Hydrogel-Coated Dental Device with Adhesion-Inhibiting and Colony-Suppressing Properties

Insights into the fabrication and antibacterial effect of fibrinogen hydrolysate-carrageenan loading apigenin and quercetin composite hydrogels

Escherichia coli and Staphylococcus aureus are the most prevalent pathogenic bacteria, often resulting in the foodborne disease outbreaks through food spoilage and foodborne infections. To prevent and control food spoilage and foodborne infections induced by Escherichia coli and Staphylococcus aureus, the antibacterial hydrogels were fabricated using fibrinogen hydrolysate-carrageenan (AHs-C) and flavonoids (apigenin and quercetin), and the antibacterial effect of the composite hydrogels against Escherichia coli and Staphylococcus aureus was further investigated. The results of mechanical property exhibited that the composite hydrogels with 0.2 % of apigenin and quercetin (AHs-C-Ap/Que) showed the highest hardness and swelling property compared with the separate addition of apigenin or quercetin. Scanning electron microscopy and atomic force microscopy showed that the dense networks were formed in the hydrogels of AHs-C-Ap/Que., and the average roughness of AHs-C-Ap/Que. significantly increased to 30.70 nm compared with AHs-C. 1H NMR and FTIR spectra demonstrated that apigenin and quercetin were bound to AHs-C by hydrogen bond, hydrophobic interaction and Schiff base, where the interactions between Ap/Que. and AHs-C was stronger compared with the separate addition of apigenin or quercetin. The hydrogels of AHs-C-Ap/Que. showed the highest antibacterial capacity and antibacterial adhesion against Escherichia coli and Staphylococcus aureus. The antibacterial adhesion assay showed that 99 % removal ratios for E. coli and S. aureus were observed in AHs-C-Ap/Que. hydrogels, which showed a great potential to prevent food spoilage and foodborne infections.

A carboxymethyl-resistant starch/polyacrylic acid semi-IPN hydrogel with excellent adhesive and antibacterial properties for peri-implantitis prevention

Hydrogels possess inherent characteristics that render them promising for the prevention of peri-implantitis. Nonetheless, hydrogels with singular network structures are incapable of concurrently achieving the desired adhesion and mechanical properties. In this work, a carboxymethyl resistant starch/polyacrylic acid semi-interpenetrating (CMRS/PAA semi-IPN) hydrogel was successfully prepared in one step. Its morphology, structure, mechanical properties, and adhesion properties were systematically assessed, which revealed a homogeneously porous structure with a commendable mechanical strength of 67.317 kPa and an adhesion strength of 63 kPa. Ciprofloxacin (Cip) was loaded in the CMRS/PAA hydrogel via in situ compounding. The in vitro kinetic study of drug release shows that the slow drug release efficiency exceeds 90 % in the weakly acidic microenvironment at the infection site after 72 h, indicating enhanced antimicrobial properties. The Cip-loaded hydrogel also exhibits a remarkable bacterial inhibition rate exceeding 99 % against the pathogenic bacterium P. gingivalis and good cytocompatibility and hemocompatibility in vitro. In summary, the current work explored a novel solution and direction for the development of anti-infective medical materials applicable to dental implants.

On-demand bactericidal and self-adaptive antifouling hydrogels for self-healing and lubricant coatings of catheters

Catheter-related infections are one of the most common nosocomial infections with increasing morbidity and mortality, and robust antibacterial or antifouling catheter coatings remain great challenges for long-term implantation. Herein, multifunctional hydrogel coatings were developed to provide persistent and self-adaptive antifouling and antibacterial effects with self-healing and lubricant capabilities. Polyvinyl alcohol (PVA) with β-cyclodextrin (β-CD) grafts (PVA-Cd) and 4-arm polyethylene glycol (PEG) with adamantane and quaternary ammonium compound (QAC) terminals (QA-PEG-Ad) were crosslinked through host-guest recognitions between adamantane and β-CD moieties to acquire PVEQ coatings. In response to bacterial infections, QACs exhibit reversible transformation between zwitterions (pH 7.4) and cationic lactones (pH 5.5) to generate on-demand bactericidal effect. Highly hydrophilic PEG/PVA backbones and zwitterionic QACs build a lubricate surface and decrease the friction coefficient 10 times compared with that of bare catheters. The antifouling hydrated layer significantly inhibits blood protein adsorption and platelet activation and reveals negligible hemolysis and cytotoxicity. The dynamic host-guest crosslinking achieves full self-healing of cracks in PVEQ hydrogels, and the mechanical profiles were recovered to over 90 % after rejuvenating the broken hydrogels, exhibiting a long-term stability after mechanical stretching, twisting, knotting and compression. After subcutaneous implantation and local bacterial infection, the retrieved PVEQ-coated catheters display no tissue adhesion and 3 log folds lower bacterial number than that of bare catheters. PVEQ coatings effectively prevent the repeated bacterial infections and there are few inflammatory reactions in the surrounding tissue, while substantial lymphoid infiltration and inflammatory cell aggregation occur in muscle tissues around the bare catheter. Thus, this study demonstrates a catheter coating strategy by on-demand bactericidal, self-adaptive antifouling, self-healing and lubricant hydrogels to address medical devices-related infections. STATEMENT OF SIGNIFICANCE: It is estimated over two billion peripheral intravenous catheters are annually used in hospitals around the world, and catheter-associated infection has become a great clinical challenge with rapidly rising morbidity and mortality. Surface coating is considered a promising approach, but substantial challenges remain in the development of coatings that simultaneously satisfy both anti-fouling and antibacterial attributes. Even more, few attempts have been made to design mechanically robust coatings and reversible antibacterial or antifouling capabilities, which are critical for long-term medical implants. To address these challenges, we propose a concise strategy to develop hydrogel coatings from commercially available poly(ethylene glycol) and polyvinyl alcohol. In addition to self-healing and lubricant capabilities, the reversible conversion between zwitterionic and cationic lactones of quaternary ammonium compounds enables on-demand bactericidal and self-adaptive antifouling effects.

Self-assembled branched polypeptides as amelogenin mimics for enamel repair

The regeneration of demineralized enamel holds great significance in the treatment of dental caries. Amelogenin (Ame), an essential protein for mediating natural enamel growth, is no longer secreted after enamel has fully matured in childhood. Although biomimetic mineralization based on peptides or proteins has made significant progress, easily accessible, low-cost, biocompatible and highly effective Ame mimics are still lacking. Herein, we construct a series of amphiphilic branched polypeptides (CAMPs) by facile coupling of the Ame's C-terminal segment and poly(γ-benzyl-L-glutamate), which serves to simulate the Ame's hydrophobic N-terminal segment. Among them, CAMP15 is the best biomimetic mineralization template with great self-assembly performance to guide the oriented crystallization of hydroxyapatite and is capable of inhibiting the adhesion of Streptococcus mutans and Staphylococcus aureus on the enamel surfaces. This work highlights the potential application of amphiphilic branched polypeptide as Ame mimics in repairing defected enamel, providing a promising strategy for prevention and treatment of dental caries.

