Showing papers on "Self-healing hydrogels published in 2019"

Hydrogels in Medicine and Pharmacy : Fundamentals

Abstract: Hydrogels in medicine and pharmacy , Hydrogels in medicine and pharmacy , کتابخانه مرکزی دانشگاه علوم پزشکی تهران

Adhesive Hemostatic Conducting Injectable Composite Hydrogels with Sustained Drug Release and Photothermal Antibacterial Activity to Promote Full-Thickness Skin Regeneration During Wound Healing

Abstract: Developing injectable nanocomposite conductive hydrogel dressings with multifunctions including adhesiveness, antibacterial, and radical scavenging ability and good mechanical property to enhance full-thickness skin wound regeneration is highly desirable in clinical application. Herein, a series of adhesive hemostatic antioxidant conductive photothermal antibacterial hydrogels based on hyaluronic acid-graft-dopamine and reduced graphene oxide (rGO) using a H2 O2 /HPR (horseradish peroxidase) system are prepared for wound dressing. These hydrogels exhibit high swelling, degradability, tunable rheological property, and similar or superior mechanical properties to human skin. The polydopamine endowed antioxidant activity, tissue adhesiveness and hemostatic ability, self-healing ability, conductivity, and NIR irradiation enhanced in vivo antibacterial behavior of the hydrogels are investigated. Moreover, drug release and zone of inhibition tests confirm sustained drug release capacity of the hydrogels. Furthermore, the hydrogel dressings significantly enhance vascularization by upregulating growth factor expression of CD31 and improve the granulation tissue thickness and collagen deposition, all of which promote wound closure and contribute to a better therapeutic effect than the commercial Tegaderm films group in a mouse full-thickness wounds model. In summary, these adhesive hemostatic antioxidative conductive hydrogels with sustained drug release property to promote complete skin regeneration are an excellent wound dressing for full-thickness skin repair.

Plant-inspired adhesive and tough hydrogel based on Ag-Lignin nanoparticles-triggered dynamic redox catechol chemistry

Abstract: Adhesive hydrogels have gained popularity in biomedical applications, however, traditional adhesive hydrogels often exhibit short-term adhesiveness, poor mechanical properties and lack of antibacterial ability. Here, a plant-inspired adhesive hydrogel has been developed based on Ag-Lignin nanoparticles (NPs)triggered dynamic redox catechol chemistry. Ag-Lignin NPs construct the dynamic catechol redox system, which creates long-lasting reductive-oxidative environment inner hydrogel networks. This redox system, generating catechol groups continuously, endows the hydrogel with long-term and repeatable adhesiveness. Furthermore, Ag-Lignin NPs generate free radicals and trigger self-gelation of the hydrogel under ambient environment. This hydrogel presents high toughness for the existence of covalent and non-covalent interaction in the hydrogel networks. The hydrogel also possesses good cell affinity and high antibacterial activity due to the catechol groups and bactericidal ability of Ag-Lignin NPs. This study proposes a strategy to design tough and adhesive hydrogels based on dynamic plant catechol chemistry.

Engineering Bioactive Self-Healing Antibacterial Exosomes Hydrogel for Promoting Chronic Diabetic Wound Healing and Complete Skin Regeneration.

Abstract: Rationale: Chronic nonhealing diabetic wound therapy and complete skin regeneration remains a critical clinical challenge. The controlled release of bioactive factors from a multifunctional hydrogel was a promising strategy to repair chronic wounds. Methods: Herein, for the first time, we developed an injectable, self-healing and antibacterial polypeptide-based FHE hydrogel (F127/OHA-EPL) with stimuli-responsive adipose-derived mesenchymal stem cells exosomes (AMSCs-exo) release for synergistically enhancing chronic wound healing and complete skin regeneration. The materials characterization, antibacterial activity, stimulated cellular behavior and in vivo full-thickness diabetic wound healing ability of the hydrogels were performed and analyzed. Results: The FHE hydrogel possessed multifunctional properties including fast self-healing process, shear-thinning injectable ability, efficient antibacterial activity, and long term pH-responsive bioactive exosomes release behavior. In vitro, the FHE@exosomes (FHE@exo) hydrogel significantly promoted the proliferation, migration and tube formation ability of human umbilical vein endothelial cells (HUVECs). In vivo, the FHE@exo hydrogel significantly enhanced the healing efficiency of diabetic full-thickness cutaneous wounds, characterized with enhanced wound closure rates, fast angiogenesis, re-epithelization and collagen deposition within the wound site. Moreover, the FHE@exo hydrogel displayed better healing outcomes than those of exosomes or FHE hydrogel alone, suggesting that the sustained release of exosomes and FHE hydrogel can synergistically facilitate diabetic wound healing. Skin appendages and less scar tissue also appeared in FHE@exo hydrogel treated wounds, indicating its potent ability to achieve complete skin regeneration. Conclusion: This work offers a new approach for repairing chronic wounds completely through a multifunctional hydrogel with controlled exosomes release.

