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Focused ultrasound has experimentally been found to enhance the diffusion of nanoparticles; our aim with this work is to study this effect closer using both experiments and non-equilibrium molecular dynamics. Measurements from single particle tracking of 40 nm polystyrene nanoparticles in an agarose hydrogel with and without focused ultrasound are presented and compared with a previous experimental study using 100 nm polystyrene nanoparticles. In both cases, we observed an increase in the mean square displacement during focused ultrasound treatment. We developed a coarse-grained non-equilibrium molecular dynamics model with an implicit solvent to investigate the increase in the mean square displacement and its frequency and amplitude dependencies. This model consists of polymer fibers and two sizes of nanoparticles, and the effect of the focused ultrasound was modeled as an external oscillating force field. A comparison between the simulation and experimental results shows similar mean square displacement trends, suggesting that the particle velocity is a significant contributor to the observed ultrasound-enhanced mean square displacement. The resulting diffusion coefficients from the model are compared to the diffusion equation for a two-time continuous time random walk. The model is found to have the same frequency dependency. At lower particle velocity amplitude values, the model has a quadratic relation with the particle velocity amplitude as described by the two-time continuous time random walk derived diffusion equation, but at higher amplitudes, the model deviates, and its diffusion coefficient reaches the non-hindered diffusion coefficient. This observation suggests that at higher ultrasound intensities in hydrogels, the non-hindered diffusion coefficient can be used. [ABSTRACT FROM AUTHOR]

Tracer diffusion in polymer networks and hydrogels is relevant in biology and technology, while it also constitutes an interesting model process for the dynamics of molecules in fluctuating, heterogeneous soft matter. Here, we systematically study the time-dependent dynamics and (non-Markovian) memory effects of tracers in polymer networks based on (Markovian) implicit-solvent Langevin simulations. In particular, we consider spherical tracer solutes at high dilution in regular, tetrafunctional bead-spring polymer networks and control the tracer–network Lennard-Jones (LJ) interactions and the polymer density. Based on the analysis of the memory (friction) kernels, we recover the expected long-time transport coefficients and demonstrate how the short-time tracer dynamics, polymer fluctuations, and the viscoelastic response are interlinked. Furthermore, we fit the characteristic memory modes of the tracers with damped harmonic oscillations and identify LJ contributions, bond vibrations, and slow network relaxations. Tuned by the LJ interaction parameter, these modes enter the kernel with an approximately linear to quadratic scaling, which we incorporate into a reduced functional form for convenient tracer memory interpolation and extrapolation. This eventually leads to highly efficient simulations utilizing the generalized Langevin equation, in which the polymer network acts as an additional thermal bath with a tunable intensity. [ABSTRACT FROM AUTHOR]

The work demonstrates, for the first time, thermo-responsive, water-insoluble, hydrogel-based, nano-fibrous filter media comprised of copolymers of N-isopropylacrylamide (NIPAM) and methyl methacrylate formed by electrospinning. Moreover, a comprehensive novel physical explanation of all aspects responsible for the physical mechanisms resulting in the thermo-responsive regulation of the water flow rate and an enhanced interception of nanoparticles by such filter membranes is given. They are the wettable-non-wettable transition, pore, and fiber-size changes, as well as a diminishing filter thickness at the lower critical solution temperature (LCST) of the copolymers developed here, which interplay with a significant reduction in the water viscosity with temperature. Poly(N-isopropylacrylamide) (PNIPAM) hydrogel is an attractive material because of its thermo-responsive properties. Its wettability changes with water temperature. This characteristic holds great promise for the development of advanced filter media and related responsive materials. In this study, PNIPAM hydrogels were designed and transformed into filter membranes for applications in water filtration in biomedical and other related systems. These thermo-responsive filter membranes offer the potential for enhanced filtration efficiency, selectivity, and the overall system performance. Here, two different procedures were adopted to form water-insoluble thermo-responsive filter media based on PNIPAM hydrogels. The PNIPAM-based hydrogels were electrospun, resulting in the formation of thermo-responsive water-insoluble nanofiber membranes. These membranes underwent a series of comprehensive experiments to assess their performance and characteristics, including mass loss, water droplets for the wettability assessment, filtration tests, shrinkage measurements, and microscopic observations. These diverse experiments yield a full understanding of the PNIPAM-based nanofiber membranes' properties and their potential applications. [ABSTRACT FROM AUTHOR]

The network structure within polymers significantly influences their mechanical properties, including their strength, toughness, and fatigue resistance. All-atom molecular dynamics (AAMD) simulations offer a method to investigate the energy dissipation mechanism within polymers during deformation and fracture; Such an approach is, however, computationally inefficient when used to analyze polymers with complex network structures, such as the common chemically double-networked hydrogels. Alternatively, coarse-grained molecular dynamics (CGMD) models, which reduce the computational degrees of freedom by concentrating a set of adjacent atoms into a coarse-grained bead, can be employed. In CGMD simulations, a coarse-grained force field (CGFF) is a critical factor affecting the simulation accuracy. In this paper, we proposed a data-based method for predicting the CGFF parameters to improve the simulation efficiency of complex cross-linked network in polymers. Here, we utilized a typical chemically double-networked hydrogel as an example. An artificial neural network was selected, and it was trained with the tensile stress–strain data from the CGMD simulations using different CGFF parameters. The CGMD simulations using the predicted CGFF parameters show good agreement with the AAMD simulations and are almost fifty times faster. The data-inspired CGMD model presented here broadens the applicability of molecular dynamics simulations to cross-linked polymers and has the potential to provide insights that will aid the design of polymers with desirable mechanical properties. [ABSTRACT FROM AUTHOR]

The presence of gradient softer outer layers, commonly observed in biological systems (such as cartilage and ocular tissues), as well as synthetic crosslinked hydrogels, profoundly influences their interactions with opposing surfaces. Our prior research demonstrated that gradient-stiffness hydrogel layers, characterized by increasing elasticity with depth, control contact mechanics, particularly in proximity to the layer thickness. We postulate that the distribution of polymers within these gradient layers imparts extraordinary stretch and adhesion characteristics due to network adaptability and stress-induced reorganization. To investigate this phenomenon, we utilized Atomic Force Microscopy nanoindentation to assess the depth-dependent adhesion behavior of polyacrylamide hydrogels with varying gradient layer thicknesses. Two gradient layer thicknesses were achieved by employing different molding materials: glass and polyoxymethylene (POM). Glass-molded hydrogels exhibited a thinner gradient layer alongside a stiffer bulk layer compared to their POM-molded counterparts. In indentation experiments, the POM-molded hydrogel had larger adhesion compared to glass-molded hydrogel. We find that indenting within the gradient layer engenders increased load-unload hysteresis due to heightened fluid transport in the sparse outer polymer network. Consequently, this led to augmented adhesion and work of separation at shallow depths. We suggest that the prominent stretching capability of the sparse outer polymer network during probe retraction contributes to enhanced adhesion. The Maugis–Dugdale adhesive model only fits well to indentations on the thin layer or indentations which engage significantly with the bulk. These results facilitate a comprehensive characterization of adhesion mechanics in gradient-stiffness hydrogels, which could foster their application across emerging contexts in health science and environmental domains. [ABSTRACT FROM AUTHOR]

Stretching or compressing hydrogels creates anisotropic environments that lead to motionally averaged alignment of embedded guest quadrupolar nuclear spins such as 23Na+. These distorted hydrogels can elicit a residual quadrupolar coupling that gives an oscillation in the trajectories of single quantum coherences (SQCs) as a function of the evolution time during a spin-echo experiment. We present solutions to equations of motion derived with a Liouvillian superoperator approach, which encompass the coherent quadrupolar interaction in conjunction with relaxation, to give a full analytical description of the evolution trajectories of rank-1 ( T ^ 1 ± 1 ), rank-2 ( T ^ 2 ± 1 ), and rank-3 ( T ^ 3 ± 1 ) SQCs. We performed simultaneous numerical fitting of the experimental 23Na nuclear magnetic resonance (NMR) spectra and rank-2 ( T ^ 2 ± 1 ) and rank-3 ( T ^ 3 ± 1 ) SQC evolution trajectories measured in double and triple quantum filtered experiments, respectively. We estimated values of the quadrupolar coupling constant CQ, rotational correlation time τC, and 3 × 3 Saupe order matrix. We performed simultaneous fitting of the analytical expressions to the experimental data to estimate values of the quadrupolar coupling frequency ωQ/2π, residual quadrupolar coupling ω Q / 2 π , and corresponding spherical order parameter S 0 * , which showed a linear dependence on the extent of uniform hydrogel stretching and compression. The analytical expressions were completely concordant with the numerical approach. The insights gained here can be extended to more complicated (biological) systems such as 23Na+ bound to proteins or located inside and outside living cells in high-field NMR experiments and, by extension, to the anisotropic environments found in vivo with 23Na magnetic resonance imaging. [ABSTRACT FROM AUTHOR]

