Dendritic Hydrogels with Robust Inherent Antibacterial Properties for Promoting Bacteria-Infected Wound Healing

A cuttlefish ink nanoparticle-reinforced biopolymer hydrogel with robust adhesive and immunomodulatory features for treating oral ulcers in diabetes

Oral ulcers can be managed using a variety of biomaterials that deliver drugs or cytokines. However, many patients experience minimal benefits from certain medical treatments because of poor compliance, short retention times in the oral cavity, and inadequate drug efficacy. Herein, we present a novel hydrogel patch (SCE2) composed of a biopolymer matrix (featuring ultraviolet-triggered adhesion properties) loaded with cuttlefish ink nanoparticles (possessing pro-healing functions). Applying a straightforward local method initiates the formation of a hydrogel barrier that adheres to mucosal injuries under the influence of ultraviolet light. SCE2 then demonstrates exceptional capabilities for near-infrared photothermal sterilization and neutralization of reactive oxygen species. These properties contribute to the elimination of bacteria and the management of the oxidation process, thus accelerating the healing phase's progression from inflammation to proliferation. In studies involving diabetic rats with oral ulcers, the SCE2 adhesive patch significantly quickens recovery by altering the inflamed state of the injured area, facilitating rapid re-epithelialization, and fostering angiogenesis. In conclusion, this light-sensitive hydrogel patch offers a promising path to expedited wound healing, potentially transforming treatment strategies for clinical oral ulcers.

Phytic Acid-Functional Cellulose Nanocrystals and Their Application in Self-Healing Nanocomposite Hydrogels

Cellulose nanocrystals (CNCs) have garnered significant attention as a modifiable substrate because of their exceptional performances, including remarkable degradability, high tensile strength, high elastic modulus, and biocompatibility. In this article, the successful adsorption of phytic acid (PA) onto the surface of cellulose nanocrystals @polydopamine (CNC@PDA) was achieved. Taking inspiration from mussels, a dopamine self-polymerization reaction was employed to coat the surface of CNCs with PDA. Utilizing Pickering emulsion, the CNC@PDA-PA nanomaterial was obtained by grafting PA onto CNC@PDA. An environmentally friendly hydrogel was prepared through various reversible interactions using poly(acrylic acid) (PAA) and Fe3+ as raw materials with the assistance of CNC@PDA-PA. By multiple hydrogen bonding and metal-ligand coordination, nanocomposite hydrogels exhibit remarkable mechanical properties (the tensile strength and strain were 1.82 MPa and 442.1%, respectively) in addition to spectacular healing abilities (96.6% after 5 h). The study aimed to develop an innovative approach for fabricating nanocomposite hydrogels with exceptional self-healing capabilities.

Carbene-mediated gelatin and hyaluronic acid hydrogel paints with ultra adhesive ability for arthroscopic cartilage repair

In articular cartilage defect, particularly in arthroscopy, regenerative hydrogels are urgently needed. It should be able to firmly adhere to the cartilage tissue and maintain sufficient mechanical strength to withstand approximately 10 kPa of arthroscopic hydraulic flushing. In this study, we report a carbene-mediated ultra adhesive hybrid hydrogel paints for arthroscopic cartilage repair, which combined the photo initiation of double crosslinking system with the addition of diatomite, as a further reinforcing agent and biological inorganic substances. The double network consisting of ultraviolet initiated polymerization of hyaluronic acid methacrylate (HAMA) and carbene insertion chemistry of diazirine-grafted gelatin (GelDA) formed an ultra-strong adhesive hydrogel paint (H2G5DE). Diatomite helped the H2G5DE hydrogel paint firmly adhere to the cartilage defect, withstanding nearly 100 kPa of hydraulic pressure, almost 10 times that in clinical arthroscopy. Furthermore, the H2G5DE hydrogel supported cell growth, proliferation, and migration, thus successfully repairing cartilage defects. Overall, this study demonstrates a proof-of-concept of ultra-adhesive polysaccharide hydrogel paints, which can firmly adhere to the articular cartilage defects, can resist continuous hydraulic pressure, can promote effective cartilage regeneration, and is very suitable for minimally invasive arthroscopy.

Antibacterial Hydrogel Adhesives Based on Bifunctional Telechelic Dendritic-Linear-Dendritic Block Copolymers

Antibiotic-resistant pathogens have been declared by the WHO as one of the major public health threats facing humanity. For that reason, there is an urgent need for materials with inherent antibacterial activity able to replace the use of antibiotics, and in this context, hydrogels have emerged as a promising strategy. Herein, we introduce the next generation of cationic hydrogels with antibacterial activity and high versatility that can be cured on demand in less than 20 s using thiol-ene click chemistry (TEC) in aqueous conditions. The approach capitalizes on a two-component system: (i) telechelic polyester-based dendritic-linear-dendritic (DLDs) block copolymers of different generations heterofunctionalized with allyl and ammonium groups, as well as (ii) polyethylene glycol (PEG) cross-linkers functionalized with thiol groups. These hydrogels resulted in highly tunable materials where the antibacterial performance can be adjusted by modifying the cross-linking density. Off-stoichiometric hydrogels showed narrow antibacterial activity directed toward Gram-negative bacteria. The presence of pending allyls opens up many possibilities for functionalization with biologically interesting molecules. As a proof-of-concept, hydrophilic cysteamine hydrochloride as well as N-hexyl-4-mercaptobutanamide, as an example of a thiol with a hydrophobic alkyl chain, generated three-component networks. In the case of cysteamine derivatives, a broader antibacterial activity was noted than the two-component networks, inhibiting the growth of Gram-positive bacteria. Additionally, these systems presented high versatility, with storage modulus values ranging from 270 to 7024 Pa and different stability profiles ranging from 1 to 56 days in swelling experiments. Good biocompatibility toward skin cells as well as strong adhesion to multiple surfaces place these hydrogels as interesting alternatives to conventional antibiotics.

Development of a Self-Healing Gel with Self-Healing Kinetics That Can Be Controlled by Heat

A self-healing gel with self-healing kinetics that can be regulated by heat is developed. The gel is composed of a polymer having benzophenone (BP) substituents, which are cross-linked with a main alkyl chain via ester bonds, titanium chloride, and zinc. This gel material shows a self-healing property at room temperature. Also, its self-healing behavior can be accelerated by heating the gel. This gel having self-healing kinetics that can be regulated by heat is favorable for practical use. When we want to use a self-healing property as a stop-gap measure, a rapid self-healing property is demanded. On the other hand, when we want materials repaired beautifully or decomposed surfaces need to be attached beautifully, a slow self-healing property is favorable. These opposite demands can be answered by the gel with self-healing kinetics that can be regulated by heat.

The Diels-Alder Cross-Linked Gelatin/Dextran Nanocomposite Hydrogels with Silver Nanoparticles for Wound Healing Applications: Synthesis, Characterization, and In Vitro Evaluation

Wound healing involves a sophisticated biological process that relies on ideal conditions to advance through various stages of repair. Modern wound dressings are designed to imitate the natural surroundings around cells and offer properties such as moisture regulation, strength, and antimicrobial defense to boost healing. A recent research project unveiled a new type of gelatin (Gel)/dextran (Dex) hydrogels, linked through Diels-Alder (D-A) reactions, loaded with silver nanoparticles (Ag-NPs) for cutting-edge wound treatment. Gel and Dex were chemically modified to form the hydrogels via the D-A reaction. The hydrogels were enriched with Ag-NPs at varying levels. Thorough analyses of the hydrogels using methods like NMR, FT-IR, and SEM were carried out to assess their structure and nanoparticle integration. Rheological tests displayed that the hydrogels had favorable mechanical attributes, particularly when Ag-NPs were included. The hydrogels demonstrated controlled swelling, responsiveness to pH changes, and were non-toxic. Testing against E. coli showcased the strong antibacterial activity of the nanocomposite hydrogels in a concentration-dependent manner. This investigation showcased the promise of these bioactive nanocomposite hydrogels in promoting speedy wound healing by maintaining a moist environment, offering an antimicrobial shield, and ensuring mechanical support at the wound site.

Multifunctional Microneedle Patch with Diphlorethohydroxycarmalol for Potential Wound Dressing

BACKGROUND

Treatment of skin wounds with diverse pathological characteristics presents significant challenges due to the limited specific and efficacy of current wound healing approaches. Microneedle (MN) patches incorporating bioactive and stimulus materials have emerged as a promising strategy to overcome these limitations and integrating bioactive materials with anti-bacterial and anti-inflammatory properties for advanced wound dressing.

