Calcium alginate/PNIPAAm hydrogel with body temperature response and great biocompatibility: Application as burn wound dressing

Chitosan nanoreactor modified with PNIPAAm as efficient catalyst for preparation of chiral boron compounds in aqueous phase

This work constructed chitosan-based core-shell catalytic nanoreactor (CS/NI/SA@Cu(II)) by free radical polymerization of biomass chitosan and temperature sensitive materials. The CS/NI/SA@Cu(II) were characterized by FT-IR, TG, XPS, SEM, TEM, and EDS to prove the formation of the nanoreactor, and the Cu content was obtained by ICP analysis. The TEM indicated that CS/NI/SA-2 presented a hollow core-shell structure with a size of about 100 nm, and the contact angle of CS/NI/SA-2 was 67°. The core-shell nanoreactors were successfully applied to the 1,4-chiral borylation reaction of α,β-unsaturated compounds, and α,β,γ,δ-unsaturated compounds, as well as the 1,6-chiral borylation reaction of methylene benzoquinone compounds in the aqueous phase. All template substrates can obtain up to 90 % yields with 90 % ee values in core-shell nanoreactors and chiral ligand in 12 h. The possible mechanism of catalytic reaction was revealed by calculation and deuteration experiment. Besides, the CS/NI/SA@Cu(II) could be easily recycled and effectively reused. Besides, the CS/NI/SA@Cu(II) could be easily recycled and effectively reused for 6 times. Remarkably, this approach provides the first report of biomass chitosan for an efficient strategy to gain chiral organic boron compounds in high yields and enantioselectivities.

Marine algal polysaccharides: Multifunctional bioactive ingredients for cosmetic formulations

Marine algal polysaccharides (MAP) are increasingly recognized as versatile bioactive ingredients in cosmetics due to their wide-ranging therapeutic benefits and eco-friendly sourcing. Sourced from red, brown, and green algae, these polysaccharides deliver numerous advantages for skin health, including antioxidant, anti-inflammatory, anti-aging, hydrating, and regenerative properties. As demand for natural and sustainable products grows, MAP offer a renewable and environmentally responsible alternative to synthetic chemicals. This review examines the chemical structures, extraction methods, biological activities, and cosmetic applications of key MAP, such as carrageenans, alginates, fucoidans, laminaran, ulvan, and sulfated rhamnan. It also discusses emerging research trends, innovative extraction techniques, and the formulation of multifunctional products that combine these polysaccharides with other bioactive compounds. As consumer preferences increasingly lean toward ethical and sustainable choices, MAP are well-positioned to contribute to the development of high-performance cosmetic products that meet both industry standards and consumer expectations.

Material Design, Fabrication Strategies, and the Development of Multifunctional Hydrogel Composites Dressings for Skin Wound Management

The skin is fragile, making it very vulnerable to damage and injury. Untreated skin wounds can pose a serious threat to human health. Three-dimensional polymer network hydrogels have broad application prospects in skin wound dressings due to their unique properties and structure. The therapeutic effect of traditional hydrogels is limited, while multifunctional composite hydrogels show greater potential. Multifunctional hydrogels can regulate wound moisture through formula adjustment. Moreover, hydrogels can be combined with bioactive ingredients to improve their performance in wound healing applications. Stimulus-responsive hydrogels can respond specifically to the wound environment and meet the needs of different wound healing stages. This review summarizes the material types, structure, properties, design considerations, and formulation strategies for multifunctional hydrogel composite dressings used in wound healing. We discuss various types of recently developed hydrogel dressings, highlights the importance of tailoring their physicochemical properties, and addresses potential challenges in preparing multifunctional hydrogel wound dressings.

Plant-derived materials for biomedical applications

With exceptional biocompatibility and biodegradability, plant-derived materials have garnered significant interest for a myriad of biomedical applications. This mini-review presents a concise overview of prevalent plant-derived materials, encompassing polysaccharide-based polymers, protein-based polymers, extracellular vesicles, mucilage, decellularized scaffolds, and whole plant-based biomass. Through different processing techniques, these plant-derived materials can be tailored into a variety of forms, such as nanoparticles, nanofibers, and hydrogels, to address the nuanced requirements of biomedical applications. With the emphasis on wound healing, tissue engineering, and drug delivery, this review underscores the unique advantages of plant-derived materials, such as lower risk of endotoxin and virus contamination, reduced ethical concerns, scalability, and eco-friendly attributes. However, challenges such as the need for the development of standardized isolation methods of these materials, and further transition from preclinical to clinical applications still remain to be solved.

