Carboxymethyl chitosan-based hydrogels containing fibroblast growth factors for triggering diabetic wound healing

Biochemical and histological insights of 1,4-polyisoprene isolated from Sphenocentrum jollyanum pierre (menispermaceae) stem in wound healing activity in streptozotocin-induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Sphenocentrum jollyanum whole stem extract is used traditionally in combination with its leaves to treat chronic wounds and also ameliorate conditions that exacerbate wounds such as diabetes mellitus.

AIM OF THE STUDY

The study isolated the major wound healing bioactive compound from the non-polar fraction of S. jollyanum extract and evaluated the in vivo wound healing activity of a 0.10% w/w 1,4-polyisoprene-based ointment in streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

The major bioactive constituent of S. jollyanum was isolated using a wound healing activity-guided approach and characterized the compound using 1D and 2D-NMR spectroscopic techniques. The wound healing activity study adopted both excision (wound contraction) and incision (biochemical) models.

RESULTS

In the excision model, the 1,4-polyisoprene caused 99% wound closure and restored the excised wound on day 12. On the 6th and 12th post-wounding days, 1,4-polyisoprene caused a significant (p < 0.001) elevation in the tensile strength (486 g) of the incision wound compared with the control (388 g). The biochemical (hexosamine and hydroxyproline) and antioxidant/inflammatory (ascorbic acid, superoxide dismutase, and glutathione peroxidase) parameters increased significantly while malondialdehyde was down-regulated in the wounds treated with 1,4-polyisoprene compared with control. The histological analysis of tissue sections taken from the edge and center of the wounds at 0-12 days post wounding revealed an increased tissue regeneration, accelerated collagen formation, and epidermal regeneration without edema or inflammation on the 12th day.

CONCLUSION

The major wound healing constituent of S. jollyanum is 1,4-polyisoprene and the study has provided a new class of compounds for further optimization.

Advanced polymer hydrogels that promote diabetic ulcer healing: mechanisms, classifications, and medical applications

Diabetic ulcers (DUs) are one of the most serious complications of diabetes mellitus. The application of a functional dressing is a crucial step in DU treatment and is associated with the patient's recovery and prognosis. However, traditional dressings with a simple structure and a single function cannot meet clinical requirements. Therefore, researchers have turned their attention to advanced polymer dressings and hydrogels to solve the therapeutic bottleneck of DU treatment. Hydrogels are a class of gels with a three-dimensional network structure that have good moisturizing properties and permeability and promote autolytic debridement and material exchange. Moreover, hydrogels mimic the natural environment of the extracellular matrix, providing suitable surroundings for cell proliferation. Thus, hydrogels with different mechanical strengths and biological properties have been extensively explored as DU dressing platforms. In this review, we define different types of hydrogels and elaborate the mechanisms by which they repair DUs. Moreover, we summarize the pathological process of DUs and review various additives used for their treatment. Finally, we examine the limitations and obstacles that exist in the development of the clinically relevant applications of these appealing technologies. This review defines different types of hydrogels and carefully elaborate the mechanisms by which they repair diabetic ulcers (DUs), summarizes the pathological process of DUs, and reviews various bioactivators used for their treatment.

Chitosan: A Potential Biopolymer in Drug Delivery and Biomedical Applications

Chitosan, a biocompatible and biodegradable polysaccharide derived from chitin, has surfaced as a material of promise for drug delivery and biomedical applications. Different chitin and chitosan extraction techniques can produce materials with unique properties, which can be further modified to enhance their bioactivities. Chitosan-based drug delivery systems have been developed for various routes of administration, including oral, ophthalmic, transdermal, nasal, and vaginal, allowing for targeted and sustained release of drugs. Additionally, chitosan has been used in numerous biomedical applications, such as bone regeneration, cartilage tissue regeneration, cardiac tissue regeneration, corneal regeneration, periodontal tissue regeneration, and wound healing. Moreover, chitosan has also been utilized in gene delivery, bioimaging, vaccination, and cosmeceutical applications. Modified chitosan derivatives have been developed to improve their biocompatibility and enhance their properties, resulting in innovative materials with promising potentials in various biomedical applications. This article summarizes the recent findings on chitosan and its application in drug delivery and biomedical science.

Injectable adhesive carboxymethyl chitosan-based hydrogels with self-mending and antimicrobial features for the potential management of periodontal diseases

Treating periodontal diseases is a great challenge owing to the motion and wet conditions, bacterial infection, and tissue defects. Therefore, designing bioactive materials with outstanding wet-tissue adhesion, antimicrobial features, as well as favorable cell responses, is highly desirable to meet practical necessity. In this work, bio-multifunctional melatonin-loaded carboxymethyl chitosan/polyaldehyde dextran (CPM) hydrogels have been developed through the dynamic Schiff-base reaction. Our results demonstrate that the CPM hydrogels display injectability, structural stability, and high tissue adhesion in the wet and motional state, as well as self-healing features. In addition, the designed hydrogels show great antibacterial properties and excellent biocompatibility. The prepared hydrogels display a slow release of melatonin. Moreover, the in vitro cellular assay indicates that the developed hydrogels containing 10 mg per mL melatonin significantly promote cell migration. Thus, the synthesized bio-multifunctional hydrogels show great promise in the treatment of periodontal disease.