METHODS

We isolated diphlorethohydroxycarmalol (DPHC) from Ishige okamurae and assessed its anti-inflammatory and anti-bacterial effects on macrophages and its antibacterial activity against Cutibacterium acnes. Subsequently, we fabricated polylactic acid (PLA) MN patches containing DPHC at various concentrations (0-0.3%) (PDPHC MN patches) and evaluated their mechanical properties and biological effects using in vitro and in vivo models.

RESUTLS

Our findings demonstrated that DPHC effectively inhibited nitric oxide production in macrophages and exhibited rapid bactericidal activity against C. acnes. The PDPHC MN patches displayed potent antibacterial effects without cytotoxicity. Moreover, in 2,4-Dinitrochlorobenzene-stimulated mouse model, the PDPHC MN patches significantly suppressed inflammatory response and cutaneous lichenification.

CONCLUSION

The results suggest that the PDPHC MN patches holds promise as a multifunctional wound dressing for skin tissue engineering, offering antibacterial properties and anti-inflammatory properties to promote wound healing process.

An adhesion-switchable hydrogel dressing for painless dressing removal without secondary damage

Hydrogels with strong adhesion to wet tissues are considered promising for wound dressings. However, the clinical application of adhesive hydrogel dressing remains a challenge due to the issues of secondary damage during dressing changes. Herein, we fabricated an adhesion-switchable hydrogel formed with poly(acrylamide)-co-poly(N-isopropyl acrylamide), quaternary ammonium chitosan and tannic acid. This hydrogel forms instant and robust adhesion to the skin at body temperature. However, as the temperature rises above the lower critical solution temperature (LCST), the hydrogel loses its adhesion towards the wound area due to the temperature-dependent volume phase transition of the copolymer, occurring around 45 °C. Consequently, the designed hydrogel can be easily detached from adhered tissues upon demand, providing a facile and effective method for painless dressing changes without secondary damage. This hydrogel holds great promise for long-term application in wound dressings.

Dental Caries Management with Antibacterial Silver-Doped Prussian Blue Hydrogel by the Combined Effects of Photothermal Response and Ion Discharge

Caries is a destructive condition caused by bacterial infection that affects the hard tissues of the teeth, significantly reducing the quality of life for individuals. Photothermal therapy (PTT) offers a noninvasive and painless treatment for caries, but the use of unsafe laser irradiance limits its application. To address this challenge, we prepared nanoparticles of silver ion-doped Prussian blue (AgPB), which was encased within cationic guar gum (CG) to form the antibacterial PTT hydrogel CG-AgPB with a photothermal conversion efficiency of 34.4%. When exposed to an 808 nm laser at a power density of 0.4 W/cm2, the hydrogel readily reached a temperature of over 50 °C in just 3 min, synchronized by the discharge of Ag+ ions from the interstitial sites of AgPB crystals, resulting in broad-spectrum and synergistic antibacterial activities (>99%) against individual oral pathogens (Streptococcus sanguinis, Streptococcus mutans, and Streptococcus sobrinus) and pathogen-induced biofilms. In vivo, CG-AgPB-mediated PTT demonstrated a capability to profoundly reduce the terminal number of cariogenic bacteria to below 1% in a rat model of caries. Given the outstanding biocompatibility, injectability, and flushability, this CG-AgPB hydrogel may hold promise as a next-generation oral hygiene adjunct for caries management in a clinical setting.

Enhancing diabetic wound healing with a pH/glucose dual-responsive hydrogel for ROS clearance and antibacterial activity

Currently, the treatment of diabetic wounds in clinical practice is still unsatisfactory due to the risks of oxidative damage and bacterial infection during the healing process. An optimal wound dressing should exhibit robust capabilities in scavenging reactive oxygen species (ROS) and combatting bacterial growth. In this study, we utilized borax as a crosslinker and prepared a pH/glucose dual-responsive composite hydrogel based on poly(vinyl alcohol) (PVA), sodium alginate (SA), and tannic acid (TA). This hydrogel, loaded with cerium dioxide, serves as an effective ROS scavenger, promoting wound closure by reducing the level of ROS in the wound area. Additionally, the hydrogel can release the antibacterial drug ofloxacin in response to the low pH and high glucose microenvironment in infected wounds. Results from skin defect model in diabetic mice demonstrated this ROS-scavenging and antibacterial hydrogel can suppress inflammation and accelerate wound healing. In summary, our work provides a new perspective on a local and stimulus-responsive drug delivery strategy for treating diabetic wounds.

Evaluation of living bacterial therapy assisted by pH/reactive oxygen species dual-responsive sodium alginate-based hydrogel for wound infections

The enhancement of antimicrobial wound dressings is of utmost importance in light of the escalating risk of antibiotic resistance caused by excessive antibiotic usage. Conventional antimicrobial materials eradicate pathogenic bacteria while impeding the proliferation of beneficial bacteria during the management of wound infections, thereby disturbing the equilibrium of the skin micro-ecosystem and engendering recurrent cutaneous complications. Lactobacillus rhamnosus (L.rha) is a probiotic that can inhibit the growth of certain pathogenic bacteria by secreting a large number of metabolites. In this paper, we synthesized a cross-linker (SPBA) with a boric acid molecule from succinic acid and 4-(bromomethyl)phenylboronic acid, which formed a boric acid ester bond with a diol on the natural polysaccharide sodium alginate (SA), and obtained a pH/reactive oxygen species (ROS) dual-responsive hydrogel (SA-SPBA) for loading L.rha to treat wound infections. The SA-SPBA@L.rha hydrogel improves the survival of L.rha during storage and has good injectability as well as self-healing properties. The hydrogel showed good biocompatibility, the antimicrobial effect increases in a dose-dependent manner, and it has a certain antioxidant and anti-inflammatory capacity, accelerating wound repair. The use of SA-SPBA@L.rha hydrogel provides a safe and effective strategy for the repair of skin wound infections.

Eugenol-loaded polyurethane gelatin dressing for efficient angiogenesis and antibacterial effects in refractory diabetic wound defect healing

The amelioration of refractory diabetic ulcers presents a formidable conundrum on a global scale, attributable to the elevated peril of contagion and protracted convalescence durations. Within the purlieus of this reparative epoch, the deployment of efficacious wound coverings endowed with both angiogenesis and antibacterial attributes is of paramount significance. Hydrogel wound dressings are distinguished by their elevated biocompatibility, adhesive tenacity, and innate regenerative capacity. Eugenol, a substance distilled from the blossoms of the lilac, serves as a precursor to metformin and is known to impede the genesis of reactive oxygen species. Although its antibacterial effects have been extensively chronicled, the angiogenic ramifications of eugenol within the context of wound remediation remain under-investigated. This research aimed to evaluate the effectiveness of eugenol-infused hydrogel as a wound dressing material. In this context, polyurethane gelatin (PG) was combined with eugenol at concentrations of 0.5% and 1%, creating PG-eugenol hydrogel mixtures with specific mass ratios for both in vivo and in vitro assessments. The in vivo studies indicated that hydrogels infused with eugenol expedited diabetic wound healing by fostering angiogenesis. Enhanced healing was noted, attributed to improved antibacterial and angiogenic properties, increased cell proliferation, tissue regeneration, and re-epithelialization. The in vitro analyses revealed that eugenol-enriched hydrogels stimulated the growth of fibroblasts (HFF-1) and human umbilical vein endothelial cells (HUVECs) and exhibited antibacterial characteristics. This investigation confirms the potential of eugenol-laden hydrogels in effectively treating diabetic wound defects.

Multifunctional double-network hydrogel with antibacterial and anti-inflammatory synergistic effects contributes to wound healing of bacterial infection

Wound infection not only hinders the time sequence of tissue repair, but also may lead to serious complications. Multifunctional wound dressings with biocompatibility, excellent mechanical properties and antibacterial properties can promote wound healing during skin infection and reduce the use of antibiotics. In this study, a multifunctional dual-network antibacterial hydrogel was constructed based on the electrostatic interaction of two polyelectrolytes, hydroxypropyl trimethyl ammonium chloride chitosan (HACC) and sodium alginate (SA). Attributing to the suitable physical crosslinking between HACC and SA, the hydrogel not only has good biocompatibility, mechanical property, but also has broad-spectrum antibacterial properties. In vivo results showed that the hydrogel could regulate M2 polarization, promote early vascular regeneration, and create a good microenvironment for wound healing. Therefore, this hydrogel is an effective multifunctional wound dressing. Consequently, we propose a novel hydrogel with combined elements to expedite the intricate repair of wound infection.

