Interpenetrated polymer networks of chitosan (CHI), polyacrylic acid (PAA) and polyacrylamide (PAM) were prepared by free radical polymerization. These hydrogels were either washed with double distilled water (CHI/PAA...Interpenetrated polymer networks of chitosan (CHI), polyacrylic acid (PAA) and polyacrylamide (PAM) were prepared by free radical polymerization. These hydrogels were either washed with double distilled water (CHI/PAA/PAM) A or hydrolyzed with 1M sodium hydroxide (NaOH), (CHI/PAA/PAM) S. Both types of hydrogels were characterized by infrared spectroscopy, microstructural techniques and compressive mechanical testing. Finally, hydrogels were loaded with bovine serum albumin (BSA) and release followed at different pHs. Infrared spectra analysis showed correspondence between hydrogels and monomer feed compositions. Hydrolyzed hydrogels, had increased water content and pH swelling dependence. Compression modulus of swelled hydrolyzed hydrogels decreased with increasing equilibrium water content. Higher BSA loadings were achieved on hydrolyzed hydrogels due to their high water content and porosity. Protein release from hydrogels was low (≤ 20% after 10 hours) at pH 1.2, but sustained release was observed at pH 6.8 and 7.4. The integrity of the protein released at 6.8 and 7.4 by hydrolyzed hydrogels was unaffected. The hydrogles showed no cytotoxic effects on human skin dermal fibroblasts as determined by MTT assay except for two compositions of (CHI/PAA/PAM) A samples, which after seven days presented a viability lower than 80% respect to the control.展开更多
The change in rheological and mechanical properties for some ionotropic cross-linked metal-alginate hydrogel complexes in particularly copper-alginate membranes in the presence of some organic solvents (benzene, tolue...The change in rheological and mechanical properties for some ionotropic cross-linked metal-alginate hydrogel complexes in particularly copper-alginate membranes in the presence of some organic solvents (benzene, toluene, xylene, carbon tetrachloride, ace-tone, chloroform, dichloroethane, isobutyl alcohol and ethyl alcohol) or buffer solutions (acetates, borates and universal buffers) have been investigated. The experimental results showed a remarkable tendency of the studied hydrogels for shrinking in polar solvents, whereas no influence was observed for the hydrogels in non-polar solvents. On the other hand, the gels were found to swell or shrink in the buffer solutions depending on the pH of the buffer used. The swelling extent for hydrogel spheres was found to decrease in the order Cu > Ba ≈ Ca > Zn > Pb-alginates in universal buffers of pH = 5.33. The factors affected this behavior have been examined and discussed.展开更多
All-season thermal management with zero energy consumption and emissions is more crucial to global decarbonization over traditional energy-intensive cooling/heating systems.However,the static single thermal management...All-season thermal management with zero energy consumption and emissions is more crucial to global decarbonization over traditional energy-intensive cooling/heating systems.However,the static single thermal management for cooling or heating fails to self-regulate the temperature in dynamic seasonal temperature condition.Herein,inspired by the dual-temperature regulation function of the fur color changes on the backs and abdomens of penguins,a smart thermal management composite hydrogel(PNA@H-PM Gel)system was subtly created though an"on-demand"dual-layer structure design strategy.The PNA@H-PM Gel system features synchronous solar and thermal radiation modulation as well as tunable phase transition temperatures to meet the variable seasonal thermal requirements and energy-saving demands via self-adaptive radiative cooling and solar heating regulation.Furthermore,this system demonstrates superb modulations of both the solar reflectance(ΔR=0.74)and thermal emissivity(ΔE=0.52)in response to ambient temperature changes,highlighting efficient temperature regulation with average radiative cooling and solar heating effects of 9.6℃in summer and 6.1℃in winter,respectively.Moreover,compared to standard building baselines,the PNA@H-PM Gel presents a more substantial energy-saving cooling/heating potentials for energy-efficient buildings across various regions and climates.This novel solution,inspired by penguins in the real world,will offer a fresh approach for producing intelligent,energy-saving thermal management materials,and serve for temperature regulation under dynamic climate conditions and even throughout all seasons.展开更多
Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm monitoring.To address these challenges,Prof.Seung H...Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm monitoring.To address these challenges,Prof.Seung Hwan Ko and Taek-Soo Kim’s team introduced a laserinduced phase separation and adhesion method for fabricating conductive hydrogels consisting of pure poly(3,4-ethylenedioxythiophene):polystyrene sulfonate on polymer substrates.The laser-induced phase separation and adhesion treated conducting polymers can be selectively transformed into conductive hydrogels that exhibit wet conductivities of 101.4 S cm^(−1) with a spatial resolution down to 5μm.Moreover,they maintain impedance and charge-storage capacity even after 1 h of sonication.The micropatterned electrode arrays demonstrate their potential in long-term in vivo signal recordings,highlighting their promising role in the field of bioelectronics.展开更多
Hydrogel-based flexible sensors are emerging as ideal candidates for wearable devices and soft robotics.However,most current hydrogels possess limited physicochemical properties,which hinder their practical applicatio...Hydrogel-based flexible sensors are emerging as ideal candidates for wearable devices and soft robotics.However,most current hydrogels possess limited physicochemical properties,which hinder their practical application in long-term and complex scenarios.Herein,inspired by the unique structure of the barnacle,we design multifunctional poly(DMAPA-co-PHEA)hydrogels(CP hydrogels)by employing multiple physical crosslinks in the presence of Ag nanoparticles and NaCl additives.Owing to the synergistic effect of cation-πinteractions,hydrophobic interactions,and ionic bonds,the CP hydrogels exhibit high stretchability(strain up to 1430%),strong adhesion(22.8 kPa),satisfactory antibacterial activity,stable anti-icing ability(<20 kPa after 20 icing-deicing cycles),and high electrical conductivity(18.5 mS/cm).Additionally,the CP hydrogels show fast and sensitive responsiveness and cycling stability and can attach directly to human skin to accurately detect both human motions and tiny physiological signals as a flexible wearable sensor.Collectively,this work significantly contributes a straightforward and efficient design strategy for the development of multifunctional hydrogels,broadening their application scenarios.展开更多