Hydrogels and hydrogel-based drug delivery systems for promoting refractory wound healing: Applications and prospects

Refractory wounds represent a significant health concern that presents considerable challenges within clinical practice. The healing process of refractory wounds, which involves various cell types and biologically active molecules, is dynamically influenced by multiple factors, including diabetes, infections, and inflammation. Owing to their hydrophilicity, biocompatibility, and capacity for drug loading, hydrogels have emerged as promising and innovative biomaterials for enhancing wound healing. In recent decades, hydrogels with inherent therapeutic properties have been identified. Moreover, advanced hydrogel-based drug delivery systems have been developed to facilitate the sustained and controlled release of therapeutic agents at the site of refractory wounds. This review aims to summarize recent advancements and applications of hydrogels, including those with intrinsic therapeutic properties and hydrogel-based drug delivery systems, in the treatment of refractory wounds. Additionally, we discuss the limitations associated with hydrogel applications and propose future perspectives, which will lead to ongoing efforts to optimize hydrogels as ideal biomaterials for refractory wound healing.

Advancing burn wound treatment: exploring hydrogel as a transdermal drug delivery system

Burn injuries are prevalent and life-threatening forms that contribute significantly to mortality rates due to associated wound infections. The management of burn wounds presents substantial challenges. Hydrogel exhibits tremendous potential as an ideal alternative to traditional wound dressings such as gauze. This is primarily attributed to its three-dimensional (3D) crosslinked polymer network, which possesses a high water content, fostering a moist environment that supports effective burn wound healing. Additionally, hydrogel facilitates the penetration of loaded therapeutic agents throughout the wound surface, combating burn wound pathogens through the hydration effect and thereby enhancing the healing process. However, the presence of eschar formation on burn wounds obstructs the passive diffusion of therapeutics, impairing the efficacy of hydrogel as a wound dressing, particularly in cases of severe burns involving deeper tissue damage. This review focuses on exploring the potential of hydrogel as a carrier for transdermal drug delivery in burn wound treatment. Furthermore, strategies aimed at enhancing the transdermal delivery of therapeutic agents from hydrogel to optimize burn wound healing are also discussed.

Caffeic acid-mediated photodynamic multifunctional hyaluronic acid-gallic acid hydrogels with instant and enduring bactericidal potency accelerate bacterial infected wound healing

The emergence of drug-resistant bacteria poses significant challenges in wound treatment. Antimicrobial photodynamic therapy has emerged as an effective approach to eliminating bacteria by inducing oxidative stress without causing drug resistance. Here, we developed a natural hyaluronic acid (HA)-gallic acid (GA) conjugation-based hydrogel combined with herbal photosensitizer-caffeic acid (CA), which exhibits self-healing ability, shape adaptability, biodegradability, and robust tissue adhesion. Under exposure to 400 nm light, caffeic acid acts as a photosensitizer, generating reactive oxygen species and oxidative damage to bacterial cell membranes. Furthermore, the presence of GA and CA displayed a continuous inhibitory effect on bacterial growth, along with antioxidant properties that promote wound healing even after the cessation of light exposure. The antibacterial mechanism of the HA-GA/CA hydrogel against MRSA, S. aureus, and E. coli was investigated through various assays measuring ATP levels, Zeta potential, hydroxyl radicals (·OH) generated by light irradiation, and biofilm clearance rate. Additionally, hydrogel's application in treating MRSA-infected wounds in mice under light irradiation demonstrated rapid wound-healing effects and biocompatibility. Overall, HA-GA/CA hydrogel provides a sustainable, antibiotic-free alternative for treating MRSA-infected wounds.

