A starch-regulated adhesive hydrogel dressing with controllable separation properties for painless dressing change

Multifunctional protocatechuic acid-polyacrylic acid hydrogel adhesives for wound dressings

Multifunctional hydrogel adhesives are highly desirable in wound healing applications, yet their preparation often requires complex material system design to achieve. Herein, a straightforward one-pot two-step polymerization method is developed to prepare adhesive hydrogels for wound dressing based on protocatechuic acid (PCA), polyacrylic acid (PAA), and polyamidoamine-epichlorohydrin (PAE), where PCA provides the catechol groups for strong adhesion, PAA serves as the primary polymer matrix, and PAE acts as a bridge connecting PCA and PAA. This design results in a PAA-PAE-PCA hydrogel having a remarkable instant 90-degree peeling interfacial toughness of 431 J m-2 on porcine skin, which is further amplified to 615 J m-2 after 30 minutes. The hydrogel also possesses the desired features for wound dressing, such as self-healing, antioxidant, anti-UV and antibacterial properties, good cytocompatibility, strong adhesion in use and weak adhesion on removal, as well as reversible and wet adhesion. Finally, in vivo data reveal that the PAA-PAE-PCA hydrogels can significantly accelerate wound healing, as evidenced by a noticeable reduction in the wound area and a diminished inflammatory response. Collectively, these results endorse the obtained multifunctional hydrogel as a promising candidate for wound healing and related fields.

Healing with precision: A multi-functional hydrogel-bioactive glass dressing boosts infected wound recovery and enhances neurogenesis in the wound bed

Chronic skin wounds, especially infected ones, pose a significant clinical challenge due to their increasing incidence and poor outcomes. The deteriorative microenvironment in such wounds, characterized by reduced extracellular matrix, impaired angiogenesis, insufficient neurogenesis, and persistent bacterial infection, has prompted the exploration of novel therapeutic strategies. In this study, we developed an injectable multifunctional hydrogel (GEL/BG@Cu + Mg) incorporating Gelatin-Tannic acid/ N-hydroxysuccinimide functionalized polyethylene glycol and Bioactive glass doped with copper and magnesium ions to accelerate the healing of infected wounds. The GEL/BG@Cu + Mg hydrogel composite demonstrates good biocompatibility, degradability, and rapid formation of a protective barrier to stop bleeding. Synergistic bactericidal effects are achieved through the photothermal properties of BG@Cu + Mg and sustained copper ions release, with the latter further promoting angiogenesis. Furthermore, the hydrogel enhances neurogenesis by stimulating axons and Schwann cells in the wound bed through the beneficial effects of magnesium ions. Our results demonstrate that the designed novel multifunctional hydrogel holds tremendous promise for treating infected wounds and allowing regenerative neurogenesis at the wound site, which provides a viable alternative for further improving clinical outcomes.

Emerging trends in the application of hydrogel-based biomaterials for enhanced wound healing: A literature review

Currently, there is a rising global incidence of diverse acute and chronic wounds, underscoring the immediate necessity for research and treatment advancements in wound repair. Hydrogels have emerged as promising materials for wound healing due to their unique physical and chemical properties. This review explores the classification and characteristics of hydrogel dressings, innovative preparation strategies, and advancements in delivering and releasing bioactive substances. Furthermore, it delves into the functional applications of hydrogels in wound healing, encompassing areas such as infection prevention, rapid hemostasis and adhesion adaptation, inflammation control and immune regulation, granulation tissue formation, re-epithelialization, and scar prevention and treatment. The mechanisms of action of various functional hydrogels are also discussed. Finally, this article also addresses the current limitations of hydrogels and provides insights into their potential future applications and upcoming innovative designs.

Recent advances in fabricating injectable hydrogels via tunable molecular interactions for bio-applications

Hydrogels with three-dimensional structures have been widely applied in various applications because of their tunable structures, which can be easily tailored with desired functionalities. However, the application of hydrogel materials in bioengineering is still constrained by their limited dosage flexibility and the requirement of invasive surgical procedures. Compared to traditional hydrogels, injectable hydrogels, with shear-thinning and/or in situ formation properties, simplify the implantation process and reduce tissue invasion, which can be directly delivered to target sites using a syringe injection, offering distinct advantages over traditional hydrogels. These injectable hydrogels incorporate physically non-covalent and/or dynamic covalent bonds, granting them self-healing abilities to recover their structural integrity after injection. This review summarizes our recent progress in preparing injectable hydrogels and discusses their performance in various bioengineering applications. Moreover, the underlying molecular interaction mechanisms that govern the injectable and functional properties of hydrogels were characterized by using nanomechanical techniques such as surface forces apparatus (SFA) and atomic force microscopy (AFM). The remaining challenges and future perspectives on the design and application of injectable hydrogels are also discussed. This work provides useful insights and guides future research directions in the field of injectable hydrogels for bioengineering.

