Thermogelling chitosan-based polymers for the treatment of oral mucosa ulcers

Platelet-Rich Plasma-Embedded Porous Polycaprolactone Film with a Large Surface Area for Effective Hemostasis

BACKGROUND

Uncontrollable and widespread bleeding caused by surgery or sudden accidents can lead to death if not treated with appropriate hemostasis. To prevent excessive life-threatening bleeding, various hemostatic agents based on polymeric biomaterials with various additives for accelerated blood coagulation have been adopted in clinical fields. In particular, platelet-rich plasma (PRP), which contains many blood coagulation factors that can accelerate blood clot formation, is considered as one of the most effective hemostatic additives.

METHODS

We investigated a PRP-embedded porous film using discarded (expired) PRP and a film with a leaf-stacked structure (FLSS), as a hemostatic agent to induce rapid hemostasis. The film, which contained an LSS on one side (PCL-FLSS), was fabricated by a simple heating-cooling technique using tetraglycol and polycaprolactone (PCL) film. Activated PRP was obtained by the thawing of frozen PRP at the end of its expiration date (the platelet cell membrane is disrupted during the freezing and thawing of PRP, thus releasing various coagulation factors) and embedded in the PCL-FLSS (PRP-FLSS).

RESULTS

From in vitro and in vivo experiments using a rat hepatic bleeding model, it was recognized that PRP-FLSS is not only biocompatible but also significantly accelerates blood clotting and thus prevents rapid bleeding, probably due to a synergistic effect of the sufficient supply of various blood coagulants from activated PRP embedded in the LSS layer and the large surface area of the LSS itself.

CONCLUSION

The study suggests that PRP-FLSS, a combination of a porous polymer matrix with a unique morphology and discarded biofunctional resources, can be an advanced hemostatic agent as well as an upcycling platform to avoid the waste of biofunctional resources.

Development and Characterization of a Novel Composite Hydrogel Biomaterial for Improved Mucoperiosteal Wound Repair

Mucoperiosteal wound healing, as it occurs after pediatric cleft palate surgery, can be challenging due to the limitations of current treatments such as tissue flaps secured with sutures and fibrin glue. In this study, we characterized the in vitro performance of a novel composite hydrogel biomaterial designed to be employed as an in situ wound filler and enhance mucoperiosteal wound healing. We evaluated a range of photopolymerizable formulations containing methacrylated gelatin (GelMA), glycol chitosan, and bioglass microparticles. Our aim was to identify one or more formulations with an appropriate balance of properties against a set of functional requirements that we established for this application. To test the formulations against these criteria, we measured photopolymerization kinetics, mechanical properties, degradation rate, in vitro biocompatibility, and ex vivo tissue adhesion. All formulations polymerized in less than 90 s using violet light. In addition, we found that GelMA-based hydrogels were more adhesive to mucoperiosteal tissue than clinical standard fibrin glue. Inclusion of small amounts of bioglass in the formulation increased mechanical compatibility with mucoperiosteal tissue, enhanced cytoconductivity, and promoted cell proliferation. Taken together, our results support the suitability of these photopolymerized composite hydrogels as in situ mucoperiosteal wound fillers. Overall, this study lays the groundwork for investigating the in vivo, pre-clinical effectiveness of these composite hydrogels in improving mucoperiosteal wound healing outcomes.

A molybdenum sulfide based nitric oxide controlled release oral gel for rapid healing of oral mucosal ulcers

Oral mucosal ulcer is the most prevalent oral mucosal lesion, affecting over 25 % of general population. The current treatment regimens lack efficacy in addressing challenges such as wound bleeding, bacterial infection and inflammation on a continuous basis. Hence, a multi-functional oral gel (termed MPCST) with a long-acting duration is designed. It is based on a tannic acid-thioctic acid (TATA) supramolecular hydrogel which absorbs tissue exudate while exhibiting robust tissue adhesion properties. To form MPCST, TATA is loaded with MPCS, which are composed of polydopamine (PDA)-coated molybdenum disulfide (MoS2) nanoflakes (MoS2@PDA) with high photothermal conversion efficiency, nitric oxide (NO) precursor nitroprusside (SNP) and cerium oxide (CeO2) with high reactive oxygen species (ROS) scavenging rate. Upon exposure to 808 nm near-infrared (NIR) irradiation, MPCS rapidly heats up and releases NO to promote angiogenesis, while exhibiting strong ROS scavenging, antibacterial (including oral common Streptococcus mutans), and anti-inflammatory properties. Animal experiments show that the MPCST oral gel, composed of MPCS and TATA hydrogel, exhibits superior therapeutic efficacy compared to the commonly used dexamethasone patch.