Pure PEDOT:PSS hydrogels

Abstract: Hydrogels of conducting polymers, particularly poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), provide a promising electrical interface with biological tissues for sensing and stimulation, owing to their favorable electrical and mechanical properties. While existing methods mostly blend PEDOT:PSS with other compositions such as non-conductive polymers, the blending can compromise resultant hydrogels’ mechanical and/or electrical properties. Here, we show that designing interconnected networks of PEDOT:PSS nanofibrils via a simple method can yield high-performance pure PEDOT:PSS hydrogels. The method involves mixing volatile additive dimethyl sulfoxide (DMSO) into aqueous PEDOT:PSS solutions followed by controlled dry-annealing and rehydration. The resultant hydrogels exhibit a set of properties highly desirable for bioelectronic applications, including high electrical conductivity (~20 S cm−1 in PBS, ~40 S cm−1 in deionized water), high stretchability (> 35% strain), low Young’s modulus (~2 MPa), superior mechanical, electrical and electrochemical stability, and tunable isotropic/anisotropic swelling in wet physiological environments. Hydrogels of conducting polymers provide an electrical interface with biological tissues for sensing and stimulation, but currently have compromised mechanical and electrical properties. Here, the authors show a simple method to achieve pure PEDOT:PSS hydrogels that exhibit superior mechanical and electrical properties, stability, and tunable swelling.

Mechanoresponsive self-growing hydrogels inspired by muscle training

Abstract: Living tissues, such as muscle, autonomously grow and remodel themselves to adapt to their surrounding mechanical environment through metabolic processes. By contrast, typical synthetic materials cannot grow and reconstruct their structures once formed. We propose a strategy for developing “self-growing” polymeric materials that respond to repetitive mechanical stress through an effective mechanochemical transduction. Robust double-network hydrogels provided with a sustained monomer supply undergo self-growth, and the materials are substantially strengthened under repetitive loading through a structural destruction-reconstruction process. This strategy also endows the hydrogels with tailored functions at desired positions by mechanical stamping. This work may pave the way for the development of self-growing gel materials for applications such as soft robots and intelligent devices.

Advances in crosslinking strategies of biomedical hydrogels

Abstract: Biomedical hydrogels as sole repair matrices or combined with pre-seeded cells and bioactive growth factors are extensively applied in tissue engineering and regenerative medicine. Hydrogels normally provide three dimensional structures for cell adhesion and proliferation or the controlled release of the loading of drugs or proteins. Various physiochemical properties of hydrogels endow them with distinct applications. In this review, we present the commonly used crosslinking method for hydrogel synthesis involving physical and chemical crosslinks and summarize their current progress and future perspectives.

Mussel-inspired, antibacterial, conductive, antioxidant, injectable composite hydrogel wound dressing to promote the regeneration of infected skin.

Abstract: 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.

Hydrogels and Their Applications in Targeted Drug Delivery.

Abstract: Conventional drug delivery approaches are plagued by issues pertaining to systemic toxicity and repeated dosing. Hydrogels offer convenient drug delivery vehicles to ensure these disadvantages are minimized and the therapeutic benefits from the drug are optimized. With exquisitely tunable physical properties that confer them great controlled drug release features and the merits they offer for labile drug protection from degradation, hydrogels emerge as very efficient drug delivery systems. The versatility and diversity of the hydrogels extend their applications beyond targeted drug delivery also to wound dressings, contact lenses and tissue engineering to name but a few. They are 90% water, and highly porous to accommodate drugs for delivery and facilitate controlled release. Herein we discuss hydrogels and how they could be manipulated for targeted drug delivery applications. Suitable examples from the literature are provided that support the recent advancements of hydrogels in targeted drug delivery in diverse disease areas and how they could be suitably modified in very different ways for achieving significant impact in targeted drug delivery. With their enormous amenability to modification, hydrogels serve as promising delivery vehicles of therapeutic molecules in several disease conditions, including cancer and diabetes.

