineered materials for successful clinical translation and discuss their potential for growth in the clinical marketplace.

Facile preparation of polysaccharides-based adhesive hydrogel with antibacterial and antioxidant properties for promoting wound healing

Infection, oxidative stress, and inflammation are the major obstacles to cutaneous wound healing. Designing adhesive wound dressings with inherent antibacterial and antioxidant properties are highly desirable. Herein, a series of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-doped multifunctional hydrogels were facilely prepared by combining quaternized carboxymethyl chitosan (QCMCS) and oxidized hyaluronate (HA-CHO). Schiff base crosslinking between amino groups in QCMCS and aldehyde groups in HA-CHO not only constructed hydrogel networks but also endowed hydrogels with good self-healing property. The hydrogel exhibited adjustable tissue adhesiveness, degradability, and rheological properties by changing the content of TEMPO groups. Moreover, the hydrogels presented excellent inherent antibacterial and antioxidant properties, along with the porous structures, swelling ability, good cytocompatibility and low hemolysis ratio, which are beneficial to promoting wound healing process. Overall, the TEMPO hydrogel showed excellent therapeutic effect in mice skin defect model, giving the hydrogel with fitness as wound dressings for treating skin wounds.

Nanotechnology-based therapeutic applications: in vitro and in vivo clinical studies for diabetic wound healing

Diabetic wounds often indicate chronic complications that are difficult to treat. Unfortunately, existing conventional treatment modalities often cause unpremeditated side effects, given the need to develop alternative therapeutic phenotypes that are safe or have minimal side effects and risks. Nanotechnology-based platforms, including nanotherapeutics, nanoparticles (NPs), nanofibers, nanohydrogels, and nanoscaffolds, have garnered attention for their groundbreaking potential to decipher the biological environment and offer personalized treatment methods for wound healing. These nanotechnology-based platforms can successfully overcome the impediments posed by drug toxicity, existing treatment modalities, and the physiology and complexity of the wound sites. Furthermore, studies have shown that they play an essential role in influencing angiogenesis, collagen production, and extracellular matrix (ECM) synthesis, which are integral in skin repair mechanisms. In this review, we emphasized the importance of various nanotechnology-based platforms for healing diabetic wounds and report on the innovative preclinical and clinical outcomes of different nanotechnology-based platforms. This review also outlined the limitations of existing conventional treatment modalities and summarized the physiology of acute and chronic diabetic wounds.

Chitosan-silica with hops β-acids added films as prospective food packaging materials: Preparation, characterization, and properties

In this study, silica (SiO₂) and β-acids were added to the chitosan films in order to improve the film's properties. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD) were used to explore the structure of film. The results of mechanical test indicated that the film containing SiO₂ (0.3%) and β-acids (0.3%) could obtain a significant tensile strength (10.04 MPa). The complex films possessed a good inhibitory effect on three types of bacteria, and good antioxidant activity (>56%, DPPH). The release mechanism of β-acids from the films exhibited Fickian diffusion (n < 0.45). During the storage of soybean oil, the films could well control the changes of the peroxide value, acid value and thiobarbituric acid reactant content. Overall, the biofilms not only possess good physical and chemical properties, but also prolongs the time of food storage.

Self-Healing Hydrogels: Preparation, Mechanism and Advancement in Biomedical Applications

Polymeric hydrogels are widely explored materials for biomedical applications. However, they have inherent limitations like poor resistance to stimuli and low mechanical strength. This drawback of hydrogels gave rise to ''smart self-healing hydrogels'' which autonomously repair themselves when ruptured or traumatized. It is superior in terms of durability and stability due to its capacity to reform its shape, injectability, and stretchability thereby regaining back the original mechanical property. This review focuses on various self-healing mechanisms (covalent and non-covalent interactions) of these hydrogels, methods used to evaluate their self-healing properties, and their applications in wound healing, drug delivery, cell encapsulation, and tissue engineering systems. Furthermore, composite materials are used to enhance the hydrogel's mechanical properties. Hence, findings of research with various composite materials are briefly discussed in order to emphasize the healing capacity of such hydrogels. Additionally, various methods to evaluate the self-healing properties of hydrogels and their recent advancements towards 3D bioprinting are also reviewed. The review is concluded by proposing several pertinent challenges encountered at present as well as some prominent future perspectives.