Bacterial infection,excessive inflammatory response,and impaired angiogenesis caused by the hyperglycemic microenvironment of diabetic wounds are the primary factors of non-healing wounds.Most contemporary wound repai...Bacterial infection,excessive inflammatory response,and impaired angiogenesis caused by the hyperglycemic microenvironment of diabetic wounds are the primary factors of non-healing wounds.Most contemporary wound repair materials passively release loaded drugs,resulting in poor therapeutic outcomes.In this study,we designed sequentially triggered triple-responsive hydrogels containing alginate(ALG)-phenylboronic acid(PBA),copper polydopamine(Cu-PDA),metformin(MET),and deferoxamine mesylate(DFO)to cover the continuous process of diabetic-infected wound healing and improve the wound microenvironment through warming in the infectious phase and on-demand drug release in the inflammatory and proliferative phase.The hydrogels exhibited good adhesivity,injectability,self-healing ability,and biocompatibility.The hydrogels show remarkable photothermal responsiveness due to the presence of PDA.Studies showed that appropriate high temperatures and the release of Cu2+resulted in the hydrogels displaying excellent bactericidal properties in the infectious phase.Furthermore,the instability of the phenyl borate bond in a hyperglycemic and acidic microenvironment enables the glucose/pH responsiveness of the release of MET and DFO from the hydrogels.Mechanistic studies have shown that the hydrogels could suppress the activity of the NOD-,LRR-,and pyrin structural domain-containing protein 3(NLRP3)/caspase-1/GasderminD(GSDMD)/IL-1βpathway and activate the hypoxia-inducible factor 1 alpha(HIF-1α)/vascular endothelial growth factor(VEGF)pathway.These effects enabled the hydrogels to promote the healing of diabetic-infected wounds.展开更多
The performance of hydrogel radical polymerization under ambient conditions is a major challenge because oxygen is an effective radical quencher and the steps to remove or neutralize it are time consuming and laboriou...The performance of hydrogel radical polymerization under ambient conditions is a major challenge because oxygen is an effective radical quencher and the steps to remove or neutralize it are time consuming and laborious.A self-initiating system consisting of transition metals and acetylacetone has been successfully developed.The system is capable of initiating free radical polymerization of hydrogels at room temperature under aerobic conditions,which is attributed to carbon radicals generated by the oxidation of acetylacetone.Some of these carbon radicals reduce oxygen to generate hydroxyl radicals,which together induce self-coagulation of hydrogels.The polymerization system was effective for a variety of monomer and hydrogel swelling and shrinking schemes,and the reaction remained successful when exposed to saturated oxygen.In conclusion,the results demonstrate that the present strategy is an effective approach to addressing the challenge of deoxygenation in polymer synthesis,and provides a convenient method for synthesizing multifunctional hydrogels under ambient conditions.展开更多
Soft self-healing materials are promising candidates for flexible electronic devices due to their excep-tional compatibility,extensibility,and self-restorability.Generally,these materials suffer from low tensile stren...Soft self-healing materials are promising candidates for flexible electronic devices due to their excep-tional compatibility,extensibility,and self-restorability.Generally,these materials suffer from low tensile strength and susceptibility to fracture because of the restricted microstructure design.Herein,we pro-pose a hydrothermal-freeze-thaw method to construct high-strength self-healing hydrogels with even in-terconnected networks and distinctive wrinkled surfaces.The integration of the wrinkled outer surface with the three-dimensional internal network confers the self-healing hydrogel with enhanced mechan-ical strength.This hydrogel achieves a tensile strength of 223 kPa,a breaking elongation of 442%,an adhesion strength of 57.6 kPa,and an adhesion energy of 237.2 J m-2.Meanwhile,the hydrogel demon-strates impressive self-repair capability(repair efficiency:93%).Moreover,the density functional theory(DFT)calculations are used to substantiate the stable existence of hydrogen bonding between the PPPBG hydrogel and water molecules which ensures the durability of the PPPBG hydrogel for long-term applica-tion.The measurements demonstrate that this multifunctional hydrogel possesses the requisite sensitivity and durability to serve as a strain sensor,which monitors a spectrum of motion signals including subtle vocalizations,pronounced facial expressions,and limb articulations.This work presents a viable strategy for healthcare monitoring,soft robotics,and interactive electronic skins.展开更多
In the current transformative era of biomedicine,hydrogels have established their presence in biomaterials due to their superior biocompatibility,tuneability and resemblance with native tissue.However,hydrogels typica...In the current transformative era of biomedicine,hydrogels have established their presence in biomaterials due to their superior biocompatibility,tuneability and resemblance with native tissue.However,hydrogels typically exhibit poor conductivity due to their hydrophilic polymer structure.Electrical conductivity provides an important enhancement to the properties of hydrogel-based systems in various biomedical applications such as drug delivery and tissue engineering.Consequently,researchers are developing combinatorial strategies to develop electrically responsive“SMART”systems to improve the therapeutic efficacy of biomolecules.Electrically conductive hydrogels have been explored for various drug delivery applications,enabling higher loading of therapeutic cargo with on-demand delivery.This review emphasizes the properties,mechanisms,fabrication techniques and recent advancements of electrically responsive“SMART”systems aiding on-site drug delivery applications.Additionally,it covers prospects for the successful translation of these systems into clinical research.展开更多
Achieving continuous motions typically requires dynamic external stimuli for cyclic deformation,or crafted geometries with intricate modules to form a self-regulated feedback loop upon static stimulation.It is still a...Achieving continuous motions typically requires dynamic external stimuli for cyclic deformation,or crafted geometries with intricate modules to form a self-regulated feedback loop upon static stimulation.It is still a grand challenge to realize self-sustained motion in soft robots subject to unchanging environment,without complex geometry or a control module.In this work,we report soft robots based on an anisotropic cylindrical hydrogel showing self-regulated,continuous rolling motions under constant light irradiation.The robots are animated by mirror-symmetry-breaking induced by photothermal strain gradient.The self-sustained motion is attributed to the fast and reversible deformation of the gel and the autonomous refresh of the irradiated region during the rolling motion.The hydrogel robots can reach a rolling speed of 1.27 mm·s^(-1)on a horizonal surface and even climb a ramp of 18°at a speed of 0.57 mm·s^(-1)in an aqueous environment.Furthermore,the hydrogel robots can overcome an obstacle,with rolling direction controllable through irradiation angle of the light and local irradiation on selective regions.This work suggests a facile strategy to develop hydrogel robots and may provide unforeseen inspirations for the design of self-regulated soft robots by using other intelligent materials.展开更多
The integration of 3D-printed hydrogels in soft robotics enables the creation of flexible,adaptable,and biocompatible systems.Hydrogels,with their high-water content and responsiveness to stimuli,are suitable for actu...The integration of 3D-printed hydrogels in soft robotics enables the creation of flexible,adaptable,and biocompatible systems.Hydrogels,with their high-water content and responsiveness to stimuli,are suitable for actuators,sensors,and robotic systems that require safe interaction and precise manipulation.Unlike traditional techniques,3D printing offers enhanced capabilities in tailoring structural complexity,resolution,and integrated functionality,enabling the direct fabrication of hydrogel systems with programmed mechanical and functional properties.In this perspective,we explore the evolving role of 3D-printed hydrogels in soft robotics,covering their material composition,fabrication techniques,and diverse applications.We highlight advancements in hydrogel-based actuators,sensors,and robots,emphasizing their ability to perform intricate motions.In addition,we discuss challenges like mechanical robustness,scalability,and integration as well as the potential of hydrogels in soft robotics and explore future directions for their development.展开更多
