This volume collects the recent progress in cellulose-based hydrogels, including gels prepared from natural cellulose and its derivatives, cellulose graft co-polymers, and composite gels based on ...cellulose, covering key aspects of cellulose-based hydrogels, including design, characterization, as well as application-focused research.
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Infection is a major obstacle to wound healing. To enhance the healing of infected wounds, dressings with antibacterial activities and multifunctional properties to promote wound ...healing are highly desirable. Herein, gelatin-grafted-dopamine (GT-DA) and polydopamine-coated carbon nanotubes (CNT-PDA) were used to engineer antibacterial, adhesive, antioxidant and conductive GT-DA/chitosan/CNT composite hydrogels through the oxidative coupling of catechol groups using a H2O2/HRP (horseradish peroxidase) catalytic system. The addition of the antibiotic doxycycline endowed the hydrogels with antimicrobial activity to treat infected full-thickness defect wounds. Additionally, CNT-PDA endowed these hydrogels with an excellent photothermal effect, leading to good in vitro and in vivo antibacterial activities against Gram-positive and Gram-negative bacteria. The catechol group and polydopamine imparted tissue adhesiveness, and the hemostatic and antioxidant abilities of these hydrogels were also investigated. The porosity, degradability, swelling, rheological, mechanical, and conductive behaviors of these hydrogels were finely regulated by changing the concentration of CNT-PDA. Hemolysis and cytocompatibility tests using L929 fibroblast cells confirmed the good biocompatibility of these hydrogels. The wound closure, collagen deposition, histomorphological examination and immunofluorescence staining results demonstrated the excellent effects of these hydrogels in an infected full-thickness mouse skin defect wound. In summary, the adhesive antibacterial and conductive GT-DA/chitosan/CNT hydrogels showed great potential as multifunctional bioactive dressings for the treatment of infected wounds.
•A series of conductive adhesive self-healing nanocomposite hydrogels were synthesized.•These hydrogels showed remarkable in vivo photothermal antibacterial property.•The hydrogels exhibited good ...hemostatic property and biodegradability.•The hydrogels showed excellent treatment effect for infected wound via photothermal therapy.
Bacteria-infected wounds and antibiotics abuse have become significant burdens to patients and medical systems. Thus, designing a non-antibiotic-dependent multifunctional wound dressing for treating bacteria-infected wounds is urgently desired. Herein, a series of conductive self-healing and adhesive nanocomposite hydrogels with a remarkable photothermal antibacterial property based on N-carboxyethyl chitosan (CEC) and benzaldehyde-terminated Pluronic F127/carbon nanotubes (PF127/CNT) were developed, and their great potential as agents for photothermal therapy (PTT) of infected wounds was demonstrated in vivo. The hydrogels exhibited a suitable gelation time, stable mechanical properties, hemostatic properties, high water absorbency, and good biodegradability. After loading the antibiotic moxifloxacin hydrochloride, the hydrogels showed a pH-responsive release profile and good antibacterial activity. The tissue adhesive property of the hydrogels allowed them to have a good hemostatic effect in a mouse liver trauma model, mouse liver incision model, and mouse tale amputation model. The addition of CNTs endowed the hydrogel with in vitro/in vivo photothermal antimicrobial activity and good conductivity. An in vivo experiment in a mouse full-thickness skin wound-infected model indicated that the hydrogels had an excellent treatment effect leading to significantly enhanced wound closure healing, collagen deposition, and angiogenesis. In summary, these conductive photothermal self-healing nanocomposite hydrogels as multifunctional wound dressing exhibit great potential for the treatment of infected wounds.
To satisfy the ever‐accelerated demands for advanced engineering biomaterials with excellent physicochemical properties, injectable and recoverable dual‐network (DN) hydrogels based on ...poly(l‐lysine)‐graft‐4‐hydroxyphenylacetic acid (PLL‐g‐HPA) and Aga are constructed by simply mixing PLL‐g‐HPA/HRP and PLL‐g‐HPA/H2O2 in Aga through enzyme‐catalyzed cross‐linkage of PLL‐g‐HPA and temperature‐adjusted sol‐gel transition of Aga. The recoverable and injectable performances of hydrogels are attributed to the reversible sol‐gel transitional feature of Aga and enzymatically cross‐linked reaction of PLL‐g‐HPA. DN hydrogels have fast and adjusted gelation time, connective pore structure, superior formability, and good biocompatibility. The helically structural Aga network endows the hydrogels with good mechanical strength and superior stability in extreme condition. Schiff‐base effect between amino in skin tissues and carbonyl formed by the oxidation of phenol groups in hydrogel imparts the hydrogels to promising tissue attachment. Bursting pressure assay illustrates that the bursting pressure (34.5 ± 2.4 kPa) for 13.6% DN hydrogel is much higher than arterial blood pressure (16 kPa). The incorporated cationic PLL‐g‐HPA gives the hydrogels remarkable antibacterial ability, which effectively prevents the bacterial infection. In conclusion, the DN hydrogel with good cytocompatibility, inherently antibacterial ability, tissue adhesion, and excellent stability in extreme environment is probably able to become a promising candidate as potential wound dressings.
