Elastic Hydrogel Research Articles

A Simple Blocking PCR-Based Method for the Synthesis of High-Copy dsDNA Tandem Repeats.

DNA tandem repeats are frequently found in eukaryotic genomes. High-copy DNA repeats can serve as building blocks of complex DNA structures, but the in vitro synthesis of DNA repeats has been challenging due to complicated procedures and the high cost. Here, a new, simple method is developed using the strategy of blocking polymerase chain reaction for highly efficient DNA repeat expansion (BPRE). With BPRE, dsDNA fragments composed of more than 40 copies of the repeat sequence can be quickly produced, while the cost is reduced by at least 90%. As a typical application, reannealing of the dsDNA repeats generates elastic hydrogels, which shows a high capacity for doxycycline absorption and prolonged release.

Liquid Thermo-Responsive Smart Window Derived from Hydrogel

Summary Buildings account for 40% of global energy consumption, while windows are the least energy-efficient part of buildings. Conventional smart windows only regulate solar transmission. For the first time, we developed high thermal energy storage thermo-responsive smart window (HTEST smart window) by trapping the hydrogel-derived liquid within glasses. The excellent thermo-responsive optical property (90% of luminous transmittance and 68.1% solar modulation) together with outstanding specific heat capacity of liquid gives the HTEST smart window excellent energy conservation performance. Simulations suggested that HTEST window can cut off 44.6% heating, ventilation, and air-conditioning (HVAC) energy consumption compared with the normal glass in Singapore. In outdoor demonstrations, the HTEST smart window showed promising energy-saving performance in summer daytime. Compared with conventional energy-saving glasses, which need expensive equipment, the thermo-responsive liquid-trapped structure offers a disruptive strategy of easy fabrication, good uniformity, and scalability, together with soundproof functionality that opens an avenue for energy-saving buildings and greenhouses.

Enzyme-Regulated Peptide-Liquid Metal Hybrid Hydrogels as Cell Amber for Single-Cell Manipulation.

Current strategies to construct cell-based bioartificial tissues largely remain on a multicell level. Taking cell diversity into account, single-cell manipulation is urgently needed for delicate bioartificial tissue construction. Current single-cell isolation and profiling techniques involve invasive processes and thus are not applicable for single-cell manipulation. Here, we managed to fabricate peptide-liquid metal hybrid hydrogels as "cell ambers" which were suitable for single-cell isolation as well as further handling. The successful preparation of uniform liquid metal nanoparticles allowed the fabrication of peptide-liquid metal hydrogel with excellent recovery property upon mechanical destruction. The alkaline phosphatase-instructed supramolecular self-assembly process allowed the formation of microhydrogel post-filling in the PDMS template. The co-culture of the hydrogel precursor and mammalian cells realized the embedding of cells into elastic hydrogels which were the so-called cell ambers. The cell ambers turned out to be biocompatible and capable of supporting cell survival. Aided with the micro-operating system and a laser scanning confocal microscope, we could arrange these as-prepared 3D single-cell ambers into various patterns as desired. Our strategy provided the possibility to manipulate a single cell, which served as a prototype of cell architecture toward cell-based bioartificial tissue construction.

Conductive cold-resistant and elastic hydrogel: A potential bionic skin for human-machine interaction control over artificial limbs

This work enables conductive cold-resistant and elastic hydrogel for a new application in electric steering engine control, demonstrating a great potential as bionic skin for goal-directed control over artificial limbs. The photocrosslinking of acrylamide provides an elastic matrix that is functionally improved by physical crosslinking of K2CO3, carrageenan and locust bean gum. The hydrogel is highly elastic with the stress of 0.04 MPa at 650% strain, and can recover immediately after being stretched to 500% or pressed to 10% of its original length. It can keep its softness and conductivity at a low temperature of −10 °C. When an intermittent bending force is applied, it synchronously outputs the resistance variation signals between 1.1 and 0.9 times the original value. We take advantages of all these physical features to create a soft controller for the convenient manipulation of electric steering engine. We translate the bending-induced resistance variation signals into digital data of between 0 and 1023, which are then encoded to direct the electric steering engine for various controlled motility. A simple bending of hydrogel can activate the electric steering engine in 0.18 s, showing a highly-synchronous control over the dynamic response of electric steering engine in many models.