When a cracked hydrogel sample immersed in water is stretched,a swelling zone near the crack tip emerges.Within the swelling zone,water diffusion occurs and swells the hydrogel.Outside the swelling zone,water diffusio...When a cracked hydrogel sample immersed in water is stretched,a swelling zone near the crack tip emerges.Within the swelling zone,water diffusion occurs and swells the hydrogel.Outside the swelling zone,water diffusion is negligible,and the material behaves like an incompressible elastomer.Since water diffusion is a time-dependent process,the size of the swelling zone changes with time.As time evolves,the size of the swelling zone grows until to the size of the hydrogel sample.There exists a competition between the size of the swelling zone and the size of the hydrogel sample,which results in complex rate-dependent fracture behavior of hydrogel.In this article,the competition effect is studied theoretically and numerically.We find that the hydrogel undergoes three stages gradually:small-scale swelling,large-scale swelling,and equilibrium as the size of the swelling zone approaches the size of the hydrogel sample.In the stage of small-scale swelling,the first invariant of stretch at the notch tip I1notch increases with the decrease of the stretch rate.In the stage of large-scale swelling,I1notch increases first and then decreases with the decrease of stretch rate.In the stage of equilibrium,the effect of water diffusion is negligible,and I1notch is independent of stretch rate.This work reveals the connection between the stretch rate,the size of the swelling zone,and the crack tip quantity I1notch,which is used to establish the fracture criterion and predict rate-dependent fracture of hydrogel.Particularly,the previous works on different trends of rate-dependent behavior of hydrogel can be unified in this work,when both small-scale swelling and large-scale swelling are considered.展开更多
Smart actuators and wearable and implantable devices have attracted much attention in healthcare and environmental sensing.Flexible electronic and ionic materials are the two main approaches used to construct these de...Smart actuators and wearable and implantable devices have attracted much attention in healthcare and environmental sensing.Flexible electronic and ionic materials are the two main approaches used to construct these devices.Among them,hydrogel-based ionic materials offer unique advantages,such as biocompatibility and adaptable mechanical properties.However,ionic hydrogels encounter challenges in achieving wirelessly powered and noncontact sensing.To address this,we introduce MXene nanosheets to construct ionotronic hydrogels.Leveraging the rich surface charges and electronic conductivity of MXene nanosheets,ionotronic hydrogels can harvest vibrational and electromagnetic waves as electrical energy and enable noncontact sensing.Under ultrasound,it can continuously generate voltages up to 85 V and light up lightemitting diodes,promising wireless charging of implanted devices.In addition,it achieves an absorption coefficient of 0.2 for 915 MHz electromagnetic waves,enabling noncontact sensing through radio frequency identification.Notably,the physically crosslinked network of the MXenebased hydrogels maintained structural and performance stability under ultrasonic stimulation and exhibited self-healing properties.Even when cut into two halves,the self-healing hydrogel fully regenerates its original performance.This study provides insight into the development of ionotronic hydrogels for wirelessly powered and noncontact sensing in smart actuators and wearable and implantable applications.展开更多
Conventional hydrogels exhibit good performance in various biomedical applications.They consist of a three-dimensional network with porous structures that are constructed from synthetic or natural polymers through phy...Conventional hydrogels exhibit good performance in various biomedical applications.They consist of a three-dimensional network with porous structures that are constructed from synthetic or natural polymers through physical or chemical crosslinking.However,a critical challenge lies in their vulnerability to mechanical damage,as conventional hydrogels often fail to maintain structural integrity under minor trauma.In response to this issue,self-healing hydrogels can autonomously repair themselves after damage,restoring their original functionality without needing external intervention.This remarkable capability significantly extends the lifespan of critical products,including wound dressings,biosensors,drug delivery and tissue engineering scaffolds.This review summarizes the synthesis mechanisms while emphasizing the latest application research advancements.By highlighting the distinct benefits of self-healing hydrogels,we systematically review recent progress in synthesis methods.Our goal is to provide valuable insights that will help researchers in designing and developing more efficient self-healing hydrogels,paving the way for enhanced biomedical solutions.展开更多
Hygroscopic hydrogel is a promising evaporativecooling material for high-power passive daytime cooling with water self-regeneration.However,undesired solar and environmental heating makes it a challenge to maintain su...Hygroscopic hydrogel is a promising evaporativecooling material for high-power passive daytime cooling with water self-regeneration.However,undesired solar and environmental heating makes it a challenge to maintain sub-ambient daytime cooling.While different strategies have been developed to mitigate heat gains,they inevitably sacrifice the evaporation and water regeneration due to highly coupled thermal and vapor transport.Here,an anisotropic synergistically performed insulation-radiation-evaporation(ASPIRE)cooler is developed by leveraging a dual-alignment structure both internal and external to the hydrogel for coordinated thermal and water transport.The ASPIRE cooler achieves an impressive average sub-ambient cooling temperature of~8.2℃ and a remarkable peak cooling power of 311 W m^(-2)under direct sunlight.Further examining the cooling mechanism reveals that the ASPIRE cooler reduces the solar and environmental heat gains without comprising the evaporation.Moreover,self-sustained multi-day cooling is possible with water self-regeneration at night under both clear and cloudy days.The synergistic design provides new insights toward high-power,sustainable,and all-weather passive cooling applications.展开更多
Xerostomia(dry mouth)is frequently experienced by patients treated with radiotherapy for head and neck cancers or with Sjögren’s syndrome,with no permanent cure existing for this debilitating condition.To this e...Xerostomia(dry mouth)is frequently experienced by patients treated with radiotherapy for head and neck cancers or with Sjögren’s syndrome,with no permanent cure existing for this debilitating condition.To this end,in vitro platforms are needed to test therapies directed at salivary(fluid-secreting)cells.However,since these are highly differentiated secretory cells,the maintenance of their differentiated state while expanding in numbers is challenging.In this study,the efficiency of three reversible thermo-ionically crosslinked gels:(1)alginate–gelatin(AG),(2)collagen-containing AG(AGC),and(3)hyaluronic acid-containing AG(AGHA),to recapitulate a native-like environment for human salivary gland(SG)cell expansion and 3D spheroid formation was compared.Although all gels were of mechanical properties comparable to human SG tissue(~11 kPa)and promoted the formation of 3D spheroids,AGHA gels produced larger(>100 cells/spheroid),viable(>93%),proliferative,and well-organized 3D SG spheroids while spatially and temporally maintaining the high expression of key SG proteins(aquaporin-5,NKCC1,ZO-1,α-amylase)for 14 days in culture.Moreover,the spheroids responded to agonist-induced stimulation by increasingα-amylase secretory granules.Here,we propose alternative lowcost,reproducible,and reversible AG-based 3D hydrogels that allow the facile and rapid retrieval of intact,highly viable 3D-SG spheroids.展开更多