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

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

Turning Polysaccharides into Injectable and Rapid Self-Healing Antibacterial Hydrogels for Antibacterial Treatment and Bacterial-Infected Wound Healing

Great efforts have been devoted to the development of novel and multifunctional wound dressing materials to meet the different needs of wound healing. Herein, we covalently grafted quaternary ammonium groups (QAGs) containing 12-carbon straight-chain alkanes to the dextran polymer skeleton. We then oxidized the resulting product into oxidized quaternized dextran (OQD). The obtained OQD polymer is rich in antibacterial QAGs and aldehyde groups. It can react with glycol chitosan (GC) via the Schiff-base reaction to form a multifunctional GC@OQD hydrogel with good self-healing behavior, hemostasis, injectability, inherent superior antibacterial activity, biocompatibility, and excellent promotion of healing of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds. The biosafe and nontoxic GC@OQD hydrogel with a three-dimensional porous network structure possesses an excellent swelling rate and water retention capacity. It can be used for hemostasis and treating irregular wounds. The designed GC@OQD hydrogel with inherent antibacterial activity possesses good antibacterial efficacy on both S. aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria), as well as MRSA bacteria, with antibacterial activity greater than 99%. It can be used for the treatment of wounds infected by MRSA and significantly promotes the healing of wounds. Thus, the multifunctional antibacterial GC@OQD hydrogel has the potential to be applied in clinical practice as a wound dressing.

Bacteria-surface interactions: role of impacting bacteria-laden droplets

Understanding the interactions of pathogenic droplets with surfaces is crucial to biomedical applications. In this study, using E. coli as the model microbe, we investigate the impact of a bacteria-laden droplet on different substrates, both bare and antimicrobial. In doing so, we unveil the significance of kinetic energy and spreading parameters of the impacting droplet in determining the microbes' proliferation capabilities. Our results indicate an inverse relationship between the impact Weber number and the bacterial ability to proliferate. We reveal that the mechanical stress generated during impact impedes the capabilities of microbes present inside the droplet to create their progeny. Following an order analysis of the mechanical stress generated, we argue that the impact does not induce lysis-driven cell death of the bacteria; rather, it promotes a stress-driven transition of viable bacteria to a viable-but-non-culturable (VBNC) state. Furthermore, variations in the concentration of particles on the antimicrobial surfaces revealed the role of the post-impact spreading behaviour in dictating bacterial proliferation capabilities. Contrary to the conventional notion, we demonstrate that during the early stages of interaction, a bare substrate may outperform an antibacterial substrate in the inactivation of the bacterial load. Finally, we present an interaction map illustrating the complex relationship between bacterial colony-forming units, bactericide concentration on the surface, and the impact Weber number. We believe that the inferences of the study, highlighting the effect of mechanical stresses on the soft cell wall of microbes, could be a useful design consideration for the development of antimicrobial surfaces.

A comprehensive review on the inherent and enhanced antifouling mechanisms of hydrogels and their applications

Biofouling remains a persistent challenge within the domains of biomedicine, tissue engineering, marine industry, and membrane separation processes. Multifunctional hydrogels have garnered substantial attention due to their complex three-dimensional architecture, hydrophilicity, biocompatibility, and flexibility. These hydrogels have shown notable advances across various engineering disciplines. The antifouling efficacy of hydrogels typically covers a range of strategies to mitigate or inhibit the adhesion of particulate matter, biological entities, or extraneous pollutants onto their external or internal surfaces. This review provides a comprehensive review of the antifouling properties and applications of hydrogels. We first focus on elucidating the fundamental principles for the inherent resistance of hydrogels to fouling. This is followed by a comprehensive investigation of the methods employed to enhance the antifouling properties enabled by the hydrogels' composition, network structure, conductivity, photothermal properties, release of reactive oxygen species (ROS), and incorporation of silicon and fluorine compounds. Additionally, we explore the emerging prospects of antifouling hydrogels to alleviate the severe challenges posed by surface contamination, membrane separation and wound dressings. The inclusion of detailed mechanistic insights and the judicious selection of antifouling hydrogels are geared toward identifying extant gaps that must be bridged to meet practical requisites while concurrently addressing long-term antifouling applications.

Synthetic and biopolymers-based antimicrobial hybrid hydrogels: a focused review

The constantly accelerating occurrence of microbial infections and their antibiotic resistance has spurred advancement in the field of material sciences and has guided the development of novel materials with anti-bacterial properties. To address the clinical exigencies, the material of choice should be biodegradable, biocompatible, and able to offer prolonged antibacterial effects. As an attractive option, hydrogels have been explored globally as a potent biomaterial platform that can furnish essential antibacterial attributes owing to its three-dimensional (3D) hydrophilic polymeric network, adequate biocompatibility, and cellular adhesion. The current review focuses on the utilization of different antimicrobial hydrogels based on their sources (natural and synthetic). Further, the review also highlights the strategies for the generation of hydrogels with their advantages and disadvantages and their applications in different biomedical fields. Finally, the prospects in the development of hydrogels-based antimicrobial biomaterials are discussed along with some key challenges encountered during their development and clinical translation.

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

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

Self-assembled peptide hydrogels for the treatment of diabetes and associated complications

Diabetes is a widespread epidemic that includes a number of comorbid conditions that greatly increase the chance of acquiring other chronic illnesses. Every year, there are significantly more people with diabetes because of the rise in type-2 diabetes prevalence. The primary causes of illness and mortality worldwide are, among these, hyperglycemia and its comorbidities. There has been a lot of interest in the creation of peptide-based hydrogels as a potentially effective platform for the treatment of diabetes and its consequences. Here, we emphasize the use of self-assembled hydrogel formulations and their unique potential for the treatment/management of type-2 diabetes and its consequences. (i.e., wounds). Key aspects covered include the characteristics of self-assembled peptide hydrogels, methods for their preparation, and their pre-clinical and clinical applications in addressing metabolic disorders such as type-2 diabetes.

Growth of Double-Network Tough Hydrogel Coatings by Surface-Initiated Polymerization

Hydrogel coatings exhibit versatile applications in biomedicine, flexible electronics, and environmental science. However, current coating methods encounter challenges in simultaneously achieving strong interfacial bonding, robust hydrogel coatings, and the ability to coat substrates with controlled thickness. This paper introduces a novel approach to grow a double-network (DN) tough hydrogel coating on various substrates. The process involves initial substrate modification using a silane coupling agent, followed by the deposition of an initiator layer on its surface. Subsequently, the substrate is immersed in a DN hydrogel precursor, where the coating grows under ultraviolet (UV) illumination. Precise control over the coating thickness is achieved by adjusting the UV illumination duration and the initiator quantity. The experimental measurement of adhesion reveals strong bonding between the DN hydrogel coating and diverse substrates, reaching up to 1012.9 J/m2 between the DN hydrogel coating and a glass substrate. The lubricity performance of the DN hydrogel coating is experimentally characterized, which is dependent on the coating thickness, applied pressure, and sliding velocity. The incorporation of 3D printing technology into the current coating method enables the creation of intricate hydrogel coating patterns on a flat substrate. Moreover, the hydrogel coating's versatility is demonstrated through its effective applications in oil-water separation and antifogging glasses, underscoring its wide-ranging potential. The robust DN hydrogel coating method presented here holds promise for advancing hydrogel applications across diverse fields.