Overview of natural hydrogels for regenerative medicine applications

Abstract: Hydrogels from different materials can be used in biomedical field as an innovative approach in regenerative medicine. Depending on the origin source, hydrogels can be synthetized through chemical and physical methods. Hydrogel can be characterized through several physical parameters, such as size, elastic modulus, swelling and degradation rate. Lately, research is focused on hydrogels derived from biologic materials. These hydrogels can be derived from protein polymers, such as collage, elastin, and polysaccharide polymers like glycosaminoglycans or alginate among others. Introduction of decellularized tissues into hydrogels synthesis displays several advantages compared to natural or synthetic based hydrogels. Preservation of natural molecules such as growth factors, glycans, bioactive cryptic peptides and natural proteins can promote cell growth, function, differentiation, angiogenesis, anti-angiogenesis, antimicrobial effects, and chemotactic effects. Versatility of hydrogels make possible multiple applications and combinations with several molecules on order to obtain the adequate characteristic for each scope. In this context, a lot of molecules such as cross link agents, drugs, grow factors or cells can be used. This review focuses on the recent progress of hydrogels synthesis and applications in order to classify the most recent and relevant matters in biomedical field.

Smart Hydrogels in Tissue Engineering and Regenerative Medicine.

Abstract: The field of regenerative medicine has tremendous potential for improved treatment outcomes and has been stimulated by advances made in bioengineering over the last few decades. The strategies of engineering tissues and assembling functional constructs that are capable of restoring, retaining, and revitalizing lost tissues and organs have impacted the whole spectrum of medicine and health care. Techniques to combine biomimetic materials, cells, and bioactive molecules play a decisive role in promoting the regeneration of damaged tissues or as therapeutic systems. Hydrogels have been used as one of the most common tissue engineering scaffolds over the past two decades due to their ability to maintain a distinct 3D structure, to provide mechanical support for the cells in the engineered tissues, and to simulate the native extracellular matrix. The high water content of hydrogels can provide an ideal environment for cell survival, and structure which mimics the native tissues. Hydrogel systems have been serving as a supportive matrix for cell immobilization and growth factor delivery. This review outlines a brief description of the properties, structure, synthesis and fabrication methods, applications, and future perspectives of smart hydrogels in tissue engineering.

Stimuli-Responsive Conductive Nanocomposite Hydrogels with High Stretchability, Self-Healing, Adhesiveness, and 3D Printability for Human Motion Sensing.

Abstract: Self-healing, adhesive conductive hydrogels are of great significance in wearable electronic devices, flexible printable electronics, and tissue engineering scaffolds. However, designing self-healing hydrogels with multifunctional properties such as high conductivity, excellent mechanical property, and high sensitivity remains a challenge. In this work, the conductive self-healing nanocomposite hydrogels based on nanoclay (laponite), multiwalled carbon nanotubes (CNTs), and N-isopropyl acrylamide are presented. The presented nanocomposite hydrogels displayed good electrical conductivity, rapid self-healing and adhesive properties, flexible and stretchable mechanical properties, and high sensitivity to near-infrared light and temperature. These excellent properties of the hydrogels are demonstrated by the three-dimensional (3D) bulky pressure-dependent device, human activity monitoring device, and 3D printed gridding scaffolds. Good cytocompatibility of the conductive hydrogels was also evaluated with L929...

Recent Progress in Biomimetic Anisotropic Hydrogel Actuators.

Abstract: Polymeric hydrogel actuators refer to intelligent stimuli-responsive hydrogels that could reversibly deform upon the trigger of various external stimuli. They have thus aroused tremendous attention and shown promising applications in many fields including soft robots, artificial muscles, valves, and so on. After a brief introduction of the driving forces that contribute to the movement of living creatures, an overview of the design principles and development history of hydrogel actuators is provided, then the diverse anisotropic structures of hydrogel actuators are summarized, presenting the promising applications of hydrogel actuators, and highlighting the development of multifunctional hydrogel actuators. Finally, the existing challenges and future perspectives of this exciting field are discussed.