Background:Spinal cord injury(SCI),which often results from traumatic incidents,leads to neural damage and impaired sensory and motor functions and may pose a serious threat to life.Secondary injury mechanisms caused ...Background:Spinal cord injury(SCI),which often results from traumatic incidents,leads to neural damage and impaired sensory and motor functions and may pose a serious threat to life.Secondary injury mechanisms caused by persistent inflammation disrupt the local microenvironment,causing neuronal cell death and hindering neural regeneration.This study used a chitosan-citric acid(CS-CA)hydrogel as a carrier for Catalpol(CAT-CS-CA),which was directly applied to the injury site to promote SCI repair.Methods:CAT-CS-CA and CS-CA hydrogels were characterized and implanted into rat SCI models.Fifty-four male Sprague-Dawley rats(230-250 g)rats were involved in the experiment.Six rats were randomly divided into two groups(n=3 per group)for in vivo degradation of hydrogels.Forty-eight rats were randomly assigned into four groups(n=12)using a randomization protocol:sham operation group(laminectomy only),SCI group,CS-CA hydrogel group,and CAT-CS-CA hydrogel group.From each group,3 rats were randomly selected for serum and spinal cord tissue extraction,followed by ELISA and RT-qPCR assays to determine the expression levels of various inflammatory factors(IL-1β,IL-6,TNF-α,and IL-10).Another 3 randomly selected rats were used for the evaluation of hindlimb motor function.The remaining 6 rats in each group were used to detect the expression of neuronal nuclei(NeuN),βIII-tubulin(Tuj1),glial fibrillary acidic protein(GFAP),and macrophage polarization(M1/M2 markers).Results:The CAT-CS-CA hydrogel retains CS-CA hydrogel's advantages and gains enhanced neuroprotective and anti-inflammatory abilities.The implantation of CAT-CS-CA into injured rat spinal cords enhanced neuronal survival,stimulated axonal regeneration,and significantly suppressed glial proliferation at the injury site.In addition,it promoted macrophage polarization to the M2 phenotype and substantially enhanced hindlimb motor function in rats with SCI.Conclusion:CAT-CS-CA hydrogel promotes neuronal survival,suppresses glial scarring,and improves motor function,offering a promising strategy for SCI repair.展开更多
Hydrogels, as a novel class of biomaterials, exhibit broad application prospects and are widely used in tissue engineering. In the field of periodontology within dental medicine, hydrogels can be employed for periodon...Hydrogels, as a novel class of biomaterials, exhibit broad application prospects and are widely used in tissue engineering. In the field of periodontology within dental medicine, hydrogels can be employed for periodontal tissue regeneration to repair the damage caused by periodontitis. At present, various hydrogels have been developed to control periodontal inflammation and repair periodontal tissues. This article, based on domestic and international literature, provides a brief review of hydrogels used in periodontal tissue regeneration.展开更多
Metal–organic frameworks(MOFs)and hydrogels have abundant pores,creating much potential for applications in water purification,organic dye adsorption,and so on.In this study,polyvinyl alcohol(PVA)or PVA/chitosan(CS)h...Metal–organic frameworks(MOFs)and hydrogels have abundant pores,creating much potential for applications in water purification,organic dye adsorption,and so on.In this study,polyvinyl alcohol(PVA)or PVA/chitosan(CS)hydrogel tubes containing in-situ synthesized MOF particles were facilely synthesized,which are capable of removing dyes from flowing fluids.The state of polymer chains during synthesis has a significant impact on microstructures and properties of obtained MOF/hydrogel composites.Hierarchical pores and polar groups endow such devices with good adsorption performance.Besides,a tubular MOF/hydrogel device was found to display excellent flexibility and stability,in which brittle ZIF-8 particles were surrounded and protected by the soft hydrogel matrix effectively.This work supplies a facile and novel strategy to prepare soft MOF/hydrogel tubes for adsorption of pollutants as well as for other potential applications.展开更多
Granular composite(GC)hydrogels have attracted considerable interest in biomedical applications due to their versatile printability and exceptional mechanical properties.However,the lack of comprehensive design guidel...Granular composite(GC)hydrogels have attracted considerable interest in biomedical applications due to their versatile printability and exceptional mechanical properties.However,the lack of comprehensive design guidelines has limited their optimal engineering,as the factors influencing their mechanical performance and printability remain largely unexamined.In this study,we developed GC hydrogels by integrating microgels with interstitial matrices of photocrosslinkable gelatin methacrylate(GelMA).We utilized confocal microscopy and nanoindentation analyses to investigate the spatial distribution and mechanical behavior of these hydrogels.Our findings indicate that the mechanical and rheological properties of GC hydrogels can be precisely tailored by adjusting the volume fraction and size of the microgels.Furthermore,hydrogen bonds were identified as significant contributors to compressive performance,although they had minimal effect on cyclic mechanical behavior.Compared to bulk GelMA hydrogels,GC hydrogels demonstrated enhanced printability and remarkable superelasticity.As a proof of concept,we illustrated their dual printability in embedded printing to create prosthetic liver models for preoperative planning.This study provides valuable insights into the design and optimization of GC hydrogels for advanced biomedical applications.展开更多
文摘Interpenetrated polymer networks of chitosan (CHI), polyacrylic acid (PAA) and polyacrylamide (PAM) were prepared by free radical polymerization. These hydrogels were either washed with double distilled water (CHI/PAA/PAM) A or hydrolyzed with 1M sodium hydroxide (NaOH), (CHI/PAA/PAM) S. Both types of hydrogels were characterized by infrared spectroscopy, microstructural techniques and compressive mechanical testing. Finally, hydrogels were loaded with bovine serum albumin (BSA) and release followed at different pHs. Infrared spectra analysis showed correspondence between hydrogels and monomer feed compositions. Hydrolyzed hydrogels, had increased water content and pH swelling dependence. Compression modulus of swelled hydrolyzed hydrogels decreased with increasing equilibrium water content. Higher BSA loadings were achieved on hydrolyzed hydrogels due to their high water content and porosity. Protein release from hydrogels was low (≤ 20% after 10 hours) at pH 1.2, but sustained release was observed at pH 6.8 and 7.4. The integrity of the protein released at 6.8 and 7.4 by hydrolyzed hydrogels was unaffected. The hydrogles showed no cytotoxic effects on human skin dermal fibroblasts as determined by MTT assay except for two compositions of (CHI/PAA/PAM) A samples, which after seven days presented a viability lower than 80% respect to the control.