Multi-functional carboxymethyl chitosan/sericin protein/halloysite composite sponge with efficient antibacterial and hemostatic properties for accelerating wound healing

The development of wound dressings with hemostatic and antibacterial properties has attracted great attention. In this study, we prepared a multi-functional natural substance sponge (CMC/Ser-Ag/HNT) composed of carboxymethyl chitosan (CMC), sericin-silver nanoparticle (Ser-Ag), and halloysite (HNT). CMC/Ser-Ag/HNT sponge was demonstrated to bear desired hygroscopicity, porosity, compressive strength and compressive stability, cytocompatibility, and hemocompatibility. The mechanical properties (compressive strength of 100 kPa) and hemostatic capacity (hemostasis time of 15 ± 3 s in the liver injury model and 12 ± 3 s in the caudal injury model) were enhanced by introducing HNT into the CMC sponge. Ser-Ag was synthesized in situ via the redox nature of tyrosine residues in sericin in a "one-step, green" way to enhance the antibacterial activity of the hybrid sponge against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In addition, the rat full-thickness skin defect model experiments demonstrated that the CMC/Ser-Ag/HNT4 sponge significantly promoted epithelialization and collagen formation. Immunofluorescence staining assays revealed that the composite sponge reduced inflammation by downregulating the expression of IL-6 and enhanced angiogenesis by upregulating VEGF expression. All the findings demonstrated the great potential of CMC/Ser-Ag/HNT sponge as versatile clinical wound dressing, especially for hemorrhagic and infected wounds.

Recent advances in carboxymethyl chitosan-based materials for biomedical applications

Chitosan (CS) and its derivatives have been applied extensively in the biomedical field owing to advantageous characteristics including biodegradability, biocompatibility, antibacterial activity and adhesive properties. The low solubility of CS at physiological pH limits its use in systems requiring higher dissolving ability and a suitable drug release rate. Besides, CS can result in fast drug release because of its high swelling degree and rapid water absorption in aqueous media. As a water-soluble derivative of CS, carboxymethyl chitosan (CMC) has certain improved properties, rendering it a more suitable candidate for wound healing, drug delivery and tissue engineering applications. This review will focus on the antibacterial, anticancer and antitumor, antioxidant and antifungal bioactivities of CMC and the most recently described applications of CMC in wound healing, drug delivery, tissue engineering, bioimaging and cosmetics.

Development of a ZIF-91-Porous-Liquid-Based Composite Hydrogel Dressing System for Diabetic Wound Healing

Porous metal-organic framework (MOF) liquids with permanent porosity, good fluidity, and fine dispersion attract broad attention in catalysis, transportation, gas storage, and chemical separations. Yet, the design and synthesis of porous MOF liquids for drug delivery remain less explored. Herein, a simple and general strategy is reported to prepare ZIF-91 porous liquid (ZIF-91-PL) via surface modification and ion exchange. The cationic nature of ZIF-91-PL not only renders it antibacterial but also with high curcumin loading capacity and sustained release. More importantly, the acrylate group on the grafted side chain of ZIF-91-PL makes it feasible to crosslink with modified gelatin through light curing, and the obtained hydrogel shows a significantly improved healing effect on the wound of diabetes. This work demonstrates for the first time, a MOF-based porous liquid for drug delivery, and the further fabrication of composite hydrogel may have potential applications in biomedical science.

Dual-drug loaded polysaccharide-based self-healing hydrogels with multifunctionality for promoting diabetic wound healing

Diabetic chronic wound healing still faces huge clinical challenge. The arrangement and coordination of healing processes are disordered in diabetic wound caused by the persistent inflammatory response, microbial infection, impaired angiogenesis, resulting in the delayed and even non-healing wounds. Here, the dual-drug loaded nanocomposite polysaccharide-based self-healing hydrogels (OCM@P) with multifunctionality were developed to promote diabetic wound healing. Curcumin (Cur) loaded mesoporous polydopamine nanoparticles (MPDA@Cur NPs) and metformin (Met) were introduced into the polymer matrix formed by the dynamic imine bonds and electrostatic interactions between carboxymethyl chitosan and oxidized hyaluronic acid to fabricate OCM@P hydrogels. OCM@P hydrogels show homogeneous and interconnected porous microstructure, which possess good tissue adhesiveness, enhanced compression strength, great anti-fatigue behavior, excellent self-recovery capacity, low cytotoxicity, rapid hemostatic ability and robust broad-spectrum antibacterial activity. Interestingly, OCM@P hydrogels exhibit rapid release of Met and long-term sustained release of Cur, thereby to effectively scavenge extracellular and intracellular free radicals. Significantly, OCM@P hydrogels remarkably promote re-epithelization, granulation tissue formation, collagen deposition and arrangement, angiogenesis as well as wound contraction in diabetic wound healing. Overall, the multifunctional synergy of OCM@P hydrogels greatly contributes to accelerating diabetic wound healing, which demonstrate promising application as scaffolds in regenerative medicine.