Effect of texture and structure of polysaccharide hydrogels containing maltose on release and hydrolysis of maltose during digestion: In vitro study

The release and hydrolysis of maltose from six classic polysaccharide-based hydrogels (agar, low acyl gellan, κ- and ι-carrageenan, sodium alginate and konjac glucomannan) containing 1% gelling agent and 10% maltose were compared under sequential in vivo oral, simulated gastric (SGD) and intestinal digestions (SID). The incorporation of maltose into hydrogels obstructed up to 35% maltose digestion and reduced the early stage of maltose hydrolysis by 40%–60%. The degree and the nature of obstruction were dependent on the polysaccharide structure and gel texture. Limited fragmentation of elastic and cohesive hydrogels and reduced maltose release in highly adhesive hydrogels both resulted in lower maltose release at the oral phase. The remaining large gel particles and dramatic gel microstructural changes as response to the gastric pH limited maltose release at SGD. Cumulative maltose release from oral processing and SGD contributed to initial maltose hydrolysis rate (HR) and the overall maltose hydrolysis in SID. Additionally, other factors were also involved. Release of polysaccharide from hydrogels under SGD stress and the formation of fine gel particles may have resulted in highly viscous or viscoelastic intestinal fluid and therefore decreased the speed of enzyme reaction. We believe that the information provided by the current study would help future design of hydrogel texture targeted at different incipient food component release and digestion profiles.

Fabrication and characterization of glycogen-based elastic, self-healable, and conductive hydrogels as a wearable strain-sensor for flexible e-skin

Developing natural polymer-based elastic and self-healable hydrogel materials and devices with functions similar to or beyond those of skin has received considerable attention. Such materials possess an impact on the lifetime and potential applications in various fields, such as wearable strain sensors, prosthesis, soft-robotics, and health monitoring systems. Herein, we report glycogen-based elastic, self-healable, and conductive hydrogel as a strain sensor for soft e-skin, which is comprehended by a physically cross-linked biopolymer-based system and containing iron (III) ions intercalated with poly (acrylic acid). The designed hydrogel successfully fulfills all the above-mentioned competencies; self-healing efficiency greater than 97%, fracture stress at 1.12 MPa, elongation at the break about 1420%, a fracture toughness equal to 10.17 MJm−3, and electrical conductivity of 22 S m−1. The use of nature-inspired hydrogels, by using a natural polymer as a skeleton may open new ways for the fabrication of intrinsically elastic and self-healable sensors for e-skin applications.

Effects of cryo-processing on the mechanical and biological properties of poly(vinyl alcohol)-gelatin theta-gels.

Poly(vinyl alcohol) (PVA), a synthetic, nontoxic polymer, is widely studied for use as a biomedical hydrogel due to its structural and physicomechanical properties. Depending on the synthesis method, PVA hydrogels can exhibit a range of selected characteristics-strength, creep resistance, energy dissipation, degree of crystallinity, and porosity. While the structural integrity and behavior of the hydrogel can be fine-tuned, common processing techniques result in a brittle, linear elastic material. In addition, PVA lacks functionality to engage and participate in cell adhesion, which can be a limitation for integrating PVA materials with tissue in situ. Thus, there is a need to further engineer PVA hydrogels to optimize its physicomechanical properties while enhancing cell adhesion and bioactivity. While the inclusion of gelatin into PVA hydrogels has been shown to impart cell-adhesive properties, the optimization of the mechanical properties of PVA-gelatin blends has not been studied in the context of traditional PVA hydrogel processing techniques. The incorporation of poly(ethylene glycol) with PVA prior to solidification forms an organized, cell instructive hydrogel with improved stiffness. The effect of cryo-processing, i.e., freeze-thaw (FT) cycling was elucidated by comparing 1 FT and 8 FT theta-cryo-gels and cryo-gels. To confirm the viability of the gels, human mesenchymal stem cell (hMSC) protein and sulfated glycosaminoglycan assays were performed to verify the nontoxicity and influence on hMSC differentiation. We have devised an elastic PVA-gelatin hydrogel utilizing the theta-gel and cryo-gel processing techniques, resulting in a stronger, more elastic material with greater potential as a scaffold for complex tissues.

Effects of extracellular matrix viscoelasticity on cellular behaviour.