A multifunctional hydrogel coating to direct fibroblast activation and infected wound healing via simultaneously controllable photobiomodulation and photodynamic therapies

Bacterial infection treatment and subsequent tissue rebuilding are the main tasks of biomaterial research. To endow implants with antibacterial activity and biological functions, the material systems are usually very complicated and ineffective. Recently, the concept of photobiomodulation (PBM), or low-level laser therapy (LLLT), has attracted increasing attention in tissue repair applications but still has not obtained wide acceptance. Because of the same laser resource, PBM could simultaneously work with 660 nm laser triggered photodynamic therapy (PDT), which will significantly simplify the material system and achieve the multiple functions of antibacterial activity and biological modulation effects. Herein, we attempt to validate the effectiveness of PBM and combine PBM with a PDT-based material system. A catechol motif-modified methacrylated gelatin containing photosensitizer Chlorin e6-loaded mesoporous polydopamine nanoparticles was fabricated (GelMAc/MPDA@Ce6). This hydrogel could be tightly adhered to titanium surfaces to serve as surface coating materials or directly used as dressings. Because of the 660 nm laser-triggered ROS generation property of Ce6, GelMAc/MPDA@Ce6 exhibited a remarkable and rapid antibacterial activity when the laser power was 1 W cm^-2. After bacterial elimination, when the power was adjusted to 100 mW cm^-2, daily irradiation brought an excellent PBM effect: the fibroblast activation was realized to accelerate wound repair. According to our in vitro and in vivo results, the fabricated hydrogel coating possessed both antibacterial activity and fibroblast activation ability only by adjusting the power of laser irradiation, which will greatly strengthen the confidence of using PBM in broader fields and give a good example to combine PBM with traditional biomaterial design.

A Multifunctional Bioactive Glass-Ceramic Nanodrug for Post-Surgical Infection/Cancer Therapy-Tissue Regeneration

The production of reactive oxygen species, persistent inflammation, bacterial infection, and recurrence after a tumor resection has become the main challenge in cancer therapy and post-surgical skin regeneration. Herein, we report a multifunctional branched bioactive Si-Ca-P-Mo glass-ceramic nanoparticle (BBGN) with inlaid molybdate nanocrystals for an effective post-surgical melanoma therapy or infection therapy and defected skin reconstruction. Mixed-valence molybdenum (Mo⁴⁺ and Mo⁶⁺) doped BBGN (BBGN-Mo) was first synthesized via a hydrothermally assisted classical synthesis of BGN, which enables the structure with a lot of free electrons and oxygen vacancies. The BBGN-Mo exhibits excellent photothermal, antibacterial, enzyme-like radical scavenging, and anti-inflammatory as well as promoted vascularized efficiencies. BBGN-Mo could kill drug-resistant methicillin-resistant Staphylococcus aureus (MRSA) bacteria in vitro (99.5%) and in vivo (97.0%) at a low photothermal temperature (42 °C) and efficiently enhance the MRSA-infected wound repair. Additionally, BBGN-Mo could effectively inhibit tumor recurrence (96.4%), continuously improve the wound anti-inflammation and vascularization microenvironment, and significantly promote the post-surgical skin regeneration. This work suggests that conventional bioceramics could be turned to the highly efficient nanodrug for treating the challenge of post-surgical cancer therapy or infection therapy and tissue regeneration, through the mixed-valence strategy.