文摘The change in rheological and mechanical properties for some ionotropic cross-linked metal-alginate hydrogel complexes in particularly copper-alginate membranes in the presence of some organic solvents (benzene, toluene, xylene, carbon tetrachloride, ace-tone, chloroform, dichloroethane, isobutyl alcohol and ethyl alcohol) or buffer solutions (acetates, borates and universal buffers) have been investigated. The experimental results showed a remarkable tendency of the studied hydrogels for shrinking in polar solvents, whereas no influence was observed for the hydrogels in non-polar solvents. On the other hand, the gels were found to swell or shrink in the buffer solutions depending on the pH of the buffer used. The swelling extent for hydrogel spheres was found to decrease in the order Cu > Ba ≈ Ca > Zn > Pb-alginates in universal buffers of pH = 5.33. The factors affected this behavior have been examined and discussed.
基金the funding and generous support of the National Natural Science Foundation of China(52103263,52271249)the Key Project of International Science&Technology Cooperation of Shaanxi Province(2023-GHZD-09)+5 种基金the Key Project of Science Foundation of Education Department of Shaanxi Province(22JY011)the Key Project of Scientific Research and Development of Shaanxi Province(2023GXLH-070)the Qinchuangyuan"Scientist+Engineer"Team of Shaanxi Province(2023KXJ-069)the Key Research and Development Program of Shaanxi(2023-YBGY-488)the Sci-tech Innovation Team of Shaanxi Province(2024RS-CXTD-46)the Key Research and Development Program of Shaanxi Province(2020ZDLGY13-11).
文摘All-season thermal management with zero energy consumption and emissions is more crucial to global decarbonization over traditional energy-intensive cooling/heating systems.However,the static single thermal management for cooling or heating fails to self-regulate the temperature in dynamic seasonal temperature condition.Herein,inspired by the dual-temperature regulation function of the fur color changes on the backs and abdomens of penguins,a smart thermal management composite hydrogel(PNA@H-PM Gel)system was subtly created though an"on-demand"dual-layer structure design strategy.The PNA@H-PM Gel system features synchronous solar and thermal radiation modulation as well as tunable phase transition temperatures to meet the variable seasonal thermal requirements and energy-saving demands via self-adaptive radiative cooling and solar heating regulation.Furthermore,this system demonstrates superb modulations of both the solar reflectance(ΔR=0.74)and thermal emissivity(ΔE=0.52)in response to ambient temperature changes,highlighting efficient temperature regulation with average radiative cooling and solar heating effects of 9.6℃in summer and 6.1℃in winter,respectively.Moreover,compared to standard building baselines,the PNA@H-PM Gel presents a more substantial energy-saving cooling/heating potentials for energy-efficient buildings across various regions and climates.This novel solution,inspired by penguins in the real world,will offer a fresh approach for producing intelligent,energy-saving thermal management materials,and serve for temperature regulation under dynamic climate conditions and even throughout all seasons.
基金supported by the National Natural Science Foundation of China(52475610)Zhejiang Provincial Natural Science Foundation of China(LDQ24E050001).
文摘Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm monitoring.To address these challenges,Prof.Seung Hwan Ko and Taek-Soo Kim’s team introduced a laserinduced phase separation and adhesion method for fabricating conductive hydrogels consisting of pure poly(3,4-ethylenedioxythiophene):polystyrene sulfonate on polymer substrates.The laser-induced phase separation and adhesion treated conducting polymers can be selectively transformed into conductive hydrogels that exhibit wet conductivities of 101.4 S cm^(−1) with a spatial resolution down to 5μm.Moreover,they maintain impedance and charge-storage capacity even after 1 h of sonication.The micropatterned electrode arrays demonstrate their potential in long-term in vivo signal recordings,highlighting their promising role in the field of bioelectronics.
基金financial support from the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515012218)Macao Science and Technology Development Fund(Nos.FDCT 0009/2020/AMJ,0027/2023/RIB1)+1 种基金National Natural Science Foundation of China(No.32301104)Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.23ptpy165).
文摘Hydrogel-based flexible sensors are emerging as ideal candidates for wearable devices and soft robotics.However,most current hydrogels possess limited physicochemical properties,which hinder their practical application in long-term and complex scenarios.Herein,inspired by the unique structure of the barnacle,we design multifunctional poly(DMAPA-co-PHEA)hydrogels(CP hydrogels)by employing multiple physical crosslinks in the presence of Ag nanoparticles and NaCl additives.Owing to the synergistic effect of cation-πinteractions,hydrophobic interactions,and ionic bonds,the CP hydrogels exhibit high stretchability(strain up to 1430%),strong adhesion(22.8 kPa),satisfactory antibacterial activity,stable anti-icing ability(<20 kPa after 20 icing-deicing cycles),and high electrical conductivity(18.5 mS/cm).Additionally,the CP hydrogels show fast and sensitive responsiveness and cycling stability and can attach directly to human skin to accurately detect both human motions and tiny physiological signals as a flexible wearable sensor.Collectively,this work significantly contributes a straightforward and efficient design strategy for the development of multifunctional hydrogels,broadening their application scenarios.
基金supported by the National Natural Science Foundation of China(Nos.81974288,82170253,and 82241018).