Biomedical potentials of alginate via physical, chemical, and biological modifications

Alginate is a linear polysaccharide with a modifiable structure and abundant functional groups, offers immense potential for tailoring diverse alginate-based materials to meet the demands of biomedical applications. Given the advancements in modification techniques, it is significant to analyze and summarize the modification of alginate by physical, chemical and biological methods. These approaches provide plentiful information on the preparation, characterization and application of alginate-based materials. Physical modification generally involves blending and physical crosslinking, while chemical modification relies on chemical reactions, mainly including acylation, sulfation, phosphorylation, carbodiimide coupling, nucleophilic substitution, graft copolymerization, terminal modification, and degradation. Chemical modified alginate contains chemically crosslinked alginate, grafted alginate and oligo-alginate. Biological modification associated with various enzymes to realize the hydrolysis or grafting. These diverse modifications hold great promise in fully harnessing the potential of alginate for its burgeoning biomedical applications in the future. In summary, this review provides a comprehensive discussion and summary of different modification methods applied to improve the properties of alginate while expanding its biomedical potentials.

Injectable dual drug-loaded thermosensitive liposome-hydrogel composite scaffold for vascularised and innervated bone regeneration

Adequate blood supply and thorough innervation are essential to the survival of tissue-engineered bones. Though great progress has been created in the application of bone tissue engineering technology to bone defect repair, many challenges remain, such as insufficient vascularisation and deficient innervation in newly regenerated bone. In the present study, we addressed these challenges by manipulating the bone regeneration microenvironment in terms of vascularisation and innervation. We used a novel injectable thermosensitive liposome-hydrogel composite scaffold as a sustained-release carrier for basic fibroblast growth factor (bFGF, which promotes angiogenesis and neurogenic differentiation) and dexamethasone (Dex, which promotes osteogenic differentiation). In vitro biological assessment demonstrated that the composite scaffold had sufficient cell compatibility; it enhanced the capacity for angiogenesis in human umbilical vein endothelial cells, and the capacity for neurogenic/osteogenic differentiation in human bone marrow mesenchymal stem cells. Moreover, the introduction of bFGF/Dex liposome-hydrogel composite scaffold to bone defect sites significantly improved vascularisation and innervated bone regeneration properties in a rabbit cranial defect model. Based on our findings, the regeneration of sufficiently vascularised and innervated bone tissue through a sustained-release scaffold with excellent injectability and body temperature sensitivity represents a promising tactic towards bone defect repair.

Hydrogels in Cutaneous Wound Healing: Insights into Characterization, Properties, Formulation and Therapeutic Potential

Hydrogels are polymeric materials that possess a set of characteristics meeting various requirements of an ideal wound dressing, making them promising for wound care. These features include, among others, the ability to absorb and retain large amounts of water and the capacity to closely mimic native structures, such as the extracellular matrix, facilitating various cellular processes like proliferation and differentiation. The polymers used in hydrogel formulations exhibit a broad spectrum of properties, allowing them to be classified into two main categories: natural polymers like collagen and chitosan, and synthetic polymers such as polyurethane and polyethylene glycol. This review offers a comprehensive overview and critical analysis of the key polymers that can constitute hydrogels, beginning with a brief contextualization of the polymers. It delves into their function, origin, and chemical structure, highlighting key sources of extraction and obtaining. Additionally, this review encompasses the main intrinsic properties of these polymers and their roles in the wound healing process, accompanied, whenever available, by explanations of the underlying mechanisms of action. It also addresses limitations and describes some studies on the effectiveness of isolated polymers in promoting skin regeneration and wound healing. Subsequently, we briefly discuss some application strategies of hydrogels derived from their intrinsic potential to promote the wound healing process. This can be achieved due to their role in the stimulation of angiogenesis, for example, or through the incorporation of substances like growth factors or drugs, such as antimicrobials, imparting new properties to the hydrogels. In addition to substance incorporation, the potential of hydrogels is also related to their ability to serve as a three-dimensional matrix for cell culture, whether it involves loading cells into the hydrogel or recruiting cells to the wound site, where they proliferate on the scaffold to form new tissue. The latter strategy presupposes the incorporation of biosensors into the hydrogel for real-time monitoring of wound conditions, such as temperature and pH. Future prospects are then ultimately addressed. As far as we are aware, this manuscript represents the first comprehensive approach that brings together and critically analyzes fundamental aspects of both natural and synthetic polymers constituting hydrogels in the context of cutaneous wound healing. It will serve as a foundational point for future studies, aiming to contribute to the development of an effective and environmentally friendly dressing for wounds.