Innovations in drug delivery for chronic wound healing

Wound healing is a varied and complex process designed to promptly restore standard skin structure, function, and appearance. To achieve this goal, different immune and biological systems participate in coordination through four separate steps, including homeostasis, inflammation, proliferation, and regeneration. Each step involves the function of other cells, cytokines, and growth factors. However, chronic ulcers, which are classified into three types of ulcers, namely vascular ulcers, diabetic ulcers, and pressure ulcers, cannot heal through the mentioned natural stages. It causes mental and physical problems for these people and, as a result, imposes high economic and social costs on society. In this regard, using a system that can accelerate the healing process of such chronic wounds, as an urgent need in the community, should be considered. Therefore, in this study, the innovations of drug delivery systems for the healing of chronic wounds using hydrogels, nanomaterial, and membranes are discussed and reviewed.

Novel Diabetic Foot Wound Dressing Based on Multifunctional Hydrogels with Extensive Temperature-Tolerant, Durable, Adhesive, and Intrinsic Antibacterial Properties

Diabetic foot ulcers (DFUs) are hard-healing chronic wounds and susceptible to bacterial infection. Conventional hydrogel dressings easily lose water at high temperature or freeze at low temperature, making them unsuitable for long-term use or in extreme environments. Herein, a temperature-tolerant (-20 to 60 °C) antibacterial hydrogel dressing is fabricated by the assembly of polyacrylamide, gelatin, and ε-polylysine. Owing to the water/glycerin (Gly) binary solvent system, the resultant hydrogel (G-PAGL) displayed good heat resistance and antifreezing properties. Within the wide temperature range (-20 to 60 °C), all the desirable features of the hydrogel, including superstretchability (>1400%), enduring water retention, adhesiveness, and persistent antibacterial property, are quite stable. Remarkably, the hydrogel wound dressing displayed lasting and broad antibacterial activity against Gram-positive and Gram-negative bacteria. Satisfactorily, the double-network (DN) G-PAGL hydrogel dressing could effectively promote the healing of DFUs by accelerating collagen deposition, promoting angiogenesis, and inhibiting bacterial breed. As far as we know, this is the first time that the extensive temperature-tolerant DN hydrogel with antibacterial ability is developed to use as DFU wound dressing. The G-PAGL hydrogel provides more choices for DFU wound dressings that could be used in extreme environments.

Bioactive glass: A multifunctional delivery system

Bioactive glasses (BAGs) were invented five decades ago and have been widely used clinically in orthopedic and stomatology. However, in the past two decades, BAGs have been explored immensely by several researchers worldwide as a multifunctional delivery system for a multitude of therapeutics ranging from metal ions to small molecules (e.g., drugs) and macromolecules (e.g., DNA). The impetus for devising a BAG-based delivery system in the 21st century is based upon the facilitative properties it offers for entrapment of a wide range of therapeutic molecules and the tailorable controlled release kinetics to the target tissue site along with the biological activity of the ionic dissolution products in several pathological conditions such as osteoporosis, cancer, infection, and inflammation. This review comprises two parts: the first part discusses the need for a new delivery system and how the journey from melt quench progressed towards template-based sol-gel mesoporous. In the second part, we have comprehended the scientific advancements made so far, emphasizing BAGs as a delivery system ranging from therapeutic ions to phytopharmaceuticals. We have also highlighted a few loopholes that have prevented bench-to-bedside clinical translation of a plethora of elucidative researches done so far.

Injectable Hydrogels for Chronic Skin Wound Management: A Concise Review

Diabetic foot ulcers (DFU) are a predominant impediment among diabetic patients, increasing morbidity and wound care costs. There are various strategies including using biomaterials have been explored for the management of DFU. This paper will review the injectable hydrogel application as the most studied polymer-based hydrogel based on published journals and articles. The main key factors that will be discussed in chronic wounds focusing on diabetic ulcers include the socioeconomic burden of chronic wounds, biomaterials implicated by the government for DFU management, commercial hydrogel product, mechanism of injectable hydrogel, the current study of novel injectable hydrogel and the future perspectives of injectable hydrogel for the management of DFU.