The Efficiency and Safety of Platelet-Rich Plasma Dressing in the Treatment of Chronic Wounds: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Recently, many clinical trials have applied platelet-rich plasma (PRP) dressings to treat wounds that have stopped healing, which are also called chronic wounds. However, the clinical efficiency of PRP dressings in treating chronic wounds is still controversial. Therefore, we conducted this study to compare PRP dressings with normal saline dressings in treating chronic wounds. Relevant randomized controlled trials focusing on utilizing PRP dressings in treating chronic wounds were extracted from bibliographic databases. Finally, 330 patients with chronic wounds, reported in eight randomized controlled trials, were included in this study. In total, 169 out of 330 (51.21%) were treated with PRP dressings, and 161 out of 330 (48.79%) were treated with normal saline dressings. The pooled results showed that the complete healing rate of the PRP group was significantly higher than that of saline group at 8 weeks and 12 weeks, respectively. In addition, there were no significant differences in wound infection and adverse events. Compared with normal saline dressing, the PRP dressing could effectively enhance the prognosis of chronic wounds. Furthermore, the PRP did not increase wound infection rate or occurrence of adverse events as an available treatment for chronic wounds.

Stimuli-Responsive and Antibacterial Cellulose-Chitosan Hydrogels Containing Polydiacetylene Nanosheets

Herein, we report a stimuli-responsive hydrogel with inhibitory activity against Escherichia coli prepared by chemical crosslinking of carboxymethyl chitosan (CMCs) and hydroxyethyl cellulose (HEC). The hydrogels were prepared by esterification of chitosan (Cs) with monochloroacetic acid to produce CMCs which were then chemically crosslinked to HEC using citric acid as the crosslinking agent. To impart a stimuli responsiveness property to the hydrogels, polydiacetylene-zinc oxide (PDA-ZnO) nanosheets were synthesized in situ during the crosslinking reaction followed by photopolymerization of the resultant composite. To achieve this, ZnO was anchored on carboxylic groups in 10,12-pentacosadiynoic acid (PCDA) layers to restrict the movement of the alkyl portion of PCDA during crosslinking CMCs and HEC hydrogels. This was followed by irradiating the composite with UV radiation to photopolymerize the PCDA to PDA within the hydrogel matrix so as to impart thermal and pH responsiveness to the hydrogel. From the results obtained, the prepared hydrogel had a pH-dependent swelling capacity as it absorbed more water in acidic media as compared to basic media. The incorporation of PDA-ZnO resulted in a thermochromic composite responsive to pH evidenced by a visible colour transition from pale purple to pale pink. Upon swelling, PDA-ZnO-CMCs-HEC hydrogels had significant inhibitory activity against E. coli attributed to the slow release of the ZnO nanoparticles as compared to CMCs-HEC hydrogels. In conclusion, the developed hydrogel was found to have stimuli-responsive properties and inhibitory activity against E. coli attributed to zinc nanoparticles.

Stimuli-Responsive Polysaccharide Hydrogels and Their Composites for Wound Healing Applications

There is a growing concern about wound care, since traditional dressings such as bandages and sutures can no longer meet existing needs. To address the demanding requirements, naturally occurring polymers have been extensively exploited for use in modern wound management. Polysaccharides, being the most abundant biopolymers, have some distinct characteristics, including biocompatibility and biodegradability, which render them ideal candidates for wound healing applications. Combining them with inorganic and organic moieties can produce effective multifunctional composites with the desired mechanical properties, high wound healing efficiencies and excellent antibacterial behavior. Recent research endeavors focus on the development of stimuli-responsive polysaccharide composites for biomedical applications. Polysaccharide composites, being sensitive to the local environment, such as changes of the solution temperature, pH, etc., can sense and react to the wound conditions, thus promoting an effective interaction with the wound. This review highlights the recent advances in stimuli-responsive polysaccharide hydrogels and their composites for use in wound healing applications. The synthetic approaches, physical, chemical, and biochemical properties as well as their function in wound healing will be discussed.

Biomimetic, Injectable, and Self-Healing Hydrogels with Sustained Release of Ranibizumab to Treat Retinal Neovascularization

Retinal neovascularization (RNV) is a typical feature of ischemic retinal diseases that can lead to traction retinal detachment and even blindness in patients, in which the vascular endothelial cell growth factor (VEGF) plays a pivotal role. However, most anti-VEGF drugs currently used for treating RNV, such as ranibizumab, need frequent and repeated intravitreal injections due to their short intravitreal half-life, which increases the incidence of complications. Herein, a hydrogel intravitreal drug delivery system (DDS) is prepared by a dynamic Schiff base reaction between aminated hyaluronic acid and aldehyde-functionalized Pluronic 127 for sustained release of ranibizumab. The prepared hydrogel system named HP@Ran exhibits excellent injectability, self-healing ability, structural stability, cytocompatibility, and blood compatibility. According to an in vitro drug release study, the hydrogel system continuously releases the model drug bovine serum albumin for more than 56 days. Importantly, in an in vivo rabbit persistent RNV model, the HP@Ran hydrogel system continuously releases pharmacologically active ranibizumab for more than 7 weeks and also exhibits superior anti-angiogenic efficacy over ranibizumab treatment by decreasing vascular leakage and neovascularization at 12 weeks. Thus, the developed HP@Ran hydrogel system possesses great potential for intravitreal DDS for the treatment of RNV.