Luteolin-incorporated fish collagen hydrogel scaffold: An effective drug delivery strategy for wound healing

In clinical practice, wound care has always been challenging. Hydrogels play a key role in facilitating active wound recovery by absorbing exudates, maintaining moisture, and alleviating pain through cooling. In this study, type I collagen was isolated from the skin of crucian carp (Carassius carassius) and verified by amino acid analysis, FTIR, and SDS-PAGE. By adopting a new approach, luteolin was added to collagen hydrogels in situ after being dissolved in an alkaline solution. XRD and SEM confirmed the luteolin was incorporated and entirely distributed throughout the hydrogel. The plastic compression improved the young's modulus of hydrogel to 15.24 ± 0.59 kPa, which is adequate for wound protection. The drug loading efficiency was 98 ± 1.47 % in the selected formulation. The luteolin-incorporated hydrogel enabled regulated drug release. We assessed the cytotoxicity using MTT and live-dead assays, as well as examined the hemocompatibility to determine the biocompatibility of the hydrogel. In vivo experiments showed that the hydrogel with luteolin had the highest wound closure rate (94.01 ± 2.1 %) and improved wound healing with granular tissue formation, collagen deposition, and re-epithelialization. These findings indicate that this efficient drug delivery technology can accelerate the process of wound healing.

Laponite/lactoferrin hydrogel loaded with eugenol for methicillin-resistant Staphylococcus aureus-infected chronic skin wound healing

Severe bacterial infections can give rise to protracted wound healing processes, thereby posing a significant risk to a patient's well-being. Consequently, the development of a versatile hydrogel dressing possessing robust bioactivity becomes imperative, as it holds the potential to expedite wound healing and yield enhanced clinical therapeutic outcomes. In this context, the present study involves the formulation of an injectable multifunctional hydrogel utilizing laponite (LAP) and lactoferrin (LF) as foundational components and loaded with eugenol (EG). This hydrogel is fabricated employing a straightforward one-pot mixing approach that leverages the principle of electrostatic interaction. The resulting LAP/LF/EG2% composite hydrogel can be conveniently injected to address irregular wound geometries effectively. Once administered, the hydrogel continually releases lactoferrin and eugenol, mitigating unwarranted oxidative stress and eradicating bacterial infections. This orchestrated action culminates in the acceleration of wound healing specifically in the context of MRSA-infected wounds. Importantly, the LAP/LF/EG2% hydrogel exhibits commendable qualities including exceptional injectability, potent antioxidant attributes, and proficient hemostatic functionality. Furthermore, the hydrogel composition notably encourages cellular migration while maintaining favorable cytocompatibility. Additionally, the hydrogel manifests noteworthy bactericidal efficacy against the formidable multidrug-resistant MRSA bacterium. Most significantly, this hydrogel formulation distinctly expedites the healing of MRSA-infected wounds by promptly inducing hemostasis, curbing bacterial proliferation, and fostering angiogenesis, collagen deposition, and re-epithelialization processes. As such, the innovative hydrogel material introduced in this investigation emerges as a promising dressing for the facilitation of bacterial-infected wound healing and consequent tissue regeneration.

Modulating macrophage phenotype for accelerated wound healing with chlorogenic acid-loaded nanocomposite hydrogel

Wound healing involves distinct phases, including hemostasis, inflammation, proliferation, and remodeling, which is a complex and dynamic process. Conventional preparations often fail to meet multiple demands and provide prompt information about wound status. Here, a pH/ROS dual-responsive hydrogel (OHA-PP@Z-CA@EGF) was constructed based on oxidized hyaluronic acid (OHA), phenylboronic acid-grafted ε-polylysine (PP), chlorogenic acid (CA)-loaded ZIF-8 (Z-CA), and epidermal growth factor (EGF), which possesses intrinsic antibacterial, antioxidant, and angiogenic capacities. Due to the Schiff base and Phenylboronate ester bonds, the hydrogel exhibited excellent mechanical properties, strong adhesion, good biodegradability, high biocompatibility, stable rheological properties, and self-healing ability. Moreover, introducing Z-CA as an initiator and nanofiller led to the additional cross-linking of hydrogel through coordination bonds, which further improved the mechanical properties and antioxidant capabilities. Bleeding models of liver and tail amputations demonstrated rapid hemostatic properties of the hydrogel. Besides, the hydrogel regulated macrophage phenotypes via the NF-κB/JAK-STAT pathways, relieved oxidative stress, promoted cell migration and angiogenesis, and accelerated diabetic wound healing. The hydrogel also enabled real-time monitoring of the wound healing stages by colorimetric detection. This multifunctional hydrogel opens new avenues for the treatment and management of full-thickness diabetic wounds.

Dermal extracellular matrix gelatin delivering Prussian blue nanoparticles to relieve skin flap ischemia

The survival rate of flap is a crucial factor for determining the success of tissue repair and reconstruction. Flap transplantation surgery often leads to ischemic and reperfusion injury, causing apoptosis and tissue necrosis, which significantly reduces the survival rate of flap. To address this issue, we developed a porcine skin decellularized matrix gel nanocomplex loaded with alprostadil (Alp) in Prussian blue nanoparticles (PB NPs) called Alp@PB-Gel. This gel not only maintained the cell affinity of the extracellular scaffold but also exhibited a high degree of plasticity. In vitro assays demonstrated that Alp@PB-Gel possessed antioxidant activity, scavenging ROS ability, and effectively promoted the angiogenesis and migration of human vascular endothelial cells (HUVECs) by stimulating the proliferation of vascular epithelial cells and fibroblasts. In vivo assays further confirmed that Alp@PB-Gel could effectively alleviate necrosis in the early and late stages after surgery, downregulate the levels of NLRP3 and CD68 to inhibit apoptosis and attenuate inflammation, while upregulate the levels of VEGF and CD31 to promote vascular tissue regeneration. Moreover, Alp@PB-Gel exhibited excellent cell affinity and biocompatibility, highlighting its potential for clinical application.

Collagen/chitosan/genipin hydrogel loaded with phycocyanin nanoparticles and ND-336 for diabetic wound healing

Diabetic wound healing remains a healthcare challenge due to the overexpression of matrix metalloproteinase-9 (MMP-9) and the imbalance between angiogenic factors and vascular inhibitory factors. In this study, we developed a nanocomposite injectable collagen/chitosan hydrogel for the treatment of delayed diabetic wound healing, which can promote cell migration to the wound site (through the addition of phycocyanin) and reduce the expression of MMP-9 (through the use of ND-336) to improve the therapeutic effect of diabetic wound healing. Furthermore, different weight ratios of collagen and chitosan hydrogels were prepared to select the hydrogel with proper mechanical properties. In vitro experiments confirmed that all hydrogels have favorable biocompatibility and hemocompatibility. Notably, Gel 2, with a weight ratio of collagen and chitosan at 25:75, was found to have an excellent capability to facilitate cell migration and in vivo studies further proved that Gel 2 nanocomposite hydrogel had the best ability to improve diabetic wound healing by promoting cell migration and decreasing MMP-9 expression. The collagen/chitosan/genipin hydrogel loaded phycocyanin and ND-336 can be harnessed for non-toxic and efficient treatment of wound healing management of diabetes.

Advanced multifunctional hydrogels for diabetic foot ulcer healing: Active substances and biological functions

AIM

Hydrogels with excellent biocompatibility and biodegradability can be used as the desirable dressings for the therapy of diabetic foot ulcer (DFU). This review aimed to summarize the biological functions of hydrogels, combining with the pathogenesis of DFU.

METHODS

The studies in the last 10 years were searched and summarized from the online database PubMed using a combination of keywords such as hydrogel and diabetes. The biological functions of hydrogels and their healing mechanism on DFU were elaborated.

RESULTS

In this review, hydrogels were classified by their active substances such as drugs, cytokines, photosensitizers, and biomimetic peptide. Based on this, the biological functions of hydrogels were summarized by associating the pathogenesis of DFU, including oxidative stress, chronic inflammation, cell phenotype change, vasculopathy, and infection. This review also pointed out some of the shortcomings of hydrogels in present researches.

CONCLUSIONS

Hydrogels were classified into carrier hydrogels and self-functioning hydrogels in this review. Besides, the functions and components of existing hydrogels were clarified to provide assistance for future researches and clinical applications.

