Thermal-responsive Hydrogel Research Articles

Operando Decoding Ion-Conductive Switch in Stimuli-Responsive Hydrogel by Nanodiamond-Based Quantum Sensing.

Thermal-responsive hydrogels are developed as ion-conductive switchs for energy storage devices, however, the molecule mechanism of switch on/off remains unclear. Here, poly(N-isopropylacrylamide-co-acrylamide) hydrogel is synthesized as a model material and nanodiamond (ND) based quantum sensing for phase change study is developed. First, micro-scale phase separation with cross-linked mesh structure after sol-gel transition is visualized in situ and water molecules are trapped by polymer chains and on a chemically "frozen" state. Then, the nano-scale inhomogeneous distributions of viscosity, thermal conductivity and ionic mobility in hydrogel at high temperature are observed by measuring the rotation, translation and zero-field splitting of NDs. Besides, the ionic mobility of hydrogel is found to be dependent not only on temperature but also on polymer concentration. These observations suggested that the physical "wall" induced by inhomogeneous phase separation at microscopic scale blocked the ion conduction pathways, providing a potential intrinsic explanation for ion migration shut-down of ionic hydrogels at high temperature.

UV Light-Mediated Hydrolytic Reaction to Develop Magnetic Hydrogel Actuators with Spatially Distributed Ferriferous Oxide Microparticles.

Magnetic hydrogel actuators are developed by incorporating magnetic fillers into the hydrogel matrix. Regulating the distribution of these fillers is key to the exhibited functionalities but is still challenging. Here a facile way to spatially synthesize ferrosoferric oxide(Fe3O4) microparticles in situ in a thermal-responsive hydrogel is reported. This method involves the photo-reduction of Fe3+ ions coordinated with carboxylate groups in polymer chains, and the hydrolytic reaction of the reduced Fe2+ ions with residual Fe3+ ions. By controlling the irradiation time and position, the concentration of Fe3O4 microparticles can be spatially controlled, and the resulting Fe3O4 pattern enables the hydrogel to exhibit complex locomotion driven by magnet, temperature, and NIR light. This method is convenient and extendable to other hydrogel systems to realize more complicated magneto-responsive functionalities.

Vancomycin-loaded hydrogels with thermal-responsive, self-peeling, and sustainable antibacterial properties for wound dressing.

Wound dressings play an important role in wound healing. However, many wound dressings lack antibacterial properties and are difficult to remove from newly grown tissues, causing secondary wound injuries and repeated medical treatment. This study reports a new type of thermal-responsive hydrogel dressing consisting of vancomycin-loaded gelatin nanospheres (GNs) and poly((N-isopropylacrylamide)-co-N-(methylol acrylamide)) functional components that could impart self-peeling and sustainable antibacterial properties. SEM images showed that the prepared hydrogel possessed a porous microstructure and the homogeneous distribution of GNs in its network. Excellent swelling ratios and thermal-induced self-peeling characteristics were confirmed by qualitative analysis. The GNs not only enhanced the strain at break of the hydrogel, but also acted as drug carriers to slow down the drug release from the hydrogel, achieving sustainable antibacterial properties and balanced biocompatibility. Therefore, this vancomycin-loaded hydrogel with self-peeling characteristics provides an effective way of preventing wound infection and can be used as a novel platform for wide-ranging applications of wound dressings.

Coconut husk-derived nanocellulose as reinforcing additives in thermal-responsive hydrogels

Nanocellulose has been widely used as a reinforcing agent for hydrogel systems, but its functions on thermal responsive hydrogels are rarely investigated. In this study, we extracted cellulose nanofibers (CNFs) from coconut biomass (coir fibers and piths, respectively) and aimed to study their effects on the material properties on a new class of thermogel (poly(PCL/PEG/PPG urethane). The CNFs extracted from fiber (FF) and piths (FP) showed different morphology and fiber lengths. FF are uniformed individual fibrous networks with a fiber length of 664 ± 416 nm, while FP display a hybrid structure consisting of individual fiber and large bundles with a relative shorter fiber length of 443 ± 184 nm. Integrating both CNFs into thermogels remained the thermal-responsive characteristics with an enhanced rheological property. The results showed that gels with FF resulted in a higher storage modulus and lower Tan δ value compared to those with FP, indicating that the CNFs with a longer length could form a more intertwined network interacting with the thermogel matrix. Furthermore, we demonstrated the improved capabilities of the nanocomposite thermogels for sustained drug delivery in vitro. This study not only value-adds lignocellulose valorization but also elevates the versatility of thermogels.