Silicone hydrogels coated with metallic nanostructures have attracted extensive attention because of their versatile applications in biomedical devices. However, few studies have been reported for characterizing the mechanical behavior of silicone hydrogel under biaxial tensile stresses. In addition, compared to most chemical coating processes, the deposition of nanostructures on silicone hydrogel by using a laser-assisted process can avoid chemical impurities and additional sterilization processes. Herein, a laser-assisted process is used for producing polyvinylpyrrolidone (PVP) modified silver (Ag) nanoparticles (Ag-PVP NPs), which are further deposited on silicone hydrogel. In the uniaxial mechanical test, the value of Young's modulus of Ag-PVP NP coated silicone hydrogels is increased as compared to that of silicone hydrogel. The energy absorption of silicone hydrogel and Ag-PVP NP coated silicone hydrogel measured by the uniaxial mechanical test is 15.137 ± 0.412 and 22.014 ± 0.186 MJ/m3, respectively. Furthermore, the biaxial test is applied to study the mechanical properties of silicone hydrogel coated with Ag-PVP NPs. Meanwhile, a constitutive model was applied to further understand the mechanical behavior of silicone hydrogel coated with Ag-PVP NPs. The result indicates that silicone hydrogel coated with Ag-PVP NPs shows a pseudo-elastic nonlinear behavior which is similar to collagen-based tissue substitutes. [ABSTRACT FROM AUTHOR]

The shortage of water resources is a crisis for human ecosystems. Compared with other ecosystems, the impact on agricultural ecosystems is more prominent. In order to alleviate this situation, a new type of agricultural hydrogel, agarose-bacterial cellulose hydrogel, was synthesized by replacing the traditional petroleum-based monomer with natural polysaccharide. Bacterial cellulose was used as raw material for the synthesis of hydrogels using agarose as matrix template and N, N'- methylenebisacrylamide as cross-linkers. In the present study, the hydrogel has optimized the ratio of the three synthesized polymers and characterized this hydrogel using FTIR spectra, XRD, and SEM. The findings demonstrated that bacterial cellulose was adequately incorporated into the agarose hydrogel and that the pores of AB1 were more significant than those of AA and AB2, which provided crucial support for the hydrogel's ability to encourage plant development. By mixing hydrogel with soil, the effects of soil which have composite hydrogel and without composite hydrogel on plant germination and growth were studied. The results showed that adding bacterial cellulose increased the water retention and holding capacity of agarose hydrogel. Moreover, the plant germination rate and growing trend in soil with hydrogel were better than those without hydrogel. This low-cost, quickly made hydrogel has great application potential in agricultural soil. [ABSTRACT FROM AUTHOR]

Hydrogel is a research hotspot in the field of polymer materials and has great application value in many fields, such as wearable devices. However, the mechanical properties of hydrogel limit its application range. As a natural biopolymer, sodium alginate (SA) has good biocompatibility, but SA hydrogels lack toughness and cannot meet the requirements of strain sensors. In this work, guar gum (GG) is used to enhance the toughness of SA hydrogels so that it can be used to prepare wearable devices. Scanning electron microscopy was used for morphological and structural studies, and Fourier transform infrared spectroscopy was used for cross-linking characterization. The results show that the SA/GG hydrogels prepared by the one-pot method have good tensile properties, and the wearable devices assembled based on them have good stimulus responsiveness, long-term operational stability and excellent water retention. Among them, the SA/GG-2 composite hydrogel has the most excellent comprehensive performance, with the maximum stress and strain reaching 36.5 kPa and 7.3%, and the water retention of the assembled sensors reaching more than 98%, and the resistance and capacitance change rate reaching more than 25%. The SA/GG composite hydrogel has a potential application prospect in the field of wearable devices. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) were derived from saponin and introduced into polyacrylamide hydrogel to prepare a novel bifunctional material (CQDs@HG). This hydrogel emitted strong blue fluorescence under ultraviolet light (365 nm) and exhibited stable adsorption and detection of iron(III) in water samples. The morphological characteristics, chemical composition, Fe3+ adsorption performance, and optical properties of CQDs@HG were characterized. Depending upon the Fe3+ concentration, CQDs@HG exhibited different quenching effects to allow Fe3+ determination. The limit of detection was 0.115 μM, and the adsorption was as high as 12.13 mg/g. The mechanism was due to both static and dynamic quenching. Notably, the sensor based on CQDs@HG successfully determined Fe3+ in water samples, with spiked recoveries between 95.32% and 103.11%. When combined with software image analysis, the sensor semi-quantitatively determined Fe3+ in the field. This fluorescent hydrogel provides a reference for constructing portable sensors for monitoring hazardous substances in water. [ABSTRACT FROM AUTHOR]

[Display omitted] Supramolecular self-assembly is ubiquitous in living system and is usually controlled to proceed in time and space through sophisticated reaction–diffusion processes, underpinning various vital cellular functions. In this contribution, we demonstrate how spatiotemporal self-assembly of supramolecular hydrogels can be realized through a simple reaction–diffusion-mediated transient transduction of pH signal. In the reaction–diffusion system, a relatively faster diffusion of acid followed by delayed enzymatic production and diffusion of base from the opposite site enables a transient transduction of pH signal in the substrate. By coupling such reaction–diffusion system with pH-sensitive gelators, dynamic supramolecular hydrogels with tunable lifetimes are formed at defined locations. The hydrogel fibers show interesting dynamic growing behaviors under the regulation of transient pH signal, reminiscent of their biological counterpart. We further demonstrate a proof-of-concept application of the developed methodology for dynamic information encoding in a soft substrate. We envision that this work may provide a potent approach to enable transient transduction of various chemical signals for the construction of new colloidal materials with the capability to evolve their structures and functionalities in time and space. [ABSTRACT FROM AUTHOR]

The interpenetrating polymer networks PVA-SA-PPy hydrogels were prepared by the freeze-thawing and in-situ polymerization method. The PVA network and SA network formed interpenetrating networks through hydrogen bonding and physical entanglement, which boosted the mechanical properties and ion diffusion characteristics. [Display omitted] Flexible supercapacitors (FSCs) have attracted much attention due to their strong mechanical flexibility, wearability and portability, which greatly rely on the employed flexible electrodes. The conductive polymer hydrogels with excellent flexibility, processability and capacitive performance are one of the most promising candidates, which are still limited by their poor mechanical properties. Constructing robust interpenetrating polymer networks (IPN) is an effective approach to promote their mechanical properties. Herein, interpenetrating polyvinyl alcohol (PVA)-sodium alginate (SA)-polypyrrole (PPy) hydrogels are prepared by the freeze–thaw and in-situ polymerization method. The IPN structure composed of PVA and SA not only enhances the mechanical properties of hydrogels, but also provides substantial active sites for electrochemical reactions. Moreover, the hydrogen-bonding interaction between different components in the PVA-SA-PPy hydrogel boosts the charge/ion transfer. The optimal PVA-SA-PPy hydrogels show an elongation at break of 380 %, a tensile strength of 1.5 MPa, and a specific capacitance of 2646 mF cm−2 at 2 mA cm−2. The symmetric PVA-SA-PPy FSCs show an energy density of 96.7 μWh cm−2 at a power density of 999.9 μW cm−2, and the capacitance retention is 66.3 % after 10,000 cycles. These exceptional mechanical and electrochemical properties make the PVA-SA-PPy hydrogels a promising candidate for FSCs. [ABSTRACT FROM AUTHOR]