Surface functionalization of endotracheal tubes coated with laccase-gadolinium phosphate hybrid nanoparticles for antibiofilm activity and contrasting properties

Ventilator-associated pneumonia (VAP) is a severe hospital-acquired infection that endangers patients' treatment in intensive care units (ICUs). One of the leading causes of VAP is biofilm formation on the endotracheal tube (ETT) during ventilation. This study reports a combination of laccase-gadolinium phosphate hybrid nanoparticles (laccase@GdPO4·HNPs) and enzyme mediator with an antibiofilm property coated on the surface of the ETT. The hybrid nanostructures were fabricated through a simple, rapid, and facile laccase immobilization method, resulting in efficiency and yield percentages of 82 ± 6% and 83 ± 5%, respectively. The surface of the ETT was then functionalized and coated with the constructed HNP/catechol. The layered ETT was able to reduce the surface adhesion of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus by 82.1%, 84.5%, and 77.1%, respectively. The prepared ETT did not affect the viability of human lung epithelial cells L929 and A549 at concentrations of 1-5 mg mL-1. The layered ETT produced a strong computed tomography (CT) signal in comparison with iobitridol. The HNP/catechol-coated ETT exhibited a Gd3+ release of 0.45 ppm over 72 h, indicating reduced risks of cytotoxicity arising from the metal ions. In this research we develop a biofilm-resistant and contrasting agent-based ETT coated with green synthesized laccase@GdPO4·HNPs.

Highly Adhesive and Self-Healing Zwitterionic Hydrogels as Antibacterial Coatings for Medical Devices

Bacterial infection of medical devices has caused incalculable losses to maintenance costs and health care. A single coating with antibacterial function cannot guarantee the long-term use of the device, because the coating will be damaged and fall off during reuse. To solve this problem, the development of coatings with high adhesion and self-healing ability is a wise direction. In this paper, a multifunctional polyzwitterionic antibacterial hydrogel coating (PZG) composed of amphozwitterion monomer, anionic monomer, and quaternary ammonium cationic monomer was synthesized by dipping UV photoinitiated polymerization. The structure of PZGs was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Ascribing to the hydrogel internal electrostatic interaction, hydrogen bond, and cation-π interaction, the obtained PZGs exhibited high ductility (>1200% strain) and appropriate strength (>189 kPa). Remarkably, PZGs could also adhere firmly on different substrates through noncovalent interaction, and their adhesion could be controlled by adjusting the amount of zwitterionic. Reversible physical interactions in polymer networks endowed hydrogels with excellent self-healing properties. In addition, PZGs exhibit good antibacterial activity and biocompatibility due to the synergistic effect of quaternary ammonium cation and amphozwitterion monomer. This work provides a multifunctional antibacterial coating for medical equipment and has broad application prospects in the biomedical field.

Current State and Future Perspective of Diabetic Wound Healing Treatment: Present Evidence from Clinical Trials

Diabetes is a chronic metabolic condition that is becoming more common and is characterised by sustained hyperglycaemia and long-term health effects. Diabetes-related wounds often heal slowly and are more susceptible to infection because of hyperglycaemia in the wound beds. The diabetic lesion becomes harder to heal after planktonic bacterial cells form biofilms. A potential approach is the creation of hydrogels with many functions. High priority is given to a variety of processes, such as antimicrobial, pro-angiogenesis, and general pro-healing. Diabetes problems include diabetic amputations or chronic wounds (DM). Chronic diabetes wounds that do not heal are often caused by low oxygen levels, increased reactive oxygen species, and impaired vascularization. Several types of hydrogels have been developed to get rid of contamination by pathogens; these hydrogels help to clean up the infection, reduce wound inflammation, and avoid necrosis. This review paper will focus on the most recent improvements and breakthroughs in antibacterial hydrogels for treating chronic wounds in people with diabetes. Prominent and significant side effects of diabetes mellitus include foot ulcers. Antioxidants, along with oxidative stress, are essential to promote the healing of diabetic wounds. Some of the problems that can come from a foot ulcer are neuropathic diabetes, ischemia, infection, inadequate glucose control, poor nutrition, also very high morbidity. Given the worrying rise in diabetes and, by extension, diabetic wounds, future treatments must focus on the rapid healing of diabetic wounds.

Bivalirudin-hydrogel coatings of polyvinyl chloride on extracorporeal membrane oxygenation for anticoagulation

Introduction

Thromboembolic events associated with extracorporeal membrane oxygenation (ECMO) in clinical treatment are typical. Heparin coating has been widely employed as a surface modification strategy for ECMO tubes. However, its clinical application is often accompanied by unavoidable complications due to its mechanism of action. As a direct thrombin inhibitor with a single target, Bivalirudin (BV) has exhibited a lower incidence of adverse events and superior pharmacokinetic performance compared to heparin.

Methods

A gelatin methacrylate hydrogel (GelMA) coating layer with BV was successfully synthesized on polyvinyl chloride, and the drug release ratio was close to complete release within 7 days.

Results and discussion

Simulated extracorporeal circulation experiments using roller pumps in vitro and jugular arteriovenous bypass experiments in rabbits demonstrated its outstanding anticoagulant efficacy. The systemic anticoagulant assay proved that BV hydrogel coating does not affect the coagulation level, and reduces the risk of complications such as systemic bleeding compared to intravenous injection. BV-Coating GelMA hydrogel tube has exhibited good biocompatibility and significantly improved anticoagulant performance, making it an optimal choice for surface materials used in blood-contacting medical devices.

An underwater stable and durable gelatin composite hydrogel coating for biomedical applications

Developing underwater stable and durable hydrogel coatings with drag-reducing, drug release, and antibacterial properties is essential for lots of biomedical applications. However, most hydrogel coatings cannot meet the requirement of underwater stability and versatility, which severely limits their widespread use. In this work, an underwater stable, durable and substrate-independent gelatin composite hydrogel (GMP) coating is developed through covalent crosslinks, where a silane coupling agent with an unsaturated double bond is grafted onto a substrate of co-deposited polydopamine and polyethylenimine. GMP coating can be easily coated onto various medical device surfaces, such as artificial joints, catheters, tracheal tubes and titanium alloys, showing excellent structural stability and mechanical tunability under extreme conditions of ultrasonic treatment for 1 h (400 W of ultrasonic power) or underwater shearing for 14 days (400 rpm). Besides, friction experiment reveals that GMP coating exhibits good lubrication properties (coefficient of friction < 0.003). The drug-loading and bacterial inhibition ring tests show that the GMP coating has a tunable drug release ability with the final releasing ratios of 70-95% by changing the content of poly (ethylene glycol) diacrylate. This work offers a scalable approach of fabricating bio-functional and stable hydrogel coatings, which can be potentially used in biomedical applications.