A thermal-responsive hydrogel to capture uranium(VI) from aqueous solution: properties and mechanism

A thermal-responsive hydrogel to capture uranium(VI) from aqueous solution: properties and mechanism

Thermal responsive smart lanthanide luminescent hydrogel actuator

Among stimuli-responsive soft materials, thermal responsive hydrogels are the most attractive one because temperature is the most easily regulated external stimuli. We here report a thermal responsive bilayer smart luminescent hydrogel actuator with tough mechanical strength and thermal reversible deformation behavior. The bilayer hydrogel is composed of Poly(N-isopropylacrylamide)-Laponite-Tb complex (PNIPAM-Lap-Tb·L3) layer and Poly(N,N-dimethylacrylamide)-Laponite-Eu complex (PDMA-Lap-Eu·L3) layer. Upon alternative heating and cooling, the PNIPAM-Lap-Tb·L3 layer undergoes reversible shrink and expansion, while the PDMA-Lap-Eu·L3 layer is not affected, leading to asymmetric deformation behavior. The luminescent intensity of the bilayer hydrogel was enhanced by heating, and the maximum bending angle was 371° in 15 min. By processing the bilayer hydrogel into complex 2D and 3D structure, we further demonstrate their great potential as smart soft actuators.

PH and temperature dual-responsive hydrogel actuator with bidirectional bending behavior and ultra large bending angle

Smart hydrogels have received attentions for the great potentials in biomedical and robots applications. However, the deformation performance of hydrogels still needs to be improved, especially for the pH and thermal dual responsive hydrogels. In this study, a pH and temperature dual-responsive poly(acrylamide-acrylic acid-3-acrylamidophenylboronic acid)/Poly(N-isopropylacrylamide) (P(AAm-AAc-3-AAPBA)/PNIPAM) bilayer structures have been prepared by UV polymerization. The PNIPAM layer shrinks/swells when the temperature is higher/lower than the low critical solution temperature, while P(AAm-AAc-3-AAPBA) layer will swell/shrink when pH is too high/low. The volume change trend of the two layer is different, resulting in the bending behaviors of P(AAm-AAc-3-AAPBA)/PNIPAM hydrogel actuator. The bidirectional bending performance can be reversibly, repeatedly, and precisely controlled by pH and temperature-induced cooperative swelling-shrinking properties from both layers. The bending angle of the bilayer structure achieves about 1420° at the environment of pH 2 and 55 ℃. It takes about 70 s to convert the bending angle of the bilayer structures from 355° (10 ℃, pH 2) to −360° (55 ℃, pH 12). In addition, three kinds of biomimetic hydrogel structures, such as mechanical gripper, bionic flower and bionic hand, have been prepared and demonstrated good performance. The obtained P(AAm-AAc-3-AAPBA)/PNIPAM hydrogels exhibit excellent pH and thermal responsive bending properties, which enable them as an ideal smart hydrogel system.

Highly stretchable, self-healable and adhesive, thermal responsive conductive hydrogel loading nanocellulose complex for a flexible sensor

Currently, with the widespread concerns of smart soft sensors in wearable electronics, human health detection and electronic skin, flexible conductive hydrogels have been extensively studied. However, it remains a great challenge to develop hydrogels that have both satisfactory mechanical performance with stretchable and compressible and high conductive. Herein, based on synergistic dynamic hydrogen and metal coordination bonds, polyvinyl alcohol (PVA)/poly (2-hydroxyethyl methacrylate) (PHEMA) hydrogels doped with polypyrrole decorated cellulose nanofibers (CNFs@PPy) are developed via free radical polymerization. The loading versatile CNFs@PPy highlighted the complex hydrogels super-stretchability (approximately 2600 % elongation) and excellent toughness (2.74 MJ/m3) properties to tensile deformation, strong compressive strength (1.96 MPa), fast temperature responsiveness and outstanding strain sensing capability (GF = 3.13). Moreover, the PHEMA/PVA/CNFs@PPy hydrogels possessed rapid self-healing and powerful adhesive abilities to various interfaces without extra assistance, as well as distinguished fatigue resistance performance. Such advantages make the nanocomposite hydrogel displayed high stability and repeatable to both pressure and strain in a wide range of deformations, enabling a promising candidate in the fields of motion monitoring and healthcare management.