Substantial research over the past two decades has established that extracellular matrix (ECM) elasticity, or stiffness, affects fundamental cellular processes, including spreading, growth, proliferation, migration, differentiation and organoid formation. Linearly elastic polyacrylamide hydrogels and polydimethylsiloxane (PDMS) elastomers coated with ECM proteins are widely used to assess the role of stiffness, and results from such experiments are often assumed to reproduce the effect of the mechanical environment experienced by cells in vivo. However, tissues and ECMs are not linearly elastic materials-they exhibit far more complex mechanical behaviours, including viscoelasticity (a time-dependent response to loading or deformation), as well as mechanical plasticity and nonlinear elasticity. Here we review the complex mechanical behaviours of tissues and ECMs, discuss the effect of ECM viscoelasticity on cells, and describe the potential use of viscoelastic biomaterials in regenerative medicine. Recent work has revealed that matrix viscoelasticity regulates these same fundamental cell processes, and can promote behaviours that are not observed with elastic hydrogels in both two- and three-dimensional culture microenvironments. These findings have provided insights into cell-matrix interactions and how these interactions differentially modulate mechano-sensitive molecular pathways in cells. Moreover, these results suggest design guidelines for the next generation of biomaterials, with the goal of matching tissue and ECM mechanics for in vitro tissue models and applications in regenerative medicine.

Physicochemical Investigations of Chitosan-Based Hydrogels Containing Aloe Vera Designed for Biomedical Use.

In this work, synthesis and investigations on chitosan-based hydrogels modified with Aloe vera juice are presented. These materials were synthesized by UV radiation. Investigations involved analysis of chemical structure by FTIR spectroscopy, sorption properties in physiological liquids, strength properties by texture analyzer, surface topography by Atomic Force Microscopy (AFM technique), and in vitro cytotoxicity by MTT test using L929 murine fibroblasts. Particular attention was focused both on determining the impact of the amount and the molecular weight of the crosslinker used for the synthesis as well as on the introduced additive on the properties of hydrogels. It was proven that modified hydrogels exhibited higher swelling ability. Introduced additive affected the tensile strength of hydrogels—modified materials showed 23% higher elongation. The greater amount of the crosslinker used in the synthesis, the more compact the structure, leading to the lower elasticity and lower sorption of hydrogels was reported. Above 95%, murine fibroblasts remained viable after 24 h incubation with hydrogels. It indicates that tested materials did not exhibit cytotoxicity toward these lines. Additionally, materials with Aloe vera juice were characterized by lower surface roughness. Conducted investigations allowed us to state that such modified hydrogels may be considered as useful for biomedical purposes.

Caudicles in vandoid orchids: A carotenoid-based soft material with unique properties

130 years ago, Darwin observed that caudicles in vandoid orchids possess considerable elasticity and further hypothesized that their elasticity serves to improve pollination efficiency. However, there has been no study that seeks to either quantitatively backup Darwin's hypothesis or characterize this natural material for practical use. Here we show that vandoid caudicles are a novel kind of soft material with extremely high extensibility (1190%), low modulus (160 kPa) and density lower than that of water. Vandoid caudicles contain carotenoids that attach to basal polymers through noncovalent interactions. Inspired by the chemical structure of caudicles, we synthesize calcium-alginate/polyacrylamide hydrogels supplemented with carotenoids and demonstrate that their strength as well as stretchability are enhanced two-fold. Our findings identify a new carotenoid-based material system with unique properties that approach the current boundaries of the Ashby chart, demonstrating potential application of carotenoids as biocompatible reinforcing agent for hydrogels. Statement of SignificanceWe have investigated the microstructure, mechanical properties and chemical components of vandoid caudicles as an elastic plant tissue and demonstrated a bio-inspired design that can enhance the elasticity of hydrogels. Existing research on vandoid caudicles are very few and mainly focus on their phylogenetics and developmental process, and the potential application of caudicles in the field of material sciences remains unexplored. Our results showed that caudicles are more stretchable than most natural and synthetic elastomers and have a modulus similar to hydrogels. Carotenoids, an important chemical component of caudicles, can be used as supplements to hydrogels to improve their strength and stretchability.

Viscoelasticity, mechanical properties, and in vivo biocompatibility of injectable polyvinyl alcohol/bioactive glass composite hydrogels as potential bone tissue scaffolds

An injectable composite hydrogel composed of polyvinyl alcohol (PVA) and bioactive glass (BG) particles were synthesized by a physical crosslinking approach. The morphology, mechanical properties, and viscoelasticity of the PVA/BG composite hydrogel were characterized. Scanning electronic microscopy (SEM) showed uniform and homogeneous distribution of BG particles throughout the composite hydrogel. The incorporation of 2.5 wt% of BG particles in the composite hydrogel formulations, enhanced the static compressive strength and static elastic modulus by 325% and 150%, respectively. The storage molds (G′) was greater than the loss modules (G′′) at all the frequency range studied, which revealed a self-standing elastic composite hydrogel with a smooth injectability. The PVA/BG composite hydrogel was also implanted subcutaneously in the dorsal region of adult male rats. After 4 weeks of implantation, no inflammatory cells were seen within and around the implant, which indicated that the composite hydrogel was biocompatible. The properties of the synthesized injectable PVA/BG composite hydrogel demonstrate its capability toward bone regeneration.