Research progress of biomimetic materials in oral medicine

Biomimetic materials are able to mimic the structure and functional properties of native tissues especially natural oral tissues. They have attracted growing attention for their potential to achieve configurable and functional reconstruction in oral medicine. Though tremendous progress has been made regarding biomimetic materials, significant challenges still remain in terms of controversy on the mechanism of tooth tissue regeneration, lack of options for manufacturing such materials and insufficiency of in vivo experimental tests in related fields. In this review, the biomimetic materials used in oral medicine are summarized systematically, including tooth defect, tooth loss, periodontal diseases and maxillofacial bone defect. Various theoretical foundations of biomimetic materials research are reviewed, introducing the current and pertinent results. The benefits and limitations of these materials are summed up at the same time. Finally, challenges and potential of this field are discussed. This review provides the framework and support for further research in addition to giving a generally novel and fundamental basis for the utilization of biomimetic materials in the future.

Prevention of bacterial biofilm formation on orthodontic brackets by non-crosslinked chitosan coating

During orthodontic treatment, the patients are susceptible to dental caries as a result of the bacterial adhesion and biofilm formation around the orthodontic brackets. Prevention of the caries-related biofilm formation is of significance for maintaining both aesthetics and health of the teeth. Herein, the brackets were functionalized with antibacterial activity via coating a layer of non-crosslinked chitosan (CS). We firstly demonstrated the ability of free CS scaffolds (not coated on brackets) to inhibit the formation of Streptococcus mutans biofilms (inhibition rate 94.3 % for CS-0.3 mg) and to eradicate the mature biofilms (biofilm loss rate 99.8 % for CS-1.2 mg). Further, the inhibition of S. mutans biofilm formation on brackets by CS coating was investigated for the first time. As a result, the CS-coated brackets (Br-CS) kept the great biofilm inhibition capacity of free CS scaffolds. In detail, the Br-CS, prepared by immersing brackets in CS solutions (containing 1.0, 2.5, 5.0 and 10 mg/mL CS) and freeze-drying, showed the biofilm inhibition rate of 48.5 %, 88.6 %, 96.4 % and 99.6 %, respectively. In conclusion, coating orthodontic brackets with the non-crosslinked CS is a potential approach for inhibiting biofilm formation and protecting patients from dental caries.

Advances in antimicrobial hydrogels for dental tissue engineering: regenerative strategies for endodontics and periodontics

Dental tissue infections have been affecting millions of patients globally leading to pain, severe tissue damage, or even tooth loss. Commercial sterilizers may not be adequate to prevent frequent dental infections. Antimicrobial hydrogels have been introduced as an effective therapeutic strategy for endodontics and periodontics since they have the capability of imitating the native extracellular matrix of soft tissues. Hydrogel networks are considered excellent drug delivery platforms due to their high-water retention capacity. In this regard, drugs or nanoparticles can be incorporated into the hydrogels to endow antimicrobial properties as well as to improve their regenerative potential, once biocompatibility criteria are met avoiding high dosages. Herein, novel antimicrobial hydrogel formulations were discussed for the first time in the scope of endodontics and periodontics. Such hydrogels seem outstanding candidates especially when designed not only as simple volume fillers but also as smart biomaterials with condition-specific adaptability within the dynamic microenvironment of the defect site. Multifunctional hydrogels play a pivotal role against infections, inflammation, oxidative stress, etc. along the way of dental regeneration. Modern techniques (e.g., 3D and 4D-printing) hold promise to develop the next generation of antimicrobial hydrogels together with their limitations such as infeasibility of implantation.

Improving antibacterial ability of Ti-Cu thin films with co-sputtering method

Due to the resistance of some bacteria to antibiotics, research in the field of dealing with bacterial infections is necessary. A practical approach utilized in this study involves the preparation of an antibacterial thin film on the surfaces, which can effectively inhibit and reduce biofilm formation and bacterial adherence. In this study, we report the fabrication of bactericidal titanium (Ti) and copper (Cu) surfaces which involves a powerful co-sputtering method. This method provides a situation in which constituent elements are deposited simultaneously to control the composition of the thin film. Prepared samples were examined by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), and contact angle measurements. To evaluate antibacterial behavior, we used two bacterial strains Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Antibacterial activity of the prepared sample was assessed by determining the number of colony-forming units per milliliter (CFU/ml) using a standard viable cell count assay. Results indicated that as the Cu concentration increased, the nanoscale surfaces became rougher, with roughness values rising from 11.85 to 49.65 nm, and the contact angle increased from 40 to 80 degrees, indicating a hydrophilic character. These factors play a significant role in the antibacterial properties of the surface. The Ti-Cu films displayed superior antibacterial ability, with a 99.9% reduction (equivalent to a 5-log reduction) in bacterial viability after 2 h compared to Ti alone against both bacterial strains. Field emission scanning electron microscopy (FE-SEM) images verified that both E. coli and S. aureus cells were physically deformed and damaged the bacterial cell ultrastructure was observed. These findings highlight that adding Cu to Ti can improve the antibacterial ability of the surface while inhibiting bacterial adherence. Therefore, the Ti14-Cu86 sample with the highest percentage of Cu had the best bactericidal rate. Investigation of toxicity of Cu-Ti thin films was conducted the using the MTT assay, which revealed their biocompatibility and absence of cytotoxicity, further confirming their potential as promising biomaterials for various applications.

Recent Strategies and Future Recommendations for the Fabrication of Antimicrobial, Antibiofilm, and Antibiofouling Biomaterials

Biomaterials and biomedical devices induced life-threatening bacterial infections and other biological adverse effects such as thrombosis and fibrosis have posed a significant threat to global healthcare. Bacterial infections and adverse biological effects are often caused by the formation of microbial biofilms and the adherence of various biomacromolecules, such as platelets, proteins, fibroblasts, and immune cells, to the surfaces of biomaterials and biomedical devices. Due to the programmed interconnected networking of bacteria in microbial biofilms, they are challenging to treat and can withstand several doses of antibiotics. Additionally, antibiotics can kill bacteria but do not prevent the adsorption of biomacromolecules from physiological fluids or implanting sites, which generates a conditioning layer that promotes bacteria's reattachment, development, and eventual biofilm formation. In these viewpoints, we highlighted the magnitude of biomaterials and biomedical device-induced infections, the role of biofilm formation, and biomacromolecule adhesion in human pathogenesis. We then discussed the solutions practiced in healthcare systems for curing biomaterials and biomedical device-induced infections and their limitations. Moreover, this review comprehensively elaborated on the recent advances in designing and fabricating biomaterials and biomedical devices with these three properties: antibacterial (bacterial killing), antibiofilm (biofilm inhibition/prevention), and antibiofouling (biofouling inhibition/prevention) against microbial species and against the adhesion of other biomacromolecules. Besides we also recommended potential directions for further investigations.