Effects of a semi-interpenetrating network hydrogel loaded with oridonin and DNase-I on the healing of chemoradiotherapy-induced oral mucositis

The aim of this study was to develop a semi-interpenetrating network (IPN) hydrogel system suitable for the oral environment, capable of controlled release of DNase-I and oridonin (ORI), to exert antimicrobial, anti-inflammatory, and reparative effects on chemoradiotherapy-induced oral mucositis (OM). This IPN was based on the combination of ε-polylysine (PLL) and hetastarch (HES), loaded with DNase-I and ORI (ORI/DNase-I/IPN) for OM treatment. In vitro studies were conducted to evaluate degradation, adhesion, release analysis, and bioactivity including cell proliferation and wound healing assays using epidermal keratinocyte and fibroblast cell lines. Furthermore, the therapeutic effects of ORI/DNase-I/IPN were investigated in vivo using Sprague-Dawley (SD) rats with chemoradiotherapy-induced OM. The results demonstrated that the IPN exhibited excellent adhesion to wet mucous membranes, and the two drugs co-encapsulated in the hydrogel were released in a controlled manner, exerting inhibitory effects on bacteria and degrading NETs in wound tissues. The in vivo wound repair effect, microbiological assays, H&E and Masson staining supported the non-toxicity of ORI/DNase-I/IPN, as well as its ability to accelerate the healing of oral ulcers and reduce inflammation. Overall, ORI/DNase-I/IPN demonstrated a therapeutic effect on OM in rats by significantly accelerating the healing process. These findings provide new insights into possible therapies for OM.

Novel Functional Dressing Materials for Intraoral Wound Care

Intraoral wounds represent a particularly challenging category of mucosal and hard tissue injuries, characterized by the unique structures, complex environment, and distinctive healing processes within the oral cavity. They have a common occurrence yet frequently inflict significant inconvenience and pain on patients, causing a serious decline in the quality of life. A variety of novel functional dressings specifically designed for the moist and dynamic oral environment have been developed and realized accelerated and improved wound healing. Thoroughly analyzing and summarizing these materials is of paramount importance in enhancing the understanding and proficiently managing intraoral wounds. In this review, the particular processes and unique characteristics of intraoral wound healing are firstly described. Up-to-date knowledge of various forms, properties, and applications of existing products are then intensively discussed, which are categorized into animal products, plant extracts, natural polymers, and synthetic products. To conclude, this review presents a comprehensive framework of currently available functional intraoral wound dressings, with an aim to provoke inspiration of future studies to design more convenient and versatile materials.

Wet adhesive hydrogels based on niobium carbide for experimental research of oral mucosal impairment

Oral mucosal impairment is a prevalent oral disease that frequently causes pain for patients. Conventional treatments have limited effectiveness and can cause adverse reactions. Furthermore, the moist and dynamic nature of the oral mucosal environment makes persistent adherence of conventional materials challenging, which can affect treatment efficacy. In this study, we investigated the potential of a NbC/TA-GelMA hydrogel system, where niobium carbide (NbC) and tannic acid (TA) were added to gelatin methacryloyl (GelMA), for repairing oral mucosal impairment. The wet adhesion properties of NbC/TA-GelMA hydrogels were confirmed by the inclusion of TA with a catechol-rich group. In addition, the photothermal effect of NbC/TA-GelMA hydrogel under near-infrared light, synergizing with TA, provided sustained antibacterial action. Furthermore, the NbC/TA-GelMA hydrogel effectively healed damaged oral mucosa of rats.

A polyglutamic acid/tannic acid-based nano drug delivery system: Antibacterial, immunoregulation and sustained therapeutic strategies for oral ulcers

Oral ulcers are a common inflammatory mucosal ulcer, and the moist and dynamic environment in the oral cavity makes topical pharmacological treatment of oral ulcers challenging. Herein, oral ulcer tissue adhesion nanoparticles were prepared by using esterification reaction between polyglutamic acid and tannic acid, and at the same time doxycycline hydrochloride was loaded into the nanoparticles. The obtained slow drug release effect of the drug-loaded nanoparticles reduced the toxicity of the drug, and by penetrating into the fine crevice region of the wound tissue and adhering to it, they could in-situ release the carried drug more effectively and thus have shown significant antibacterial effects. In addition, tannic acid in the system conferred adhesion, antioxidant and immune regulation activities to the nanocarriers. A rat oral ulcer model based on fluorescent labeling was established to investigate the retention of nanoparticles at the ulcer, and the results showed that the retention rate of drug-loaded nanoparticles at the ulcer was 17 times higher than that of pure drug. Due to the antibacterial and immune regulation effects of the drug-loaded nanoparticles, the healing of oral ulcer wounds was greatly accelerated. Such application of doxycycline hydrochloride loaded polyglutamic acid/tannic acid nanoparticles is a novel and effective treatment strategy for oral ulcer.

Dendronization of chitosan to afford unprecedent thermoresponsiveness and tunable microconfinement

Convenient chemical modification of biomacromolecules to create novel biocompatible functional materials satisfies the current requirements of sustainable chemistry. Dendronization of chitosan with dendritic oligoethylene glycols (OEGs) paves a strategy for the preparation of functional dendronized chitosans (DCSs) with unprecedent thermoresponsive behavior, which inherit biological features from polysaccharides and the topological features from dendritic OEGs. In addition, densely packed dendritic OEG chains around the backbone provide efficient cooperative interactions and form an intriguing confined microenvironment based on the degradable biopolymers. In this perspective, we describe the principle for the preparation of the thermoresponsive DCSs, and focus on the molecular envelop effect from the hydrophobic microconfinement to the encapsulated guest molecules or moieties. Particular attention is put on their capacity to regulate behavior and the functions of the encapsulated guests through thermally-mediated dehydration and collapse of the densely packed dendritic OEGs. We believe that the methodology described here may provide prospects for the fabrication of functional materials from biomacromolecules, especially when used as environmentally friendly nanomaterials or in accurate diagnosis and therapy.