Owing to their excellent biocompatibility and capability of large deformation, hydrogels have attracted extensive attention for promising applications. When subjected to cyclic loads, hydrogels are susceptible to fatigue. To ensure their durability, it is crucial to have a deeper understanding on the fatigue mechanisms of hydrogels. However, there is a lack of study in the literature for predicting the fatigue damage of hydrogels under the coupling of large deformation and water diffusion. This work aims to formulate a fatigue life predictor for characterizing the crack nucleation of single-network hydrogels and unveil the effects of water diffusion on fatigue. Borrowing the concept of fatigue crack nucleation for rubber-like materials, the fatigue life predictor is developed within the framework of configurational mechanics. With the proposed predictor, the contributions of stretching and mixing to the fatigue damage of hydrogels are identified. Case studies with different swelling conditions are conducted to further distinguish various effects, including chemical potential, loading rate, and cyclic stretching amplitude, on both stretching and mixing induced damage. It is concluded that the fatigue damage accumulation in hydrogels under cyclic loading is the competing result of stretching and water diffusion. As the proposed predictor is capable of predicting the spatial fatigue damage of hydrogels, the current research can provide guidance on designing loading profiles to improve the fatigue life of hydrogels. In addition, by incorporating self-healing mechanism and multiphysics coupling, the proposed modeling framework can be further expanded to investigate the fatigue of other hydrogels, like double-network and stimuli-sensitive hydrogels. [ABSTRACT FROM AUTHOR]

Biologization of biomaterials with endothelial cells (ECs) is an important step in vascular tissue engineering, aiming at improving hemocompatibility and diminishing the thrombo-inflammatory response of implants. Since subcellular topography in the scale of nano to micrometers can influence cellular adhesion, proliferation, and differentiation, we here investigate the effect of surface roughness on the endothelialization of gelatin hydrogel scaffolds. Considering the micron and sub-micron features of the different native tissues underlying the endothelium in the body, we carried out a biomimetic approach to replicate the surface roughness of tissues and analyzed how this impacted the adhesion and proliferation of human umbilical endothelial cells (HUVECs). Using an imprinting technique, nano and micro-roughness ranging from Sa= 402 nm to Sa= 8 μm were replicated on the surface of gelatin hydrogels. Fluorescent imaging of HUVECs on consecutive days after seeding revealed that microscale topographies negatively affect cell spreading and proliferation. By contrast, nanoscale roughnesses of Sa= 402 and Sa= 538 nm promoted endothelialization as evidenced by the formation of confluent cell monolayers with prominent VE-cadherin surface expression. Collectively, we present an affordable and flexible imprinting method to replicate surface characteristics of tissues on hydrogels and demonstrate how nanoscale roughness positively supports their endothelialization. [ABSTRACT FROM AUTHOR]

Nasal cartilage diseases and injuries are known as significant challenges in reconstructive medicine, affecting a substantial number of individuals worldwide. In recent years, the advent of three-dimensional (3D) bioprinting has emerged as a promising approach for nasal cartilage reconstruction, offering potential breakthroughs in the field of regenerative medicine. This paper provides an overview of the methods and challenges associated with 3D bioprinting technologies in the procedure of reconstructing nasal cartilage tissue. The process of 3D bioprinting entails generating a digital 3D model using biomedical imaging techniques and computer-aided design to integrate both internal and external scaffold features. Then, bioinks which consist of biomaterials, cell types, and bioactive chemicals, are applied to facilitate the precise layer-by-layer bioprinting of tissue-engineered scaffolds. After undergoing in vitro and in vivo experiments, this process results in the development of the physiologically functional integrity of the tissue. The advantages of 3D bioprinting encompass the ability to customize scaffold design, enabling the precise incorporation of pore shape, size, and porosity, as well as the utilization of patient-specific cells to enhance compatibility. However, various challenges should be considered, including the optimization of biomaterials, ensuring adequate cell viability and differentiation, achieving seamless integration with the host tissue, and navigating regulatory attention. Although numerous studies have demonstrated the potential of 3D bioprinting in the rebuilding of such soft tissues, this paper covers various aspects of the bioprinted tissues to provide insights for the future development of repair techniques appropriate for clinical use. [ABSTRACT FROM AUTHOR]

Objective: Salicylic acid (SA) has been used for treatment of acne of different severity levels. However, there are few researches about the safety and efficacy for treatment of mild to moderate acne, and the improvement of the skin condition by using 2% supramolecular salicylic acid (SSA) compared to Davuwen Adapaline gel. Methods: A multicenter, randomized, assessor‐blind and parallel‐controlled study was conducted. A total of 500 patients (trial group: 249, control group: 251) with mild to moderate (grade I–II) facial acne vulgaris were recruited in this study over a 16‐week trial period. Patients in the trial group were treated with Broda 2% SSA hydrogel, while control group treated with Davuwen Adapaline gel once a day. The number of inflammatory papules, comedones, and pustules were counted and the rate of lesion reduction was calculated pre‐ and post‐treatment. Then, the skin physiological indicators, including L*a*b*, TEWL, skin sebum and hydration were measured. Statistical analysis was conducted using SAS 9.4. Significance was set at p = 0.05. Results: At the end of 12 weeks' therapy, the regression and markedly improvement rate of the trail group and the control group were 51.01% and 43.10% respectively, and there was no significant difference in the improvement rate between two groups (p = 0.0831). Although, there was no difference in adverse events rate between two groups, the adverse events rate of the trail group was 0.40%, a little lower than the control group (0.80%). Moreover, there was a significant difference in the numbers of pores at T1 between two groups. Conclusion: Both 2% SSA and Adapaline gel were equally effective in the treatment of mild to moderate acne vulgaris. 2% SSA is worth the clinical promotion and application in mild to moderate acne vulgaris. [ABSTRACT FROM AUTHOR]

The choice of sterilization method for hydrogels used for cell culture influences the ease of preparing the gel. We prepared interpenetrating gelatin/calcium alginate hydrogels containing 1% (w/v) alginate and 1–16% (w/v) gelatin by molding with the mixture of gelatin/sodium alginate solution, followed by the addition of calcium ions by incubation in calcium chloride solution. It is the simplest method to prepare autoclavable gelatin/sodium hydrogel. We measured various properties of the hydrogels including volume, Young's modulus in the compression test, storage modulus, and loss modulus in the dynamic viscoelasticity measurement. The gelatin/alginate hydrogel can be easily fabricated into any shape by this method. After autoclave treatment, the hydrogel was shrunk to smaller than the original shape in similar figures. The shape of the gelatin/alginate hydrogel can be designed into any shape with the reduction ratio of the volume. Human osteosarcoma (HOS) cells adhered to the gelatin/alginate hydrogel and then proliferated. Gelatin/calcium alginate hydrogels with a high concentration are considered to be autoclavable culture substrates because of their low deformation and gelatin elution rate after autoclaving and the high amount of cells attached to the hydrogels. [Display omitted] • We prepared an autoclavable gelatin/alginate hydrogel by molding. • The gelatin/alginate hydrogel can be designed to any 2D/3D shape. • The gelatin/alginate hydrogel has good cell adhesion property and heat stability. • The gelatin/alginate hydrogel is useful as a scaffold in tissue engineering. [ABSTRACT FROM AUTHOR]

This study proposed an innovative approach to the development of sustainable and biodegradable food packaging materials by incorporating inexpensive nano-silica (SiO2NPs) in designed hydrogel (CSG) film employing biodegradable polymers: synthetic polymer polyvinyl alcohol (PVA), natural polymer - carboxymethyl cellulose (CMC) and protein-based bio-polymer –gelatine, and a commercial crosslinker, tetraethoxysilane (TEOS) through a conventional air-dry casting technique. The CSG hydrogel blends were modified with varying amounts of SiO2NPs (0.05g, 0.1g, 0.15g and 0.2g) and compared with the blend without SiO2NPs to determine the effect of SiO2NPs loading through various characterisation techniques and applications including antioxidant and antimicrobial activity. Comprehensive characterizations of the CSG films revealed that CSG 0.1 (containing 0.1g SiO2NPs) exhibited the most favourable functional properties, low crystallinity, high flexibility, suitable pore size, thermal stability, adequate tensile strength, elongation at the breaking point and maximum stability by swelling and diffusion test. The addition of SiO2NPs consistently enhanced thermal and mechanical stability in all CSG films. Further, these CSG films were implemented for antioxidant test and antimicrobial activity against gram-positive Bacillus cereus and gram-negative Escherichia coli. SiO2NPs integration significantly elevated the antioxidant capacity in all films, with CSG 0.1 showing ⁓7% improvement. The antimicrobial activity of SiO2NPs-modified CSG films was also notable, with CSG 0.1 effectively inhibiting B. cereus by 1.2cm zone and E. coli by 0.5cm zone. A soil burial test was performed to pattern the biodegradability of CSG hydrogels. Therefore, the outstanding improvements in the intrinsic properties of CSG films, owing to SiO2NPs modification, positioned these CSG hydrogels as promising candidates for advanced food packaging materials in various industries. [ABSTRACT FROM AUTHOR]