Hydrogels for Oral Tissue Engineering: Challenges and Opportunities

Oral health is crucial to daily life, yet many people worldwide suffer from oral diseases. With the development of oral tissue engineering, there is a growing demand for dental biomaterials. Addressing oral diseases often requires a two-fold approach: fighting bacterial infections and promoting tissue growth. Hydrogels are promising tissue engineering biomaterials that show great potential for oral tissue regeneration and drug delivery. In this review, we present a classification of hydrogels commonly used in dental research, including natural and synthetic hydrogels. Furthermore, recent applications of these hydrogels in endodontic restorations, periodontal tissues, mandibular and oral soft tissue restorations, and related clinical studies are also discussed, including various antimicrobial and tissue growth promotion strategies used in the dental applications of hydrogels. While hydrogels have been increasingly studied in oral tissue engineering, there are still some challenges that need to be addressed for satisfactory clinical outcomes. This paper summarizes the current issues in the abovementioned application areas and discusses possible future developments.

Functional Surface Coatings on Orthodontic Appliances: Reviews of Friction Reduction, Antibacterial Properties, and Corrosion Resistance

Surface coating technology is an important way to improve the properties of orthodontic appliances, allowing for reduced friction, antibacterial properties, and enhanced corrosion resistance. It improves treatment efficiency, reduces side effects, and increases the safety and durability of orthodontic appliances. Existing functional coatings are prepared with suitable additional layers on the surface of the substrate to achieve the abovementioned modifications, and commonly used materials mainly include metal and metallic compound materials, carbon-based materials, polymers, and bioactive materials. In addition to single-use materials, metal-metal or metal-nonmetal materials can be combined. Methods of coating preparation include, but are not limited to, physical vapor deposition (PVD), chemical deposition, sol-gel dip coating, etc., with a variety of different conditions for preparing the coatings. In the reviewed studies, a wide variety of surface coatings were found to be effective. However, the present coating materials have not yet achieved a perfect combination of these three functions, and their safety and durability need further verification. This paper reviews and summarizes the effectiveness, advantages and disadvantages, and clinical perspectives of different coating materials for orthodontic appliances in terms of friction reduction, antibacterial properties, and enhanced corrosion resistance, and discusses more possibilities for follow-up studies as well as for clinical applications in detail.

A multifunctional chitosan-based hydrogel with self-healing, antibacterial, and immunomodulatory effects as wound dressing

Bacterial infection often leads to inflammatory responses and delays wound healing. Chitosan (CS)-based composite hydrogels can hold desirable mechanical properties and maintain excellent antibacterial abilities, and thus may be promising as wound dressings. Although CS-based hydrogels have been widely studied on the antibacterial and wound-healing abilities, their immunomodulatory abilities were rarely evaluated. Herein, we developed a multifunctional CS/Poly[2-(methacryloyloxy)ethyl] trimethyl ammonium chloride (PMETAC) hydrogel. In vitro, this hydrogel exhibited self-healing ability and excellent biocompatibility, promoted macrophage polarization towards M2 phenotype, and showed desirable antibacterial activity. In vivo, this hydrogel accelerated the wound regeneration process by reducing bacterial burden, increasing collagen deposition, stimulating angiogenesis, promoting macrophage polarization to M2 direction, and shifting the balance of T helper type 17 (Th17) cells towards anti-inflammatory regulatory T (Treg) cells. This work revealed the potential immunomodulatory effect of CS-based wound dressings and thus may provide a novel target for developing efficient wound healing tools.

Multifunctional antibacterial chitosan-based hydrogel coatings on Ti6Al4V biomaterial for biomedical implant applications

Among biomedical community, great efforts have been realized to develop antibacterial coatings that avoid implant-associated infections. To date, conventional mono-functional antibacterial strategies have not been effective enough for successful long-term implantations. Consequently, researchers have recently focused their attention on novel bifunctional or multifunctional antibacterial coatings, in which two or more antibacterial mechanisms interact synergistically. Thus, in this work different chitosan-based (CHI) hydrogel coatings were created on Ti6Al4V surface using genipin (Ti-CHIGP) and polyethylene glycol (Ti-CHIPEG) crosslinking agents. Hydrogel coatings demonstrated an exceptional in vivo biocompatibility plus a remarkable ability to promote cell proliferation and differentiation. Lastly, hydrogel coatings demonstrated an outstanding bacteria-repelling (17-28 % of S. aureus and 33-43 % of E. coli repelled) and contact killing (186-222 % of S. aureus and 72-83 % of E. coli damaged) ability. Such bifunctional antibacterial activity could be further improved by the controlled release of drugs resulting in powerful multifunctional antibacterial coatings.

Drug delivery systems based on polyethylene glycol hydrogels for enhanced bone regeneration

Drug delivery systems composed of osteogenic substances and biological materials are of great significance in enhancing bone regeneration, and appropriate biological carriers are the cornerstone for their construction. Polyethylene glycol (PEG) is favored in bone tissue engineering due to its good biocompatibility and hydrophilicity. When combined with other substances, the physicochemical properties of PEG-based hydrogels fully meet the requirements of drug delivery carriers. Therefore, this paper reviews the application of PEG-based hydrogels in the treatment of bone defects. The advantages and disadvantages of PEG as a carrier are analyzed, and various modification methods of PEG hydrogels are summarized. On this basis, the application of PEG-based hydrogel drug delivery systems in promoting bone regeneration in recent years is summarized. Finally, the shortcomings and future developments of PEG-based hydrogel drug delivery systems are discussed. This review provides a theoretical basis and fabrication strategy for the application of PEG-based composite drug delivery systems in local bone defects.

"Self-Defensive" Antifouling Zwitterionic Hydrogel Coatings on Polymeric Substrates

In biomedicine fields, biofouling can easily occur on devices such as sensors and catheters, causing some iatrogenic infections, which menace the lives and health of patients greatly. Therefore, it is of great significance to solve the problems of bacterial infection on the surfaces of medical devices. In this paper, "self-defensive" and antifouling zwitterionic hydrogel coatings were prepared by network interpenetration of the hydrogel and the polymeric substrates. The zwitterionic polysulfobetaine methacrylate (PSBMA) hydrogel coatings resisted most of the bacteria to adhere on the substrates. When a few bacteria were lucky to escape the antifouling defense and adhered to the coatings, gentamicin sulfate (GS) would be released under the trigger of a weakly acidic environment caused by bacterial metabolism to kill these bacteria. Simultaneously, the coatings of the bacteria-adhering sites would be degraded by hyaluronidase secreted by these bacteria and peeled off to remove the bacteria and renew the antifouling surfaces. The antifouling properties and mechanism of the self-defensive behavior of the hydrogel coatings on polymeric substrates were investigated. Furthermore, the in vitro and in vivo antibacterial performances, as well as the biocompatibility of the coatings, were demonstrated. The results suggested that the self-defensive antifouling zwitterionic hydrogel coatings hold great potential to be used on the surfaces of polymeric medical devices.