Antibacterial, anti-inflammatory and wet-adhesive poly(ionic liquid)-based oral patch for the treatment of oral ulcers with bacterial infection

Oral aphthous ulcers are a common inflammatory efflorescence of oral mucosa, presenting as inflammation and oral mucosal damage and manifesting as pain. The moist and highly dynamic environment of the oral cavity makes the local treatment of oral aphthous ulcers challenging. Herein, a poly(ionic liquid)-based diclofenac sodium (DS)-loaded (PIL-DS) buccal tissue adhesive patch fabricated with intrinsically antimicrobial, highly wet environment adhesive properties and anti-inflammatory activities to treat oral aphthous ulcers was developed. The PIL-DS patch was prepared via polymerization of a catechol-containing ionic liquid, acrylic acid, and butyl acrylate, followed by anion exchange with DS-. The PIL-DS can adhere to wet tissues, including mucosa muscles and organs, and efficiently deliver the carried DS- at wound sites, exerting remarkable synergistic antimicrobial (bacteria and fungi) properties. Accordingly, the PIL-DS elicited dual therapeutic effects on oral aphthous ulcers with Staphylococcus aureus infection through antibacterial and anti-inflammatory activities, significantly accelerating oral aphthous ulcer healing as an oral mucosa patch. The results indicated that the PIL-DS patch, with inherently antimicrobial and wet adhesion properties, is promising for treating oral aphthous ulcers in clinical practice. STATEMENT OF SIGNIFICANCE: Oral aphthous ulcers are a common oral mucosal disease, which could lead to bacterial infection and inflammation in severe cases, especially for people with large ulcers or low immunity. However, moist oral mucosa and highly dynamic oral environment make it challenging to maintain therapeutic agents and physical barriers at the wound surface. Therefore, an innovative drug carrier with wet adhesion is urgently needed. Herein, a poly(ionic liquid)-based diclofenac sodium (DS)-loaded (PIL-DS) buccal tissue adhesive patch was developed to treat oral aphthous ulcers showing intrinsically antimicrobial and highly wet environment adhesive properties due to the presence of catechol-containing ionic liquid monomer. Additionally, the PIL-DS showed significantly therapeutic effects on oral aphthous ulcers with S. aureus infection through antibacterial and anti-inflammatory activities. We expect that our work can provide inspiration for the development of treatment for microbially infected oral ulcers.

A novel thermoresponsive nano carrier matrix of hyaluronic acid, methotrexate and chitosan to target the cluster of differentiation 44 receptors in tumors

Major challenges in current cancer chemotherapy include drug resistance, low efficacy and non-selectivity, resulting in undesirable side effects. In this study, we demonstrate a solution to these challenges that involves a dual targeting approach for tumors that overexpress CD44 receptors. The approach employs a nano-formulation (tHAC-MTX nano assembly), fabricated from hyaluronic acid (HA), the natural ligand for CD44, conjugated with methotrexate (MTX) and complexed with the thermoresponsive polymer 6-O-carboxymethylchitosan (6-OCMC) graft poly(N-isopropylacrylamide) [6-OCMC-g-PNIPAAm]. The thermoresponsive component was designed to have a lower critical solution temperature of 39 °C (the temperature of tumor tissues). In-vitro drug release studies reveal faster release of the drug at the higher temperatures of the tumor tissue likely due to the conformation changes in the thermoresponsive component of the nano assembly. Drug release was also enhanced in the presence of hyaluronidase enzyme. Higher cellular uptake and greater cytotoxicity of the nanoparticles were demonstrated in cancer cells that overexpress CD44 receptors suggesting a receptor binding and cellular uptake mechanism. Such nano-assemblies which incorporate multiple targeting mechanisms have the potential to improve efficacy and decrease side effects of cancer chemotherapy.

A self-fused hydrogel for the treatment of glottic insufficiency through outstanding durability, extracellular matrix-inducing bioactivity and function preservation

Injection laryngoplasty with biomaterials is an effective technique to treat glottic insufficiency. However, the inadequate durability, deficient pro-secretion of extracellular matrix (ECM) and poor functional preservation of current biomaterials have yielded an unsatisfactory therapeutic effect. Herein, a self-fusing bioactive hydrogel comprising modified carboxymethyl chitosan and sodium alginate is developed through a dual-crosslinking mechanism (photo-triggered and dynamic covalent bonds). Owing to its characteristic networks, the synergistic effect of the hydrogel for vocal folds (VFs) vibration and phonation is adequately demonstrated. Notably, owing to its inherent bioactivity of polysaccharides, the hydrogel could significantly enhance the secretion of major components (type I/III collagen and elastin) in the lamina propria of the VFs both in vivo and in vitro. In a rabbit model for glottic insufficiency, the optimized hydrogel (C1A1) has demonstrated a durability far superior to that of the commercially made hyaluronic acid (HA) Gel. More importantly, owing to the ECM-inducing bioactivity, the physiological functions of the VFs treated with the C1A1 hydrogel also outperformed that of the HA Gel, and were similar to those of the normal VFs. Taken together, through a simple-yet-effective strategy, the novel hydrogel has demonstrated outstanding durability, ECM-inducing bioactivity and physiological function preservation, therefore has an appealing clinical value for treating glottic insufficiency.