Acellular embryoid body and hydroxybutyl chitosan composite hydrogels promote M2 macrophage polarization and accelerate diabetic cutaneous wound healing

Diabetic wound healing is delayed due to persistent inflammation, and macrophage-immunomodulating biomaterials can control the inflammatory phase and shorten the healing time. In this study, acellular embryoid bodies (aEBs) were prepared and mixed with thermosensitive hydroxybutyl chitosan (HBC) hydrogels to produce aEB/HBC composite hydrogels. The aEB/HBC composite hydrogels exhibited reversible temperature-sensitive phase transition behavior and a hybrid porous network. In vitro analysis showed that the aEB/HBC composite hydrogels exhibited better antimicrobial activity than the PBS control, aEBs or HBC hydrogels and promoted M0 to M2 polarization but not M1 to M2 macrophage repolarization in culture. The in vivo results showed that the aEB/HBC composite hydrogels accelerated cutaneous wound closure, re-epithelialization, ingrowth of new blood vessels, and collagen deposition and reduced the scar width during wound healing in diabetic mice over time. Macrophage phenotype analysis showed that the aEB/HBC composite hydrogels induce M2 macrophage reactions continually, upregulate M2-related mRNA and protein expression and downregulate M1-related mRNA and protein expression. Therefore, the aEB/HBC composite hydrogels have excellent antimicrobial activity, promote M2 macrophage polarization and accelerate the functional and structural healing of diabetic cutaneous wounds.

Supramolecular Assembly Based on Calix(4)arene and Aggregation-Induced Emission Photosensitizer for Phototherapy of Drug-Resistant Bacteria and Skin Flap Transplantation

Photodynamic therapy as a burgeoning and non-invasive theranostic technique has drawn great attention in the field of antibacterial treatment but often encounters undesired phototoxicity of photosensitizers during systemic circulation. Herein, a supramolecular substitution strategy is proposed for phototherapy of drug-resistant bacteria and skin flap repair by using macrocyclic p-sulfonatocalix(4)arene (SC4A) as a host, and two cationic aggregation-induced emission luminogens (AIEgens), namely TPE-QAS and TPE-2QAS, bearing quaternary ammonium group(s) as guests. Through host-guest assembly, the obtained complex exhibits obvious blue fluorescence in the solution due to the restriction of free motion of AIEgens and drastically inhibits efficient type I ROS generation. Then, upon the addition of another guest 4,4'-benzidine dihydrochloride, TPE-QAS can be competitively replaced from the cavity of SC4A to restore its pristine ROS efficiency and photoactivity in aqueous solution. The dissociative TPE-QAS shows a high bacterial binding ability with an efficient treatment for methicillin-resistant Staphylococcus aureus (MRSA) in dark and light irradiation. Meanwhile, it also exhibits an improved survival rate for MRSA-infected skin flap transplantation and largely accelerates the healing process. Thus, such cascaded host-guest assembly is an ideal platform for phototheranostics research.

Influence of chitosan and hydroxyethyl cellulose modifications towards the design of cross-linked double networks hydrogel for diabetic wound healing

The wound dressings' lack of antioxidant and antibacterial properties, and delayed wound healing limit their use in wound treatment and management. Recent advances in dressing materials are aimed at improving the limitations discussed above. Therefore, the aim of this study includes the preparation and characterization of oxidized hydroxyethyl cellulose (OHEC) and ferulic acid-grafted chitosan (CS-FA) hydrogel loaded with green synthesized selenium nanoparticles (Se NPs) (OHEC-CS-FA-Se NPs named as nanohydrogel) for diabetic wound healing. The structure and properties of the hydrogel was characterized by FTIR, FE-SEM, HR-TEM, EDAX, UV-Vis spectrophotometry, XRD, DLS, zeta potential and rheological studies. The findings of these experiments demonstrate that nanohydrogel possesses a variety of outstanding qualities, including an optimal gel time, good swelling characteristics, a fair water retention rate, a good degradation rate, and strong mechanical stability. Nanohydrogel has been shown to have a synergistic impact by significantly increasing antioxidant activity by scavenging ABTS and DPPH radicals. The nanohydrogel's strong biocompatibility was confirmed by cytocompatibility testing using L929 mouse fibroblast cells. In addition, the wound healing potential of nanohydrogel was tested on L929 cells by an in vitro scratch assay and the nanohydrogel showed a wound closure rate of 100 % after 12 h. In addition to this study, nanohydrogel has demonstrated significant antimicrobial properties against human and wound infection causing pathogens such as Bacillus subtilis, methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa. In the animal model, almost complete diabetic wound healing was achieved on day 14 after application of the nanohydrogel. The results obtained indicate that the multifunctional bioactive nature of OHEC-CS-FA-Se NPs showed exceptional antioxidant and antibacterial potential for the treatment of infected and chronic wounds.

A double-network porous hydrogel based on high internal phase emulsions as a vehicle for potassium sucrose octasulfate delivery accelerates diabetic wound healing

Diabetic wounds are a difficult medical challenge. Excessive secretion of matrix metalloproteinase-9 (MMP-9) in diabetic wounds further degrades the extracellular matrix and growth factors and causes severe vascular damage, which seriously hinders diabetic wound healing. To solve these issues, a double-network porous hydrogel composed of poly (methyl methacrylate-co-acrylamide) (p(MMA-co-AM)) and polyvinyl alcohol (PVA) was constructed by the high internal phase emulsion (HIPE) technique for the delivery of potassium sucrose octasulfate (PSO), a drug that can inhibit MMPs, increase angiogenesis and improve microcirculation. The hydrogel possessed a typical polyHIPE hierarchical microstructure with interconnected porous morphologies, high porosity, high specific surface area, excellent mechanical properties and suitable swelling properties. Meanwhile, the p(MMA-co-AM)/PVA@PSO hydrogel showed high drug-loading performance and effective PSO release. In addition, both in vitro and in vivo studies showed that the p(MMA-co-AM)/PVA@PSO hydrogel had good biocompatibility and significantly accelerated diabetic wound healing by inhibiting excessive MMP-9 in diabetic wounds, increasing growth factor secretion, improving vascularization, increasing collagen deposition and promoting re-epithelialization. Therefore, this study provided a reliable therapeutic strategy for diabetic wound healing, some theoretical basis and new insights for the rational design and preparation of wound hydrogel dressings with high porosity, high drug-loading performance and excellent mechanical properties.

Immunomodulatory hydrogels for skin wound healing: cellular targets and design strategy

Skin wounds significantly impact the global health care system and represent a significant burden on the economy and society due to their complicated dynamic healing processes, wherein a series of immune events are required to coordinate normal and sequential healing phases, involving multiple immunoregulatory cells such as neutrophils, macrophages, keratinocytes, and fibroblasts, since dysfunction of these cells may impede skin wound healing presenting persisting inflammation, impaired vascularization, and excessive collagen deposition. Therefore, cellular target-based immunomodulation is promising to promote wound healing as cells are the smallest unit of life in immune response. Recently, immunomodulatory hydrogels have become an attractive avenue to promote skin wound healing. However, a detailed and comprehensive review of cellular targets and related hydrogel design strategies remains lacking. In this review, the roles of the main immunoregulatory cells participating in skin wound healing are first discussed, and then we highlight the cellular targets and state-of-the-art design strategies for immunomodulatory hydrogels based on immunoregulatory cells that cover defect, infected, diabetic, burn and tumor wounds and related scar healing. Finally, we discuss the barriers that need to be addressed and future prospects to boost the development and prosperity of immunomodulatory hydrogels.

Programmed microalgae-gel promotes chronic wound healing in diabetes

Chronic diabetic wounds are at lifelong risk of developing diabetic foot ulcers owing to severe hypoxia, excessive reactive oxygen species (ROS), a complex inflammatory microenvironment, and the potential for bacterial infection. Here we develop a programmed treatment strategy employing live Haematococcus (HEA). By modulating light intensity, HEA can be programmed to perform a variety of functions, such as antibacterial activity, oxygen supply, ROS scavenging, and immune regulation, suggesting its potential for use in programmed therapy. Under high light intensity (658 nm, 0.5 W/cm2), green HEA (GHEA) with efficient photothermal conversion mediate wound surface disinfection. By decreasing the light intensity (658 nm, 0.1 W/cm2), the photosynthetic system of GHEA can continuously produce oxygen, effectively resolving the problems of hypoxia and promoting vascular regeneration. Continuous light irradiation induces astaxanthin (AST) accumulation in HEA cells, resulting in a gradual transformation from a green to red hue (RHEA). RHEA effectively scavenges excess ROS, enhances the expression of intracellular antioxidant enzymes, and directs polarization to M2 macrophages by secreting AST vesicles via exosomes. The living HEA hydrogel can sterilize and enhance cell proliferation and migration and promote neoangiogenesis, which could improve infected diabetic wound healing in female mice.