Magnetic bio-nanocomposite hydrogels are a promising platform for tissue engineering and drug delivery applications. This research presents the synthesis and characterization of novel magnetic bio-nanocomposite hydrogel beads based on magnetic hydroxyapatite nanoparticles and chitosan for potential pH-sensitive drug delivery. The successful synthesis was confirmed through various analysis methods. The prepared bio-nanocomposites hydrogel beads exhibited pH-sensitive swelling behavior. Furthermore, the bio-nanocomposites demonstrated a high loading capacity for doxorubicin (DOX) anticancer drug and a pH-sensitive drug release profile, with approximately 80% release rate at pH 5 and less than 10% release rate at pH 7.4. The Weibull kinetic model was the best-fitting function for DOX release from bio-nanocomposite hydrogels at pH 5. The cytotoxicity of DOX-loaded bio-nanocomposite hydrogels against HeLa cells was evaluated, which showed high cytotoxicity after incubation for 48 h at a concentration of 2.5 mg/mL. These findings suggest that the prepared magnetic bio-nanocomposite hydrogel beads have good potential for implantable pH-sensitive drug delivery in the treatment of cancerous tissue. [ABSTRACT FROM AUTHOR]

Superabsorbent polymers (SAPs) are a class of cross-coupled hydrophilic networks that have an extraordinary capacity to absorb and retain water. It is primarily because of the additional ionic cross-linking of SAPs, their porous wavy structure, a large number of hydrophilic functionalities, the high elasticity of the chains, and the enlarged free volumes between the polymeric chains, that all contribute to the enhancement of the swelling capability of superabsorbent hydrogels. These exceptional attributes have endowed them to be an alternative to conventional hydrogels in various applications. In view of the importance of this class of absorbent material and their diverse appliances, this review deliberates the experimental methods for characterizing superabsorbent polymers, including the officially accepted industrial measurements of their unique attributes, namely, swelling among others. In addition, the review highlights recent advances in the field of superabsorbent polymers encompassing nanofiltration, heat resistance, and absorbency, drug delivery, disposable hygiene products, nanomedicines, and the removal of heavy metals from wastewater and agriculture domains. [ABSTRACT FROM AUTHOR]

The present study draws attention to arsenic (V) (As(V)), chromium (III) (Cr(III)), and chromium (VI) (Cr(VI)) heavy metal pollutants, which have negative effects on aquatic ecosystems and indirectly pose a serious threat to the health of living things in the environment. Homopolymer and copolymer hydrogels were synthesized by the UV polymerization technique using 2-acrylamido-2-methyl-1-propansulfonic acid sodium salt (AMPS) and 3-acrlylamidopropil-trimethyl ammonium chloride monomers, and a crosslinker aimed to improve the swelling properties and metal sorption of the prepared hydrogels. The swelling balance values of hydrogels were determined by the gravimetric method in deionized water and different pH values, and their structural characterizations were carried out by Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA) techniques. Sorption efficiencies and sorption capacities of the synthesized hydrogels were determined using aqueous solutions containing As(V), Cr(III), and Cr(VI) heavy metal ions at 25 °C. It was determined that there was a significant increase in p(AMPS) (AM1)-based hydrogel's balance swelling value in deionized water compared to p(AP1) and p(AMPS-co-APTMACl) (AMAP1)-based hydrogels. The lowest equilibrium swelling value was reached in the AMAP1 hydrogel, and the main reason for this result was thought to be due to the closure of the active functional groups of the increased cross-links between AMPS and APTMACl monomer. When sorption results were examined, it was observed that the highest heavy metal ion removal for AM1, AP1, and AMAP1 was in As(V) metal. The highest metal ion holding capacity of AM1, AP1, and AMAP1 was found to be 494 mg/g, 2336 mg/g, and 1439 mg/g for As(V), 323 mg/g, 111 mg/g, and 276 mg/g for Cr(III), and 303 mg/g, 723 mg/g, and 554 mg/g for Cr(VI), respectively. Considering the swelling and sorption results, it is thought that the synthesized hydrogels will provide a significant advantage in the removal of heavy metal ions, which have negative effects on environmental pollution and live health. [ABSTRACT FROM AUTHOR]

Natural gum polysaccharides have poor mechanical and physical properties and need to be modified with synthetic monomers. In this study, one-step in situ synthesis of Tragacanth gum grafted polyaniline hydrogel (TG-g-PANI) was used to prepare a new biodegradable and an inexpensive adsorbent for the removal of uranyl ions from aqueous solutions followed by the determination using UV–Vis spectrophotometry. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The FTIR spectrum identified functional groups in TG-g-PANI. SEM micrographs of Tragacanth gum revealed smooth surface, whereas TG-g-PANI present nanoparticles with rough surface and spherical shape that were compactly accumulated on the surface of hydrogel. The effective experimental parameters on the removal of uranyl ions such as sample pH, adsorbent dosage, contact time, and initial uranyl concentration were investigated. The results of optimization showed that one gram of hydrogel adsorbed 26 mg uranyl ions from aqueous solutions. The Langmuir and Freundlich models were examined to evaluate the adsorption isotherm. The data of sorption process were fitted well with the Freundlich isotherm. The adsorption rates of uranyl ions onto the adsorbent followed pseudo-second-order kinetic model and efficient removal of uranyl ions have occurred within 4 h. The thermodynamic investigation revealed that the adsorption process was exothermic and spontaneous. The adsorbent could be recycled for two times usage with removal efficiency of 90% after acid wash treatment. Finally, the adsorbent was successfully employed for removal of uranyl ions from bio-aggressive media such as seawater and ground water. [ABSTRACT FROM AUTHOR]

Summary: Aqueous solutions of Konjac glucomannan (KGM)/κ‐Carrageenan (κ‐C) of different ratios (1:2, 1:5, 1:8 and 1:10) and a fixed κ‐C content of 1.5%, were proposed as a new 3D food printing ink. Their thermo‐responsive behaviour was evaluated by temperature ramp rheological tests. This characterisation allowed for the evaluation of the synergistic effect between KGM and κ‐C and gave indications useful to the printing performance. Both elastic (G′) and loss (G″) moduli were found to increase by increasing the KGM concentration. Samples were printed by controlling the thermally reversible sol/gel transition occurring during the process. Direct pressure and flow rate measurements in the 3D printer were used to obtain the viscosity versus shear rate curves under processing conditions, useful to validate a scaling law relating the printing filament diameter to the relevant process and material properties (inks viscosity and printing pressure). The 3D printing performance of inks was evaluated by means of a novel, integrated score system. The results obtained indicate that aqueous mixtures of KGM/κ‐C can be successfully employed as a base for 3D printing food hydrogels. The use of the score system above outlined proved to be an easy yet efficient tool for the optimisation of the gel composition. [ABSTRACT FROM AUTHOR]

One of the most important challenges related to fresh meat products (especially sheep liver) is the short shelf-life of the product. For this purpose, synthetic preservative compounds are used to extend their shelf life, which have many side effects on human health. In this research, the effect of using an edible coating containing phenolic compounds of pomegranate peel cross-linked in the structure of aloe vera hydrogel was studied to extend the shelf life of sheep liver. Physicochemical (pH, peroxide index, total volatile nitrogen, thiobarbituric acid index and color parameters L* a *b * ) and sensory (aroma, color, texture and overall acceptability) properties of the product in storage days of 1, 3 and 7 days and in the storage temperature of +4oC was evaluated. The results indicated that, the lowest value of monohydroperoxide formation (i.e. peroxide index) was observed in test samples coated with aleo vera gel containing phenolic compound of pomegranate peel extract that corresponding to the lowest total volatile nitrogen. Generally, in accordance to the results of sensory evaluation and quality tests, using of aleo vera gel containing bioactive compounds of pomegranate peel extract is recommended for shelf life extending of sheep liver. [ABSTRACT FROM AUTHOR]