A Sustainable Solution to Skin Diseases: Ecofriendly Transdermal Patches

Skin is the largest epithelial surface of the human body, with a surface area of 2 m2 for the average adult human. Being an external organ, it is susceptible to more than 3000 potential skin diseases, including injury, inflammation, microbial and viral infections, and skin cancer. Due to its nature, it offers a large accessible site for administrating several medications against these diseases. The dermal and transdermal delivery of such medications are often ensured by utilizing dermal/transdermal patches or microneedles made of biocompatible and biodegradable materials. These tools provide controlled delivery of drugs to the site of action in a rapid and therapeutically effective manner with enhanced diffusivity and minimal side effects. Regrettably, they are usually fabricated using synthetic materials with possible harmful environmental effects. Manufacturing such tools using green synthesis routes and raw materials is hence essential for both ecological and economic sustainability. In this review, natural materials including chitosan/chitin, alginate, keratin, gelatin, cellulose, hyaluronic acid, pectin, and collagen utilized in designing ecofriendly patches will be explored. Their implementation in wound healing, skin cancer, inflammations, and infections will be discussed, and the significance of these studies will be evaluated with future perspectives.

Betamethasone-loaded dissolvable microneedle patch for oral ulcer treatment

Oral inflammatory disease (OID) is among the most common oral lesions, affecting people's quality of life and even leading to oral cancer. Oral ulcers are the most common OID. However, the pain and fear caused by the localized injection of hormones hinder the clinical treatment of oral ulcers. To address this problem, soluble hyaluronic acid (HA) microneedle patches (BSP-BDP@HAMN) containing betamethasone 21-phosphate sodium (BSP) and betamethasone 17,21-dipropionate (BDP) were fabricated for potential application in oral ulcers. BSP-BDP@HAMNs had the sufficient mechanical strength to penetrate the rat tongue abdomen mucosa with an insertion depth of approximately 207 ± 3 µm. The rapidly solubilized HA microneedle carrier released BSP and BDP into the ulcer base within 3 min of entering the mucosa. Cellular assays have shown that BDP@HAMNs have wound healing-promoting and anti-inflammatory effects. Compared with topical injections and creams, BSP-BDP@HAMNs not only penetrated the ulcer surface painlessly but also worked deep in the ulcer for a long time. In conclusion, the proposed BSP-BDP@HAMN patch can improve the comfort and efficacy of oral ulcer treatment, thus providing a new prospect for oral ulcer treatment.

Potential Biological Properties of Lycopene in a Self-Emulsifying Drug Delivery System

In recent years, lycopene has been highlighted due to its antioxidant and anti-inflammatory properties, associated with a beneficial effect on human health. The aim of this study was to advance the studies of antioxidant and anti-inflammatory mechanisms on human keratinocytes cells (HaCaT) of a self-emulsifying drug delivery system (SEDDS) loaded with lycopene purified from red guava (nanoLPG). The characteristics of nanoLPG were a hydrodynamic diameter of 205 nm, a polydispersity index of 0.21 and a zeta potential of -20.57, providing physical stability for the nanosystem. NanoLPG demonstrated antioxidant capacity, as shown using the ORAC methodology, and prevented DNA degradation (DNA agarose). Proinflammatory activity was evaluated by quantifying the cytokines TNF-α, IL-6 and IL-8, with only IL-8 showing a significant increase (p < 0.0001). NanoLPG showed greater inhibition of the tyrosinase and elastase enzymes, involved in the skin aging process, compared to purified lycopene (LPG). In vitro treatment for 24 h with 5.0 µg/mL of nanoLPG did not affect the viability of HaCaT cells. The ultrastructure of HaCaT cells demonstrated the maintenance of morphology. This contrasts with endoplasmic reticulum stresses and autophagic vacuoles when treated with LPG after stimulation or not with LPS. Therefore, the use of lycopene in a nanoemulsion may be beneficial in strategies and products associated with skin health.

Renewable marine polysaccharides for microenvironment-responsive wound healing

Marine polysaccharides (MPs) are an eco-friendly and renewable resource with a distinctive set of biological functions and are regarded as biological materials that can be in contact with tissues and body fluids for an extended time and promote tissue or organ regeneration. Skin tissue is easily invaded by the external environment due to its softness and large surface area. However, the body's natural physiological healing process is often too slow or suffers from the incomplete restoration of skin structure and function. Functional wound dressings are crucial for skin tissue engineering. Herein, popular MPs from different sources are summarized systematically. In particular, the structure-effectiveness of MP-based wound dressings and the physiological remodeling process of different wounds are reviewed in detail. Finally, the prospect of MP-based smart wound dressings is stated in conjunction with the wound microenvironment and provides new opportunities for high-value biomedical applications of MPs.