Mineralized Soft and Elastic Polymer Dot Hydrogel for a Flexible Self-Powered Electronic Skin Sensor.

We propose an integrated, self-powered, flexible electronic skin device containing an alginate-derived polymer dot (A-PD)-incorporated mineralized hydrogel-based energy storage unit and a chitosan-derived n-type carbon dot (N-CD)-based solar cell for an energy-harvesting unit. This study demonstrates a unique architecture of mineralized hydrogel comprising A-PD-incorporated poly(acrylic acid) (PAA)/CaCO3/laponite containing soft and sensitive layers, deposited with a polyaniline electrode to serve as an energy storage unit. The self-assembly was achieved through the ionic cross-linking between A-PD and PAA driven by the mineralization process, resulting in excellent dimensional stability and improved mechanical properties of the hydrogel. The sp2 carbon-rich A-PD enhances the electrochemical performance and the overall photon-to-electrical conversion and storage efficiency for self-powered devices by the formation of the bridge of electrons between the ionized polymer and metal ion. The capacitive sensor developed in this study exhibits high sensitivity in detecting small pressure changes, such as the falling of small water droplets. The self-powered sensing device can detect and monitor various human motions continuously by harvesting light energy from outdoor sunlight. Furthermore, the energy-autonomous device exhibits unique responses for handwriting characters stably and repeatedly. The proposed system may be applicable to human-machine interfaces, biomonitoring systems, secure communication, and wearable devices.

Fibrillar Collagen Type I Participates in the Survival and Aggregation of Primary Hepatocytes Cultured on Soft Hydrogels.

Liver is an essential organ that carries out multiple functions such as glycogen storage, the synthesis of plasma proteins, and the detoxification of xenobiotics. Hepatocytes are the parenchyma that sustain almost all the functions supported by this organ. Hepatocytes and non-parenchymal cells respond to the mechanical alterations that occur in the extracellular matrix (ECM) caused by organogenesis and regenerating processes. Rearrangements of the ECM modify the composition and mechanical properties that result in specific dedifferentiation programs inside the hepatic cells. Quiescent hepatocytes are embedded in the soft ECM, which contains an important concentration of fibrillar collagens in combination with a basement membrane-associated matrix (BM). This work aims to evaluate the role of fibrillar collagens and BM on actin cytoskeleton organization and the function of rat primary hepatocytes cultured on soft elastic polyacrylamide hydrogels (PAA HGs). We used rat tail collagen type I and Matrigel® as references of fibrillar collagens and BM respectively and mixed different percentages of collagen type I in combination with BM. We also used peptides obtained from decellularized liver matrices (dECM). Remarkably, hepatocytes showed a poor adhesion in the absence of collagen on soft PAA HGs. We demonstrated that collagen type I inhibited apoptosis and activated extracellular signal-regulated kinases 1/2 (ERK1/2) in primary hepatocytes cultured on soft hydrogels. Epidermal growth factor (EGF) was not able to rescue cell viability in conjugated BM but affected cell aggregation in soft PAA HGs conjugated with combinations of different proportions of collagen and BM. Interestingly, actin cytoskeleton was localized and preserved close to plasma membrane (cortical actin) and proximal to intercellular ducts (canaliculi-like structures) in soft conditions; however, albumin protein expression was not preserved, even though primary hepatocytes did not remodel their actin cytoskeleton significantly in soft conditions. This investigation highlights the important role of fibrillar collagens on soft hydrogels for the maintenance of survival and aggregation of the hepatocytes. Data suggest evaluating the conditions that allow the establishment of optimal biomimetic environments for physiology and cell biology studies, where the phenotype of primary cells may be preserved for longer periods of time.