文摘Bacterial infection,excessive inflammatory response,and impaired angiogenesis caused by the hyperglycemic microenvironment of diabetic wounds are the primary factors of non-healing wounds.Most contemporary wound repair materials passively release loaded drugs,resulting in poor therapeutic outcomes.In this study,we designed sequentially triggered triple-responsive hydrogels containing alginate(ALG)-phenylboronic acid(PBA),copper polydopamine(Cu-PDA),metformin(MET),and deferoxamine mesylate(DFO)to cover the continuous process of diabetic-infected wound healing and improve the wound microenvironment through warming in the infectious phase and on-demand drug release in the inflammatory and proliferative phase.The hydrogels exhibited good adhesivity,injectability,self-healing ability,and biocompatibility.The hydrogels show remarkable photothermal responsiveness due to the presence of PDA.Studies showed that appropriate high temperatures and the release of Cu2+resulted in the hydrogels displaying excellent bactericidal properties in the infectious phase.Furthermore,the instability of the phenyl borate bond in a hyperglycemic and acidic microenvironment enables the glucose/pH responsiveness of the release of MET and DFO from the hydrogels.Mechanistic studies have shown that the hydrogels could suppress the activity of the NOD-,LRR-,and pyrin structural domain-containing protein 3(NLRP3)/caspase-1/GasderminD(GSDMD)/IL-1βpathway and activate the hypoxia-inducible factor 1 alpha(HIF-1α)/vascular endothelial growth factor(VEGF)pathway.These effects enabled the hydrogels to promote the healing of diabetic-infected wounds.
基金funded by the National Key R&D Program of China(No.2022YFF0904000)Cross-disciplinary Innovation Project of Jilin University(No.JLUXKJC2021ZZ01)the financial support from National Natural Science Foundation of China(No.62201497).
文摘The performance of hydrogel radical polymerization under ambient conditions is a major challenge because oxygen is an effective radical quencher and the steps to remove or neutralize it are time consuming and laborious.A self-initiating system consisting of transition metals and acetylacetone has been successfully developed.The system is capable of initiating free radical polymerization of hydrogels at room temperature under aerobic conditions,which is attributed to carbon radicals generated by the oxidation of acetylacetone.Some of these carbon radicals reduce oxygen to generate hydroxyl radicals,which together induce self-coagulation of hydrogels.The polymerization system was effective for a variety of monomer and hydrogel swelling and shrinking schemes,and the reaction remained successful when exposed to saturated oxygen.In conclusion,the results demonstrate that the present strategy is an effective approach to addressing the challenge of deoxygenation in polymer synthesis,and provides a convenient method for synthesizing multifunctional hydrogels under ambient conditions.
基金supported by the National Natural Science Foundation of China(Nos.U21A6004,U21A20172,61804091,21574076,and U1510121)the Science and Technology Major Project of Shanxi(No.202101030201022)+1 种基金the Fundamental Research Program of Shanxi Province(No.202103021223019)the Open Fund of the Key Lab of Organic Optoelectronics&Molecular Engineering.
文摘Soft self-healing materials are promising candidates for flexible electronic devices due to their excep-tional compatibility,extensibility,and self-restorability.Generally,these materials suffer from low tensile strength and susceptibility to fracture because of the restricted microstructure design.Herein,we pro-pose a hydrothermal-freeze-thaw method to construct high-strength self-healing hydrogels with even in-terconnected networks and distinctive wrinkled surfaces.The integration of the wrinkled outer surface with the three-dimensional internal network confers the self-healing hydrogel with enhanced mechan-ical strength.This hydrogel achieves a tensile strength of 223 kPa,a breaking elongation of 442%,an adhesion strength of 57.6 kPa,and an adhesion energy of 237.2 J m-2.Meanwhile,the hydrogel demon-strates impressive self-repair capability(repair efficiency:93%).Moreover,the density functional theory(DFT)calculations are used to substantiate the stable existence of hydrogen bonding between the PPPBG hydrogel and water molecules which ensures the durability of the PPPBG hydrogel for long-term applica-tion.The measurements demonstrate that this multifunctional hydrogel possesses the requisite sensitivity and durability to serve as a strain sensor,which monitors a spectrum of motion signals including subtle vocalizations,pronounced facial expressions,and limb articulations.This work presents a viable strategy for healthcare monitoring,soft robotics,and interactive electronic skins.
基金the Ministry of Human Resource and Development (MHRD) Government of India for funding
文摘In the current transformative era of biomedicine,hydrogels have established their presence in biomaterials due to their superior biocompatibility,tuneability and resemblance with native tissue.However,hydrogels typically exhibit poor conductivity due to their hydrophilic polymer structure.Electrical conductivity provides an important enhancement to the properties of hydrogel-based systems in various biomedical applications such as drug delivery and tissue engineering.Consequently,researchers are developing combinatorial strategies to develop electrically responsive“SMART”systems to improve the therapeutic efficacy of biomolecules.Electrically conductive hydrogels have been explored for various drug delivery applications,enabling higher loading of therapeutic cargo with on-demand delivery.This review emphasizes the properties,mechanisms,fabrication techniques and recent advancements of electrically responsive“SMART”systems aiding on-site drug delivery applications.Additionally,it covers prospects for the successful translation of these systems into clinical research.
基金supported by the National Natural Science Foundation of China(Nos.52325302 and 52173012)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(No.2022SZ-FR005)。
文摘Achieving continuous motions typically requires dynamic external stimuli for cyclic deformation,or crafted geometries with intricate modules to form a self-regulated feedback loop upon static stimulation.It is still a grand challenge to realize self-sustained motion in soft robots subject to unchanging environment,without complex geometry or a control module.In this work,we report soft robots based on an anisotropic cylindrical hydrogel showing self-regulated,continuous rolling motions under constant light irradiation.The robots are animated by mirror-symmetry-breaking induced by photothermal strain gradient.The self-sustained motion is attributed to the fast and reversible deformation of the gel and the autonomous refresh of the irradiated region during the rolling motion.The hydrogel robots can reach a rolling speed of 1.27 mm·s^(-1)on a horizonal surface and even climb a ramp of 18°at a speed of 0.57 mm·s^(-1)in an aqueous environment.Furthermore,the hydrogel robots can overcome an obstacle,with rolling direction controllable through irradiation angle of the light and local irradiation on selective regions.This work suggests a facile strategy to develop hydrogel robots and may provide unforeseen inspirations for the design of self-regulated soft robots by using other intelligent materials.