An Injectable, Adhesive, and Self-Healing Hydrogel with Inherently Antibacterial Property for Wound Dressing

Antibacterial hydrogel has emerged as an excellent candidate for wound dressing with the ability to eliminate infection and promote wound healing. Herein, a dynamic hydrogel is developed by Schiff base reaction of mixed charged polypeptides and oxidized dextran (ODex). Specifically, biodegradable polypeptides of 1-(propylthio)acetic acid-3-butylimidazole-modified poly(L-lysine) (PLL-PBIM) and adipate dihydrazide-modified poly(L-glutamic acid) (PLG-ADH) are achieved with tunable substitution and charge. By mixing with ODex, charged polypeptides of PLL-PBIM and PLG-ADH led to an injectable and self-healing hydrogel in seconds. The injectable and self-healing performances of the hydrogels are ascribed to the reversible imine and hydrazone bonds formed between polypeptides and ODex. The positively charged hydrogels exhibited over 95% antibacterial activity against E. coli and S. aureus. An optimized balancing of PLG-ADH and PLL-PBIM significantly reduced the hemolysis rate and cytotoxicity of hydrogels. Therefore, the dynamic hydrogel with excellent biocompatibility and inherently antibacterial ability can have potential application for wound dressing.

Wound microenvironment-responsive dually cross-linked nanofibrillar peptide hydrogels for efficient hemostatic control and multi-faceted wound management

The wound microenvironment-responsive hydrogel, featuring a dually cross-linked architecture, offers distinct advantages in the realm of drug delivery due to its exceptional mechanical properties and responsiveness to stimuli. In this investigation, a versatile dually cross-linked hydrogel was synthesized. The initial framework was established through non-covalent interactions employing a self-assembling peptide indomethacin-Gly-Phe-Phe-Tyr-Gly-Arg-Gly-Asp (abbreviated as IDM-1), while the second framework underwent chemical cross-linking of chitosan (CS) mediated by genipin. This dually-network arrangement significantly bolstered the structure, proving effective for hemostatic control. In addition, hydrogels can be triggered for degradation by proteases highly expressed in the wound microenvironment, releasing drugs like indomethacin (IDM) and CS. This characteristic introduced efficient multi-faceted wound management in vitro and in vivo, such as anti-inflammatory and antibacterial activities, ultimately augmenting the wound healing process. Thus, the development of a dually cross-linked hydrogel that enables smart drug release triggered by specific wound microenvironment presents considerable potential within the realm of wound management.

Physicochemical, rheological, antioxidant and immunological properties of four novel non-inulin (poly)saccharides from Asparagus cochinchinensis

The impacts of four extraction techniques, including hot water, ultrasonic-assisted, complex enzyme-assisted and acid-assisted methods, on the morphological, physicochemical properties and bioactivities of Asparagus cochinchinensis (poly)saccharides (EACP, WACP, UACP, and AACP) were investigated and compared. The four samples were mainly composed of glucose, fructose, and galactose with molar ratios of 50.8:22.7:4.4 for WACP, 53.9:26.0:5.3 for UACP, 35.6:14.1:21.4 for AACP and 45.0:15.6:9.0 for EACP, respectively. The rheological result showed that ACPs were non-Newtonian fluids. EACP with high purity (97.65 %) had good DPPH, O2- and ABTS+ radical scavenging activities, and significantly promoted the proliferation of the RAW264.7 cells at low concentration. UACP had good Fe2+ chelating ability, radical (DPPH, O2- and OH) scavenging activities, which might be attributed to the existence of triple-helix structure. AACP had high yield, molecular weight (17,477.2 Da), high crystallinity (23.33 %), and good radical (OH and ABTS+) scavenging activities. All four significantly stimulated the transcript expression levels of TNF-α, IL-1β and IL-6, as determined by RT-PCR. These results suggest that the exploitation and utilization of non-inulin (poly)saccharides extracted by ultrasonic-assisted, complex enzyme-assisted and acid-assisted extraction methods are potentially valuable as effective and natural immune adjuvants and antioxidants.

Emulsion template fabricated gelatin-based scaffold functionalized by dialdehyde starch complex with antibacterial antioxidant properties for accelerated wound healing

Gelatin and starch are considered as promising sustainable materials for their abundant production and good biodegradability. Efforts have been made to explore their medical application. Herein, scaffolds based on gelatin and starch with a preferred microstructure and antibacterial antioxidant property were fabricated by the emulsion template method. The dialdehyde starch was firstly combined with silver nanoparticles and curcumin to carry out the efficient hybrid antibacterial agent. Then, the gelatin microsphere of appropriate size was prepared by emulsification and gathered by the above agent to obtain gelatin-based scaffolds. The prepared scaffolds showed porous microstructures with high porosity of over 74 % and the preferred pore sizes of ∼65 μm, which is conducive to skin regeneration. Moreover, the scaffolds possessed a good swelling ability of over 640 %, good degradability of over 18 days, excellent blood compatibility, and cell compatibility. The promising antibacterial and antioxidant properties came from the hybrid antibacterial agent were affirmed. As expected, the gelatin-based scaffolds fabricated by the emulsion template method with a preferred microstructure can facilitate more adhered fibroblasts. In summary, gelatin-based scaffolds functionalized by starch-based complex expanded the application of abundant sustainable materials in the biomedical field, especially as antibacterial antioxidant wound dressings.

Delivery of Agarose-aided Sprays to the Posterior Nose for Mucosa Immunization and Short-term Protection against Infectious Respiratory Diseases

AIM

The study aimed to deliver sprays to the posterior nose for mucosa immunization or short-term protection.

BACKGROUND

Respiratory infectious diseases often enter the human body through the nose. Sars- Cov-2 virus preferentially binds to the ACE2-rich tissue cells in the Nasopharynx (NP). Delivering medications to the nose, especially to the NP region, provides either a short-term protective/ therapeutic layer or long-term mucosa immunization. Hydrogel-aided medications can assist film formation, prolong film life, and control drug release. However, conventional nasal sprays have failed to dispense mediations to the posterior nose, with most sprays lost in the nasal valve and front turbinate.

OBJECTIVE

The objective of the study was to develop a practical delivery system targeting the posterior nose and quantify the dosimetry distribution of agarose-saline solutions in the nasal cavity.

METHODS

The solution viscosities with various hydrogel concentrations (0.1-1%) were measured at different temperatures. Dripping tests on a vertical plate were conducted to understand the hydrogel concentration effects on the liquid film stability and mobility. Transparent nasal airway models were used to visualize the nasal spray deposition and liquid film translocation.

RESULTS

Spray dosimetry with different hydrogel concentrations and inhalation flow rates was quantified on a total and regional basis. The solution viscosity increased with decreasing temperature, particularly in the range of 60-40oC. The liquid viscosity, nasal spray atomization, and liquid film mobility were highly sensitive to the hydrogel concentration. Liquid film translocations significantly enhanced delivered doses to the caudal turbinate and nasopharynx when the sprays were administered at 60oC under an inhalation flow rate of 11 L/min with hydrogel concentrations no more than 0.5%. On the other hand, sprays with 1% hydrogel or administered at 40oC would significantly compromise the delivered doses to the posterior nose.

CONCLUSION

Delivering sufficient doses of hydrogel sprays to the posterior nose is feasible by leveraging the post-administration liquid film translocation.

A temperature and pH dual-responsive injectable self-healing hydrogel prepared by chitosan oligosaccharide and aldehyde hyaluronic acid for promoting diabetic foot ulcer healing

Chronic wound, such as skin defect after burn, pressure ulcer, and diabetic foot ulcer is very difficult to cure. Its pathological process is often accompanied with local temperature rise, pH decrease, and other phenomena. Owing to their outstanding hydrophilic, biocompatibility, and responsive properties, hydrogels could accelerate the healing process. In this study, we chose chitosan oligosaccharide (COS) grafted with Pluronic F127 (F127-COS). Aldehyde hyaluronic acid (A-HA) oxidized by NaIO4. And added boric acid (BA) to prepare a thermosensitive and pH-responsive injectable self-healing F127-COS/A-HA/COS/BA (FCAB) hydrogel, loaded with drug deferoxamine (DFO) in order to have an accurate release and promote angiogenesis of diabetic foot ulcer. In vitro experiments had verified that the FCAB hydrogel system loaded with DFO (FCAB/D) could promote migration and angiogenesis of HUVEC. A diabetes rat back wound model further confirmed its role in promoting angiogenesis in wound repair process. The results showed that the FCAB/D hydrogel exhibited unique physicochemical properties, excellent biocompatibility, and significantly enhanced therapeutic effects for diabetic foot ulcer.