This study's purpose is to synthesize fluorescent hydrogel membranes using polyvinyl alcohol, chitosan and gelatin as bio-friendly substances, and to analyze the strengthening effect of graphitic carbon nitride/carbon quantum dots nanocomposite (g-C3N4/CQDs) on optical, mechanical and rheological properties of the synthesized hydrogel membranes (HMs). A two-step pyrolysis of the mixture of starch as a natural resource and urea as a nitrogen resource with 1:10 weight proportion was utilized to synthesize g-C3N4/CQDs nanocomposite via microwave-assisted system. Water absorption value in the synthesized samples was calculated 237–275%. UV absorbance and fluorescence features were investigated by UV–visible and photoluminescence spectroscopy. Results indicated that adding 0.5 wt% and 1 wt% g-C3N4/CQDs to HMs matrix led to UV absorption in 225, 275 and 395 nm wavelengths and strong fluorescence emission in 515 nm (green region). Samples flexibility was figured 22–56% by tensile test results so that by an increase in filler content, flexibility was driven down but tensile strength was driven up. Rheometry test findings confirmed that g-C3N4/CQDs adding resulted in improvement of rheological properties of the HMs like storage modulus and loss modulus, and growth of complex viscosity. [ABSTRACT FROM AUTHOR]

Objective(s): Basal cell carcinoma (BCC) is the most common form of skin cancer and the most frequently occurring form of all cancers, affecting sun-exposed areas like the face. Surgery is the main treatment, focusing on safe and minimally invasive methods for better outcomes. Technology has enabled the development of artificial skin substitutes for tissue repair. Tissue engineering uses scaffolds to create functional replacements. This project aims to create an alginate-based hydrogel with PEG-coated gold nanoparticles. Materials and Methods: The project extensively explored the modification of alginate hydrogels with PEG-coated gold nanoparticles, involving the synthesis of gold nanoparticles, their integration with the polymer, and the subsequent preparation of the concentrated hybrid hydrogel. Utilizing various physicochemical techniques, such as UV-visible spectroscopy, transmission electron microscopy, dynamic light scattering, zeta potential analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy, the fabrication process was optimized and characterized. Results: The successful synthesis of the hybrid biomaterial was achieved through robust and highly reproducible methods. The MTT assay results offered valuable insights into the biocompatibility and safety of the PEG-coated gold nanoparticle-loaded alginate-based films. The incorporation of PEG-coated gold nanoparticles allowed for potential drug loading on the nanoparticle surface and, consequently, within the hydrogel. Cellular assays were conducted to assess the potential applications of this novel biomaterial. Conclusion: The addition of polyethylene glycol made it possible to load different drugs onto the gold nanoparticles and also within the hydrogel. This makes it a promising choice for potential uses in tissue engineering. [ABSTRACT FROM AUTHOR]

Stem cells are cells with self-renewal, reproductive activity, and multiple differentiation potential. The native cell-extracellular matrix (ECM) is a hydrated network of proteins and polysaccharides that provide the surrounding environment to maintain stem cells. Hydrogels possess broadly tunable biofunctions and adequate mechanical strength, as well as ECM-like conditions for better cellular activity. Hydrogels are considered one of the most utilized and relevant options in terms of mimicking the native ECM. This review article summarizes the recent advances in the field of using hydrogels as a stem cell niche to regulate cell fate from design strategies. Furthermore, we also review how hydrogels regulate stem cell fate and differentiate into hepatocytes. Looking forward, we envision that with the adoption of an increasing number of interdisciplinary methods, it is reasonable to combine multiple strategies to prepare hydrogels with enhanced performance. Due to the special arrangement or interaction between multiple scales and multiple components, a new combination of hydrogels has emerged, which provides opportunities for further innovation of hydrogels in regulating cell fate. [ABSTRACT FROM AUTHOR]

Inflammation‐responsive hydrogels loaded with therapeutic factors are effective biomaterials for bone tissue engineering and regenerative medicine. In this study, a matrix metalloproteinase (MMP)‐responsive injectable hydrogel is constructed by integrating an MMP‐cleavable peptide (pp) into a covalent tetra‐armed poly‐(ethylene glycol) (PEG) network for precise drug release upon inflammation stimulation. To establish a pro‐regenerative environment, phosphatidylserine (PS) is encapsulated into a scaffold to form the PEG‐pp‐PS network, which could be triggered by MMP to release a large amount of PS during the early stage of inflammation and retain drug release persistently until the later stage of bone repair. The hydrogel is found to be mechanically and biologically adaptable to the complex bone defect area. In vivo and in vitro studies further demonstrated the ability of PEG‐pp‐PS to transform macrophages into the anti‐inflammatory M2 phenotype and promote osteogenic differentiation, thus, resulting in new bone regeneration. Therefore, this study provides a facile, safe, and promising cell‐free strategy on simultaneous immunoregulation and osteoinduction in bone engineering. [ABSTRACT FROM AUTHOR]

Enhancing the output performance of triboelectric nanogenerators (TENGs) is essential for increasing their application in smart devices. Oxygen‐vacancy‐rich BiO2‐x nanosheets (BiO2‐x NSs) are advanced‐engineered nanomaterials with excellent piezoelectric properties. Herein, a stretchable unsymmetrical BiO2‐x NSs deposited‐hydrogel made of polyacrylamide (PAM) as a multimodal TENG is rationally fabricated, and the performance of TENG can be tailored by controlling the BiO2‐x NSs deposition amount and spatial distribution. The alteration of resistance caused by the Poisson effect of PAM/BiO2‐x composite hydrogel (H‐BiO2‐x) can be used as a piezoresistive sensor, and the piezoelectricity of BiO2‐x NSs can effectively enhance the density of transfer charge, thus improving the output performance of the H‐BiO2‐x‐based TENG. In addition, the chemical cross–linking between the BiO2‐x NSs and the PAM polymer chain allows the hydrogel electrode to have a higher tensile capacity (867%). Used for biomechanical motion signal detection, the sensors made of H‐BiO2‐x have high sensitivity (gauge factor = 6.93) and can discriminate a range of forces (0.1–5.0 N) at low frequencies (0.5–2.0 Hz). Finally, the prepared TENG can collect biological energy and convert it into electricity. Consequently, the improved TENG shows a good application prospect as multimodal biomechanical sensors by combining piezoresistive, piezoelectric, and triboelectric effects. [ABSTRACT FROM AUTHOR]

In this work, gum ghatti-cl-poly(NIPAm)/-o-MWCNT (GGNIPACNT) hydrogels were prepared via free radical polymerization technique. The synthesized hydrogels were characterized through FTIR analysis, which suggested the successful binding of -o-MWCNTs to the hydrogels. This study explored the influence of the content of oxidised multiwalled carbon nanotubes (-o-MWCNTs) on the rheological and mechanical properties of gum ghatti-cl-poly(NIPAm) hydrogels. To evaluate their rheological behavior and processibility, we mixed different concentrations of oxidised multiwalled carbon nanotubes (-o-MWNTs) in the hydrogel, and their rheological properties were measured using a cone and plate rheometer. It was found that with an increase in the aspect ratio or concentration of -o-MWNTs, -o-MWNT interactions became stronger, as indicated by the higher storage modulus G′, complex viscosity ‖η*‖, and steady shear viscosity η. All hydrogels demonstrated shear thinning behavior and the nanotubes showed a statistically substantial arrangement in the direction of shear flow. The flow curves of the hydrogel samples displayed non-Newtonian behavior. The flow viscosity vs. shear rate profiles were calculated using the power law model, while flow shear stress vs. shear rate curves were evaluated by applying the Herschel–Bulkley model, where both the models were found to be the best fitting models. The frequency-dependent rheological behaviors of the nanocomposites in the linear viscoelastic region indicated that the storage modulus (G′), loss modulus (G′′), and complex viscosity (‖η*‖) increased with an increase in the content of -o-MWCNTs. The linear viscoelastic measurements showed that both the complex viscosity and moduli of the nanocomposites increased with an increase in the -o-MWCNT concentration. The results showed that the mechanical properties of the composite hydrogels were considerably enhanced with an increase in the content of -o-MWCNTs. Therefore, these hydrogels have potential applications in biomedical fields without the restrictions of water capacity and mechanical properties. [ABSTRACT FROM AUTHOR]