Design strategies for adhesive hydrogels with natural antibacterial agents as wound dressings: Status and trends

The wound healing process is usually susceptible to different bacterial infections due to the complex physiological environment, which significantly impairs wound healing. The topical application of antibiotics is not desirable for wound healing because the excessive use of antibiotics might cause bacteria to develop resistance and even the production of super bacteria, posing significant harm to human well-being. Wound dressings based on adhesive, biocompatible, and multi-functional hydrogels with natural antibacterial agents have been widely recognized as effective wound treatments. Hydrogels, which are three-dimensional (3D) polymer networks cross-linked through physical interactions or covalent bonds, are promising for topical antibacterial applications because of their excellent adhesion, antibacterial properties, and biocompatibility. To further improve the healing performance of hydrogels, various modification methods have been developed with superior biocompatibility, antibacterial activity, mechanical properties, and wound repair capabilities. This review summarizes hundreds of typical studies on various ingredients, preparation methods, antibacterial mechanisms, and internal antibacterial factors to understand adhesive hydrogels with natural antibacterial agents for wound dressings. Additionally, we provide prospects for adhesive and antibacterial hydrogels in biomedical applications and clinical research.

Bioengineering Approaches to Fight against Orthopedic Biomaterials Related-Infections

One of the most serious complications following the implantation of orthopedic biomaterials is the development of infection. Orthopedic implant-related infections do not only entail clinical problems and patient suffering, but also cause a burden on healthcare care systems. Additionally, the ageing of the world population, in particular in developed countries, has led to an increase in the population above 60 years. This is a significantly vulnerable population segment insofar as biomaterials use is concerned. Implanted materials are highly susceptible to bacterial and fungal colonization and the consequent infection. These microorganisms are often opportunistic, taking advantage of the weakening of the body defenses at the implant surface–tissue interface to attach to tissues or implant surfaces, instigating biofilm formation and subsequent development of infection. The establishment of biofilm leads to tissue destruction, systemic dissemination of the pathogen, and dysfunction of the implant/bone joint, leading to implant failure. Moreover, the contaminated implant can be a reservoir for infection of the surrounding tissue where microorganisms are protected. Therefore, the biofilm increases the pathogenesis of infection since that structure offers protection against host defenses and antimicrobial therapies. Additionally, the rapid emergence of bacterial strains resistant to antibiotics prompted the development of new alternative approaches to prevent and control implant-related infections. Several concepts and approaches have been developed to obtain biomaterials endowed with anti-infective properties. In this review, several anti-infective strategies based on biomaterial engineering are described and discussed in terms of design and fabrication, mechanisms of action, benefits, and drawbacks for preventing and treating orthopaedic biomaterials-related infections.

Recent Developments in Multifunctional Antimicrobial Surfaces and Applications toward Advanced Nitric Oxide-Based Biomaterials

Implant-associated infections arising from biofilm development are known to have detrimental effects with compromised quality of life for the patients, implying a progressing issue in healthcare. It has been a struggle for more than 50 years for the biomaterials field to achieve long-term success of medical implants by discouraging bacterial and protein adhesion without adversely affecting the surrounding tissue and cell functions. However, the rate of infections associated with medical devices is continuously escalating because of the intricate nature of bacterial biofilms, antibiotic resistance, and the lack of ability of monofunctional antibacterial materials to prevent the colonization of bacteria on the device surface. For this reason, many current strategies are focused on the development of novel antibacterial surfaces with dual antimicrobial functionality. These surfaces are based on the combination of two components into one system that can eradicate attached bacteria (antibiotics, peptides, nitric oxide, ammonium salts, light, etc.) and also resist or release adhesion of bacteria (hydrophilic polymers, zwitterionic, antiadhesive, topography, bioinspired surfaces, etc.). This review aims to outline the progress made in the field of biomedical engineering and biomaterials for the development of multifunctional antibacterial biomedical devices. Additionally, principles for material design and fabrication are highlighted using characteristic examples, with a special focus on combinational nitric oxide-releasing biomedical interfaces. A brief perspective on future research directions for engineering of dual-function antibacterial surfaces is also presented.

Bio-inspired special wettability in oral antibacterial applications

Most oral diseases originate from biofilms whose formation is originated from the adhesion of salivary proteins and pioneer bacteria. Therefore, antimicrobial materials are mainly based on bactericidal methods, most of which have drug resistance and toxicity. Natural antifouling surfaces inspire new antibacterial strategies. The super wettable surfaces of lotus leaves and fish scales prompt design of biomimetic oral materials covered or mixed with super wettable materials to prevent adhesion. Bioinspired slippery surfaces come from pitcher plants, whose porous surfaces are infiltrated with lubricating liquid to form superhydrophobic surfaces to reduce the contact with liquids. It is believed that these new methods could provide promising directions for oral antimicrobial practice, improving antimicrobial efficacy.

Dental Materials for Oral Microbiota Dysbiosis: An Update

The balance or dysbiosis of the microbial community is a major factor in maintaining human health or causing disease. The unique microenvironment of the oral cavity provides optimal conditions for colonization and proliferation of microbiota, regulated through complex biological signaling systems and interactions with the host. Once the oral microbiota is out of balance, microorganisms produce virulence factors and metabolites, which will cause dental caries, periodontal disease, etc. Microbial metabolism and host immune response change the local microenvironment in turn and further promote the excessive proliferation of dominant microbes in dysbiosis. As the product of interdisciplinary development of materials science, stomatology, and biomedical engineering, oral biomaterials are playing an increasingly important role in regulating the balance of the oral microbiome and treating oral diseases. In this perspective, we discuss the mechanisms underlying the pathogenesis of oral microbiota dysbiosis and introduce emerging materials focusing on oral microbiota dysbiosis in recent years, including inorganic materials, organic materials, and some biomolecules. In addition, the limitations of the current study and possible research trends are also summarized. It is hoped that this review can provide reference and enlightenment for subsequent research on effective treatment strategies for diseases related to oral microbiota dysbiosis.