Multi-functional nanogel with cascade catalytic performance for treatment of diabetic oral mucosa ulcer

Introduction: Diabetic oral mucosa ulcers face challenges of hypoxia, hyperglycemia and high oxidative stress, which result in delayed healing process. Oxygen is regarded as an important substance in cell proliferation, differentiation and migration, which is beneficial to ulcer recovery. Methods: This study developed a multi-functional GOx-CAT nanogel (GCN) system for the treatment of diabetic oral mucosa ulcers. The catalytic activity, ROS scavenge and oxygen supply ability of GCN was validated. The therapeutic effect of GCN was verified in the diabetic gingival ulcer model. Results: The results showed that the nanoscale GCN was capable of significantly eliminating intracellular ROS, increasing intracellular oxygen concentration and accelerating cell migration of human gingival fibroblasts, which could promote diabetic oral gingival ulcer healing in vivo by alleviating inflammation and promoting angiogenesis. Discussion: This multifunctional GCN with ROS depletion, continuous oxygen supply and good biocompatibility, which might provide a novel therapeutic strategy for effective treatment of diabetic oral mucosa ulcers.

Dual-light defined in situ oral mucosal lesion therapy through a mode switchable anti-bacterial and anti-inflammatory mucoadhesive hydrogel

Oral mucosal ulcer is the most prevalent oral mucosal lesion, affecting the quality of life. Due to the moist and highly dynamic oral lining, the existing oral mucoadhesives are unable to serially address the challenges of residency, hemorrhage, bacterial infection and inflammatory reaction. Herein, a dual-light defined oral mucoadhesive (ZPTA-G/HMA) was proposed, with a methacrylate gelatin-methacrylate hyaluronic acid (GelMA-HAMA, G/HMA) double network hydrogel as a matrix, tannic acid (TA) as a high content anchor moiety provider for the moist oral mucosa, and polydopamine modified zinc oxide (ZnO@PDA, ZP) as a photocatalytic antibacterial substance. This platform had good adhesive and hemostatic properties both in vitro and in vivo. Under 520 nm green light (GL) irradiation, ZPTA-G/HMA would anchor to the wet mucosa surface by crosslinking and exert broad-spectrum antibacterial ability (even including Candida albicans) by in situ producing reactive oxygen species (ROS). Moreover, under 808 nm near-infrared (NIR) irradiation, the increased release of TA combined with the photothermal effect of ZP endowed ZPTA-G/HMA with enhanced anti-inflammatory and pro-healing performance. Collectively, ZPTA-G/HMA could be switched by light sources to achieve the dual-mode real-time adjustment of in situ anti-bacterial function and controlled anti-inflammation, combined with ideal mucosal residence, thus promising in developing personalized sequential strategies for varied oral mucosal lesions.

Chitosan as a potential biomaterial for the management of oral mucositis, a common complication of cancer treatment

Oral mucositis is a serious issue in patients receiving oncological therapies. Mucosal protectants considered to be one of the preferred choices used in the management of mucositis. However, the protective efficacy of currently available mucosal protectants has been significantly compromised due to poor retention, lack of lubrication, poor biodegradability, and inability to manage secondary complications. Chitosan is a promising material for mucosal applications due to its beneficial biomedical properties. Chitosan is also anti-inflammatory, anti-microbial, and capable of scavenging free radicals, makes it a good candidate for the treatment of oral mucositis. Additionally, chitosan's amino polysaccharide skeleton permits a number of chemical alterations with better bioactive performance. This article provides a summary of key biological properties of chitosan and its derivatives that are useful for treating oral mucositis. Current literature evidence shows that Chitosan has superior mucosal protective properties when utilised alone or as delivery systems for co-encapsulated drugs.

Nanoenzyme-chitosan hydrogel complex with cascade catalytic and self-reinforced antibacterial performance for accelerated healing of diabetic wounds

The significant disability and fatality rate of diabetes chronic wounds necessitates the development of efficient diabetic wound healing techniques. The present oxygen treatments for wound healing is restricted by issues such as poor penetration, inadequate supply, and absorption difficulties as well as tanglesome diabetic wound microenvironment issues such as hyperglycemia, excessive reactive oxygen species (ROS), and hypoxia. Herein, we designed a multifunctional glucose oxidase (GOx) and catalase (CAT) nanoenzyme-chitosan (GCNC) hydrogel complex to improve the microenvironment of diabetic wounds and provide continuous oxygen delivery for efficient wound healing. By simultaneously forming the GOx-CAT nanoenzyme (GCNE) composite, the GCNC hydrogel complex could effectively reduce glucose and ROS (H₂O₂) concentrations in diabetic wounds through cascade catalytic reactions and achieve continuous oxygen supply, which promoted cell proliferation, migration, and angiogenesis, thereby accelerating diabetic wound healing. In addition, the byproduct gluconic acid produced by the cascade reaction can activate the amino group of chitosan to reinforce the antibacterial performance and prevent microbial infection. This multifunctional GCNC hydrogel complex with continuous oxygen supply, self-reinforcing antibacterial properties, and byproduct-free features provides a general strategy for repairing the extensive tissue damage in diabetes.