An ECM-mimicking assembled gelatin/hyaluronic acid hydrogel with antibacterial and radical scavenging functions for accelerating open wound healing

A multifunctional hydrogel dressing with hemostatic, antibacterial, and reactive oxygen species (ROS)-removing properties is highly desirable for the clinical treatment of open wounds. Although many wound dressings have been prepared, the modification of polymers is often involved in the preparation process, and the uncertainty of biological safety and stability of modified polymers hinders the clinical application of products. In this study, inspired by the composition and crosslinking pattern of extracellular matrix (ECM), a deeply ECM-mimicking multifunctional hydrogel dressing is created. Tannic acid (TA) and poly-ϵ-lysine (EPL) are added into a gelatin/hyaluronic acid (Gel/HA) matrix, and a stable hydrogel is formed due to the formation of the triple helix bundles of gelatin and hydrogen bonds between polymers. The introduction of TA and EPL endows the ECM-mimicking hydrogel with stable rheological properties, as well as antibacterial and hemostatic functions. The as-produced hydrogels have suitable swelling ratio, enzyme degradability, and good biocompatibility. In addition, it also shows a significant ability to eliminate ROS, which is confirmed by the elimination of 2,2-diphenyl-1-picrylhydrazyl free radical. Full-thickness skin wound repair experiment and histological analysis of the healing site in mice demonstrate that the developed ECM-mimicking Gel/HA hydrogels have a prominent effect on ECM formation and promotion of wound closure. Taken together, these findings suggest that the multifunctional hydrogels deeply mimicking the ECM are promising candidates for the clinical treatment of open wounds.

pH-Responsive Injectable Multifunctional Pluronic F127/Gelatin-Based Hydrogels with Hydrogen Production for Treating Diabetic Wounds

Diabetic chronic wounds remain a major clinical challenge with long-term inflammatory responses and extreme oxidative damage. Hence, a pH-responsive injectable multifunctional hydrogel [Gel/CUR-FCHO/Mg (GCM) micromotors] via a Schiff base reaction between gelatin and benzaldehyde-grafted Pluronic F127 drug-loaded micelles (FCHO) was fabricated for the first time. Dynamic Schiff base linkage endowed the GCM hydrogel with the ability to be self-healing, injectable, and pH-responsive for on-demand drug delivery at the wound site. Curcumin (CUR), a hydrophobic drug with antioxidative, anti-inflammatory, and antibacterial activities, was encapsulated into the hydrogel matrix by micellization (CUR-FCHO micelles). Simultaneously, magnesium-based micromotors (Mg micromotors) were physically entrapped into the system for providing active hydrogen (H2) to scavenge reactive oxygen species and alleviate inflammatory responses. As a result, the GCM micromotor hydrogel displayed an inherent antibacterial property, extraordinary antioxidative performance, and remarkable biocompatibility. In the diabetic mouse with a full-thickness cutaneous defect wound, the GCM hydrogel could remodel the inflammatory microenvironment and stimulate vascularization and collagen deposition, thereby facilitating wound closure and enhancing tissue regeneration, which offered a promising therapeutic option for diabetic chronic wound management.

Guanosine-driven hyaluronic acid-based supramolecular hydrogels with peroxidase-like activity for chronic diabetic wound treatment

Guanosine is often used to construct supramolecular hydrogels due to its self-assembly properties, however, the high temperature and strong alkaline construction methods greatly limit its application in biomedical fields. In this work, a guanosine-driven hyaluronic acid-based supramolecular hydrogel was developed under mild condition by employing phenylboronic acid-functionalized hyaluronic acid (HA-PBA) backbone and guanosine molecules. Guanosines self-assembled into G-quartet planes under potassium ion conditions, and formed boronic ester bonds with HA-PBA, which induced rapid formation of dynamically cross-linked hydrogels. Hemin was then binding to the G-quartet plane via π-π interactions in the hydrogels, which exhibited peroxidase activity and were highly effective in killing bacteria by generating hydroxyl radicals in the presence of H2O2. Furthermore, glucose oxidase (GOx) was incorporated into the hydrogels and the HP/G@hemin@GOx hydrogels showed good antibacterial properties, modulation of wound glucose and ROS level, and good therapeutic efficacy for diabetic chronic wounds. Overall, the self-assembly of guanosine has been shown for the first time to be a feasible method for constructing natural polymer-based supramolecular hydrogels. This guanosine-driven HA-based supramolecular hydrogel can act as a potential wound dressing for chronic diabetic wound treatment. STATEMENT OF SIGNIFICANCE: Chronic wound repair remains an unsolved clinical challenge. Herein, we propose to utilize phenylboronic acid-modified hyaluronic acid and guanosine to construct supramolecular gels with peroxidase activity for chronic wound treatment. The self-assembly behavior of guanosine drives the natural macromolecular backbone to form the hydrogel, and the proposed method simplifies the gelation conditions and improves its biosafety. The G-quartets formed by the self-assembly of guanosine can act as the loading site for hemin. G-quartet/hemin complex imported peroxidase activity to the hydrogels, endowing them with the ability to kill bacteria and regulate ROS levels of cells in the wound site. This guanosine-driven supramolecular hydrogel significantly increased the rate of wound healing in diabetic mice, promising a new strategy for chronic wound treatment.

Multifunctional and theranostic hydrogels for wound healing acceleration: An emphasis on diabetic-related chronic wounds

Hydrogels represent intricate three-dimensional polymeric structures, renowned for their compatibility with living systems and their ability to naturally degrade. These networks stand as promising and viable foundations for a range of biomedical uses. The practical feasibility of employing hydrogels in clinical trials has been well-demonstrated. Among the prevalent biomedical uses of hydrogels, a significant application arises in the context of wound healing. This intricate progression involves distinct phases of inflammation, proliferation, and remodeling, often triggered by trauma, skin injuries, and various diseases. Metabolic conditions like diabetes have the potential to give rise to persistent wounds, leading to delayed healing processes. This current review consolidates a collection of experiments focused on the utilization of hydrogels to expedite the recovery of wounds. Hydrogels have the capacity to improve the inflammatory conditions at the wound site, and they achieve this by diminishing levels of reactive oxygen species (ROS), thereby exhibiting antioxidant effects. Hydrogels have the potential to enhance the growth of fibroblasts and keratinocytes at the wound site. They also possess the capability to inhibit both Gram-positive and Gram-negative bacteria, effectively managing wounds infected by drug-resistant bacteria. Hydrogels can trigger angiogenesis and neovascularization processes, while also promoting the M2 polarization of macrophages, which in turn mitigates inflammation at the wound site. Intelligent and versatile hydrogels, encompassing features such as pH sensitivity, reactivity to reactive oxygen species (ROS), and responsiveness to light and temperature, have proven advantageous in expediting wound healing. Furthermore, hydrogels synthesized using environmentally friendly methods, characterized by high levels of biocompatibility and biodegradability, hold the potential for enhancing the wound healing process. Hydrogels can facilitate the controlled discharge of bioactive substances. More recently, there has been progress in the creation of conductive hydrogels, which, when subjected to electrical stimulation, contribute to the enhancement of wound healing. Diabetes mellitus, a metabolic disorder, leads to a slowdown in the wound healing process, often resulting in the formation of persistent wounds. Hydrogels have the capability to expedite the healing of diabetic wounds, facilitating the transition from the inflammatory phase to the proliferative stage. The current review sheds light on the biological functionalities of hydrogels, encompassing their role in modulating diverse mechanisms and cell types, including inflammation, oxidative stress, macrophages, and bacteriology. Additionally, this review emphasizes the significance of smart hydrogels with responsiveness to external stimuli, as well as conductive hydrogels for promoting wound healing. Lastly, the discussion delves into the advancement of environmentally friendly hydrogels with high biocompatibility, aimed at accelerating the wound healing process.

Sprayable Ti3C2 MXene hydrogel for wound healing and drug release system

Wound healing is a critical process that facilitates the body's recovery from injuries and helps prevent infections, thereby maintaining overall tissue and organ functionality. However, delayed wound healing owing to various factors can lead to bacterial infections and secondary complications. In this study, a ciprofloxacin (CIP)-loaded MXene/sodium alginate (SA) hydrogel was fabricated to inhibit bacterial infections and enhance wound healing. The hydrogel was formulated in a sprayable state by blending CIP-loaded MXene (CIP-MX) with SA. This hydrogel was found to exhibit excellent photothermal conversion capability and biocompatibility under near-infrared (NIR) irradiation. In addition, the hydrogel enabled controlled drug release based on NIR irradiation, ultimately enabling improved antibacterial activity. Based on the in vitro and in vivo experiments, the CIP-loaded MXene/SA hydrogel (CIP-MX@Gel) accelerated wound healing. Overall, the CIP-MX@Gel has excellent potential as an effective wound healing material.