Combining a reversible sol–gel transitional Aga network with an enzyme‐catalyzed cross‐linked PLL network, an injectable, rapid‐formed, and recoverable DN hydrogel is constructed. The DN gels possessing the strengths of PLL and Aga exhibit inherent anti‐bacterial properties, tissue adhesiveness, and mechanical stability. The DN hydrogels with excellent comprehensive performances could potentially become an excellent candidate as tissue adhesive dressings.
The incidence of ocular diseases such as diabetic retinopathy, macular degeneration, and glaucoma is projected to increase significantly by 2050. Aside from severely affecting quality of life, visual ...impairment can also increase morbidity and mortality in non-ocular diseases. Hydrogels, which can be designed to mimic normal tissue with adequate biosafety, have played an important role in the biomedical field. Studies have shown that hydrogels can extend the residence time of drugs, maintain drug release, and improve the bioavailability of drugs. New hydrogel-based materials and designs are therefore crucial for advancing ocular disease research and are a trending topic in the field. This article reviews the construction methods, related chemicals, and performance characteristics of novel hydrogels based on physical, chemical interactions and composite hydrogels with nanoparticles. The design and applications of these new hydrogels in the treatment of ocular diseases such as uveitis and macular diseases are also discussed.
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•Gelatin–PEG composite hydrogel fibers were prepared by gel-spinning.•DCMC could improve the biological properties of the hydrogel fibers.•DCMC was an ideal crosslinking reagent to fix the hydrogel ...fibers.•The hydrogel fiber was well-suited for biomedical applications with low cytotoxicity.
Gelatin-based composite hydrogel fibers were prepared by gel-spinning with PEG6000 as the modifier. Dialdehyde carboxymethyl cellulose (DCMC), as an ideal crosslinking reagent for protein, was used to fix the composite hydrogel fibers. Then the biological properties of the hydrogel fibers for wound dressings were evaluated. The results indicate that the hydrogen bond interactions and CN linkages between gelatin and DCMC can be formed. The addition of DCMC can efficiently improve the mechanical properties, enzymatic stability and blood compatibility of the hydrogel fibers. Crosslinking with DCMC can reduce the degree of swelling of the hydrogel fibers, which is beneficial for hydrogel fibers to avoid undesired reduction in mechanical properties. Moreover, the composite hydrogel fibers present three-dimensional structure, porous networks and low cytotoxicity. The study suggests that DCMC is an effective crosslinking reagent for biomaterials fixation. The developed composite hydrogel fibers can be well-suited for biomedical applications such as wound dressings.
Generating electricity in hydrogel is very important but remains difficult. Hydrogel with electricity generation capability is more capable in bio‐relevant tasks such as tissue engineering, ...artificial skin, or medical treatment, because electricity is indispensable in regulating physiological activities. Here, a porous and phase blending hydrogel structure for effective piezoionic electricity generation is developed. Dynamic electric field is generated taking advantage of the difference in streaming speeds of sodium and chloride in the material. Microscopic porosity and hydrophilic‐hydrophobic phase blending are the two key factors for prominent piezoionic performance. Voltages as high as 600 mV are first realized in hydrogels in response to medical ultrasound stimulation. The hydrogel structure is also subjective to effective substance exchange and can actively enrich proteins from surroundings under mechanical stimuli. Preliminary applications in neural stimulation, constructing complex spatial‐temporal chemical and electric field distribution patterns, mimetic tactile sensor, sample pretreatment in fast detection, and enzyme immobilization are demonstrated.
Potent piezoionic electricity is achieved in a porous and phase hybrid hydrogel, taking advantage of the engineered differences in flow velocities between sodium and chloride ions upon mechanical stimuli. Dynamic voltages up to 600 mV and effective protein adsorptions are obtained. Potential application in nerve function adjustment, mimetic tactile sensors, hydrogel P/N heterojunction building, and enzyme immobilization are proposed.