Multi-crosslinking hydrogels with robust bio-adhesion and pro-coagulant activity for first-aid hemostasis and infected wound healing

Bio-adhesive polysaccharide-based hydrogels have attracted much attention in first-aid hemostasis and wound healing for excellent biocompatibility, antibacterial property and pro-healing bioactivity. Yet, the inadequate mechanical properties and bio-adhesion limit their applications. Herein, based on dynamic covalent bonds, photo-triggered covalent bonds and hydrogen bonds, multifunctional bio-adhesive hydrogels comprising modified carboxymethyl chitosan, modified sodium alginate and tannic acid are developed. Multi-crosslinking strategy endows hydrogels with improved strength and flexibility simultaneously. Owing to cohesion enhancement strategy and self-healing ability, considerable bio-adhesion is presented by the hydrogel with a maximal adhesion strength of 162.6 kPa, 12.3-fold that of commercial fibrin glue. Based on bio-adhesion and pro-coagulant activity (e.g., the stimulative aggregation and adhesion of erythrocytes and platelets), the hydrogel reveals superior hemostatic performance in rabbit liver injury model with blood loss of 0.32 g, only 54.2% of that in fibrin glue. The healing efficiency of hydrogel for infected wounds is markedly better than commercial EGF Gel and Ag+ Gel due to the enhanced antibacterial and antioxidant properties. Through the multi-crosslinking strategy, the hydrogels show enhanced mechanical properties, fabulous bio-adhesion, superior hemostatic performance and promoting healing ability, thereby have an appealing application value for the first-aid hemostasis and infected wound healing.

A Polyanionic Tartrate-containing Temperature-responsive Hydrogel

Thermogels, a class of hydrogels which show spontaneous sol-gel phase transition when warmed, are an important class of soft biomaterials. To date, however, most amphiphilic polymers that are able to form thermogels in aqueous solution are uncharged, and the influence of ionisable groups on thermogelation are largely unknown. Herein, we report the first example of a polyanionic amphiphilic multi-block copolymer, containing multiple pendant carboxylate groups, that can form transparent thermogels spontaneously when warmed up to physiological temperature. We demonstrate that introducing negative charges onto thermogelling polymers could significantly alter the properties of the micelles and thermogels formed. Furthermore, the polymer's polyanionic character provides new options for modulating the gel rheological properties, such as stiffness and gelation temperatures, through electrostatic interactions with different cations. We also demonstrated the polyanionic thermogel allowed slower sustained release of a cationic model drug compound compared to an anionic one over 2 weeks. The findings from our study demonstrate exciting new possibilities for advanced biomedical applications using charged polyelectrolyte thermogel materials.

Copper-containing nanoparticles: Mechanism of antimicrobial effect and application in dentistry-a narrative review

Copper has been used as an antimicrobial agent long time ago. Nowadays, copper-containing nanoparticles (NPs) with antimicrobial properties have been widely used in all aspects of our daily life. Copper-containing NPs may also be incorporated or coated on the surface of dental materials to inhibit oral pathogenic microorganisms. This review aims to detail copper-containing NPs' antimicrobial mechanism, cytotoxic effect and their application in dentistry.

Marine collagen peptides: A novel biomaterial for the healing of oral mucosal ulcers

The purpose of this study was to analyze the therapeutic effects of marine collagen peptides (MCPs) from tilapia skin on oral mucosal ulcers in a rat model. CCK-8 and wound healing assays were performed in vitro to evaluate proliferation and migration of L929 cells after treatment with MCPs. The effects of MCPs on the healing of oral mucosal ulcers in a rat model were macroscopically and microscopically analyzed in vivo. Results showed that MCPs promoted proliferation and migration of L929 cells. Moreover, 75%MCPs enhanced the ulcer healing process, suppressed inflammatory response and up-regulated the expression levels of vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF). MCPs are potentially used as a new therapeutic strategy for oral mucosal ulceration.

Full-Thickness Oral Mucoperiosteal Defects: Challenges and Opportunities

Regenerative engineering strategies for the oral mucoperiosteum, as may be needed following surgeries, such as cleft palate repair and tumor resection, are underdeveloped compared with those for maxillofacial bone. However, critical-size tissue defects left to heal by secondary intention can lead to complications, such as infection, fistula formation, scarring, and midface hypoplasia. This review describes current clinical practice for replacing mucoperiosteal tissue, including autografts and allografts. Potentially paradigm-shifting experimental regenerative engineering strategies for mucoperiosteal wound healing, such as hybrid grafts and engineered matrices, are also discussed. Throughout the review, the advantages and disadvantages of each replacement or regeneration strategy are outlined in the context of clinical outcomes, quality of life for the patient, availability of materials, and cost of care. Finally, future directions for research and development in the area of mucoperiosteum repair are proposed, with an emphasis on identifying globally available and affordable solutions for promoting mucoperiosteal regeneration. Impact statement Unassisted oral mucoperiosteal wound healing can lead to severe complications such as infection, fistulae, scarring, and developmental abnormalities. Thus, strategies for promoting wound healing must be considered when mucoperiosteal defects are incident to oral surgery, as in palatoplasty or tumor resection. Emerging mucoperiosteal tissue engineering strategies, described in this study, have the potential to overcome the limitations of current standard-of-care donor tissue grafts. For example, the use of engineered mucoperiosteal biomaterials could circumvent concerns about tissue availability and immunogenicity. Moreover, employment of tissue engineering strategies may improve the equity of oral wound care by increasing global affordability and accessibility of materials.