Influence of viscosity on chondrogenic differentiation of mesenchymal stem cells during 3D culture in viscous gelatin solution-embedded hydrogels

Differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs) is regulated by a variety of cues of their surrounding microenvironments. In particular, mechanical properties of cell culture matrices have been recently disclosed to play a pivotal role in stem cell differentiation. However, it remains elusive how viscosity affects the chondrogenic differentiation of hMSCs during three-dimensional (3D) culture. In this study, a 3D culture system that was established by embedding viscous gelatin solution in chemically cross-linked gelatin hydrogels was used for 3D culture of hMSCs in gelatin solutions with different viscosities. The influence of solution viscosity on chondrogenic differentiation of hMSCs was investigated. Viscous gelatin solutions promoted cell proliferation in the order of low, middle and high viscosity while elastic hydrogels restricted cell proliferation. High viscosity gelatin solution led to increased production of the cartilaginous matrix. Under the synergistic stimulation of chondrogenic induction factors, high viscosity was beneficial for the chondrogenic differentiation of hMSCs. The results suggested the role of viscosity should be considered as one of the dominant mechanical cues affecting stem cell differentiation.

Chemical and physical properties of alginate-like exopolymers of aerobic granules and flocs produced from different wastewaters

The influence of wastewater (WW) composition and the bioaggregates types (floccular vs. aerobic granular sludge - AGS) on the content, physical-chemical, hydrogel and rheological properties of Alginate-Like Exopolymers (ALE) was studied. Results showed that ALE are a complex mixture of proteins, humic acids and polysaccharides. Overall, rather similar ALE content and composition was observed for the different types of sludge. Only the AGS fed with acetate and propionate yielded significantly larger amount of ALE (261 ± 33 mg VSALE/g VSsludge, +49%) and of uronic sugars in ALE (254 ± 32 mgglucuronic acid/g VSALE, +62%) than bioaggregates fed with no/very little volatile fatty acids. Mannuronic acids are involved in the cohesion of the hydrogels. ALE hydrogels elasticity changed significantly with the type/origin of the bioaggregates. ALE hydrogels elasticity from AGS was always higher than from flocs when fed with real WW. Hence, different types of sludge impact the properties of the recovered ALE.

Gelation of the internal core of liposomes as a strategy for stabilization and modified drug delivery I. Physico-chemistry study.

Since the application of nanotechnology to drug delivery, both polymer-based and lipid-based nanocarriers have demonstrated clinical benefits, improving both drug efficacy and safety. However, to further address the challenges of the drug delivery field, hybrid lipid-polymer nanocomposites have been designed to merge the beneficial features of both polymer-based and lipid-based delivery systems in a single nanocarrier. Within this scenario, this work is aimed at developing novel hybrid vesicles following the recent strategy of modifying the internal structure of liposomes. Specifically, polyethylene glycol-dimethacrylate (PEG-DMA, molecular weight 750 or 4000), was entrapped within unilamellar liposomes made of hydrogenated soybean phosphatidylcholine/cholesterol, and photo-crosslinked, in order to transform the aqueous inner core of liposomes into a soft and elastic hydrogel. After appropriate optimization of the preparation and gelation procedures, the primary objective of this work was to analyze the effect of the molecular weight of PEG-DMA on the main properties of these Gel-in-Liposome (GiL) systems. Indeed, by varying the molecular weight of PEG-DMA also its hydrophilic/lipophilic balance was modified and different arrangements of the polymer within the structure of liposomes as well as different interaction with their membrane were obtained. Both polymers were found in the inner core of the liposomes, however, the more hydrophobic PEG750-DMA also formed localized clusters within the liposome membrane, whereas the more hydrophilic PEG4000-DMA formed a polymeric corona on the vesicle surface. Preliminary cytotoxicity studies were also performed to evaluate the biological safety of these GiL systems and their suitability as innovative materials drug delivery application.

Freezing-Tolerant, Highly Sensitive Strain and Pressure Sensors Assembled from Ionic Conductive Hydrogels with Dynamic Cross-Links.