Ferric chloride induces ferroptosis in Pseudomonas aeruginosa and heals wound infection in a mouse model

As one of the most common pathogens leading to fatal human infection, Pseudomonas aeruginosa has been evolving complex drug resistance, posing significant challenges to the current antibiotic-dependent healthcare system. New therapeutic approaches are urgently required to treat infections caused by P. aeruginosa. Inspired by ferroptosis, we investigated the antibacterial effects of iron compounds on P. aeruginosa via direct exposure, and developed thermal-responsive hydrogels to carry FeCl3 as a wound dressing to treat P. aeruginosa-induced wound infection in mice model. The results showed that 200 μM FeCl3 killed more than 99.9% P. aeruginosa cells. The FeCl3-mediated cell death in P. aeruginosa was associated with ferroptosis hallmarks of mammal cells, e.g., reactive oxygen species (ROS) burst, lipid peroxidation, and DNA damage. Either catalase or Fe2+ chelator alleviated the FeCl3-mediated cell death, indicating that H2O2 and labile Fe2+ facilitated the Fenton reaction leading to the cell death. Further proteomics analysis showed that proteins related to glutathione (GSH) synthesis and glutathione peroxidase (GPX) family were significantly down-regulated after FeCl3 treatment, equivalent to GPX4 inactivation in ferroptosis-occurring mammal cells. We further evaluated the therapeutic effect of FeCl3 on P. aeruginosa in a mouse wound infection model using polyvinyl alcohol-boric acid (PB) hydrogels as the carrier of FeCl3. Strikingly, FeCl3-PB hydrogels completely cleared pus on wounds and promoted the healing of wounds. These results indicated that FeCl3 facilitates microbial ferroptosis in the gram-negative pathogen P. aeruginosa and has high therapeutic potential in P. aeruginosa wound infection.

A novel Solution-Diffusion-Flory-Rehner model to predict flux behavior during forward osmosis with thermo-responsive hydrogel as draw agent

Although hydrogels as excellent draw agents have been extensively investigated, the relationship between the driving force of hydrogel and mass transfer behavior during forward osmosis (FO) remains unclear. The hydrogel-driven FO requires a mass transfer model to clarify its driving mechanism, yet no model was available at present. In the current study, a water flux model driven by thermal-responsive hydrogel was first developed by coupling solution-diffusion model and Flory-Rehner model (SDFR). Considering the diffusion characteristics of hydrogel, a redefined parameter DH corresponding to water diffusion coefficient in hydrogel matrix was introduced to the SDFR model. The validity of the model and DH were verified by comparing experimental water flux data for different concentrations of feed solution with the corresponding simulating results from SDFR model. The SDFR model successfully predicted the flux behavior of FO under wide varieties of operating conditions. Furthermore, the existence of internal concentration polarization phenomenon in hydrogel-driven FO was unveiled by modeling the pressure distribution across FO membrane, and its effect on flux behavior was quantified. The SDFR model was also employed to design a novel ionic thermal-responsive hydrogel with better FO performance. The new insights gained from the SDFR model in this study will help to develop more efficient FO applications with hydrogel-based draw agents.

Salt sensitive purely zwitterionic physical hydrogel for prevention of postoperative tissue adhesion.