Self-Healing Hydrogels: The Next Paradigm Shift in Tissue Engineering?

Abstract: Given their durability and long-term stability, self-healable hydrogels have, in the past few years, emerged as promising replacements for the many brittle hydrogels currently being used in preclinical or clinical trials. To this end, the incompatibility between hydrogel toughness and rapid self-healing remains unaddressed, and therefore most of the self-healable hydrogels still face serious challenges within the dynamic and mechanically demanding environment of human organs/tissues. Furthermore, depending on the target tissue, the self-healing hydrogels must comply with a wide range of properties including electrical, biological, and mechanical. Notably, the incorporation of nanomaterials into double-network hydrogels is showing great promise as a feasible way to generate self-healable hydrogels with the above-mentioned attributes. Here, the recent progress in the development of multifunctional and self-healable hydrogels for various tissue engineering applications is discussed in detail. Their potential applications within the rapidly expanding areas of bioelectronic hydrogels, cyborganics, and soft robotics are further highlighted.

Review of alginate-based hydrogel bioprinting for application in tissue engineering.

Abstract: The dawn of 3D printing in medicals has pinned the domain with hopes of vitality in many patients combating with multitude of diseases. Also entitled as Bio-printing, this is appertained to its sequential printing of precursor ink, embodying cells and polymer/composite, in predetermined trajectory. Precursor ink, in addition to cells, constitutes predominantly hydrogels ascribed to its biodegradability and mimic ability of body's anatomy and mechanical features, e.g. bones, etc. This review paper is devoted to explicate bio-printing (3D/4D) of alginate hydrogels, which are the extract from brown algae, through extrusion additive manufacturing. Alginates are salt derivative of alginic acid and constitute long chain of polysaccharides, which furnishes pliability and gelling adeptness to its structure. Alginate hydrogel (employed for extrusion) can be pristine or composite relying on the requisite properties (target application controlled or in-vivo environment) e.g. Alginate-natural (gelatin/agarose/collagen/hyaluronic acid/etc.) and Alginate-synthetic (polyethylene glycol (PEG)/pluronic F127/etc.). Extrusion additive manufacturing of Alginate is preponderate among others with its uncomplicated processing, material efficiency (cut down on wastage), and outspread adaptability for viscosities (0.03-6*104 Pa.s) but the procedure is limited by resolution(200 ?m) in addition to accuracy. However, 3D-fabricated bio-structures display rigidness (unvarying with conditions) that lacks smart response which is reassured by accounting time feature as noteworthy accessory to printing, interpreting as 4D Bio-printing. This review propounds specific processing itinerary for alginate (meanwhile traversing across its composites/blends with natural and synthetic consideration) in extrusion along with its pre-/during/post-processing parameters intrinsic to process. Furthermore, propensity is also presented in its (Alginate extrusion processing) application for tissue engineering, i.e. bones, cartilage (joints), brain (neural), ear, heart (cardiac), eyes (corneal), etc. due to worldwide quandary over accessibility to natural organs for diverse kinds of diseases. Additionally, the review contemplates recently invented advance printing i.e. 4D printing for biotic species with its challenges and future opportunities.

Supramolecular nanofibrillar hydrogels as highly stretchable, elastic and sensitive ionic sensors

Abstract: There is a growing demand for flexible and stretchable strain/pressure sensors for different applications. However, existing conductors usually cannot meet all the requirements for use in next-generation wearable sensors. In this work, we demonstrate a new class of nature-inspired ionic conductors based on supramolecular sodium alginate (SA) nanofibrillar double network (DN) hydrogels with complex shapes by injection. Owing to their dermis-mimicking structures, these hydrogels exhibit unique features, such as high transparency (99.6%), high tension/compression strength (0.750 MPa/4 MPa), high stretchability (3120%), high toughness (4.77 MJ m−3) and superior elasticity (100%) at high strain (1000%). In particular, the use of salts (e.g., NaCl) as triggers in supramolecular assembly combining SA makes the hydrogels ideal ionic conductors. The ionic conductors were demonstrated as strain sensors with high sensitivity to an extremely broad strain window (0.3–1800%) and a low applied voltage (down to 0.04 V), as well as with high pressure sensitivity (1.45 kPa−1). These hydrogel-based ionic sensors may find applications in sports monitoring, human/machine interfaces and soft robotics.