Oxidized sodium alginate/polyacrylamide hydrogels adhesive for promoting wheat growth

Chemical modification of sodium alginate (SA) polymer chains can increase its functional group species. Sodium periodate (SP) was usually used to oxidize the hydroxyl groups on the chain of SA to aldehyde groups, the preparation of oxidized sodium alginate (OSA) using SP is not only complicated, also limits the variety of functional groups on the chain of OSA. By contrast, we have developed an innovative strategy for OSA, in which ammonium persulfate (APS) was used to oxidize SA, providing a clear elucidation of the oxidizing process and mechanism. OSA/PAM hydrogels were synthesized using OSA, the hydrogels possess excellent adhesion properties to various non-metallic and metallic substrates. Tensile and compression tests show that the cross-linked OSA/PAM hydrogels have superior mechanical properties. We exploit OSA/PAM hydrogels as soil adhesive and water-retaining agents for wheat growth. OSA/PAM hydrogels significantly improve the survival time of wheat grown in brown loam soil under a water-shortage environment, and slow down the wilting of wheat in a water-shortage environment and prolong the survival time of wheat in sandy soils. Our trials should make hydrogels important for wheat cultivation in brown loam soils and the development of desert areas.

A Janus supramolecular hydrogel prepared by one-pot method for wound dressing

Despite the adhesive hydrogels have gained progress and popularity, it is still an enormous challenge to develop a smart adhesion hydrogel for clinical medicine, which is an asymmetric adhesion hydrogel with on-demand detachment. Motivated by the thermal phase transition mechanism of gelatin, we have synthesized a Janus supramolecular hydrogel dressing with skin temperature-triggered adhesion by a simple one-pot process. This hydrogel has asymmetric and controllable adhesion, which not only can become the external objects barrier but also can achieve repeated adhesion and on-demand detachment triggered by temperature in tens of seconds. This hydrogel presents great mechanical performance (compressive strain of 65 %, 1.38 MPa) owing to the presence of supramolecular interactions in the hydrogel. Additionally, this hydrogel exhibits excellent antibacterial activity and biocompatibility. The synergistic effect of modified gelatin and ionic liquid greatly facilitates wound healing of full-thickness skin with high wound healing efficiency (98.45 %). Therefore, thanks to all these advantages, the Janus supramolecular hydrogel can be applied for wound management and treatment, which has huge potential in healing skin wounds.

A functional lignin for heavy metal ions adsorption and wound care dressing

Recently, the application of lignin activation by demethylation to improve reactivity and enrich multiple functions has intensively attracted attention. However, it is still challenge up to now due to the low reactivity and complexity of lignin structure. Here, an effective demethylation way was explored by microwave-assisted method for substantially enhancing the hydroxyl (-OH) content and retaining the structure of lignin. Then, the optimum demethylated lignin was used to removal heavy metal ions and promote wound healing, respectively. In detail, for microwave-assisted demethylated poplar lignin (M-DPOL), the contents of phenolic (Ar-OH) and total hydroxyl (Tot-OH) groups reached the maximum for 60 min at 90 °C in DMF with 7.38 and 9.13 mmol/g, respectively. After demethylation, with this M-DPOL as lignin-based adsorbent, the maximum adsorption capacity (Q_max) for Pb²⁺ ions reached 104.16 mg/g. Based on the isotherm, kinetic and thermodynamic models analyses, the chemisorption occurred in monolayer on the surface of M-DPOL, and all adsorption processes were endothermic and spontaneous. Meanwhile, M-DPOL as a wound dressing had excellent antioxidant property, outstanding bactericidal activity and remarkable biocompatibility, suggesting that it did not interfere with cell proliferation. Besides, the wounded rats treated with M-DPOL significantly promoted its formation of re-epithelialization and wound healing of full-thickness skin defects. Overall, microwave-assisted method of demethylated lignin can offer great advantages for heavy metal ions removal and wound care dressing, which facilitates high value application of lignin.

Highly hygroscopicity and antioxidant nanofibrous dressing base on alginate for accelerating wound healing

The removal of bacterium and free radicals is important for wound healing. Therefore, it is necessary to prepare biological dressings with antibacterial and antioxidant properties. In this study, high-performance calcium alginate/carbon polymer dots/forsythin composite nanofibrous membrane (CA/CPDs/FT) was explored under the influence of carbon polymer dots and forsythin. The addition of carbon polymer dots improved the nanofiber morphology and therefore enhanced the mechanical strength of the composite membrane. Moreover, CA/CPDs/FT membranes displayed satisfactory antibacterial and antioxidant properties because of the natural properties of forsythin. Meanwhile, outstanding hygroscopicity over 700% was also obtained for the composite membrane. In vitro and in vivo experiments showed that the CA/CPDs/FT nanofibrous membrane could prevent the invasion of bacteria, scavenge free radicals, and promote wound healing. Moreover, its good hygroscopicity and antioxidation characteristics were friendly for the clinical application of high-exudate wounds.