Abdominal adhesions are a class of serious complications following abdominal surgery, resulting in a complicated and severe syndrome and sometimes leading to a Gordian knot. Traditional therapies employ hydrogels synthesized using complicated chemical formulations-often with click chemistry or thermal responsive hydrogel. The complicated synthesis process and severe conditions limit the extent of the hydrogels' applications. In this work, poly 3-[2-(methacryloyloxy)ethyl](dimethyl)-ammonio]-1-propanesulfonate (PSBMA) polymer was synthesized to self-assemble into physical hydrogels due to the inter- and intramolecular ion interactions. The strong static interaction bonding density has a substantial impact on the gelation and physicochemical properties, which is beneficial to clinical applications and offers a novel way to obtain the desired hydrogel for a specific biomedical application. Intriguingly, this PSBMA polymer can be customized into a transient network with outstanding antifouling capability depending on the ion concentration. As ion concentration increases, the PSBMA hydrogel dissociated completely, endowing it as a candidate for adhesion prevention. In the cecum-sidewall model, the PSBMA hydrogel demonstrated superior anti-adhesion properties than commercial HA hydrogel. Furthermore, we have demonstrated that this PSBMA hydrogel could inhibit the inflammatory response and encourage anti-fibrosis resulting in adhesion prevention. Most surprisingly, the recovered skins of cecum and sidewall are as smooth as the control skin without any scar and damage. In conclusion, a practical hydrogel was synthesized using a facile method based on purely zwitterionic materials, and this ion-sensitive, antifouling adjustable supramolecular hydrogel with great clinic transform potential is a promising barrier for preventing postoperative tissue adhesion. STATEMENT OF SIGNIFICANCE: The development of hydrogels with satisfactory coverage, long retention time, facile synthetic method, and good biocompatibility is vital for preventing peritoneal adhesions. Herein, we developed a salt sensitive purely zwitterionic physical hydrogel poly 3-[2-(methacryloyloxy)ethyl](dimethyl)-ammonio]-1-propanesulfonate (PSBMA) hydrogel to effectively prevent postoperative and recurrent abdominal adhesions. The hydrogel was simple to synthesize and easy to use. In the cecum-sidewall model, PSBMA hydrogel could instantaneously adhere and fix on irregular surfaces and stay in the wound for more than 10 days. The PSBMA hydrogel could inhibit the inflammatory response, encourage anti-fibrosis, and restore smoothness to damaged surfaces resulting in adhesion prevention. Overall, the PSBMA hydrogel is a promising candidate for the next generation of anti-adhesion materials to meet clinical needs.

Fast thermal responsive hydrogels consisting of electrospun fibers with highly tunable conductivity

Stimuli-responsive hydrogels with fibrous structure are highly promising in biological sensors and actuators because of their fast response rate. In this paper, we first fabricate poly(N-isopropylacrylamide) based hydrogels consisting of electrospun nanofibers and applied them as hydrogel matrices to introduce doped poly(aniline) (PANI) via in-situ polymerization. Regardless of the PANI introduced, the fast thermal-responsive feature brought by the fibrous structure is maintained successfully. The continuous channel for electron transfer is provided by PANI located at fibers’ surfaces and inside fibers. The effect of PANI incorporated in hydrogel matrices on: 1) fiber morphology in both swollen and contracted states; 2) swelling/contraction capability of the hydrogels and 3) conductivity of the hybrid hydrogels are investigated. The electric conductive properties of this hybrid hydrogel vary consistently with its swelling degree in response to temperature alternation. Subsequently, an evaluation system, aiming at general understanding and comparison of both conductive and responsive capabilities for this type of hybrid hydrogel, is established. This evaluation system is applied to forecast their potential applications based on corresponding thermal-responsive and conductive properties. In this work, a hybrid hydrogel system has been successfully fabricated via in-situ polymerization of PANI in a fibrous-structured PNIPAM hydrogels. Without sacrificing the excellent temperature-responsive capability brought by the nano fibrous structure, the integration of PANI introduces the electrical conductivity feature to this hybrid system. Upon consideration of both temperature responsiveness and electrical conductivity of this hybrid hydrogel, a evaluating system has been proposed, for the first time, to guide the potential application for this fibrous-structured hybrid hydrogels. • Introduction PANI into PNIPAM-based nanofibers via in-situ polymerization • Reservation of the thermal responsiveness and electrical conductivity • Correlation of the thermal responsiveness and electrical conductivity of the PNIPAM/PANI hybrid hydrogels • Establishment of the thermal responsiveness-electrical conductivity model to guide the potential application of this fibrous hybrid hydrogels

Fast-response photothermal bilayer actuator based on poly(N-isopropylacrylamide)-graphene oxide-hydroxyethyl methacrylate/polydimethylsiloxane.