Polydopamine functionalized polyurethane shape memory sponge with controllable expansion performance triggered by near-infrared light for incompressible hemorrhage control

Uncontrolled expansion of shape memory sponges face a significant challenge in the treatment of lethal incompressible hemorrhage, which can lead to blood overflow or damage to the surrounding tissue. Herein, we developed a polydopamine functionalized polyurethane shape memory sponge (PDA-TPI-PU) with a controllable degree of expansion by near-infrared (NIR) light-triggered stimulation for the treatment of incompressible hemorrhage. The sponge has excellent liquid absorption performance and robust mechanical strength as well as good photothermal conversion ability. Under NIR light of 0.32 W/cm2, the maximum recovery rate of the fixed-shape compression sponge was 91% within 25 s in air and 80% within 25 s in blood. In the SD rat liver penetrating injury model, compared with commercial medical gelatin sponge and PVA sponge, the PDA-TPI-PU sponge could effectively control the bleeding under the NIR light irradiation and did not cause excessive compression of the wound. The sponge with these characteristics shows potential application prospects as a hemostatic material.

Double-network cellulose-based hybrid hydrogels with favourable biocompatibility and antibacterial activity for wound healing

Bacterial infections are among the leading causes of delayed wound healing. At present, a series of antibacterial materials, such as antibiotics, antimicrobial peptides (AMPs), metals and metal oxides (MMOs), have been used to fabricate antibacterial wound dressings. However, their translational potential is limited owing to their poor biocompatibility. ε-Polylysine (ε-PL) is a natural macromolecule with excellent biocompatibility and broad-spectrum antibacterial activity. Herein, ε-PL was incorporated into a cellulose/γ-polyglutamic acid (γ-PGA) composite hydrogel to form a novel double-network hydrogel termed as CGLH. The elastic modulus of CGLH increased from 0.097 ± 0.015 MPa to 0.441 ± 0.096 MPa, and the equilibrium swelling ratio increased from 382.7 ± 24.3 % to 611.2 ± 8.6 %. Several preclinical models were used to investigate the translational potential of this hydrogel. CGLH exhibited good biocompatibility and antibacterial activity, which promoted the healing of infected and critical-size wounds within 12 days. CGLH had positive effects on collagen synthesis, vascularization and cell proliferation. As a result, this study not only provided an effective alternative for wound healing but also proposed a double-network strategy for creating biocompatible and antibacterial biomaterials.

Bandage modified with antibacterial films of quaternized chitosan & sodium carboxymethyl cellulose microgels/baicalein nanoparticles for accelerating infected wound healing

Wound dressings capable of sterilizing pathogenic bacteria and scavenging free radicals are important to inhibit bacterial invasion and accelerate wound healing. The target of this work is to develop an antibacterial dressing by modifying bandages with films composed of biological macromolecule microgels and baicalein@tannic acid (Bai@TA) nanoparticles (NPs). Firstly, hydrophobic Bai was made into water soluble Bai@TA NPs using a solvent exchange method with TA as stabilizer. Polymeric microgels of sodium carboxymethyl cellulose (CMC)&hydroxypropyltrimethyl ammonium chloride chitosan (HACC) were then prepared by a simple blending method. Further, CMC&HACC/Bai@TA multilayer films were deposited on medical bandages by using a layer-by-layer assembly technique to obtain an antibacterial dressing. The as-prepared dressings showed great antibacterial ability against E. coli, S. aureus and methicillin resistant Staphylococcus aureus (MRSA), excellent antioxidant activity and good biological safety. In addition, compared to conventional medical bandages, the dressings could efficaciously diminish inflammation in the wound, accelerate skin regeneration and functional restoration, and promote the in vivo healing speed of full-thickness skin wounds infected by MRSA. We believe that as a low-cost but effective wound dressing, the antibacterial bandage modified with CMC&HACC/Bai@TA films has potentials to replace traditional dressings in the clinical management of infected wounds.

A phellinus igniarius polysaccharide/chitosan-arginine hydrogel for promoting diabetic wound healing

Inadequate angiogenesis and inflammation at the wound site have always been a major threat to skin wounds, especially for diabetic wounds that are difficult to heal. Therefore, hydrogel dressings with angiogenesis and antibacterial properties are very necessary in practical applications. This study reported a hydrogel (PCA) based on L-arginine conjugated chitosan (CA) and aldehyde functionalized polysaccharides of Phellinus igniarius (OPPI) as an antibacterial and pro-angiogenesis dressing for wound repair in diabetes for the first time. and discussed its possible mechanism for promoting wound healing. The results showed that PCA had good antioxidant, antibacterial, biological safety and other characteristics, and effectively promoted the healing course of diabetic wound model. In detail, the H&E and Masson staining results showed that PCA promoted normal epithelial formation and collagen deposition. The Western blot results confirmed that PCA decreased the inflammation by inhibiting the IKBα/NF-κB signaling pathway and enhanced angiogenesis by adjusting the level of HIF-1α. In conclusion, PCA is a promising candidate for promoting wound healing in diabetes. Graphic abstract.

ROS-Mediated Fragmentation Alters the Effects of Hyaluronan on Corneal Epithelial Wound Healing

A buildup of reactive oxygen species (ROS) occurs in virtually all pathological conditions. Hyaluronan (HA) is a major extracellular matrix component and is susceptible to oxidation by reactive oxygen species (ROS), yet the precise chemical structures of oxidized HA products (oxHA) and their physiological properties remain largely unknown. This study characterized the molecular weight (MW), structures, and physiological properties of oxHA. For this, high-molecular-weight HA (HMWHA) was oxidized using increasing molar ratios of hydrogen peroxide (H2O2) or hypochlorous acid (HOCl). ROS lead to the fragmentation of HA, with the oxHA products produced by HOCl exhibiting an altered chemical structure while those produced by H2O2 do not. HMWHA promotes the viability of human corneal epithelial cells (hTCEpi), while low MWHA (LMWHA), ultra-LMWHA (ULMWHA), and most forms of oxHA do not. HMWHA and LMWHA promote hTCEpi proliferation, while ULMWHA and all forms of oxHA do not. LMWHA and some forms of oxHA promote hTCEpi migration, while HMWHA does not. Finally, all native forms of HA and oxHA produced by HOCl promote in vivo corneal wound healing, while oxHA produced by H2O2 does not. Taken together, our results show that HA fragmentation by ROS can alter the physiological activity of HA by altering its MW and structure.

Development of Composite Sponge Scaffolds Based on Carrageenan (CRG) and Cerium Oxide Nanoparticles (CeO2 NPs) for Hemostatic Applications

In this study, a novel absorbable hemostatic agent was developed using carrageenan (CRG) as a natural polymer and cerium oxide nanoparticles (CeO2 NPs). CRG-CeO2-0.5 and CRG-CeO2-1 composites were prepared by compositing CeO2 to CRG + CeO2 at a weight ratio of 0.5:100 and 1:100, respectively. The physicochemical and structural properties of these compounds were studied and compared with pristine CRG. Upon incorporation of CeO2 nanoparticles into the CRG matrix, significant reductions in hydrogel degradation were observed. In addition, it was noted that CRG-CeO2 exhibited better antibacterial and hemostatic properties than CRG hydrogel without CeO2 NPs. The biocompatibility of the materials was tested using the NIH 3T3 cell line, and all samples were found to be nontoxic. Particularly, CRG-CeO2-1 demonstrated superior hemostatic effects, biocompatibility, and a lower degradation rate since more CeO2 NPs were present in the CRG matrix. Therefore, CRG-CeO2-1 has the potential to be used as a hemostatic agent and wound dressing.

Spatiotemporally Responsive Hydrogel Dressing with Self-Adaptive Antibacterial Activity and Cell Compatibility for Wound Sealing and Healing

Adhesive hydrogels containing quaternary ammonium salt (QAS) moieties have shown attractive advantages in treatment for acute wounds, attributed to their high performances in wound sealing and sterilization. However, the introduction of QAS commonly leads to high cytotoxicity and adhesive deterioration. Herein, aimed to solve these two issues, a self-adaptive dressing with delicate spatiotemporal responsiveness is developed by employing cellulose sulfate (CS) as dynamic layers to coat QAS-based hydrogel. In detail, due to the acid environment of wound in the early stages of healing, the CS coating will quickly detach to expose the active QAS groups for maximum disinfectant efficacy; meanwhile, as the wound gradually heals and recovers to a neutral pH, the CS will remain stable to keep QAS screened, realizing a high cell growth-promoting activity for epithelium regeneration. Additionally, attributed to the synergy of temporary hydrophobicity by CS and slow water absorption kinetics of the hydrogel, the resultant dressing possesses outstanding wound sealing and hemostasis performance. At last, this work anticipates this approach to intelligent wound dressings based on dynamic and responsive intermolecular interaction can also be applied to a wide range of self-adaptive biomedical materials employing different chemistries for applications in medical therapy and health monitoring.