Janus mucosal dressing with a tough and adhesive hydrogel based on synergistic effects of gelatin, polydopamine, and nano-clay

There are many problems and challenges related to the treatment of highly prevalent oral mucosal diseases and oral drug delivery because of a large amount of saliva present in the oral cavity, the accompanying oral movements, and unconscious swallowing in the mouth. Therefore, an ideal oral dressing should possess stable adhesion and superior tough strength in the oral cavity. However, this fundamental requirement greatly limits the use of synthetic adhesive dressings for oral dressings. Here, we developed a mussel-inspired Janus gelatin-polydopamine-nano-clay (GPC) hydrogel with controlled adhesion and toughness through the synergistic physical and chemical interaction of gelatin (Gel), nano-clay, and dopamine (DA). The hydrogel not only exhibits strong wet adhesion force (63 kPa) but also has high toughness (1026 ± 100 J m^-3). Interfacial adhesion of hydrogels is achieved by modulating the interaction of catechol groups of the hydrogel with specific functional groups (e.g., NH₂, SH, OH, and COOH) on the tissue surface. The matrix dissipation of the hydrogel is regulated by physical crosslinking of gelatin, chemical crosslinking of gelatin with polydopamine (Michael addition and Schiff base formation), and nano-clay-induced constraint of the molecular chain. In addition, the GPC hydrogel shows high cell affinity and favors cell adhesion and proliferation. The hydrogel's instant and strong mucoadhesive properties provide a long-lasting therapeutic effect of the drug, thereby enhancing the healing of oral ulcers. Therefore, mussel-inspired wet-adhesion Janus GPC hydrogels can be used as a platform for mucosal dressing and drug delivery systems. STATEMENT OF SIGNIFICANCE: It is a great challenge to treat oral mucosal diseases due to the large amount of saliva present in the oral cavity, the accompanying oral movements, unconscious swallowing, and flushing of drugs in the mouth. To overcome the significant limitations of clinical bioadhesives, such as weakness, toxicity, and poor usage, in the present study, we developed a simple method through the synergistic effects of gelatin, polydopamine, and nano-clay to prepare an optimal mucosal dressing (Janus GPC) that integrates Janus, adhesion, toughness, and drug release property. It fits effectively in the mouth, resists saliva flushing and oral movements, provides oral drug delivery, and reduces patient discomfort. The Janus GPC adhesive hydrogels have great commercial potential to support further the development of innovative therapies for oral mucosal diseases.

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.

Branched PCL-Based Thermogelling Copolymers: Controlling Polymer Architecture to Tune Drug Release Profiles

Temperature-responsive hydrogels, or thermogels, are a unique class of biomaterials that show facile and spontaneous transition from solution to gel when warmed. Their high biocompatibility, and ease of formulation with both small molecule drugs and biologics have made these materials prime candidates as injectable gel depots for sustained local drug delivery. At present, controlling the kinetics and profile of drug release from thermogels is achieved mainly by varying the ratio of hydrophobic: hydrophilic composition and the polymer molecular weight. Herein, we introduce polymer branching as a hitherto-overlooked polymer design parameter that exhibits profound influences on the rate and profile of drug release. Through a family of amphiphilic thermogelling polymers with systematic variations in degree of branching, we demonstrate that more highly-branched polymers are able to pack less efficiently with each other during thermogel formation, with implications on their physical properties and stability towards gel erosion. This in turn resulted in faster rates of release for both encapsulated small molecule hydrophobic drug and protein. Our results demonstrate the possibility of exploiting polymer branching as a hitherto-overlooked design parameter for tailoring the kinetics and profile of drug release in injectable thermogel depots.

Fabrication and evaluation of Cs/PVP sponge containing platelet-rich fibrin as a wound healing accelerator: An in vitro and in vivo study

Despite significant advances in surgery and postoperative care, there are still challenges in the treatment of wounds. In the current study, a freeze-dried chitosan (Cs)/polyvinylpyrrolidone (PVP) sponges containing platelet-rich fibrin (PRF at 1, 1.5 and 2% w/v) for wound dressing application is fabricated and fully characterized. Addition of 1% w/v of PRF to Cs/PVP (CS/PVP/1PRF) sample significantly increased the tensile strength (from 0.147 ± 0.005 to 0.242 ± 0.001 MPa), elastic modulus (from 0.414 ± 0.014 to 0.611 ± 0.022 MPa) and strain at break (from 53.4 ± 0.9 to 61.83 ± 1.17%) compared to Cs sample, and was hence selected as the optimal sample. The antibacterial activity of Cs/PVP/1PRF sponge wound dressing against E. coli and S. aureus was confirmed to be effective. Enzyme-linked immunosorbent assays revealed that the release of both VEGF and PDGF-AB from PRF powder, as well as PDGF-AB from Cs/PVP/1PRF sample was time-independent, but the release of VEGF from Cs/PVP/1PRF sample increased significantly with time. According to MTT and CAM assays, the Cs/PVP/1PRF sample significantly increased proliferation and angiogenic potential, respectively. Furthermore, in vivo studies demonstrated a 97.16 ± 1.55% wound closure for Cs/PVP/1PRF group after 14 days.