Design and Applications of Photoresponsive Hydrogels.

Abstract: Hydrogels are the most relevant biochemical scaffold due to their tunable properties, inherent biocompatibility, and similarity with tissue and cell environments. Over the past decade, hydrogels have developed from static materials to "smart" responsive materials adapting to various stimuli, such as pH, temperature, chemical, electrical, or light. Light stimulation is particularly interesting for many applications because of the capability of contact-free remote manipulation of biomaterial properties and inherent spatial and temporal control. Moreover, light can be finely adjusted in its intrinsic properties, such as wavelength and intensity (i.e., the energy of an individual photon as well as the number of photons over time). Water is almost transparent for light in the photochemically relevant range (NIR-UV), thus hydrogels are well-suited scaffolds for light-responsive functionality. Hydrogels' chemical and physical variety combined with light responsiveness makes photoresponsive hydrogels ideal candidates for applications in several fields, ranging from biomaterials, medicine to soft robotics. Herein, the progress and new developments in the field of light-responsive hydrogels are elaborated by first introducing the relevant photochemistries before discussing selected applications in detail.

Scaffolding strategies for tissue engineering and regenerative medicine applications

Abstract: During the past two decades, tissue engineering and the regenerative medicine field have invested in the regeneration and reconstruction of pathologically altered tissues, such as cartilage, bone, skin, heart valves, nerves and tendons, and many others. The 3D structured scaffolds and hydrogels alone or combined with bioactive molecules or genes and cells are able to guide the development of functional engineered tissues, and provide mechanical support during in vivo implantation. Naturally derived and synthetic polymers, bioresorbable inorganic materials, and respective hybrids, and decellularized tissue have been considered as scaffolding biomaterials, owing to their boosted structural, mechanical, and biological properties. A diversity of biomaterials, current treatment strategies, and emergent technologies used for 3D scaffolds and hydrogel processing, and the tissue-specific considerations for scaffolding for Tissue engineering (TE) purposes are herein highlighted and discussed in depth. The newest procedures focusing on the 3D behavior and multi-cellular interactions of native tissues for further use for in vitro model processing are also outlined. Completed and ongoing preclinical research trials for TE applications using scaffolds and hydrogels, challenges, and future prospects of research in the regenerative medicine field are also presented.

A Self-Healing Integrated All-in-One Zinc-Ion Battery.

Abstract: The self-healing of zinc-ion batteries (ZIBs) will not only significantly improve the durability and extend the lifetime of devices, but also decrease electronic waste and economic cost. A poly(vinyl alcohol)/zinc trifluoromethanesulfonate (PVA/Zn(CF3 SO3 )2 ) hydrogel electrolyte was fabricated by a facile freeze/thaw strategy. PVA/Zn(CF3 SO3 )2 hydrogels possess excellent ionic conductivity and stable electrochemical performance. Such hydrogel electrolytes can autonomously self-heal by hydrogen bonding without any external stimulus. All-in-one integrated ZIBs can be assembled by incorporating the cathode, separator, and anode into hydrogel matrix since the fabrication of PVA/Zn(CF3 SO3 )2 hydrogel is a process of converting the liquid to quasi-solid state. The ZIBs show an outstanding self-healing and can recover electrochemical performance completely even after several cutting/healing cycles.

Stretchable, Injectable, and Self-Healing Conductive Hydrogel Enabled by Multiple Hydrogen Bonding toward Wearable Electronics

Abstract: Conducting polymer hydrogels have been employed in diverse fields such as energy storage and bioelectronics, which possess both the mechanical properties of hydrogels and electronic transport properties of conducting polymers. However, the rigid and fragile nature of conducting polymers hinders the long-time stability of the hydrogels and limits their applications in emerging flexible electronic devices. In this work, we have developed a novel type of multifunctional conductive polymer hydrogel, of which high conductivity is integrated with excellent stretchability, injectability, and rapid self-healing capability, by incorporating multiple hydrogen-bonding 2-ureido-4[1H]-pyrimidinone (UPy) groups as cross-linking points into a brittle polyaniline/poly(4-styrenesulfonate) (PANI/PSS) network. The formation of the interpenetrating PANI/PSS network offers the hydrogel electronic conduction assisted by ionic transport, showing a conductivity of 13 S/m and a linear response (gauge factor = 3.4) to external str...