Demands for highly deformable and responsive intelligent actuators are increasing rapidly. Herein, a photothermal bilayer actuator consisting of a photothermal-responsive composite hydrogel layer and a polydimethylsiloxane (PDMS) layer is presented. The photothermal-responsive composite hydrogel is prepared by compositing hydroxyethyl methacrylate (HEMA) and the photothermal material graphene oxide (GO) with the thermal-responsive hydrogel poly(N-isopropylacrylamide) (PNIPAM). The HEMA improves the transport efficiency of water molecules inside the hydrogel network, eliciting a fast response and large deformation, facilitating greater bending behavior of the bilayer actuator, and improving the mechanical and tensile properties of the hydrogel. Moreover, GO enhances the mechanical properties and the photothermal conversion efficiency of the hydrogel in the thermal environment. This photothermal bilayer actuator can be driven under various conditions, such as hot solution, simulated sunlight, and laser, and can achieve large bending deformation with desirable tensile properties, broadening the application conditions for bilayer actuators, such as artificial muscles, bionic actuators, and soft robotics.

Thermal-Responsive Hydrogel Actuators with Photo-Programmable Shapes and Actuating Trajectories.

Thermal-responsive hydrogel actuators have aroused a wide scope of research interest and have been extensively studied. However, their actuating behaviors are usually monotonous due to their unchangeable shapes and structures. Here, we report thermal-responsive poly(isopropylacrylamide-co-2-(dimethylamino)ethyl methacrylate)/alginate hydrogels with programmable external shapes and internal actuating trajectories. The volume phase transition temperatures of the resulting hydrogels can be tuned in a wide temperature range from 32 to above 50 °C by adjusting the monomer composition. While the formation and photo-dissociation of Fe3+-carboxylate tri-coordinates within the entire hydrogel network enable photo-responsive shape memory property, the insufficient dissociation of the tri-coordinates along the irradiation path gives rise to gradient crosslinking for realizing thermal-responsive actuation. Controlling the evolution of the gradient structure facilitates the regulation of the actuating amplitude. Furthermore, we show that the combination of these two types of shape-changing functionalities leads to more flexible and intricate shape-changing behaviors. One interesting application, a programmable hook with changeable actuating behaviors for lifting different objects with specific shapes, is also demonstrated. The proposed strategy can be extended to other types of actuating hydrogels with more advanced actuating behaviors.

Research progress and clinical application of stimuli-responsive hydrogels in cervical cancer

Cervical cancer is the fourth most common malignancy in women worldwide and poses a great risk to women's health. There is an urgent need to develop a range of effective and innovative therapeutic options to overcome the shortcomings of conventional treatments: poor efficacy and toxic side effects. As an alternative therapy, a number of advances have been made in hydrogel-based drug delivery systems that enable targeted and localized therapy, as well as controlled release of drugs at the tumor site. These advantages can effectively increase drug concentration and reduce damage to normal sites caused by chemical drug toxicity. This paper reviews the progress of research applications of stimuli-responsive hydrogels in cervical cancer. The response mechanisms of hydrogels and the principles of enhanced drug efficacy are discussed in focus. These include thermal-responsive hydrogels, pH-responsive hydrogels, light-responsive hydrogels, enzyme-responsive hydrogels, and dual-responsive hydrogels. It is also argued that through the increasing understanding of hydrogels, it can be used clinically as an effective and durable therapeutic tool.

Constitutive modeling for hydrogel with chain entanglements and application to adaptive hydrogel composite structures

Hydrogel is one of typical smart materials and has been used in many engineering applications, such as flexible electronics, flexible robots, and biomedical engineering. Modern industries with complex working environments require hydrogel to have higher strength without losing flexibility. Many published experimental studies focus on the preparation technique of hydrogel composite with high strength and toughness. However, the theoretical investigation into the influence of entanglements on the hydrogel deformation is rarely reported for the structure analysis and deformation mechanism of hydrogel composite, as a purpose to design of hydrogel devices. In this paper, the constitutive model is developed for thermal responsive hydrogel with chain entanglements, based on Flory-Rehner theory and slip-link model, and numerically solved by a user subroutine in ABAQUS. The uniaxial tensile and compressive simulations of standard specimens are carried out to validate the proposed model and demonstrate the applicability of the hydrogel composite, in which a great agreement is obtained by comparing the simulation results to the experimental data from published work. Subsequently, the hydrogel composites with three types of structure, such as hydrogel grippers, scaffolds and skins, are designed to improve the overall strength and maintain the flexibility of the devices, inspired by the deformation mismatch characteristics of multilayer hydrogels. The results show that the properties of composite hydrogels are closely related to the level of entanglements, cross-link and composite structures. This work may contribute to the preparation of reinforced hydrogels and provide insights for the design of hydrogel multifunctional devices.