Effect of nano-chitosan and nano-doxycycline gel on healing of induced oral ulcer in rat model: histological and immunohistochemical study

OBJECTIVES

The aim of this study was to investigate the effect of nano-chitosan and nano-doxycycline gel on healing of oral ulcers.

METHODS

In this study, 37 rats were used, four of which acted as normal controls (group 1), while the remaining 33 were distributed into three groups, each with 11 rats. Oral ulcers were chemically induced in the labial mucosa, after which (group 2), ulcer group received no treatment, (group 3) received nano-chitosan gel, and (group 4) received nano-doxycycline gel. They were scarified after 14 days and histologically examined as well as immunostaining for vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (PCNA).

RESULTS

The best clinical and histologic healing results were shown in nano-chitosan group, followed by nano-doxycycline group, while the ulcer group showed incomplete healing. This was confirmed by immunostaining as area % of VEGF and number PCNA were the highest in nano-chitosan group followed by nano-doxycycline group, then ulcer group.

CONCLUSION

Both nano-chitosan and nano-doxycycline gels improved the healing of chemically induced oral ulcers; however, nano-chitosan exhibited better healing outcomes.

CLINICAL RELEVANCE

Nano-chitosan and nano-doxycycline gels are both viable and safe alternatives to current ulcer treatments.

Preparation of triamcinolone acetonide-loaded chitosan/fucoidan hydrogel and its potential application as an oral mucosa patch

Oral inflammatory diseases (OIDs) are among the most common lesions in the oral cavity, affecting the quality of human life and even causing oral cancer. However, most of the current oral mucosa patches still have some limitations, particularly instant, poor mechanical strength and conformability, low adhesion to tissue, and foreign body sensation. Herein, triamcinolone acetonide (TA)-loaded chitosan/fucoidan (CF) composite hydrogels were prepared via chemical crosslinking. The macro/microscopic morphologies and (bio)physicochemical properties of composite hydrogels were investigated. Incorporating fucoidan in chitosan hydrogels greatly enhanced their swelling behavior, mechanical strength, and adhesion properties. Further, the addition of TA in CF hydrogels improved their elastic feature, inhibited inflammatory response, and promoted the formation of mature and well-organized collagen fibers. The developed composite hydrogels displayed not only good antibacterial properties but also good cytocompatibility and histocompatibility. Thus, the designed hydrogels allow the development of oral mucosa patches as a potential treatment for OIDs.

Haemostatic materials for wound healing applications

Wounds are one of the most common health issues, and the cost of wound care and healing has continued to increase over the past decade. The first step in wound healing is haemostasis, and the development of haemostatic materials that aid wound healing has accelerated in the past 5 years. Numerous haemostatic materials have been fabricated, composed of different active components (including natural polymers, synthetic polymers, silicon-based materials and metal-containing materials) and in various forms (including sponges, hydrogels, nanofibres and particles). In this Review, we provide an overview of haemostatic materials in wound healing, focusing on their chemical design and operation. We describe the physiological process of haemostasis to elucidate the principles that underpin the design of haemostatic wound dressings. We also highlight the advantages and limitations of the different active components and forms of haemostatic materials. The main challenges and future directions in the development of haemostatic materials for wound healing are proposed.

Flexible polymeric nanosized micelles for ophthalmic drug delivery: research progress in the last three years

The eye is a complex structure with a variety of anatomical barriers and clearance mechanisms, so the provision of safe and effective ophthalmic drug delivery technology is a major challenge. In the past few decades, a number of reports have shown that nano-delivery platforms based on polymeric micelles are of great interest, because of their hydrophobic core that encapsulates lipid-soluble drugs and small size with high penetration, allowing long-term drug retention and posterior penetration in the eye. Furthermore, as an ocular delivery platform, polymeric micelles not only cover the single micellar drug delivery system formed by poloxamer, chitosan or other polymers, but also include composite drug delivery systems like micelle-encapsulated hydrogels and micelle-embedded contact lenses. In this review, a number of ophthalmic micelles that have emerged in the last three years will be systematically reviewed, with a summary of and discussion on their unique advantages or unique drug delivery performance. Last but not least, the current challenges of polymeric micelle formulations in potential clinical ophthalmic therapeutic applications will also be proposed, which might be helpful for future design of ocular drug delivery formulations.

Thermo-Responsive Hydrogels: From Recent Progress to Biomedical Applications

Thermogels are also known as thermo-sensitive or thermo-responsive hydrogels and can undergo a sol-gel transition as the temperature increases. This thermogelling behavior is the result of combined action from multiscale thermo-responsive mechanisms. From micro to macro, these mechanisms can be attributed to LCST behavior, micellization, and micelle aggregation of thermogelling polymers. Due to its facile phase conversion properties, thermogels are injectable yet can form an in situ gel in the human body. Thermogels act as a useful platform biomaterial that operates at physiological body temperatures. The purpose of this review is to summarize the recent progress in thermogel research, including investigations on the thermogel gelation mechanism and its applications in drug delivery, 3D cell culture, and tissue engineering. The review also discusses emerging directions in the study of thermogels.