基金supported by Singapore MOE Tier-2 Award MOE-T2EP50123-0015.
文摘The integration of 3D-printed hydrogels in soft robotics enables the creation of flexible,adaptable,and biocompatible systems.Hydrogels,with their high-water content and responsiveness to stimuli,are suitable for actuators,sensors,and robotic systems that require safe interaction and precise manipulation.Unlike traditional techniques,3D printing offers enhanced capabilities in tailoring structural complexity,resolution,and integrated functionality,enabling the direct fabrication of hydrogel systems with programmed mechanical and functional properties.In this perspective,we explore the evolving role of 3D-printed hydrogels in soft robotics,covering their material composition,fabrication techniques,and diverse applications.We highlight advancements in hydrogel-based actuators,sensors,and robots,emphasizing their ability to perform intricate motions.In addition,we discuss challenges like mechanical robustness,scalability,and integration as well as the potential of hydrogels in soft robotics and explore future directions for their development.
基金supported by the Postdoctoral Fellowship Program of CPSF(Grant No.GZB20240607)the Postdoctoral Program of Shaanxi Province(Grant No.25010103232)。
文摘When a cracked hydrogel sample immersed in water is stretched,a swelling zone near the crack tip emerges.Within the swelling zone,water diffusion occurs and swells the hydrogel.Outside the swelling zone,water diffusion is negligible,and the material behaves like an incompressible elastomer.Since water diffusion is a time-dependent process,the size of the swelling zone changes with time.As time evolves,the size of the swelling zone grows until to the size of the hydrogel sample.There exists a competition between the size of the swelling zone and the size of the hydrogel sample,which results in complex rate-dependent fracture behavior of hydrogel.In this article,the competition effect is studied theoretically and numerically.We find that the hydrogel undergoes three stages gradually:small-scale swelling,large-scale swelling,and equilibrium as the size of the swelling zone approaches the size of the hydrogel sample.In the stage of small-scale swelling,the first invariant of stretch at the notch tip I1notch increases with the decrease of the stretch rate.In the stage of large-scale swelling,I1notch increases first and then decreases with the decrease of stretch rate.In the stage of equilibrium,the effect of water diffusion is negligible,and I1notch is independent of stretch rate.This work reveals the connection between the stretch rate,the size of the swelling zone,and the crack tip quantity I1notch,which is used to establish the fracture criterion and predict rate-dependent fracture of hydrogel.Particularly,the previous works on different trends of rate-dependent behavior of hydrogel can be unified in this work,when both small-scale swelling and large-scale swelling are considered.
基金financially supported by the National Natural Science Foundation of China(No.22305033 received by Z.Y.L.,No.52161135102 received by P.Y.W.)the Fundamental Research Funds for the Central Universities(No.2232024A-05 received by Z.Y.L.)。
文摘Smart actuators and wearable and implantable devices have attracted much attention in healthcare and environmental sensing.Flexible electronic and ionic materials are the two main approaches used to construct these devices.Among them,hydrogel-based ionic materials offer unique advantages,such as biocompatibility and adaptable mechanical properties.However,ionic hydrogels encounter challenges in achieving wirelessly powered and noncontact sensing.To address this,we introduce MXene nanosheets to construct ionotronic hydrogels.Leveraging the rich surface charges and electronic conductivity of MXene nanosheets,ionotronic hydrogels can harvest vibrational and electromagnetic waves as electrical energy and enable noncontact sensing.Under ultrasound,it can continuously generate voltages up to 85 V and light up lightemitting diodes,promising wireless charging of implanted devices.In addition,it achieves an absorption coefficient of 0.2 for 915 MHz electromagnetic waves,enabling noncontact sensing through radio frequency identification.Notably,the physically crosslinked network of the MXenebased hydrogels maintained structural and performance stability under ultrasonic stimulation and exhibited self-healing properties.Even when cut into two halves,the self-healing hydrogel fully regenerates its original performance.This study provides insight into the development of ionotronic hydrogels for wirelessly powered and noncontact sensing in smart actuators and wearable and implantable applications.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.5173162 and 21204071).
文摘Conventional hydrogels exhibit good performance in various biomedical applications.They consist of a three-dimensional network with porous structures that are constructed from synthetic or natural polymers through physical or chemical crosslinking.However,a critical challenge lies in their vulnerability to mechanical damage,as conventional hydrogels often fail to maintain structural integrity under minor trauma.In response to this issue,self-healing hydrogels can autonomously repair themselves after damage,restoring their original functionality without needing external intervention.This remarkable capability significantly extends the lifespan of critical products,including wound dressings,biosensors,drug delivery and tissue engineering scaffolds.This review summarizes the synthesis mechanisms while emphasizing the latest application research advancements.By highlighting the distinct benefits of self-healing hydrogels,we systematically review recent progress in synthesis methods.Our goal is to provide valuable insights that will help researchers in designing and developing more efficient self-healing hydrogels,paving the way for enhanced biomedical solutions.
基金financially supported by the Young Scientists Fund of National Natural Science Foundation of China(Grant No.52303106)Research Grants Council of Hong Kong SAR(16200720)+3 种基金Environment and Conservation Fund of Hong Kong SAR(Project No.21/2022)Research Institute of Sports Science and Technology(Project No.P0043535)Research Institute of Advanced Manufacturing(Project No.P0046125)the start-up fund for new recruits of Poly U(Project No.P0038855 and P0038858)。
文摘Hygroscopic hydrogel is a promising evaporativecooling material for high-power passive daytime cooling with water self-regeneration.However,undesired solar and environmental heating makes it a challenge to maintain sub-ambient daytime cooling.While different strategies have been developed to mitigate heat gains,they inevitably sacrifice the evaporation and water regeneration due to highly coupled thermal and vapor transport.Here,an anisotropic synergistically performed insulation-radiation-evaporation(ASPIRE)cooler is developed by leveraging a dual-alignment structure both internal and external to the hydrogel for coordinated thermal and water transport.The ASPIRE cooler achieves an impressive average sub-ambient cooling temperature of~8.2℃ and a remarkable peak cooling power of 311 W m^(-2)under direct sunlight.Further examining the cooling mechanism reveals that the ASPIRE cooler reduces the solar and environmental heat gains without comprising the evaporation.Moreover,self-sustained multi-day cooling is possible with water self-regeneration at night under both clear and cloudy days.The synergistic design provides new insights toward high-power,sustainable,and all-weather passive cooling applications.