Electrospun fibrous sponge via short fiber for mimicking 3D ECM

BACKGROUND

Most of the natural extracellular matrix (ECM) is a three-dimensional (3D) network structure of micro/nanofibers for cell adhesion and growth of 3D. Electrospun fibers distinctive mimicked 2D ECM, however, it is impossible to simulate 3D ECM because of longitudinal collapse of continuous micro/nanofibers. Herein, 3D electrospun micro/nano-fibrous sponge was fabricated via electrospinning, homogenization, shaping and thermal crosslinking for 3D tissue regeneration of cells and vascular.

RESULTS

Fibrous sponge exhibited high porosity, water absorption and compression resilience and no chemical crosslinked agent was used in preparation process. In vitro studies showed that the 3D short fiber sponge provided an oxygen-rich environment for cell growth, which was conducive to the 3D proliferation and growth of HUVECs, stimulated the expression of VEGF, and well promoted the vascularization of HUVECs. In vivo studies showed that the 3D short fiber sponges had a good 3D adhesion to the chronic wound of diabetes in rats. Furthermore, 3D short fibrous sponges were better than 2D micro/nanofiber membranes in promoting the repair of diabetic full-thickness skin defects including wound healing, hair follicle regeneration, angiogenesis, collagen secretion.

CONCLUSION

Therefore, electrospun short fibrous sponges are special candidates for mimicking the 3D ECM and promoting 3D regeneration of tissue.

Multifunctional Injectable Hydrogel Loaded with Cerium-Containing Bioactive Glass Nanoparticles for Diabetic Wound Healing

Diabetic foot wound healing is a major clinical problem due to impaired angiogenesis and bacterial infection. Therefore, an effective regenerative dressing is desiderated with the function of promoting revascularization and anti-bacteria. Herein, a multifunctional injectable composite hydrogel was prepared by incorporation of the cerium-containing bioactive glass (Ce-BG) into Gelatin methacryloyl (GelMA) hydrogel. The Ce-BG was synthesized by combining sol-gel method with template method, which maintained spherical shape, chemical structure and phase constitution of bioactive glass (BG). The Ce-BG/GelMA hydrogels had good cytocompatibility, promoted endothelial cells migration and tube formation by releasing Si ion. In vitro antibacterial tests showed that 5 mol % CeO2-containing bioactive glass/GelMA (5/G) composite hydrogel exhibited excellent antibacterial properties. In vivo study demonstrated that the 5/G hydrogel could significantly improve wound healing in diabetic rats by accelerating the formation of granulation tissue, collagen deposition and angiogenesis. All in all, these results indicate that the 5/G hydrogel could enhance diabetic wound healing. Therefore, the development of multifunctional materials with antibacterial and angiogenic functions is of great significance to promote the repair of diabetic wound healing.

Multifunctional mats by antimicrobial nanoparticles decoration for bioinspired smart wound dressing solutions

Developing advanced materials for wound dressings is a very challenging, yet unaddressed task. These systems are supposed to act as temporary skin substitutes, performing multiple functions, including fluid absorption and antimicrobial action, supporting cell proliferation and migration in order to promote the skin regeneration process. Following a global bioinspired approach, in this study, we developed a multifunctional textile for wound dressing applications. Biodegradable polyhydroxybutyrate/poly-3-caprolactone (PHB/PCL) mats were fabricated by electrospinning to mimic the extracellular matrix (ECM), thus providing structural and biochemical support to tissue regeneration. Furthermore, inspired by nature's strategy which exploits melanin as an effective weapon against pathogens infection, PHB/PCL mats were modified with hybrid Melanin-TiO₂ nanostructures. These were combined to PHB/PCL mats following two different strategies: in-situ incorporation during electrospinning process, alternately ex-post coating by electrospraying onto obtained mats. All samples revealed huge water uptake and poor cytotoxicity towards HaCat eukaryotic cells. Melanin-TiO₂ coating conferred PHB/PCL mats significant antimicrobial activity towards both Gram(+) and Gram(-) strains, marked hydrophilic properties as well as bioactivity which is expected to promote materials-cells interaction. This study is going to provide a novel paradigm for the design of active wound dressings for regenerative medicine.