Diverse Antibacterial Treatments beyond Antibiotics for Diabetic Foot Ulcer Therapy

Diabetic foot ulcer (DFU), a common complication of diabetes, has become a great burden to both patients and the society. The delayed wound closure of ulcer sites resulting from vascular damage and neutrophil dysfunction facilitates bacterial infection. Once drug resistance occurs or bacterial biofilm is formed, conventional therapy tends to fail and amputation is unavoidable. Therefore, effective antibacterial treatment beyond antibiotics is of utmost importance to accelerate the wound healing process and prevent amputation. Considering the complexity of multidrug resistance, biofilm formation, and special microenvironments (such as hyperglycemia, hypoxia, and abnormal pH value) at the infected site of DFU, several antibacterial agents and different mechanisms have been explored to achieve the desired outcome. The present review focuses on the recent progress of antibacterial treatments, including metal-based medications, natural and synthesized antimicrobial peptides, antibacterial polymers, and sensitizer-based therapy. This review provides a valuable reference for the innovation of antibacterial material design for DFU therapy.

Mussel bioinspired, silver-coated and insulin-loaded mesoporous polydopamine nanoparticles reinforced hyaluronate-based fibrous hydrogel for potential diabetic wound healing

Diabetes wounds take longer to heal due to extended inflammation, decreased angiogenesis, bacterial infection, and oxidative stress. These factors underscore the need for biocompatible and multifunctional dressings with appropriate physicochemical and swelling properties to accelerate wound healing. Herein, insulin (Ins)-loaded, and silver (Ag) coated mesoporous polydopamine (mPD) nanoparticles were synthesized (Ag@Ins-mPD). The nanoparticles were dispersed into polycaprolactone/methacrylated hyaluronate aldehyde dispersion, electrospun to form nanofibers, and then photochemically crosslinked to form a fibrous hydrogel. The nanoparticle, fibrous hydrogel, and nanoparticle-reinforced fibrous hydrogel were characterized for their morphological, mechanical, physicochemical, swelling, drug-release, antibacterial, antioxidant, and cytocompatibility properties. The diabetic wound reconstruction potential of nanoparticle-reinforced fibrous hydrogel was studied using BALB/c mice. The results indicated that Ins-mPD acted as a reductant to synthesize Ag nanoparticles on their surface, held antibacterial and antioxidant potential, and their mesoporous properties are crucial for insulin loading and sustained release. The nanoparticle-reinforced scaffolds were uniform in architecture, porous, mechanically stable, showed good swelling, and possessed superior antibacterial, and cell-responsive properties. Furthermore, the designed fibrous hydrogel scaffold demonstrated good angiogenic, anti-inflammatory, increased collagen deposition, and faster wound repair capabilities, therefore, it could be used as a potential candidate for diabetic wound treatment.

Evolution of the Chronic Venous Leg Ulcer Microenvironment and Its Impact on Medical Devices and Wound Care Therapies

Studies have reported that the constituents of the wound microenvironment are likely to have critical roles in the degradation and fate of the polymeric matrix and the compounds dissolved in the wound dressing matrix. Thus, chronic wound assessment and the design of effective medical devices and drug products for wound care partly rely on an in-depth understanding of the wound microenvironment. The main aim of this review is to identify and discuss the different stages of chronic wound progression, focusing on the changes in the biochemical composition of the wound microenvironment, with particular attention given to venous leg ulcers (VLUs), as they are one of the most prevalent chronic wound aetiologies. The pathophysiology of venous ulcers is detailed, followed by a thorough review of what is known about the VLU microenvironment and its changes as a function of the evolution of the VLU. Simulating conditions for VLU are then discussed with the view of highlighting potentially relevant simulating media as a function of VLU evolution for a better assessment of biological safety, in particular medical devices intended to be in contact with these wounds.

Photocatalytic and Photothermal Antimicrobial Mussel-Inspired Nanocomposites for Biomedical Applications

Bacterial infection has traditionally been treated with antibiotics, but their overuse is leading to the development of antibiotic resistance. This may be mitigated by alternative approaches to prevent or treat bacterial infections without utilization of antibiotics. Among the alternatives is the use of photo-responsive antimicrobial nanoparticles and/or nanocomposites, which present unique properties activated by light. In this study, we explored the combined use of titanium oxide and polydopamine to create nanoparticles with photocatalytic and photothermal antibacterial properties triggered by visible or near-infrared light. Furthermore, as a proof-of-concept, these photo-responsive nanoparticles were combined with mussel-inspired catechol-modified hyaluronic acid hydrogels to form novel light-driven antibacterial nanocomposites. The materials were challenged with models of Gram-negative and Gram-positive bacteria. For visible light, the average percentage killed (PK) was 94.6 for E. coli and 92.3 for S. aureus. For near-infrared light, PK for E. coli reported 52.8 and 99.2 for S. aureus. These results confirm the exciting potential of these nanocomposites to prevent the development of antibiotic resistance and also to open the door for further studies to optimize their composition in order to increase their bactericidal efficacy for biomedical applications.

Chitosan-based double network hydrogel loading herbal small molecule for accelerating wound healing

Skin injuries are one of the most common clinical traumas worldwide, and wound dressings are considered to be one of key factors in wound healing. Natural polymer-based hydrogels have been developed as ideal materials for a new generation of dressings due to their excellent biocompatibility and wetting ability. However, the inadequate mechanical performances and lack of efficacy in promoting wound healing have limited the application of natural polymer-based hydrogels as wound dressings. In this work, a double network hydrogel based on natural chitosan molecules was constructed to enhance the mechanical properties, and emodin, a herbal natural product, was loaded into the hydrogel to improve the healing effect of the dressing. The structure of the chitosan-emodin network formed by Schiff base reaction and microcrystalline network of biocompatible polyvinyl alcohol endowed hydrogels with excellent mechanical properties and ensured its integrity as wound dressings. Moreover, the hydrogel showed excellent wound healing properties due to the loading of emodin. The hydrogel dressing could promote cell proliferation, cell migration, and secretion of growth factors. The animal experimental results also demonstrated that the hydrogel dressing facilitated the regeneration of blood vessels and collagen and accelerated wound healing.

Mussel-inspired self-healing hydrogel form pectin and cellulose for hemostasis and diabetic wound repairing

Diabetic wound is considered as a kind of chronic wound prone to infection and difficult to repair due to high glucose level in the blood of patients. In this research, a biodegradable self-healing hydrogel with mussel inspired bioadhesion and anti-oxidation properties is fabricated based on Schiff-base cross-linking. The hydrogel was designed from dopamine coupled pectin hydrazide (Pec-DH) and oxidized carboxymethyl cellulose (DCMC) for mEGF loading as a diabetic wound repair dressing. The Pectin and CMC as natural feedstock endowed the hydrogel with biodegradability to avoid possible side effects, while the coupled catechol structure could enhance the tissue adhesion of the hydrogel for hemostasis. The results showed the Pec-DH/DCMC hydrogel formed fast and can cover irregular wounds with good sealing effect. The catechol structure also improved the reactive oxygen species (ROS) scavenging ability of the hydrogel, which can eliminate the negative effect of ROS during wound healing. The in vivo diabetic wound healing experiment revealed the hydrogel as mEGF loading vehicle greatly enhanced the diabetic wound repairing rate in mice model. As a result, the Pec-DH/DCMC hydrogel could show advantages as EGF carrier in wound healing applications.

Quaternized chitosan coated copper sulfide nanozyme with peroxidase-like activity for synergistic antibacteria and promoting infected wound healing

Bacterial infection can hinder the infected wound healing process. Because of the growing drug-resistance bacteria, there is an urgent desire to develop alternative antibacterial strategies to the antibiotics. Herein, the quaternized chitosan coated CuS (CuS-QCS) nanozyme with peroxidase (POD)-like activity was developed through a facile biomineralized approach for synergistic efficient antibacterial therapy and wound healing. The CuS-QCS killed bacteria by the electrostatic bonding of positive charged QCS with bacteria and releasing Cu2+ to damage bacterial membrane. And importantly, CuS-QCS nanozyme exhibited higher intrinsic POD-like activity, which converted H2O2 with low concentration into highly toxic hydroxyl radical (OH) for the elimination of bacteria by oxidative stress. Through cooperation of POD-like activity, Cu2+ and QCS, CuS-QCS nanozyme exhibited excellent antibacterial efficacy of approximate 99.9 % against E. coli and S. aureus in vitro. In addition, the QCS-CuS was successfully used to promote the healing of S. aureus infected wound with good biocompatibility. This synergistic nanoplatform presented here shows great potential applications in the field of wound infection management.