Rational design of dual-functional surfaces on polypropylene with antifouling and antibacterial performances via a micropatterning strategy

The hydrophobicity and inertness of the polypropylene (PP) material surface usually lead to serious biofouling and bacterial infections, which hamper its potential application as a biomedical polymer. Many strategies have been developed to improve its antifouling or antibacterial properties, yet designing a surface to achieve both antifouling and antibacterial performances simultaneously remains a challenge. Herein, we construct a dual-function micropatterned PP surface with antifouling and antibacterial properties through plasma activation, photomask technology and ultraviolet light-induced graft polymerization. Based on the antifouling agent poly(2-methacryloyloxyethyl phosphate choline) (PMPC) and the antibacterial agent quaternized poly(N,N-dimethylamino)ethyl methacrylate (QPDMAEMA), two different micropatterning structures have been successfully prepared: PP-PMPC-QPDMAEMA in which QPDMAEMA is the micropattern and PMPC is the coating polymer, and PP-QPDMAEMA-PMPC in which PMPC is the micropattern and QPDMAEMA is the coating polymer. The composition, elemental distribution and surface morphology of PP-PMPC-QPDMAEMA and PP-QPDMAEMA-PMPC have been thoroughly characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. Compared with pristine PP, the two types of micropatterned PP films exhibit good surface hydrophilicity as characterized by water contact angle measurements. The results of anti-protein adsorption, platelet adhesion and antibacterial evaluation showed that PP-PMPC-QPDMAEMA and PP-QPDMAEMA-PMPC had good anti-protein adsorption properties, especially for lysozyme (Lyz). They can effectively prevent platelet adhesion, and the anti-platelet adhesion performance of PP-QPDMAEMA-PMPC is slightly better than that of the PP-PMPC-QPDMAEMA sample. The sterilization rate of S. aureus and E. coli is as high as 95% for the two types of micropatterned PP films. Due to the rational design of micropatterns on the PP surface, the two classes of dual-functional PP materials realize both the resistance of protein and platelet adhesion, and the killing of bacteria at the same time. We anticipate that this work could provide a design strategy for the construction of multifunctional biomedical polymer materials.

Efficient Antimicrobial Effect of Alginate-Catechol/Fe2+ Coating on Hydroxyapatite toward Oral Care Application

Reducing the formation of oral bacterial biofilms is critical to prevent common dental diseases. Though many strategies for restricting bacterial adhesion on tooth surfaces have been reported, a simple method for efficient oral bacteriostasis is still highly expected. Herein, we have proved a soft gel made of an alginate-catechol conjugate (SA-DA) and the ferrous cation (Fe²⁺) as an effective antibacterial coating on hydroxyapatite (HAP, a tooth model). As suggested by quartz crystal microbalance (QCM) measurements, SA-DA/Fe²⁺ coating possessed a high binding affinity to HAP without destruction by either immersion in artificial saliva or simulated tooth brushing. Significantly less protein (bovine serum albumin) and Streptococcus mutans (S. mutans, an oral bacterial model) could be found on HAP after coating with SA-DA/Fe²⁺, indicating that the prepared gel could resist well the adhesion of biofouling and microbes due to its hydrophilicity. Notably, such an antibacterial effect (around 70% S. mutans was inhibited) could be maintained for 3 d, which resulted from the extremely good stability of SA-DA/Fe²⁺ coating, as confirmed by QCM analysis. Our results may offer possibilities for developing applications in order to further improve oral hygiene.

Multimodal therapy strategies based on hydrogels for the repair of spinal cord injury

Spinal cord injury (SCI) is a serious traumatic disease of the central nervous system, which can give rise to the loss of motor and sensory function. Due to its complex pathological mechanism, the treatment of this disease still faces a huge challenge. Hydrogels with good biocompatibility and biodegradability can well imitate the extracellular matrix in the microenvironment of spinal cord. Hydrogels have been regarded as promising SCI repair material in recent years and continuous studies have confirmed that hydrogel-based therapy can effectively eliminate inflammation and promote spinal cord repair and regeneration to improve SCI. In this review, hydrogel-based multimodal therapeutic strategies to repair SCI are provided, and a combination of hydrogel scaffolds and other therapeutic modalities are discussed, with particular emphasis on the repair mechanism of SCI.

Progress in hydrogels for skin wound repair

As the first defensive line between the human body and the outside world, the skin is vulnerable to damage from the external environment. Skin wounds can be divided into acute wounds (mechanical injuries, chemical injuries and surgical wounds, etc.) and chronic wounds (burns, infections, diabetes, etc.). In order to manage skin wound, a variety of wound dressings have been developed, including gauze, films, foams, nanofibers, hydrocolloids and hydrogels. Recently, hydrogels have received much attention because of their natural extracellular matrix (ECM)-mimik structure, tunable mechanical properties, and facile bioactive substance delivery capability. They show great potential application in skin wound repair. This paper first introduces the anatomy and function of the skin, the process of wound healing and conventional wound dressings, and then introduces the composition and construction methods of hydrogels. Next, this paper introduces the necessary properties of hydrogels in skin wound repair and the latest research progress of hydrogel dressings for skin wound repair. Finally, the future development goals of hydrogel materials in the field of wound healing are proposed. This article is protected by copyright. All rights reserved.

Phosphorylated and Phosphonated Low-Complexity Protein Segments for Biomimetic Mineralization and Repair of Tooth Enamel

Biomimetic mineralization based on self-assembly has made great progress, providing bottom-up strategies for the construction of new organic-inorganic hybrid materials applied in the treatment of hard tissue defects. Herein, inspired by the cooperative effects of key components in biomineralization microenvironments, a new type of biocompatible peptide scaffold based on flexibly self-assembling low-complexity protein segments (LCPSs) containing phosphate or phosphonate groups is developed. These LCPSs can retard the transformation of amorphous calcium phosphate into hydroxyapatite (HAP), leading to merged mineralization structures. Moreover, the application of phosphonated LCPS over phosphorylated LCPS can prevent hydrolysis by phosphatases that are enriched in extracellular mineralization microenvironments. After being coated on the etched tooth enamel, these LCPSs facilitate the growth of HAP to generate new enamel layers comparable to the natural layers and mitigate the adhesion of Streptococcus mutans. In addition, they can effectively stimulate the differentiation pathways of osteoblasts. These results shed light on the potential biomedical applications of two LCPSs in hard tissue repair.

Facile preparation of thermosensitive and antibiofouling physically crosslinked hydrogel/powder for wound healing

To improve the therapeutic effect of hydrogel for damaged tissue, a series of hydroxybutyl chitosan (HBC) and poly (sulfobetaine methacrylate) (PSBMA) composite hydrogels (HBC-PSB) with thermosensitivity, self-healing, antibiofouling, and synergistic...

Decellularized Scaffold-based Poly(ethylene glycol) Biomimetic Vascular Patches Modified with Polyelectrolyte Multilayer of Heparin and Chitosan: Preparation and Vascular Tissue Engineering Applications in a Porcine Model

The mechanical property mismatch between vascular patches and native blood vessels can result in post-operation failure, so it is important to develop vascular patches that mimic the biomechanical properties of...

Cyclodextrin-Containing Hydrogels: A Review of Preparation Method, Drug Delivery, and Degradation Behavior

Hydrogels possess porous structures, which are widely applied in the field of materials and biomedicine. As a natural oligosaccharide, cyclodextrin (CD) has shown remarkable application prospects in the synthesis and utilization of hydrogels. CD can be incorporated into hydrogels to form chemically or physically cross-linked networks. Furthermore, the unique cavity structure of CD makes it an ideal vehicle for the delivery of active ingredients into target tissues. This review describes useful methods to prepare CD-containing hydrogels. In addition, the potential biomedical applications of CD-containing hydrogels are reviewed. The release and degradation process of CD-containing hydrogels under different conditions are discussed. Finally, the current challenges and future research directions on CD-containing hydrogels are presented.