Nanocomposite scaffolds for accelerating chronic wound healing by enhancing angiogenesis

Skin is the body's first barrier against external pathogens that maintains the homeostasis of the body. Any serious damage to the skin could have an impact on human health and quality of life. Tissue engineering aims to improve the quality of damaged tissue regeneration. One of the most effective treatments for skin tissue regeneration is to improve angiogenesis during the healing period. Over the last decade, there has been an impressive growth of new potential applications for nanobiomaterials in tissue engineering. Various approaches have been developed to improve the rate and quality of the healing process using angiogenic nanomaterials. In this review, we focused on molecular mechanisms and key factors in angiogenesis, the role of nanobiomaterials in angiogenesis, and scaffold-based tissue engineering approaches for accelerated wound healing based on improved angiogenesis.

Nanotechnology-driven advances in the treatment of diabetic wounds

Diabetic foot ulcers (DFUs) are chronic severe complications of diabetes disease and remain a worldwide clinical challenge with social and economic consequences. Diabetic wounds can cause infection, amputation of lower extremities, and even death. Several factors including impaired angiogenesis, vascular insufficiency, and bacterial infections result in a delayed process of wound healing in diabetic patients. Treatment of wound infections using traditional antibiotics has become a critical status. Thus, finding new therapeutic strategies to manage diabetic wounds is urgently needed. Nanotechnology has emerged as an efficient approach for this purpose. This review aimed to summarize recent advances using nanotechnology for the treatment of diabetic wounds.

"Hard" ceramics for "Soft" tissue engineering: Paradox or opportunity?

Tissue engineering provides great possibilities to manage tissue damages and injuries in modern medicine. The involvement of hard biocompatible materials in tissue engineering-based therapies for the healing of soft tissue defects has impressively increased over the last few years: in this regard, different types of bioceramics were developed, examined and applied either alone or in combination with polymers to produce composites. Bioactive glasses, carbon nanostructures, and hydroxyapatite nanoparticles are among the most widely-proposed hard materials for treating a broad range of soft tissue damages, from acute and chronic skin wounds to complex injuries of nervous and cardiopulmonary systems. Although being originally developed for use in contact with bone, these substances were also shown to offer excellent key features for repair and regeneration of wounds and "delicate" structures of the body, including improved cell proliferation and differentiation, enhanced angiogenesis, and antibacterial/anti-inflammatory activities. Furthermore, when embedded in a soft matrix, these hard materials can improve the mechanical properties of the implant. They could be applied in various forms and formulations such as fine powders, granules, and micro- or nanofibers. There are some pre-clinical trials in which bioceramics are being utilized for skin wounds; however, some crucial questions should still be addressed before the extensive and safe use of bioceramics in soft tissue healing. For example, defining optimal formulations, dosages, and administration routes remain to be fixed and summarized as standard guidelines in the clinic. This review paper aims at providing a comprehensive picture of the use and potential of bioceramics in treatment, reconstruction, and preservation of soft tissues (skin, cardiovascular and pulmonary systems, peripheral nervous system, gastrointestinal tract, skeletal muscles, and ophthalmic tissues) and critically discusses their pros and cons (e.g., the risk of calcification and ectopic bone formation as well as the local and systemic toxicity) in this regard. STATEMENT OF SIGNIFICANCE: Soft tissues form a big part of the human body and play vital roles in maintaining both structure and function of various organs; however, optimal repair and regeneration of injured soft tissues (e.g., skin, peripheral nerve) still remain a grand challenge in biomedicine. Although polymers were extensively applied to restore the lost or injured soft tissues, the use of bioceramics has the potential to provides new opportunities which are still partially unexplored or at the very beginning. This reviews summarizes the state of the art of bioceramics in this field, highlighting the latest evolutions and the new horizons that can be opened by their use in the context of soft tissue engineering. Existing results and future challenges are discussed in order to provide an up-to-date contribution that is useful to both experienced scientists and early-stage researchers of the biomaterials community.