Conductive hydrogels have attracted intensive attention for versatile functions in flexible electronics because of their unique combination of mechanical flexibility and conductivity. However, hydrogels containing plenty of water inevitably freeze at subzero temperature, leading to invalid electronics with failed mechanical advantages and negligible conductivity. Moreover, the inferior elasticity and fatigue resistance of hydrogels result in unstable sensing performance and poor reusability of hydrogel-based electronics. Herein, a freezing-tolerant, high-sensitive, durable strain and pressure sensor was constructed from an ionic conductive chitosan-poly(acrylamide-co-acrylic acid) double-network [CS-P(AM-co-AA) DN] hydrogel with dual-dynamic cross-links (chitosan physical network and ionic coordination [CO2LFeIII]), which was feasibly fabricated by soaking the CS-P(AM-co-AA) composite hydrogel in FeCl3 solution. The ions immobilized in dynamic cross-links exerted crucial effects on improving mechanics [prominent tensile performance, supercompressibility, extraordinary elasticity, fast self-recovery capacity, and remarkable fatigue resistance (1000 cycles)]; meanwhile, the free ions in the hydrogel rendered the hydrogel excellent conductivity and strong freezing tolerance concurrently. The sensor assembled from the DN hydrogel exhibited cycling stability and good durability in detecting pressure, various deformations (elongation, compression, and bend), and human motions even at a low temperature (-20 °C). Notably, the sensitivity on detecting strain and pressure at both room and subzero temperature was superior than most of the reported organohydrogel and hydrogel sensors. Thus, we believe that this work will provide a platform for construction and application of high-sensitive strain and pressure hydrogel sensors with cycling stability and good durability in a wide temperature range.

Elasticizing tissues for reversible shape transformation and accelerated molecular labeling.

We developed entangled link-augmented stretchable tissue-hydrogel (ELAST), a technology that transforms tissues into elastic hydrogels to enhance macromolecular accessibility and mechanical stability simultaneously. ELASTicized tissues are highly stretchable and compressible, which enables reversible shape transformation and faster delivery of probes into intact tissue specimens via mechanical thinning. This universal platform may facilitate rapid and scalable molecular phenotyping of large-scale biological systems, such as human organs.

Stiffness Matters: Fine-Tuned Hydrogel Elasticity Alters Chondrogenic Redifferentiation.

Biomechanical cues such as shear stress, stretching, compression, and matrix elasticity are vital in the establishment of next generation physiological in vitro tissue models. Matrix elasticity, for instance, is known to guide stem cell differentiation, influence healing processes and modulate extracellular matrix (ECM) deposition needed for tissue development and maintenance. To better understand the biomechanical effect of matrix elasticity on the formation of articular cartilage analogs in vitro, this study aims at assessing the redifferentiation capacity of primary human chondrocytes in three different hydrogel matrices of predefined matrix elasticities. The hydrogel elasticities were chosen to represent a broad spectrum of tissue stiffness ranging from very soft tissues with a Young’s modulus of 1 kPa up to elasticities of 30 kPa, representative of the perichondral-space. In addition, the interplay of matrix elasticity and transforming growth factor beta-3 (TGF-β3) on the redifferentiation of primary human articular chondrocytes was studied by analyzing both qualitative (viability, morphology, histology) and quantitative (RT-qPCR, sGAG, DNA) parameters, crucial to the chondrotypic phenotype. Results show that fibrin hydrogels of 30 kPa Young’s modulus best guide chondrocyte redifferentiation resulting in a native-like morphology as well as induces the synthesis of physiologic ECM constituents such as glycosaminoglycans (sGAG) and collagen type II. This comprehensive study sheds light onto the mechanobiological impact of matrix elasticity on formation and maintenance of articular cartilage and thus represents a major step toward meeting the need for advanced in vitro tissue models to study both re- and degeneration of articular cartilage.

Engineering Tough, Injectable, Naturally Derived, Bioadhesive Composite Hydrogels.

Engineering mechanically robust bioadhesive hydrogels that can withstand large strains may open new opportunities for the sutureless sealing of highly stretchable tissues. While typical chemical modifications of hydrogels, such as increasing the functional group density of crosslinkable moieties and blending them with other polymers or nanomaterials have resulted in improved mechanical stiffness, the modified hydrogels have often exhibited increased brittleness resulting in deteriorated sealing capabilities under large strains. Furthermore, highly elastic hydrogels, such as tropoelastin derivatives are highly expensive. Here, gelatin methacryloyl (GelMA) is hybridized with methacrylate-modified alginate (AlgMA) to enable ion-induced reversible crosslinking that can dissipate energy under strain. The hybrid hydrogels provide a photocrosslinkable, injectable, and bioadhesive platform with an excellent toughness that can be tailored using divalent cations, such as calcium. This class of hybrid biopolymers with more than 600% improved toughness compared to GelMA may set the stage for durable, mechanically resilient, and cost-effective tissue sealants. This strategy to increase the toughness of hydrogels may be extended to other crosslinkable polymers with similarly reactive moieties.