Current status and future of delivery systems for prevention and treatment of infections in the oral cavity

Oral health reflects the general health, and it is fundamental to well-being and quality of life. An infection in the oral cavity can be associated with serious complications in human health. Local therapy of these infections offers many advantages over systemic drug administration, targeting directly to the diseased area while minimizing systemic side effects. Specialized drug delivery systems into the oral cavity have to be designed in such a fashion that they resist to the aqueous environment that is constantly bathed in saliva and subject to mechanical forces. Additionally, a prolonged release of drug should also be provided, which would enhance the efficacy and also decrease the repeated dosing. This review is aimed to summarize the current most relevant findings related to local drug delivery of various drug groups for prevention and treatment of infections (viral, bacterial, fungal) and infection-related manifestations in the oral cavity. Current therapeutic challenges in regard to effective local drug delivery systems will be discussed, and the recent approaches to overcome these obstacles will be reviewed. Finally, future prospects will be overviewed to promote novel strategies that can be implemented in clinical management for prevention and treatment of oral infections.

Recent advances in thermo-sensitive hydrogels for drug delivery

Thermo-sensitive hydrogels based on different polymers have been broadly used in the pharmaceutical fields. In this review, the state-of-the-art thermo-sensitive hydrogels for drug delivery are elaborated

Polymeric hydrogels as a vitreous replacement strategy in the eye

Vitreous endo-tamponades are commonly used in the treatment of retinal detachments and tears. They function by providing a tamponading force to support the retina after retina surgery. Current clinical vitreous endo-tamponades include expansile gases (such as sulfur hexafluoride (SF₆) and perfluoropropane (C₃F₈)) and also sislicone oil (SiO). They are effective in promoting recovery but are disadvantaged by their lower refractive indices and lower densities as compared to the native vitreous, resulting in immediate blurred vision after surgery and necessitating patients to assume prolonged face-down positioning respectively. While the gas implants diffuse out over time, the SiO implants are non-biodegradable and require surgical removal. Therefore, there is much demand to develop an ideal vitreous endo-tamponade that can combine therapeutic effectiveness with patient comfort. Polymeric hydrogels have since attracted much attention due to their favourable properties such as high water content, high clarity, suitable refractive indices, suitable density, tuneable rheological properties, injectability, and biocompatibility. Many design strategies have been employed to design polymeric hydrogel-based vitreous endo-tamponades and they can be classified into four main strategies. This review seeks to analyse these various strategies and evaluate their effectiveness and also propose the key criteria to design successful polymeric hydrogel vitreous endo-tamponades.

Supramolecular thermogels from branched PCL-containing polyurethanes

Thermogels are temperature-responsive hydrogels which are most commonly formed by supramolecular self-assembly of polymer amphiphiles comprising of both hydrophobic and hydrophilic segments. Although polyurethane thermogels have shown great promise as biomaterials, their synthesis by step-growth polymerisation of diols and diisocyanates can also result in formation of allophanate branches, which arise from the reaction between free isocyanate groups and urethane linkages along the polymer backbone. In this paper, we investigate the effects of different synthetic conditions on the degree of allophanate branching on polyurethane amphiphiles, and explore the influences of these branches on the polymers' critical micelle concentration (CMC), thermodynamics of micellization and subsequent thermogel properties. Our findings offer new insights into the relationship between polymer structure, micelle and gel properties. These results highlight the importance of taking polymer branching into account for understanding the hierarchical self-assembly of polymer amphiphiles and the resulting thermogel properties and behaviour.

Nano and microscale delivery platforms for enhanced oral peptide/protein bioavailability

In recent years, peptide/protein drugs have attracted considerable attention owing to their superior targeting and therapeutic effect and fewer side effects compared with chemical drugs. Oral administration modality with enhanced patient compliance is increasingly being recognized as an ideal route for peptide/protein delivery. However, the limited permeation efficiency and low oral bioavailability of peptide/protein drugs significantly hinder therapeutic advances. To address these problems, various nano and microscale delivery platforms have been developed, which offer significant advantages in oral peptide/protein delivery. In this review, we briefly introduce the transport mechanisms of oral peptide/protein delivery and the primary barriers to this delivery process. We also highlight the recent advances in various nano and microscale delivery platforms designed for oral peptide/protein delivery. We then summarize the existing strategies used in these delivery platforms to improve the oral bioavailability and permeation efficiency of peptide/protein therapeutics. Finally, we discuss the major challenges faced when nano and microscale systems are used for oral peptide/protein delivery. This review is expected to provide critical insight into the design and development of oral peptide/protein delivery systems with significant therapeutic advances.

New Developments in Medical Applications of Hybrid Hydrogels Containing Natural Polymers

New trends in biomedical applications of the hybrid polymeric hydrogels, obtained by combining natural polymers with synthetic ones, have been reviewed. Homopolysaccharides, heteropolysaccharides, as well as polypeptides, proteins and nucleic acids, are presented from the point of view of their ability to form hydrogels with synthetic polymers, the preparation procedures for polymeric organic hybrid hydrogels, general physico-chemical properties and main biomedical applications (i.e., tissue engineering, wound dressing, drug delivery, etc.).