Tough, Adhesive, Self-Healable, and Transparent Ionically Conductive Zwitterionic Nanocomposite Hydrogels as Skin Strain Sensors.

Abstract: It is desired to create skin strain sensors composed of multifunctional conductive hydrogels with excellent toughness and adhesion properties to sustain cyclic loadings during use and facilitate the electrical signal transmission. Herein, we prepared transparent, compliant, and adhesive zwitterionic nanocomposite hydrogels with excellent mechanical properties. The incorporated zwitterionic polymers can form interchain dipole–dipole associations to offer additional physical cross-linking of the network. The hydrogels show a high fracture elongation up to 2000%, a fracture strength up to 0.27 MPa, and a fracture toughness up to 2.45 MJ/m3. Moreover, the reversible physical interaction imparts the hydrogels with rapid self-healing ability without any stimuli. The hydrogels are adhesive to many surfaces including polyelectrolyte hydrogels, skin, glasses, silicone rubbers, and nitrile rubbers. The presence of abundant zwitterionic groups facilitates ionic conductivity in the hydrogels. The combination of these...

Inorganic Salts Induce Thermally Reversible and Anti‐Freezing Cellulose Hydrogels

Abstract: Inspired by the anti-freezing mechanisms found in nature, ionic compounds (ZnCl2 /CaCl2 ) are integrated into cellulose hydrogel networks to enhance the freezing resistance. In this work, cotton cellulose is dissolved by a specially designed ZnCl2 /CaCl2 system, which endows the cellulose hydrogels specific properties such as excellent freeze-tolerance, good ion conductivity, and superior thermal reversibility. Interestingly, the rate of cellulose coagulation could be promoted by the addition of extra water or glycerol. This new type of cellulose-based hydrogel may be suitable for the construction of flexible devices used at temperature as low as -70 °C.

Muscle-like fatigue-resistant hydrogels by mechanical training

Abstract: Skeletal muscles possess the combinational properties of high fatigue resistance (1,000 J/m2), high strength (1 MPa), low Young's modulus (100 kPa), and high water content (70 to 80 wt %), which have not been achieved in synthetic hydrogels. The muscle-like properties are highly desirable for hydrogels' nascent applications in load-bearing artificial tissues and soft devices. Here, we propose a strategy of mechanical training to achieve the aligned nanofibrillar architectures of skeletal muscles in synthetic hydrogels, resulting in the combinational muscle-like properties. These properties are obtained through the training-induced alignment of nanofibrils, without additional chemical modifications or additives. In situ confocal microscopy of the hydrogels' fracturing processes reveals that the fatigue resistance results from the crack pinning by the aligned nanofibrils, which require much higher energy to fracture than the corresponding amorphous polymer chains. This strategy is particularly applicable for 3D-printed microstructures of hydrogels, in which we can achieve isotropically fatigue-resistant, strong yet compliant properties.

Recent advances of self-assembling peptide-based hydrogels for biomedical applications

Abstract: Peptide-based hydrogels have been proven to be preeminent biomedical materials due to their high water content, tunable mechanical stability, great biocompatibility and excellent injectability. The ability of peptide-based hydrogels to provide extracellular matrix-mimicking environments opens up opportunities for their biomedical applications in fields such as drug delivery, tissue engineering, and wound healing. In this review, we first describe several methods commonly used for the fabrication of robust peptide-based hydrogels, including spontaneous hydrogelation, enzyme-controlled hydrogelation and cross-linking-enhanced hydrogelation. We then introduce some representative studies on their applications in drug delivery and antitumor therapy, antimicrobial and wound healing materials, and 3D bioprinting and tissue engineering. We hope that this review facilitates the advances of hydrogels in biomedical applications.