基金support from Fonds de Recherche du Québec Santé(FRQS,grant no.281271)support from FRQS doctoral award #304367funding from CFI,Rheolution Inc.,and Investissement Québec.
文摘Xerostomia(dry mouth)is frequently experienced by patients treated with radiotherapy for head and neck cancers or with Sjögren’s syndrome,with no permanent cure existing for this debilitating condition.To this end,in vitro platforms are needed to test therapies directed at salivary(fluid-secreting)cells.However,since these are highly differentiated secretory cells,the maintenance of their differentiated state while expanding in numbers is challenging.In this study,the efficiency of three reversible thermo-ionically crosslinked gels:(1)alginate–gelatin(AG),(2)collagen-containing AG(AGC),and(3)hyaluronic acid-containing AG(AGHA),to recapitulate a native-like environment for human salivary gland(SG)cell expansion and 3D spheroid formation was compared.Although all gels were of mechanical properties comparable to human SG tissue(~11 kPa)and promoted the formation of 3D spheroids,AGHA gels produced larger(>100 cells/spheroid),viable(>93%),proliferative,and well-organized 3D SG spheroids while spatially and temporally maintaining the high expression of key SG proteins(aquaporin-5,NKCC1,ZO-1,α-amylase)for 14 days in culture.Moreover,the spheroids responded to agonist-induced stimulation by increasingα-amylase secretory granules.Here,we propose alternative lowcost,reproducible,and reversible AG-based 3D hydrogels that allow the facile and rapid retrieval of intact,highly viable 3D-SG spheroids.
基金supported by the Medicine health science and technology development program of Shandong Province(202403070969)。
文摘Background:Spinal cord injury(SCI),which often results from traumatic incidents,leads to neural damage and impaired sensory and motor functions and may pose a serious threat to life.Secondary injury mechanisms caused by persistent inflammation disrupt the local microenvironment,causing neuronal cell death and hindering neural regeneration.This study used a chitosan-citric acid(CS-CA)hydrogel as a carrier for Catalpol(CAT-CS-CA),which was directly applied to the injury site to promote SCI repair.Methods:CAT-CS-CA and CS-CA hydrogels were characterized and implanted into rat SCI models.Fifty-four male Sprague-Dawley rats(230-250 g)rats were involved in the experiment.Six rats were randomly divided into two groups(n=3 per group)for in vivo degradation of hydrogels.Forty-eight rats were randomly assigned into four groups(n=12)using a randomization protocol:sham operation group(laminectomy only),SCI group,CS-CA hydrogel group,and CAT-CS-CA hydrogel group.From each group,3 rats were randomly selected for serum and spinal cord tissue extraction,followed by ELISA and RT-qPCR assays to determine the expression levels of various inflammatory factors(IL-1β,IL-6,TNF-α,and IL-10).Another 3 randomly selected rats were used for the evaluation of hindlimb motor function.The remaining 6 rats in each group were used to detect the expression of neuronal nuclei(NeuN),βIII-tubulin(Tuj1),glial fibrillary acidic protein(GFAP),and macrophage polarization(M1/M2 markers).Results:The CAT-CS-CA hydrogel retains CS-CA hydrogel's advantages and gains enhanced neuroprotective and anti-inflammatory abilities.The implantation of CAT-CS-CA into injured rat spinal cords enhanced neuronal survival,stimulated axonal regeneration,and significantly suppressed glial proliferation at the injury site.In addition,it promoted macrophage polarization to the M2 phenotype and substantially enhanced hindlimb motor function in rats with SCI.Conclusion:CAT-CS-CA hydrogel promotes neuronal survival,suppresses glial scarring,and improves motor function,offering a promising strategy for SCI repair.
文摘Hydrogels, as a novel class of biomaterials, exhibit broad application prospects and are widely used in tissue engineering. In the field of periodontology within dental medicine, hydrogels can be employed for periodontal tissue regeneration to repair the damage caused by periodontitis. At present, various hydrogels have been developed to control periodontal inflammation and repair periodontal tissues. This article, based on domestic and international literature, provides a brief review of hydrogels used in periodontal tissue regeneration.
基金supported by the National Natural Science Foundation of China(52302145)the Natural Science Foundation of Shandong Province(ZR2023QE126)the Young Talent of Lifting engineering for Science and Technology in Shandong(SDAST2024QTA017).
文摘Metal–organic frameworks(MOFs)and hydrogels have abundant pores,creating much potential for applications in water purification,organic dye adsorption,and so on.In this study,polyvinyl alcohol(PVA)or PVA/chitosan(CS)hydrogel tubes containing in-situ synthesized MOF particles were facilely synthesized,which are capable of removing dyes from flowing fluids.The state of polymer chains during synthesis has a significant impact on microstructures and properties of obtained MOF/hydrogel composites.Hierarchical pores and polar groups endow such devices with good adsorption performance.Besides,a tubular MOF/hydrogel device was found to display excellent flexibility and stability,in which brittle ZIF-8 particles were surrounded and protected by the soft hydrogel matrix effectively.This work supplies a facile and novel strategy to prepare soft MOF/hydrogel tubes for adsorption of pollutants as well as for other potential applications.
基金support from the National Natural Science Foundation of China(Nos.U21A20394 and 52305314)the Beijing Natural Science Foundation(Nos.7252285 and L246001)the National Key Research and Development Program of China(No.2023YFB4605800)。
文摘Granular composite(GC)hydrogels have attracted considerable interest in biomedical applications due to their versatile printability and exceptional mechanical properties.However,the lack of comprehensive design guidelines has limited their optimal engineering,as the factors influencing their mechanical performance and printability remain largely unexamined.In this study,we developed GC hydrogels by integrating microgels with interstitial matrices of photocrosslinkable gelatin methacrylate(GelMA).We utilized confocal microscopy and nanoindentation analyses to investigate the spatial distribution and mechanical behavior of these hydrogels.Our findings indicate that the mechanical and rheological properties of GC hydrogels can be precisely tailored by adjusting the volume fraction and size of the microgels.Furthermore,hydrogen bonds were identified as significant contributors to compressive performance,although they had minimal effect on cyclic mechanical behavior.Compared to bulk GelMA hydrogels,GC hydrogels demonstrated enhanced printability and remarkable superelasticity.As a proof of concept,we illustrated their dual printability in embedded printing to create prosthetic liver models for preoperative planning.This study provides valuable insights into the design and optimization of GC hydrogels for advanced biomedical applications.