A Comprehensive Review on Forward Osmosis Water Treatment: Recent Advances and Prospects of Membranes and Draw Solutes.

Forward osmosis (FO) is an evolving membrane separation technology for water treatment and reclamation. However, FO water treatment technology is limited by factors such as concentration polarization, membrane fouling, and reverse solute flux. Therefore, it is of a great importance to prepare an efficient high-density porous membrane and to select an appropriate draw solute to reduce concentration polarization, membrane fouling, and reverse solute flux. This review aims to present a thorough evaluation of the advancement of different draw solutes and membranes with their effects on FO performance. NaCl is still widely used in a large number of studies, and several general draw solutes, such as organic-based and inorganic-based, are selected based on their osmotic pressure and water solubility. The selection criteria for reusable solutes, such as heat-recovered gaseous draw, magnetic field-recovered MNPs, and electrically or thermally-responsive hydrogel are primarily based on their industrial efficiency and energy requirements. CA membranes are resistant to chlorine degradation and are hydrophilic, while TFC/TFN exhibit a high inhibition of bio-adhesion and hydrolysis. AQPs are emerging membranes, due to proteins with complete retention capacity. Moreover, the development of the hybrid system combining FO with other energy or water treatment technologies is crucial to the sustainability of FO.

Biomimetic Self-Adhesive Structures for Wearable Sensors.

Inspired by the adhesion ability of various organisms in nature, the research of biomimetic adhesion has shown a promising application prospect in fields such as manipulators, climbing robots and wearable medical devices. In order to achieve effective adhesion between human skin and a variety of wearable sensors, two natural creatures, octopus and mussel, were selected for bio-imitation in this paper. Through imitating the octopus sucker structure, a micro-cavity array with a large inner cavity and small outer cavity was designed. The fabrication was completed by double-layer adhesive photolithography and PDMS molding, and the adhesion capacity of the structure was further enhanced by the coating of thermal responsive hydrogel PNIPAM. The adhesive force of 3.91 N/cm2 was obtained in the range of the human body temperature. PDA-Lap-PAM hydrogel was prepared by combining mussel foot protein (Mfps) with nano-clay (Lap) as biomimetic mussel mucus. It was found that 0.02 g PDA-Lap-PAM hydrogel can obtain about 2.216 N adhesion, with good hydrophilicity. Through oxygen plasma surface treatment and functional silane surface modification, the fusion of the PDMS film with biomimetic octopus sucker structure and the biomimetic mussel mucus hydrogel patch was realized. The biomimetic octopus sucker structure was attached to the human skin surface to solve the problem of shape-preserving attachment, and the biomimetic mussel mucus hydrogel was attached to the sensor surface to solve the problem of sensor surface adaptation. The fusion structure was used to attach a rigid substrate piezoelectric sensor to the skin for a human pulsewave test. The results verified the self-adhesion feasibility of wearable sensors with biomimetic structures.

Cholesteric cellulose liquid crystal ink for three-dimensional structural coloration

SignificanceWe propose a printable structural color ink composed of cholesteric cellulose liquid crystals together with gelatin and a thermal-responsive hydrogel. The ink is endowed with vivid structural colors and printability due to its constituents. Based on this, we print a series of graphics and three-dimensional (3D) objects with vivid color appearances. Moreover, the printed objects possess dual thermal responsiveness, which results in visible color change around body temperature. These performances, together with the biocompatibility of the constituents, indicate that the present ink represents a leap forward to the next-generation 3D printing and would unlock a wide range of real-life applications.

Double-layer temperature-sensitive hydrogel fabricated by 4D printing with fast shape deformation

Sensitive stimuli-responsive hydrogel has contributed much to the field of intelligent actuators. The ability to fabricate second-level response hydrogel has so far been elusive. Here, we fabricated a bilayer structure hydrogel by poly(NIPAM-co-DMAPMA)/clay composite hydrogel by 4D printing. The highest rate of angular velocity has reached 0.495 °/s. The initiated time is 1 s, and the whole deformation time is within 60 s. The quick response originates from the double-layer structure and the huge swelling ratio difference between the two-layer materials. And the grasping function of the palm provides a way to realize the multi-component 3D printing molding of various irregular-shaped thermal-responsive hydrogels, which is expected to promote the development and application of bionic simulation.