Cadherin-responsive hydrogel combined with dental pulp stem cells and fibroblast growth factor 21 promotes diabetic scald repair via regulating epithelial-mesenchymal transition and necroptosis

Diabetes causes a loss of sensation in the skin, so diabetics are prone to burns when using heating devices. Diabetic scalded skin is often difficult to heal due to the microenvironment of high glucose, high oxidation, and low blood perfusion. The treatment of diabetic scald mainly focuses on three aspects: 1) promote the formation of the epithelium; 2) promote angiogenesis; and 3) maintain intracellular homeostasis. In response to these three major repair factors, we developed a cadherin-responsive hydrogel combined with FGF21 and dental pulp stem cells (DPSCs) to accelerate epithelial formation by recruiting cadherin to the epidermis and promoting the transformation of N cadherin to E cadherin; promoting angiogenesis to increase wound blood perfusion; regulating the stability of lysosomal and activating autophagy to maintain intracellular homeostasis in order to comprehensively advance the recovery of diabetic scald.

Effect of injectable calcium alginate-amelogenin hydrogel on macrophage polarization and promotion of jawbone osteogenesis

Due to persistent inflammation and limited osteogenesis, jawbone defects present a considerable challenge in regenerative medicine. Amelogenin, a major protein constituent of the developing enamel matrix, demonstrates promising capabilities in inducing regeneration of periodontal supporting tissues and exerting immunomodulatory effects. These properties render it a potential therapeutic agent for enhancing jawbone osteogenesis. Nevertheless, its clinical application is hindered by the limitations of monotherapy and its rapid release characteristics, which compromise its efficacy and delivery efficiency. In this context, calcium alginate hydrogel, recognized for its superior physicochemical properties and biocompatibility, emerges as a candidate for developing a synergistic bioengineered drug delivery system. This study describes the synthesis of an injectable calcium amelogenin/calcium alginate hydrogel using calcium alginate loaded with amelogenin. We comprehensively investigated its physical properties, its role in modulating the immunological environment conducive to bone healing, and its osteogenic efficacy in areas of jawbone defects. Our experimental findings indicate that this synthesized composite hydrogel possesses desirable mechanical properties such as injectability, biocompatibility, and biodegradability. Furthermore, it facilitates jawbone formation by regulating the bone-healing microenvironment and directly inducing osteogenesis. This research provides novel insights into the development of bone-tissue regeneration materials, potentially advancing their clinical application.

Preparation and optimization of agarose or polyacrylamide/amino acid-based double network hydrogels for photocontrolled drug release

The high water content and biocompatibility of amino-acid-based supramolecular hydrogels have generated growing interest in drug delivery research. Nevertheless, the existing dominant approach of constructing such hydrogels, the exploitation of a single amino acid type, typically comes with several drawbacks such as weak mechanical properties and long gelation times, hindering their applications. Here, we design a near-infrared (NIR) light-responsive double network (DN) structure, containing amino acids and different synthetic or natural polymers, i.e., polyacrylamide, poly(N-isopropylacrylamide), agarose, or low-gelling agarose. The hydrogels displayed high mechanical strength and high drug-loading capacity. Adjusting the ratio of Fmoc-Tyr-OH/Fmoc-Tyr(Bzl)-OH or Fmoc-Phe-OH/Fmoc-Tyr(Bzl)-OH, we could drastically shorten the gelation time of the DN hydrogels at room and body temperatures. Moreover, introducing photothermal agents (graphene oxide, carbon nanotubes, molybdenum disulfide nanosheets, or indocyanine green), we equipped the hydrogels with NIR responsivity. We demonstrated the light-triggered release of the drug baclofen, which is used in severe spasticity treatment. Rheology and stability tests confirmed the positive impact of the polymers on the mechanical strength of the hydrogels, while maintaining good stability under physiological conditions. Overall, our study contributed a novel hydrogel formulation with high mechanical resistance, rapid gel formation, and efficient NIR-controlled drug release, offering new opportunities for biomedical applications.