Natural Compounds and Biopolymers-Based Hydrogels Join Forces to Promote Wound Healing

Rapid and complete wound healing is a clinical emergency, mainly in pathological conditions such as Type 2 Diabetes mellitus. Many therapeutic tools are not resolutive, and the research for a more efficient remedial remains a challenge. Wound dressings play an essential role in diabetic wound healing. In particular, biocompatible hydrogels represent the most attractive wound dressings due to their ability to retain moisture as well as ability to act as a barrier against bacteria. In the last years, different functionalized hydrogels have been proposed as wound dressing materials, showing encouraging outcomes with great benefits in the healing of the diabetic wounds. Specifically, because of their excellent biocompatibility and biodegradability, natural bioactive compounds, as well as biomacromolecules such as polysaccharides and protein, are usually employed in the biomedical field. In this review, readers can find the main discoveries regarding the employment of naturally occurring compounds and biopolymers as wound healing promoters with antibacterial activity. The emerging approaches and engineered devices for effective wound care in diabetic patients are reported and deeply investigated.

Light-Mediated 3D Printing of Micro-Pyramid-Decorated Tailorable Wound Dressings with Endogenous Growth Factor Sequestration for Improved Wound Healing

Medical dressings play an important role in the field of tissue engineering owing to their ability to accelerate the process of wound healing. Great efforts have been made to fabricate wound dressings with distinctive features for promoting wound healing. However, most of the current synthesis methods either generate dressings of uniform size or involve complex fabrication techniques, thus limiting their commercialization for the personalized dressings. We report here a dressing, which presents a paradigm shift in the design of the dressing from uniform films to a micro-patterned film. The hypothesis driving the design is the ability of the 3D patterns to provide an efficient transient matrix filling the depth of the wound rather than just providing a barrier and slight re-epithelialization. We demonstrate the use of the digital light processing 3D printing technique to generate micro-pyramid-decorated wound healing dressings with individualized design and with bio-compatible gelatin methacryloyl to contact the wounded areas. In addition to providing better adhesion to the migratory cells, the micro-pyramids also enable covalent conjugation of heparin, providing capability to sequester endogenous growth factors (GFs). Based on these advantages, the developed dressing not only adheres strongly to the wound bed but also promotes the treatment of a rat wound model by utilizing the power of endogenous GFs for tissue regeneration. Thus, it is believed that the developed dressing can break through the limitation of traditional wound treatment and be an ideal candidate for wound healing.

Antibacterial quaternary ammonium chitosan/carboxymethyl starch/alginate sponges with enhanced hemostatic property for the prevention of dry socket

Tooth extraction commonly leads to postoperative wound bleeding, bacterial infection, and even the occurrence of dry socket. Therefore, developing a biomedical material with favorable antibacterial and excellent hemostatic properties to prevent the post-extraction dry socket is necessary. Herein, quaternary ammonium chitosan/ carboxymethyl starch/alginate (ACQ) sponges are developed via Ca²⁺ cross-linking, electrostatic interaction, and lyophilization methods. The results show that the bio-multifunctional sponges exhibit interconnected porous structures with significant fluid absorption rates and suitable water vapor transmission rates. In vitro cellular and hemolysis experiments indicate that the developed sponges have acceptable biocompatibility. Notably, the constructed sponges effectively inhibit the growth of E. coli, S. aureus, and C. albicans, as well as achieve rapid hemostasis in the mouse liver injury and mini-pig tooth extraction models by absorbing blood and promoting red blood cell adhesion. Thus, the created bio-multifunctional sponges show tremendous promise as a hemostatic material for wound management after tooth extraction.

Development of ε-poly(L-lysine) carbon dots-modified magnetic nanoparticles and their applications as novel antibacterial agents

Magnetic nanoparticles (MNPs) are widely applied in antibacterial therapy owing to their distinct nanoscale structure, intrinsic peroxidase-like activities, and magnetic behavior. However, some deficiencies, such as the tendency to aggregate in water, unsatisfactory biocompatibility, and limited antibacterial effect, hindered their further clinical applications. Surface modification of MNPs is one of the main strategies to improve their (bio)physicochemical properties and enhance biological functions. Herein, antibacterial ε-poly (L-lysine) carbon dots (PL-CDs) modified MNPs (CMNPs) were synthesized to investigate their performance in eliminating pathogenic bacteria. It was found that the PL-CDs were successfully loaded on the surface of MNPs by detecting their morphology, surface charges, functional groups, and other physicochemical properties. The positively charged CMNPs show superparamagnetic properties and are well dispersed in water. Furthermore, bacterial experiments indicate that the CMNPs exhibited highly effective antimicrobial properties against Staphylococcus aureus. Notably, the in vitro cellular assays show that CMNPs have favorable cytocompatibility. Thus, CMNPs acting as novel smart nanomaterials could offer great potential for the clinical treatment of bacterial infections.