Inspired by nature, self‐regulation can be introduced in synthetic hydrogels by incorporating chemo‐mechanical signals or coupled chemical reactions to maintain or adapt the material's physico‐chemical properties when exposed to external triggers. In this work, we present redox and light dual stimuli responsive hydrogels capable of rapidly adapting the polymer crosslinking network while maintaining hydrogel stability. Upon irradiation with UV light, polymer hydrogels containing redox responsive disulfide crosslinks and light responsive ortho‐nitrobenzyl moieties show a release of payload accompanied by adaptation of the hydrogel network towards higher stiffness due to in situ crosslinking by S‐nitrosylation. Whereas the hydrogel design allows the network to either become softer in presence of reducing agent glutathione or stiffer upon UV irradiation, simultaneous application of both stimuli induces network self‐regulation resulting in a pulsatile form of payload release from the hydrogel. Finally, adaptive stiffness was used to make tunable hydrogels as substrates for different cell lines. [ABSTRACT FROM AUTHOR]

The rechargeable aqueous Zn||MnO2 chemistry has been extensively explored, but its electrochemical reaction mechanisms, especially in the context of MnO2/Mn2+ conversion and Zn2+/H+ intercalation chemistry, remain not fully understood. Here, we designed an amphiphilic hydrogel electrolyte, which distinguished the MnO2/Mn2+ conversion, Zn2+ intercalation, and H+ intercalation and conversion processes at three distinct discharge plateaus of an aqueous Zn||MnO2 battery. The amphiphilic hydrogel electrolyte is featured with an extended electrochemical stability window up to 3.0 V, high ionic conductivity, Zn2+‐selective ion tunnels, and hydrophobic associations with cathode materials. This specifically designed electrolyte allows the MnO2/Mn2+ conversion reaction at a discharge plateau of 1.75 V. More interesting, the discharge plateaus of ~1.33 V, previously assigned as the co‐intercalation of Zn2+ and H+ ions in the MnO2 cathode, are specified as the exclusive intercalation of Zn2+ ions, leading to an ultra‐flat voltage plateau. Furthermore, with a distinct three‐step electrochemical energy storage process, a high areal capacity of 1.8 mAh cm−2 and high specific energy of 0.858 Wh cm−2, even at a low MnO2 loading mass of 0.5 mg cm−2 are achieved. To our knowledge, this is the first report to fully distinguish different mechanisms at different potentials in aqueous Zn||MnO2 batteries. [ABSTRACT FROM AUTHOR]

BACKGROUND: Gold nanoparticles are of great significance in the development of multifunctional transdermal drug delivery systems. Smaller gold nanoparticles can penetrate the dermis through the intercellular pathway, but are limited to their easy agglomeration and colloidal morphology, which makes it difficult to exert effects on low delivery efficiency. OBJECTIVE: To develop an ultrasound-optimized hydrogel delivery system by combining phase change nanodroplets with bio-adhesive hydrogel for percutaneous delivery of gold nanoparticles. METHODS: The ultrasound-responsive nanodroplets loaded with gold nanoparticles were prepared by the emulsion solvent evaporation method and loaded into the polydopamine-modified methylacryloyl gelatin hydrogel to prepare a composite hydrogel scaffold. The structure and chemical composition of the ultrasound-responsive nanogold carrier were characterized. The microstructure, porosity, permeability, rheology, in vitro hemostasis, and antibacterial properties of the composite hydrogel were characterized. The cell compatibility of the hydrogel scaffold was evaluated by live/dead staining, and the optimization effects of low-intensity pulsed ultrasound on the permeability, porosity, and mechanical properties of hydrogel were evaluated. RESULTS AND CONCLUSION: (1) Transmission electron microscopy and ultraviolet-visible spectroscopy proved the successful construction of nanogold carriers. The particle size and potential results demonstrated that the synthesized nanoscaled ultrasonic responsive carrier had good stability. (2) Live/dead cell staining proved that the prepared composite hydrogel scaffold had certain biocompatibility. (3) Scanning electron microscopy exhibited that the prepared composite hydrogel scaffold had a porous network structure, and numerous pores of about 2 μm appeared inside the macropores after the addition of nanodroplets and ultrasonic irradiation. The permeability experiment displayed that low-intensity pulsed ultrasound could optimize the porosity and permeability of hydrogel materials. The hemostatic performance of the composite hydrogel scaffold was better than that of the hemostatic sponge and polydopamine@ methylacrylylated gelatin hydrogel scaffold. Under the irradiation of low-intensity pulsed ultrasound, the composite hydrogel scaffolds had good antioxidant effects and antibacterial properties. (4) Thermal imaging results manifested that gold nanoparticles were encapsulated in ultrasound-responsive nanobubbles, and more uniform dispersion could be obtained under ultrasonic excitation. (5) The results of the mechanical property test demonstrated that the storage modulus of the hydrogel increased before and after loading gold nanoparticles-nanodroplets, which showed stronger mechanical properties. The elongation at break was 122%, and the ductility was better than that without gold nanoparticles-nanodroplets (P < 0.05). (6) These findings indicate that the composite hydrogel scaffold has good biocompatibility, antibacterial property, oxidation resistance, and hemostatic effect. [ABSTRACT FROM AUTHOR]

Electronic skin (E‐skin) that can mimic the flexibility and stretchability of human skin with sensing capabilities, holds transformative potential in robotics, wearable technology, and healthcare. However, developing E‐skin poses significant challenges such as creating durable materials with skin‐like flexibility, integrating biosensing abilities, and using advanced fabrication techniques for wearable or implantable applications. To overcome these hurdles, a 3D‐printed electronic skin utilizing a novel class of nanoengineered hydrogels with tunable electronic and thermal biosensing capabilities is fabricated. This methodology takes advantage of the shear–thinning behavior in hydrogel precursors, allowing to construct intricate 2D and 3D electronic structures. The elasticity of skin using triple crosslinking in a robust fungal exopolysaccharide, and pullulan is simulated, while defect‐rich 2D molybdenum disulfide (MoS2) nanoassemblies ensure high electrical conductivity. The addition of polydopamine nanoparticles enhances adhesion to wet tissue. The hydrogel exhibits outstanding flexibility, stretchability, adhesion, moldability, and electrical conductivity. A distinctive feature of this technology is the precise detection of dynamic changes in strain, pressure, and temperature. As a human motion tracker, phonatory‐recognition platform, flexible touchpad, and thermometer, this technology represents a breakthrough in flexible wearable skins and holds transformative potential for the future of robotics and human‐machine interfaces. [ABSTRACT FROM AUTHOR]

Hydrogels are made tough to resist crack propagation. However, for seamless integration into devices and machines, it necessitates robustness against cyclic loads. Central to this objective is enhancing fatigue resistance, an indispensable attribute facilitating the optimal performance of hydrogels within a multitude of biological contexts, spanning various plant and animal tissues, as well as diverse biomedical and engineering areas. In this review, recent research concerning the fatigue behavior of hydrogels, presenting a comprehensive consolidation of the inherent mechanisms that underpin diverse strategies aimed at fortifying fatigue resistance, is summarized. A critical facet in the architectural blueprint of fatigue‐resistant hydrogels is emphasized, involving the imposition of spatial constraints upon the main chains at the crack tips, thereby effectuating a protracted delay in their fracture initiation during prolonged cyclic loading. The integration of multiscale mechanisms encompassing networks, interactions, media, and structures stands as a pivotal factor in the design of fatigue‐resistant hydrogels. It is hoped that the review will considerably propel the pragmatic deployment of fatigue‐resistant hydrogels across a diverse array of applications, thus catalyzing advancements in multiple fields. [ABSTRACT FROM AUTHOR]

Silver is an antimicrobial commonly used within wound care chiefly in advanced dressings or in a topical cream form, such as silver sulfadiazine (SSD). Although silver is effective at controlling the growth of many common wound bacteria, it can be cytotoxic and can build up in tissue, stalling the healing process. Here, we demonstrate the development of an on-demand release system for delivery of silver from a composite hydrogel comprising sodium polyacrylate particles dispersed in a cryo-crosslinked polyvinyl alcohol carrier gel. Application of cold atmospheric plasma (CAP) jet to the silver loaded hydrogel resulted in controlled release of silver. This release is thought to occur due to the formation of nitrous acids in the hydrogel by the CAP, resulting in protonation of carboxylate groups in the hydrogel and subsequent gel de-swelling due to the reduction in interchain charge repulsion. The location of silver within the sodium polyacrylate particles was probed using scanning electron microscopy and EDX imaging. The released silver inhibited the growth of Enterococcus faecalis, Pseudomonas aeruginosa, and Staphylococcus aureus and significantly reduced the viable cell count of the P. aeruginosa biofilm. [ABSTRACT FROM AUTHOR]