A low-cost wound dressing with efficient sterilization and exhibiting long-term antimicrobial activity is required for the absence of antibiotics, particularly for the wound healing of patients with ...chronic wounds or long-term activities under low sanitary conditions (e.g., battlefield and poverty-stricken areas). Here, a dual dynamic crosslinking hydrogel was introduced. The hydrogel was supported by gallic acid grafted chitosan and oxidized Bletilla striata polysaccharide as the scaffold and formed by two types of dynamic crosslinking: Schiff base, pyrogallol-Fe3+. It exhibited its adhesion, self-healing, good biocompatibility, great intrinsic antibacterial, and near-infrared photothermal conversion activity. In addition, the use of two types of polysaccharides, and the existence of the photothermal effect, making the hydrogel has the functions of accelerating gelation, degradation on-demand, and rapid sterilization. In brief, such cost-effective multifunctional hydrogel could support wound healing in patients prone to bacterial infection, and it has a promising application in the care of infected wounds.
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Thromboembolic and infectious complications stemming from the use of cardiovascular medical devices are still common and result in significant morbidity and mortality. There is no strategy to date ...that effectively addresses both challenges at the same time. Various surface modification strategies (e.g., silver, heparin, and liquid‐impregnated surfaces) are proposed yet each has several limitations and shortcomings. Here, it is shown that the incorporation of an ultrathin and mechanically robust hydrogel layer reduces bacterial adhesion to medical‐grade tubing by 95%. It is additionally demonstrated, through a combination of in vitro and in vivo tests, that the hydrogel layer significantly reduces the formation and adhesion of blood clots to the tubing without affecting the blood's intrinsic clotting ability. The adhesion of clots to the tubing walls is reduced by over 90% (in vitro model), which results in an ≈60% increase in the device occlusion time (time before closure due to clot formation) in an in vivo porcine model. The advantageous properties of this passive coating make it a promising surface material candidate for medical devices interfacing with blood.
Thromboembolic and infectious complications associated with use of cardiovascular devices remain common and increase patient morbidity and mortality. Currently, no single technology addresses these challenges. Here, it is shown that applying a thin hydrogel layer onto medical tubing reduces friction and the adhesion of bacteria and blood components. This coating presents a promising surface material for medical devices interfacing with blood.
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We report injectable nanoengineered hemostats for enhanced wound healing and tissue regeneration. The nanoengineered system consists of the natural polysaccharide, κ-carrageenan ...(κCA), loaded with synthetic two-dimensional (2D) nanosilicates. Nanoengineered hydrogels showed shear-thinning characteristics and can be injected for minimally invasive approaches. The injectable gels can be physically crosslinked in presence of monovalent ions to form mechanically strong hydrogels. By controlling the ratio between κCA and nanosilicates, compressive stiffness of crosslinked hydrogels can be modulated between 20 and 200 kPa. Despite high mechanical stiffness, nanocomposite hydrogels are highly porous with an interconnected network. The addition of nanosilicates to κCA increases protein adsorption on nanocomposite hydrogels that results in enhance cell adhesion and spreading, increase platelets binding and reduce blood clotting time. Moreover, due to presence of nanosilicates, a range of therapeutic biomacromolecules can be deliver in a sustain manner. The addition of nanosilicates significantly suppresses the release of entrap vascular endothelial growth factor (VEGF) and facilitate in vitro tissue regeneration and wound healing. Thus, this multifunctional nanocomposite hydrogel can be used as an injectable hemostat and an efficient vehicle for therapeutic delivery to facilitate tissue regeneration.
Hemorrhage is a leading cause of death in battlefield wounds, anastomosis hemorrhage and percutaneous intervention. Thus, there is a need for the development of novel bioactive materials to reduce the likelihood of hemorrhagic shock stemming from internal wounds. Here, we introduce an injectable hemostat from kappa-carrageenan and two-dimensional (2D) nanosilicates. Nanosilicates mechanically reinforce the hydrogels, provide enhanced physiological stability and accelerate the clotting time by two-fold. The sustained release of entrapped therapeutics due to presence of nanosilicates promotes enhanced wound healing. The multifunctional nanocomposite hydrogels could be used as an injectable hemostat for penetrating injury and percutaneous intervention during surgery.
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