Root-shaped antibacterial alginate sponges with enhanced hemostasis and osteogenesis for the prevention of dry socket

Tooth extraction commonly causes uncontrolled bleeding, loss of blood clots, and bacterial infection, leading to the dry socket and bone resorption. Thus, it is highly attractive to design a bio-multifunctional scaffold with outstanding antimicrobial, hemostatic, and osteogenic performances for avoiding dry sockets in clinical applications. Herein, alginate (AG)/quaternized chitosan (Qch)/diatomite (Di) sponges were fabricated via electrostatic interaction, Ca²⁺ cross-linking, as well as lyophilization methods. The composite sponges are facilely made into the shape of the tooth root, which could be well integrated into the alveolar fossa. The sponge shows a highly interconnected and hierarchical porous structure at the macro/micro/nano levels. The prepared sponges also possess enhanced hemostatic and antibacterial abilities. Moreover, in vitro cellular assessment indicates that the developed sponges have favorable cytocompatibility and significantly facilitate osteogenesis by upregulating the formation of alkaline phosphatase and calcium nodules. The designed bio-multifunctional sponges display great potential for trauma treatment after tooth extraction.

Injectable self-healing chitosan-based POSS-PEG hybrid hydrogel as wound dressing to promote diabetic wound healing

Promoting the healing of diabetic wounds remains a major challenge in scientific research today. A star-like eight-arm cross-linker octafunctionalized POSS of benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO) was synthesized, and crosslinked with hydroxypropyltrimethyl ammonium chloride chitosan (HACC) via Schiff base reaction to obtain Chitosan-based POSS-PEG hybrid hydrogels. The designed composite hydrogels exhibited strong mechanical strength, injectability, excellent self-healing efficiency, good cytocompatibility and antibacterial properties. Furthermore, the composite hydrogels could accelerate cells migration and proliferation, as expected by remarkably promoting wound healing in diabetic mice. The wounds treated with the composite hydrogels displayed faster regeneration of epithelial tissue, fewer inflammatory cells, more collagen deposition and higher expression level of VEGF. Therefore, Chitosan-based POSS-PEG hybrid hydrogel has great application potential as a dressing for promoting the healing of diabetic wounds.

Biomaterials Based on Chitosan and Its Derivatives and Their Potential in Tissue Engineering and Other Biomedical Applications-A Review

In the times of dynamically developing regenerative medicine, more and more attention is focused on the use of natural polymers. This is due to their high biocompatibility and biodegradability without the production of toxic compounds, which means that they do not hurt humans and the natural environment. Chitosan and its derivatives are polymers made most often from the shells of crustaceans and are biodegradable and biocompatible. Some of them have antibacterial or metal-chelating properties. This review article presents the development of biomaterials based on chitosan and its derivatives used in regenerative medicine, such as a dressing or graft of soft tissues or bones. Various examples of preparations based on chitosan and its derivatives in the form of gels, films, and 3D structures and crosslinking products with another polymer are discussed herein. This article summarizes the latest advances in medicine with the use of biomaterials based on chitosan and its derivatives and provides perspectives on future research activities.

Signaling pathways in cutaneous wound healing

Wound healing is a very complex process, where variety of different pathways is activated, depending on the phase of healing. Improper or interrupted healing might result in development of chronic wounds. Therefore, novel approaches based on detailed knowledge of signalling pathways that are activated during acute or chronic cutaneous wound healing enables quicker and more effective healing. This review outlined new possibilities of cutaneous wound healing by modulation of some signalling molecules, e.g., gasotransmitters, or calcium. Special focus is given to gasotransmitters, since these bioactive signalling molecules that can freely diffuse into the cell and exert antioxidative effects. Calcium is an important booster of immune system and it can significantly contribute to healing process. Special interest is given to chronic wounds caused by diabetes mellitus and overcoming problems with the inflammation.

Immunomodulating Hydrogels as Stealth Platform for Drug Delivery Applications

Non-targeted persistent immune activation or suppression by different drug delivery platforms can cause adverse and chronic physiological effects including cancer and arthritis. Therefore, non-toxic materials that do not trigger an immunogenic response during delivery are crucial for safe and effective in vivo treatment. Hydrogels are excellent candidates that can be engineered to control immune responses by modulating biomolecule release/adsorption, improving regeneration of lymphoid tissues, and enhancing function during antigen presentation. This review discusses the aspects of hydrogel-based systems used as drug delivery platforms for various diseases. A detailed investigation on different immunomodulation strategies for various delivery options and deliberate upon the outlook of such drug delivery platforms are conducted.