As an emerging energy storage device, zinc ion hybrid supercapacitors (ZHSCs) have attracted wide interest because of their intrinsic safety, high energy/power densities, and long cycle life. However, problems of liquid leakage and zinc dendrite growth seriously hinder its widespread application. To solve the above problems, a gelatin/polyacrylamide/agarose/Zn(CF3SO3)2 hydrogel electrolyte (G/PAAm/AG/Zn(CF3SO3)2) was designed by constructing a multi-crosslinked network of physically crosslinked gelatin and agarose coupled with chemically crosslinked polyacrylamide. The tested results show that G/PAAm/AG/Zn(CF3SO3)2 can effectively prevent electrolyte leakage and inhibit zinc dendrite growth. Moreover, G/PAAm/AG/Zn(CF3SO3)2 possesses high ionic conductivity (2.64 S m−1), high tensile strength (72.4 kPa at 489.2%), and high compressive strength (164.5 kPa at 80%). Additionally, a highly connected porous carbon material (denoted as HSSPC) with high specific surface area (2930.9 m2 g−1) was synthesized, which exhibits a reversible capacity of 183.5 mA h g−1 and good cycling stability (the capacity remains at 96.6% after 10 000 cycles). More importantly, the quasi-solid-state ZHSC based on G/PAAm/AG/Zn(CF3SO3)2 and HSSPC delivers a high specific capacity (122.8 mA h g−1, 0.25 A g−1), high energy/power densities (96.1 Wh kg−1/14.4 kW kg−1), and good cycling stability (capacity retention can be maintained at 114.0% of the initial capacity after 14 000 cycles). [ABSTRACT FROM AUTHOR]

Researchers are showing a great deal of interest in hydrogels due to the presence of high-water content, self-healing variants. Despite this, research into the development of smart hydrogels that have the combination of toughness, self-healing, and responsiveness to external stimuli is still lacking. Here, tough, and intelligent nanocomposite (NC) hydrogels have been developed by utilizing modified nano-crosslinker by means of gold-selenium (Au-Se) coordination interaction. The NC hydrogels demonstrate remarkable elasticity and strength, even when exposed to notches. With the optimal formulation, the nanocomposite hydrogel can achieve a maximum elongation of 1970%, a maximum fracture stress of 2.48 MPa, and a toughness of up to 9.95 MJ/m3, thanks to the dynamic gold crosslinks with improved branching. The presence of this structural attributes facilitates efficient energy dissipation within the hydrogel system. Combining Au-Se interaction as a healing element and the remarkable optothermal effect of nanoparticles, NC hydrogels can be quickly self-healed in near-infrared light exposure of 2 min, achieving a self-healing efficiency of 91%. Additionally, the hydrogels demonstrate repair potential when exposed to microwave irradiation, acid solution, and ultrasound stimulus. Moreover, a multi-responsive hydrogel composed of photothermal gold nanostructures can serve as a light-controlled drug carrier, which has smart drug release ability under external light stimulation. The advantageous properties of hydrogel make it a great option for biomedical and engineering fields. [ABSTRACT FROM AUTHOR]

Stress response, an intricate and autonomously coordinated reaction in living organisms, holds a reversible, multi‐path, and multi‐state nature. However, existing stimuli‐responsive materials often exhibit single‐step and monotonous reactions due to the limited integration of structural components. Inspired by the cooperative interplay of extensor and flexor cells within Mimosa's pulvini, we present a hydrogel with differentiated hydrogen‐bonding (H‐bonding) networks designed to enable the biological stress response. Weak H‐bonding domains resemble flexor cells, confined within a hydrophobic network stabilized by strong H‐bonding clusters (acting like extensor cells). Under external force, strong H‐bonding clusters are disrupted, facilitating water diffusion from the bottom layer and enabling transient expansion pressure gradient along the thickness direction. Subsequently, water diffuses upward, gradually equalizing the pressure, while weak H‐bonding domains undergo cooperative elastic deformation. Consequently, the hydrogel autonomously undergoes a sequence of reversible and pluralistic motion responses, similar to Mimosa's touch‐triggered stress response. Intriguingly, it exhibits stress‐dependent color shifts under polarized light, highlighting its potential for applications in time‐sensitive "double‐lock" information encryption systems. This work achieves the coordinated stress response inspired by natural tissues using a simple hydrogel, paving the way for substantial advancements in the development of intelligent soft robots. [ABSTRACT FROM AUTHOR]

Hydrogels hold great promise as electrolytes for emerging aqueous batteries, for which establishing a robust electrode‐hydrogel interface is crucial for mitigating side reactions. Conventional hydrogel electrolytes fabricated by ex situ polymerization through either thermal stimulation or photo exposure cannot ensure complete interfacial contact with electrodes. Herein, we introduce an in situ electropolymerization approach for constructing hydrogel electrolytes. The hydrogel is spontaneously generated during the initial cycling of the battery, eliminating the need of additional initiators for polymerization. The involvement of electrodes during the hydrogel synthesis yields well‐bonded and deep infiltrated electrode‐electrolyte interfaces. As a case study, we attest that, the in situ‐formed polyanionic hydrogel in Zn‐MnO2 battery substantially improves the stability and kinetics of both Zn anode and porous MnO2 cathode owing to the robust interfaces. This research provides insight to the function of hydrogel electrolyte interfaces and constitutes a critical advancement in designing highly durable aqueous batteries. [ABSTRACT FROM AUTHOR]

Stress response, an intricate and autonomously coordinated reaction in living organisms, holds a reversible, multi‐path, and multi‐state nature. However, existing stimuli‐responsive materials often exhibit single‐step and monotonous reactions due to the limited integration of structural components. Inspired by the cooperative interplay of extensor and flexor cells within Mimosa's pulvini, we present a hydrogel with differentiated hydrogen‐bonding (H‐bonding) networks designed to enable the biological stress response. Weak H‐bonding domains resemble flexor cells, confined within a hydrophobic network stabilized by strong H‐bonding clusters (acting like extensor cells). Under external force, strong H‐bonding clusters are disrupted, facilitating water diffusion from the bottom layer and enabling transient expansion pressure gradient along the thickness direction. Subsequently, water diffuses upward, gradually equalizing the pressure, while weak H‐bonding domains undergo cooperative elastic deformation. Consequently, the hydrogel autonomously undergoes a sequence of reversible and pluralistic motion responses, similar to Mimosa's touch‐triggered stress response. Intriguingly, it exhibits stress‐dependent color shifts under polarized light, highlighting its potential for applications in time‐sensitive "double‐lock" information encryption systems. This work achieves the coordinated stress response inspired by natural tissues using a simple hydrogel, paving the way for substantial advancements in the development of intelligent soft robots. [ABSTRACT FROM AUTHOR]

Hydrogels hold great promise as electrolytes for emerging aqueous batteries, for which establishing a robust electrode‐hydrogel interface is crucial for mitigating side reactions. Conventional hydrogel electrolytes fabricated by ex situ polymerization through either thermal stimulation or photo exposure cannot ensure complete interfacial contact with electrodes. Herein, we introduce an in situ electropolymerization approach for constructing hydrogel electrolytes. The hydrogel is spontaneously generated during the initial cycling of the battery, eliminating the need of additional initiators for polymerization. The involvement of electrodes during the hydrogel synthesis yields well‐bonded and deep infiltrated electrode‐electrolyte interfaces. As a case study, we attest that, the in situ‐formed polyanionic hydrogel in Zn‐MnO2 battery substantially improves the stability and kinetics of both Zn anode and porous MnO2 cathode owing to the robust interfaces. This research provides insight to the function of hydrogel electrolyte interfaces and constitutes a critical advancement in designing highly durable aqueous batteries. [ABSTRACT FROM AUTHOR]