Polymeric Hydrogel Systems as Emerging Biomaterial Platforms to Enable Hemostasis and Wound Healing

Broad interest in developing new hemostatic technologies arises from unmet needs in mitigating uncontrolled hemorrhage in emergency, surgical, and battlefield settings. Although a variety of hemostats, sealants, and adhesives are available, development of ideal hemostatic compositions that offer a range of remarkable properties including capability to effectively and immediately manage bleeding, excellent mechanical properties, biocompatibility, biodegradability, antibacterial effect, and strong tissue adhesion properties, under wet and dynamic conditions, still remains a challenge. Benefiting from tunable mechanical properties, high porosity, biocompatibility, injectability and ease of handling, polymeric hydrogels with outstanding hemostatic properties have been receiving increasing attention over the past several years. In this review, after shedding light on hemostasis and wound healing processes, the most recent progresses in hydrogel systems engineered from natural and synthetic polymers for hemostatic applications are discussed based on a comprehensive literature review. Most studies described used in vivo models with accessible and compressible wounds to assess the hemostatic performance of hydrogels. The challenges that need to be tackled to accelerate the translation of these novel hemostatic hydrogel systems to clinical practice are emphasized and future directions for research in the field are presented.

Bioinspired biliverdin/silk fibroin hydrogel for antiglioma photothermal therapy and wound healing

Rationale: Photothermal therapy employs the photoabsorbers to generate heat under the near-infrared (NIR) irradiation for thermal tumor ablation. However, NIR irradiation might damage the adjacent tissue due to the leakage of the photoabsorbers and the residual materials after treatment might hinder the local healing process. A bifunctional hydrogel that holds both photothermal property and potent pro-healing ability provides a viable option to resolve this issue. Methods: In this study, we developed a bioinspired green hydrogel (BVSF) with the integration of bioproduct biliverdin into natural derived silk fibroin matrix for antiglioma photothermal therapy and wound healing. Results: The BVSF hydrogel possessed excellent and controllable photothermal activity under NIR irradiation and resulted in effective tumor ablation both in vitro and in vivo. Additionally, the BVSF hydrogel exerted anti-inflammatory effects both in vitro and in vivo, and stimulated angiogenesis and wound healing in a full-thickness defect rat model. Conclusion: Overall, this proof-of-concept study was aimed to determine the feasibility and reliability of using an all-natural green formulation for photothermal therapy and post-treatment care.

Bioactive Glasses: A Promising Therapeutic Ion Release Strategy for Enhancing Wound Healing

The morbidity, mortality, and burden of burn victims and patients with severe diabetic wounds are still high, which leads to an extensively growing demand for novel treatments with high clinical efficacy. Biomaterial-based wound treatment approaches have progressed over time from simple cotton wool dressings to advanced skin substitutes containing cells and growth factors; however, no wound care approach is yet completely satisfying. Bioactive glasses are materials with potential in many areas that exhibit unique features in biomedical applications. Today, bioactive glasses are not only amorphous solid structures that can be used as a substitute in hard tissue but also are promising materials for soft tissue regeneration and wound healing applications. Biologically active elements such as Ag, B, Ca, Ce, Co, Cu, Ga, Mg, Se, Sr, and Zn can be incorporated in glass networks; hence, the superiority of these multifunctional materials over current materials results from their ability to release multiple therapeutic ions in the wound environment, which target different stages of the wound healing process. Bioactive glasses and their dissolution products have high potency for inducing angiogenesis and exerting several biological impacts on cell functions, which are involved in wound healing and some other features that are valuable in wound healing applications, namely hemostatic and antibacterial properties. In this review, we focus on skin structure, the dynamic process of wound healing in injured skin, and existing wound care approaches. The basic concepts of bioactive glasses are reviewed to better understand the relationship between glass structure and its properties. We illustrate the active role of bioactive glasses in wound repair and regeneration. Finally, research studies that have used bioactive glasses in wound healing applications are summarized and the future trends in this field are elaborated.