The success of biomaterial-based tissue engineering strategies for peripheral nerve regeneration

Peripheral nerve injury is a clinically common injury that causes sensory dysfunction and locomotor system degeneration, which seriously affects the quality of the patients’ daily life. Long gapped defects in large nerve are difficult to repair via surgery and limited donor source of autologous nerve greatly challenges the successful nerve repair by transplantation. Significantly, remarkable progress has been made in repairing the peripheral nerve injury using artificial nerve grafts and a variety of products for peripheral nerve repair have emerged been approved globally in recent years. The raw materials of these commercial products includes natural/synthetic polymers, extracellular matrix. Despite a lot of effort, the desirable functional recovery still remains great challenges in long gapped nerve defects. Thus this review discusses the recent development of tissue engineering products for peripheral nerve repair and the design of bionic grafts improving the local microenvironment for accelerating nerve regeneration against locomotor disorder, which may provide potential strategies for the repair of long gaps or thick nerve defects by multifunctional biomaterials.

An Investigation for Skin Tissue Regeneration Enhancement/Augmentation by Curcumin-Loaded Self-Emulsifying Drug Delivery System (SEDDS)

Diabetes, one of the global metabolic disorders, is often associated with delayed wound healing due to the elevated level of free radicals at the wound site, which hampers skin regeneration. This study aimed at developing a curcumin-loaded self-emulsifying drug delivery system (SEDDS) for diabetic wound healing and skin tissue regeneration. For this purpose, various curcumin-loaded SEDDS formulations were prepared and optimized. Then, the SEDDS formulations were characterized by the emulsion droplet size, surface charge, drug content/entrapment efficiency, drug release, and stability. In vitro, the formulations were assessed for the cellular uptake, cytotoxicity, cell migration, and inhibition of the intracellular ROS production in the NIH3T3 fibroblasts. In vivo, the formulations' wound healing and skin regeneration potential were evaluated on the induced diabetic rats. The results indicated that, after being dispersed in the aqueous medium, the optimized SEDDS formulation was readily emulsified and formed a homogenous dispersion with a droplet size of 37.29 ± 3.47 nm, surface charge of -20.75 ± 0.07 mV, and PDI value of less than 0.3. The drug content in the optimized formulation was found to be 70.51% ± 2.31%, with an encapsulation efficiency of 87.36% ± 0.61%. The SEDDS showed a delayed drug release pattern compared to the pure drug solution, and the drug release rate followed the Fickian diffusion kinetically. In the cell culture, the formulations showed lower cytotoxicity, higher cellular uptake, and increased ROS production inhibition, and promoted the cell migration in the scratch assay compared to the pure drug. The in vivo data indicated that the curcumin-loaded SEDDS-treated diabetic rats had significantly faster-wound healing and re-epithelialization compared with the untreated and pure drug-treated groups. Our findings in this work suggest that the curcumin-loaded SEDDS might have great potential in facilitating diabetic wound healing and skin tissue regeneration.

Fucoidan-derived carbon dots against Enterococcus faecalis biofilm and infected dentinal tubules for the treatment of persistent endodontic infections

Enterococcus faecalis (E. faecalis) biofilm-associated persistent endodontic infections (PEIs) are one of the most common tooth lesions, causing chronic periapical periodontitis, root resorption, and even tooth loss. Clinical root canal disinfectants have the risk of damaging soft tissues (e.g., mucosa and tongue) and teeth in the oral cavity, unsatisfactory to the therapy of PEIs. Nanomaterials with remarkable antibacterial properties and good biocompatibility have been developed as a promising strategy for removing pathogenic bacteria and related biofilm. Herein, carbon dots (CDs) derived from fucoidan (FD) are prepared through a one-pot hydrothermal method for the treatment of PEIs. The prepared FDCDs (7.15 nm) with sulfate groups and fluorescence property are well dispersed and stable in water. Further, it is found that in vitro FDCDs display excellent inhibiting effects on E. faecalis and its biofilm by inducing the formation of intracellular and extracellular reactive oxygen species and altering bacterial permeability. Importantly, the FDCDs penetrated the root canals and dentinal tubules, removing located E. faecalis biofilm. Moreover, the cellular assays show that the developed FDCDs have satisfactory cytocompatibility and promote macrophage recruitment. Thus, the developed FDCDs hold great potential for the management of PEIs.

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

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

Enhanced Eradication of Enterococcus faecalis Biofilms by Quaternized Chitosan-Coated Upconversion Nanoparticles for Photodynamic Therapy in Persistent Endodontic Infections