The ideal and highly anticipated dressing for skin wounds should provide a moist environment, possess antibacterial properties, and ensure sustained drug release. In the present work, a hyaluronic acid‐based hydrogel was formed by cross‐linking crocetin and CaCO3@polyelectrolyte materials (CaCO3@PEM) microspheres with HA hydrogels via hydrogen bond and amido bonding (CaCO3@PEM@Cro@HA hydrogel, CPC@HA hydrogel). Moreover, the CPC@HA hydrogel had the capability of sustained, controlled release of calcium ions and crocetin via pH‐sensitive and accelerated skin wound healing. The experiment results showed that the CPC@HA hydrogel exhibited porous network structures, stable physical properties, and had antibacterial properties and biocompatibility in vitro. In addition, the CPC@HA hydrogel covering on the skin wound could reduce inflammation and promote wound healing. The high expression of angiogenic cytokines (CD31) and epidermal terminal differentiation markers (Loricrin) of wound healing tissue suggested the CPC@HA hydrogel also had the function of promoting the remodeling of regenerated skin. Overall, CPC@HA hydrogel has promising potential for clinical applications in accelerating skin wound repair. [ABSTRACT FROM AUTHOR]

A new 3D metal–organic frameworks [Cd6(L)4(bipy)3(H2O)2·H2O] (1) was gained by employing Cd(II) and organic ligand [H3L = 4,4′,4′′-(benzene-1,3,5-triyltris(oxy))tribenzoic acid)benzene acid; bipy = 4,4′-bipyridine] in the solvothermal condition, which has been fully examined via single-X ray diffraction, FTIR and elemental analysis and so on. Using natural polysaccharides hyaluronic acid (HA) and carboxymethyl chitosan (CMCS) as raw materials, we successfully prepared HA/CMCS hydrogels and observed their internal micromorphology by scanning electron microscopy. Using doxorubicin (Dox) as a drug model, we synthesized a novel metal gel particle loaded with doxorubicin, and their encapsulation and release effects were studied using fluorescence spectroscopy, followed by further investigation of their components through thermogravimetric analysis. Based on this, the therapeutic effect on leukemia was evaluated. Finally, an enhanced learning method for automatically designing new ligand structures from host ligands was proposed. Through generative modeling and molecular docking simulations, the biological behavior of the host and predicted cadmium complexes was extensively studied. [ABSTRACT FROM AUTHOR]

Gels made of telechelic polymers connected by reversible cross-linkers are a versatile design platform for biocompatible viscoelastic materials. Their linear response to a step strain displays a fast, near-exponential relaxation when using low-valence cross-linkers, while larger supramolecular cross-linkers bring about much slower dynamics involving a wide distribution of timescales whose physical origin is still debated. Here, we propose a model where the relaxation of polymer gels in the dilute regime originates from elementary events in which the bonds connecting two neighboring cross-linkers all disconnect. Larger cross-linkers allow for a greater average number of bonds connecting them but also generate more heterogeneity. We characterize the resulting distribution of relaxation timescales analytically and accurately reproduce stress relaxation measurements on metal-coordinated hydrogels with a variety of cross-linker sizes including ions, metal-organic cages, and nanoparticles. Our approach is simple enough to be extended to any cross-linker size and could thus be harnessed for the rational design of complex viscoelastic materials. [ABSTRACT FROM AUTHOR]

Soil conservation is one of the best methods to improve soil fertility and enhance crop growth efficiency. Replacing plastic mulch with biomass is an environmentally friendly strategy. Innovative encapsulated soil granules (ESGs) were developed using PVA/PC film as the wall material and rural soil as the core. The PVA/PC was synthesized using 60% protein polypeptide (PC) from leather waste scrap and 35% poly (vinyl alcohol) (PVA), which was optimized for water absorption expansion and water retention performance. The ESG-10 granulated with 10% PVA/PC exhibited good water absorption, moisture retention, and resistance to water solubility. As an auxiliary material for soil improvement, the amount of ESGs mixed with the topsoil at ratios of 0 g/m2, 200 g/m2, and 400 g/m2 was proportional to the soil insulation and moisture retention. In rapeseed cultivation, the experimental results indicated that the soil mulched with ESG-10 can maintain seedling vitality for a long time under low water content conditions. [ABSTRACT FROM AUTHOR]

Three-dimensional extrusion bioprinting technology aims to become a fundamental tool for tissue regeneration using cell-loaded hydrogels. These biomaterials must have highly specific mechanical and biological properties that allow them to generate biosimilar structures by successive layering of material while maintaining cell viability. The rheological properties of hydrogels used as bioinks are critical to their printability. Correct printability of hydrogels allows the replication of biomimetic structures, which are of great use in medicine, tissue engineering and other fields of study that require the three-dimensional replication of different tissues. When bioprinting cell-loaded hydrogels, a small amount of culture medium can be added to ensure adequate survival, which can modify the rheological properties of the hydrogels. GelMA is a hydrogel used in bioprinting, with very interesting properties and rheological parameters that have been studied and defined for its basic formulation. However, the changes that occur in its rheological parameters and therefore in its printability, when it is mixed with the culture medium necessary to house the cells inside, are unknown. Therefore, in this work, a comparative study of GelMA 100% and GelMA in the proportions 3:1 (GelMA 75%) and 1:1 (GelMA 50%) with culture medium was carried out to determine the printability of the gel (using a device of our own invention), its main rheological parameters and its toxicity after the addition of the medium and to observe whether significant differences in cell viability occur. This raises the possibility of its use in regenerative medicine using a 3D extrusion bioprinter. [ABSTRACT FROM AUTHOR]

Hydrogels, recognized for their flexibility and diverse characteristics, are extensively used in medical fields such as wearable sensors and soft robotics. However, many hydrogel sensors derived from biomaterials lack mechanical strength and fatigue resistance, emphasizing the necessity for enhanced formulations. In this work, we utilized acrylamide and polyacrylamide as the primary polymer network, incorporated chemically modified poly(ethylene glycol) (DF-PEG) as a physical crosslinker, and introduced varying amounts of methacrylated lysine (LysMA) to prepare a series of hydrogels. This formulation was labeled as poly(acrylamide)-DF-PEG-LysMA, abbreviated as pADLx, with x denoting the weight/volume percentage of LysMA. We observed that when the hydrogel contained 2.5% w/v LysMA (pADL2.5), compared to hydrogels without LysMA (pADL0), its stress increased by 642 ± 76%, strain increased by 1790 ± 95%, and toughness increased by 2037 ± 320%. Our speculation regarding the enhanced mechanical performance of the pADL2.5 hydrogel revolves around the synergistic effects arising from the co-polymerization of LysMA with acrylamide and the formation of multiple intermolecular hydrogen bonds within the network structures. Moreover, the acid, amine, and amide groups present in the LysMA molecules have proven to be instrumental contributors to the self-adhesion capability of the hydrogel. The validation of the pADL2.5 hydrogel's exceptional mechanical properties through rigorous tensile tests further underscores its suitability for use in strain sensors. The outstanding stretchability, adhesive strength, and fatigue resistance demonstrated by this hydrogel affirm its potential as a key component in the development of robust and reliable strain sensors that fulfill practical requirements. [ABSTRACT FROM AUTHOR]

Sodium hyaluronate (HA) is a natural polysaccharide. This biopolymer occurs in many tissues of living organisms. The regenerating, nourishing, and moisturizing properties as well as the rheological properties of HA enable its application in the pharmaceutical industry as a carrier of medicinal substances. The aim of this work was to assess the release of naproxen sodium (Nap) in the presence of lidocaine hydrochloride (Lid) from the biopolymer-based hydrogels and to determine the respective kinetic parameters of this process. The possible interaction between the HA polysaccharide carrier and the selected drugs was also investigated. Three hydrogels containing Nap and Lid with different concentrations of the biopolymer were prepared. The release of Nap was studied by employing USP apparatus 5. The infrared study and differential scanning calorimetry analysis of physical mixtures and dried formulations were performed. The highest amount of Nap was released from the formulation with the lowest concentration of the biopolymer. The most representative kinetic model that described the dissolution of Nap was obtained through the Korsmeyer–Peppas equation. The release rate constants were in the range of 1.0 ± 0.1 × 10−2 min−n–1.7 ± 0.1 × 10−2 min−n. Lid did not influence the dissolution of Nap from the formulations tested; however, in the desiccated samples of assessed formulations, the interaction between the polysaccharide and both drugs was observed. [ABSTRACT FROM AUTHOR]