The Application of Chitosan Nanostructures in Stomatology

Chitosan (CS) is a natural polymer with a positive charge, a deacetylated derivative of chitin. Chitosan nanostructures (nano-CS) have received increasing interest due to their potential applications and remarkable properties. They offer advantages in stomatology due to their excellent biocompatibility, their antibacterial properties, and their biodegradability. Nano-CSs can be applied as drug carriers for soft tissue diseases, bone tissue engineering and dental hard tissue remineralization; furthermore, they have been used in endodontics due to their antibacterial properties; and, finally, nano-CS can improve the adhesion and mechanical properties of dental-restorative materials due to their physical blend and chemical combinations. In this review, recent developments in the application of nano-CS for stomatology are summarized, with an emphasis on nano-CS’s performance characteristics in different application fields. Moreover, the challenges posed by and the future trends in its application are assessed.

Chinese herb microneedle patch for wound healing

Traditional Chinese medicine and Chinese herbs have a demonstrated value for disease therapy and sub-health improvement. Attempts in this area tend to develop new forms to make their applications more convenient and wider. Here, we propose a novel Chinese herb microneedle (CHMN) patch by integrating the herbal extracts, Premna microphylla and Centella asiatica, with microstructure of microneedle for wound healing. Such path is composed of sap extracted from the herbal leaves via traditional kneading method and solidified by plant ash derived from the brine induced process of tofu in a well-designed mold. Because the leaves of the Premna microphylla are rich in pectin and various amino acids, the CHMN could be imparted with medicinal efficacy of heat clearing, detoxicating, detumescence and hemostatic. Besides, with the excellent pharmaceutical activity of Asiatic acid extracted from Centella asiatica, the CHMN is potential in promoting relevant growth factor genes expression in fibroblasts and showing excellent performance in anti-oxidant, anti-inflammatory and anti-bacterial activity. Taking advantages of these pure herbal compositions, we have demonstrated that the derived CHMN was with dramatical achievement in anti-bacteria, inhibiting inflammatory, collagen deposition, angiogenesis and tissue reconstruction during the wound closure. These results indicate that the integration of traditional Chinese herbs with progressive technologies will facilitate the development and promotion of traditional Chinese medicine in modern society.

Functional hydrogels for diabetic wound management

Diabetic wounds often have a slow healing process and become easily infected owing to hyperglycemia in wound beds. Once planktonic bacterial cells develop into biofilms, the diabetic wound becomes more resistant to treatment. Although it remains challenging to accelerate healing in a diabetic wound due to complex pathology, including bacterial infection, high reactive oxygen species, chronic inflammation, and impaired angiogenesis, the development of multifunctional hydrogels is a promising strategy. Multiple functions, including antibacterial, pro-angiogenesis, and overall pro-healing, are high priorities. Here, design strategies, mechanisms of action, performance, and application of functional hydrogels are systematically discussed. The unique properties of hydrogels, including bactericidal and wound healing promotive effects, are reviewed. Considering the clinical need, stimuli-responsive and multifunctional hydrogels that can accelerate diabetic wound healing are likely to form an important part of future diabetic wound management.

A Bacteria and Cell Repellent Zwitterionic Polymer Coating on Titanium Base Substrates towards Smart Implant Devices

Biofouling and biofilm formation on implant surfaces are serious issues that more than often lead to inflammatory reactions and the necessity of lengthy post-operation treatments or the removal of the implant, thus entailing a protracted healing process. This issue may be tackled with a biocompatible polymeric coating that at the same time prevents biofouling. In this work, oxygen plasma-activated silanized titanium substrates are coated with poly(sulfobetaine methacrylate), a zwitterionic antibiofouling polymer, using photopolymerization. The characterization of polymer films includes FT-IR, AFM, and adhesion strength measurements, where adhesion strength is analyzed using a cylindrical flat punch indenter and water contact angle (WCA) measurements. Both cytotoxicity analysis with primary human fibroblasts and fluorescence microscopy with fibroblasts and plaque bacteria are also performed is this work, with each procedure including seeding on coated and control surfaces. The film morphology obtained by the AFM shows a fine structure akin to nanoropes. The coatings can resist ultrasonic and sterilization treatments. The adhesion strength properties substantially increase when the films are soaked in 0.51 M of NaCl prior to testing when compared to deionized water. The coatings are superhydrophilic with a WCA of 10° that increases to 15° after dry aging. The viability of fibroblasts in the presence of coated substrates is comparable to that of bare titanium. When in direct contact with fibroblasts or bacteria, marginal adhesion for both species occurs on coating imperfections. Because photopolymerization can easily be adapted to surface patterning, smart devices that promote both osseointegration (in non-coated areas) and prevent cell overgrowth and biofilm formation (in coated areas) demonstrate practical potential.

Preparation and Application of Quaternized Chitosan- and AgNPs-Base Synergistic Antibacterial Hydrogel for Burn Wound Healing

Infection is the major reason that people die from burns; however, traditional medical dressings such as gauze cannot restrain bacterial growth and enhance the healing process. Herein, an organic- and inorganic-base hydrogel with antibacterial activities was designed and prepared to treat burn wounds. Oxidized dextran (ODex) and adipic dihydrazide grafted hyaluronic acid (HA-ADH) were prepared, mixed with quaternized chitosan (HACC) and silver nanoparticles to fabricate Ag@ODex/HA-ADH/HACC hydrogel. The hydrogel, composed of nature biomaterials, has a good cytocompatibility and biodegradability. Moreover, the hydrogel has an excellent antibacterial ability and presents fast healing for burn wounds compared with commercial Ag dressings. The Ag@ODex/HA-ADH/HACC hydrogel will be a promising wound dressing to repair burn wounds and will significantly decrease the possibility of bacterial infection.

Recent breakthroughs of antibacterial and antiviral protective polymeric materials during COVID-19 pandemic and after pandemic: Coating, packaging, and textile applications

The global epidemic owing to COVID-19 has generated awareness to ensuring best practices for avoiding the microorganism spread. Indeed, because of the increase in infections caused by bacteria and viruses such as SARS-CoV-2, the global demand for antimicrobial materials is growing. New technologies by using polymeric systems are of great interest. Virus transmission by contaminated surfaces leads to the spread of infectious diseases, so antimicrobial coatings are significant in this regard. Moreover, antimicrobial food packaging is beneficial to prevent the spread of microorganisms during food processing and transportation. Furthermore, antimicrobial textiles show an effective role. We aim to provide a review of prepared antimicrobial polymeric materials for use in coating, food packaging, and textile during the COVID-19 pandemic and after pandemic.