Due to the persistent presence of Enterococcus faecalis biofilms in apical root canals, persistent endodontic infections (PEIs) have always been an intractable disease to solve. The conventional root canal disinfectants (e.g., calcium hydroxide, chlorhexidine) are arduous to scavenge the stubborn infection. With the progress of nanomedicine in the biomedical field, antimicrobial photodynamic therapy (aPDT) is emerging as a prospective anti-infective therapy for PEIs. Herein, quaternized chitosan (QCh) modified upconversion nanoparticles (UCNP)@SiO₂/methylene blue (MB) are developed with enhanced antibacterial/biofilm performance for aPDT in PEIs. QCh is coated on the UCNP@SiO₂/MB by testing the changes in diameter, chemical functional group, and charge. Interestingly, QCh also increases the conversion efficiency of UCNP to generate more reactive oxygen species (ROS). Furthermore, the prepared UCNP@SiO₂/MB@QCh exhibits highly effective antibacterial activity against free E. faecalis and related biofilm in vitro and extracted teeth. Importantly, the additional QCh with positive charges enhance UCNP@SiO₂/MB@QCh contact with E. faecalis (negative charges) through electrostatic interaction. Then, UCNP@SiO₂/MB@QCh could stick close to the E. faecalis and generate ROS under the irradiation by a 980 nm laser. The in vitro cellular test shows that UCNP@SiO₂/MB@QCh has acceptable cytocompatibility. Thus, UCNP@SiO₂/MB@QCh could offer a novel strategy for the potential aPDT clinical applications in the treatment of PEIs.

Glucose/ROS cascade-responsive ceria nanozymes for diabetic wound healing

Diabetic wounds have an extremely complex microenvironment of hyperglycemia, hypoxia and high reactive oxygen species (ROS). Therefore, the regulation and management of this microenvironment may provide a new and improved treatment method for chronic diabetic wound healing. Herein, a glucose/ROS cascade-responsive nanozyme (CHA@GOx) was developed for diabetic wound treatment based on Ce-driven coassembly by a special dual ligand (alendronic acid and 2-methylimidazole) and glucose oxidase (GOx). It possesses superoxide dismutase and catalase mimic activities, which effectively remove excess ROS. In particular, it can catalyze excessive hydrogen peroxide generated by the glucose oxidation reaction to produce oxygen, regulate the oxygen balance of the wound, and reduce the toxic side effects of GOx, thus achieving the purpose of synergistically repairing diabetic wounds. In vitro experiments show that CHA@GOx assists mouse fibroblast migration and promotes human umbilical vein endothelial cell tube formation. In vivo, it can induce angiogenesis, collagen deposition, and re-epithelialization during wound healing in diabetic mice. Taken together, this study indicates that the coassembly of multifunctional nanozymes has implications in diabetic wound healing.

Chitosan-CaP microflowers and metronidazole loaded calcium alginate sponges with enhanced antibacterial, hemostatic and osteogenic properties for the prevention of dry socket after tooth removal

Tooth removal, particularly for patients with severe periodontitis, can frequently cause massive bleeding, postoperative infection, and bone resorption, resulting in a dry socket. Thus, developing bio-multifunctional materials with excellent antibacterial, hemostatic, and osteogenic characteristics for the prevention of dry sockets after tooth removal is highly desirable in clinical applications. Herein, chitosan-CaP microflowers (CM) and metronidazole (MD) loaded calcium alginate (CA) sponges (CA@CM/MD) with enhanced antibacterial, hemostatic, and osteogenic properties were developed via Ca²⁺ crosslinking, lyophilization, and electrostatic interaction for the prevention of dry socket after tooth removal. The fabricated CM particles display 3-dimensional, relatively homogeneous, and flower-shaped architectures. The CA@CM/MD composite sponges were facilely shaped into the tooth root as well as exhibit interconnected porous and lamellar structures with remarkable porosity, suitable maximum swelling ratio, as well as excellent compressive and hemostatic performance. Besides, the in vitro cellular assessment demonstrates that the prepared CA@CM/MD composite sponges possess satisfactory cytocompatibility. Importantly, the designed sponges significantly suppress the growth of S. aureus and E. coli, as well as promote cellular osteogenic differentiation by upregulating the formation of alkaline phosphatase. Our findings indicate that the tooth root-shaped composite sponges hold great promise for wound management after tooth removal.

Injectable Self-Healing First-Aid Tissue Adhesives with Outstanding Hemostatic and Antibacterial Performances for Trauma Emergency Care

Soft-tissue trauma emergency caused by natural disasters and traffic accidents is highly prevalent, which can result in massive bleeding, pathogen infection, and even death. Although numerous tissue adhesives can bind to tissue surfaces and cover wounds, most of them still have several deficiencies, including long gelation time, poor adhesive strength, and anti-infection, making them inappropriate for use as first-aid bandages. Herein, injectable and self-healing four-arm-PEG-CHO/polyethyleneimine (PEI) tissue adhesives as liquid first-aid supplies are developed via the dynamic Schiff base reaction for trauma emergency. It is found that the prepared hydrogel adhesives exhibit short and controlled gelation time (9∼88 s), strong adhesive strength, and excellent antibacterial ability. Their hemostatic and antimicrobial performances can be tailored by the mass ratio of four-arm-PEG-CHO/PEI. Moreover, in vitro biological assays display that the developed tissue adhesives possess satisfactory cyto/hemocompatibility. Importantly, in vivo the designed adhesives show fast hemostatic capacity and excellent anti-infection as compared to commercial Prontosan gel. Thus, this work indicates that the four-arm-PEG-CHO/PEI first-aid tissue adhesives display great potential for wound emergency management.