Hydrogel Micropillar Array for Temperature Sensing in Fluid

Localized temperature sensing and control on a micron-scale have diverse applications in biological systems. We present a micron-sized hydrogel pillar array as potential temperature probes and actuators by exploiting sensitive temperature dependence of their volume change. Soft lithography-based molding processes were presented to fabricate poly N-isopropyl acrylamide (p-NIPAAm)-based hydrogel pillar array on a glass substrate. Au nanorods as light-induced heating elements were embedded within the hydrogel pillars, and near-infrared (NIR) light was used to modulate temperature in a local area. First, static responses of the micro-pillar array were characterized as a function of its temperature. It was shown that the hydrogel had a sensitive volume transition near its low critical solution temperature (LCST). Furthermore, we showed that LCST could be readily adjusted by utilizing copolymerizing with acrylamide (AAM). To demonstrate the feasibility of spatiotemporal temperature mapping and modulation using the presented pillar array, pulsed NIR light was illuminated on a local area of the hydrogel pillar array, and its responses were recorded. Dynamic temperature change in water was mapped based on the abrupt volume change characteristics of the hydrogel pillar, and its potential actuation using NIR light was successfully demonstrated. Considering that the structure can be arrayed in a two-dimensional pixel format with high spatial resolution and high sensitive temperature characteristics, the presented method and the device structure can have diverse applications to change and sense local temperatures in liquid. This is particularly useful in biological systems, where their physiological temperature can be modulated and mapped with high spatial resolution.

Coaxial microfluidic spinning design produced high strength alginate membranes for antibacterial activity and drug release

Directional drug delivery and sufficient strength are two conditions that need to be met for wound dressing. In this paper, an oriented fibrous alginate membrane with sufficient strength was constructed via coaxial microfluidic spinning, and zeolitic imidazolate framework-8/ascorbic acid was used to realize drug delivery and antibacterial activity. The effects of the process parameters of the coaxial microfluidic spinning on the mechanical properties of the alginate membrane were discussed. In addition, it was found that the antimicrobial activity mechanism of zeolitic imidazolate framework-8 was attributed to the disruptive effect of reactive oxygen species (ROS) on bacteria, and the quantitative amount of generated ROS were evaluated by detecting •OH and H₂O₂. Furthermore, a mathematical drug diffusion model was established and showed high consistency with the experimental data (R² = 0.99). This study provides a new idea for the preparation of dressing materials with high strength and directional drug delivery and also provides some guidance for the development of coaxial microfluidic spin technology to be used in functional materials for drug release.

Preparation, thermal response mechanisms and biomedical applications of thermosensitive hydrogels for drug delivery

INTRODUCTION

Drug treatment is one of the main ways of coping with disease today. For the disadvantages of drug management, thermosensitive hydrogel is used as a countermeasure, which can realize the simple sustained release of drugs and the controlled release of drugs in complex physiological environments.

AREAS COVERED

This paper talks about thermosensitive hydrogels that can be used as drug carriers. The common preparation materials, material forms, thermal response mechanisms, characteristics of thermosensitive hydrogels for drug release and main disease treatment applications are reviewed.

EXPERT OPINION

When thermosensitive hydrogels are used as drug loading and delivery platforms, desired drug release patterns and release profiles can be tailored by selecting raw materials, thermal response mechanisms, and material forms. The properties of hydrogels prepared from synthetic polymers will be more stable than natural polymers. Integrating multiple thermosensitive mechanisms or different kinds of thermosensitive mechanisms on the same hydrogel is expected to realize the spatiotemporal differential delivery of multiple drugs under temperature stimulation. The industrial transformation of thermosensitive hydrogels as drug delivery platforms needs to meet some important conditions.

Research advances in prevention and treatment of burn wound deepening in early stage

The burn wound is a dynamic living environment that is affected by many factors. It may present a progressive expansion of necrosis into the initially viable zone of stasis within a short time postburn. Therefore, how to salvage of the zone of stasis is of crucial importance in prevention and treatment strategies of burn wound progressive deepening. This review focuses on the cellular basis of tissue injury and the current progress of prevention and treatment strategies of burn wound progressive deepening, in order to provide references for the treatment of burn wounds in the early phase.