Journal articles: 'Stimuli-responsive hydrogel'

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Jiang, Yuheng, Ying Wang, Qin Li, Chen Yu, and Wanli Chu. "Natural Polymer-based Stimuli-responsive Hydrogels." Current Medicinal Chemistry 27, no. 16 (June 4, 2020): 2631–57. http://dx.doi.org/10.2174/0929867326666191122144916.

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The abilities of intelligent polymer hydrogels to change their structure and volume phase in response to external stimuli have provided new possibilities for various advanced technologies and great research and application potentials in the medical field. The natural polymer-based hydrogels have the advantages of environment-friendliness, rich sources and good biocompatibility. Based on their responsiveness to external stimuli, the natural polymer-based hydrogels can be classified into the temperature-responsive hydrogel, pH-responsive hydrogel, light-responsive hydrogel, electricresponsive hydrogel, redox-responsive hydrogel, enzyme-responsive hydrogel, magnetic-responsive hydrogel, multi-responsive hydrogel, etc. In this review, we have compiled some recent studies on natural polymer-based stimuli-responsive hydrogels, especially the hydrogels prepared from polysaccharides. The preparation methods, properties and applications of these hydrogels in the medical field are highlighted.

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Gorantla, Srividya, Tejashree Waghule, Vamshi Krishna Rapalli, Prem Prakash Singh, Sunil Kumar Dubey, Ranendra Narayan Saha, and Gautam Singhvi. "Advanced Hydrogels Based Drug Delivery Systems for Ophthalmic Delivery." Recent Patents on Drug Delivery & Formulation 13, no. 4 (April 29, 2020): 291–300. http://dx.doi.org/10.2174/1872211314666200108094851.

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Hydrogels are aqueous gels composed of cross-linked networks of hydrophilic polymers. Stimuli-responsive based hydrogels have gained focus over the past 20 years for treating ophthalmic diseases. Different stimuli-responsive mechanisms are involved in forming polymer hydrogel networks, including change in temperature, pH, ions, and others including light, thrombin, pressure, antigen, and glucose-responsive. Incorporation of nanocarriers with these smart stimuli-responsive drug delivery systems that can extend the duration of action by increasing ocular bioavailability and reducing the dosing frequency. This review will focus on the hydrogel drug delivery systems highlighting the gelling mechanisms and emerging stimuli-responsive hydrogels from preformed gels, nanogels, and the role of advanced 3D printed hydrogels in vision-threatening diseases like age-related macular degeneration and retinitis pigmentosa. It also provides insight into the limitations of hydrogels along with the safety and biocompatibility of the hydrogel drug delivery systems.

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Štular, Danaja, Matic Šobak, Mohor Mihelčič, Ervin Šest, Ilija German Ilić, Ivan Jerman, Barbara Simončič, and Brigita Tomšič. "Proactive Release of Antimicrobial Essential Oil from a “Smart” Cotton Fabric." Coatings 9, no. 4 (April 10, 2019): 242. http://dx.doi.org/10.3390/coatings9040242.

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Two temperature and pH responsive submicron hydrogels based on poly(N- methylenebisacrylamide), chitosan and β-cyclodextrines (PNCS/CD hydrogel) with varying poly(N-isopropylacrylamide) to chitosan ratios were synthesized according to a simplified procedure, reflecting improved stimuli responsive properties and excellent bio-barrier properties, granted by incorporated chitosan. Hydrogels were applied to cotton-cellulose fabric as active coatings. Subsequently, antimicrobially active savory essential oil (EO) was embedded into the hydrogels in order to develop temperature- and pH-responsive cotton-cellulose fabric with double antimicrobial activity, i.e., bio-barrier formation of chitosan along with the proactive release of savory EO at predetermined conditions. The influence of the hydrogels chemical composition on stimuli responsive and antibacterial properties were assessed. Both PNCS/CD hydrogels showed stimuli responsiveness along with controlled release of savory EO. The chemical composition of the hydrogels strongly influenced the size of the hydrogel particles, their temperature and pH responsiveness, and the bio-barrier forming activity. The increased concentration of chitosan resulted in superior overall stimuli responsiveness and excellent synergy between the antimicrobial activities of the hydrogel and released savory EO.

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Kabir, M. Hasnat, Yosuke Watanabe, Masato Makino, Jin Gong, and Hidemitsu Furukawa. "J0440104 External Stimuli Responsive Hydrogel." Proceedings of Mechanical Engineering Congress, Japan 2014 (2014): _J0440104——_J0440104—. http://dx.doi.org/10.1299/jsmemecj.2014._j0440104-.

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Tokarev, Ihor, and Sergiy Minko. "Stimuli-responsive hydrogel thin films." Soft Matter 5, no. 3 (2009): 511–24. http://dx.doi.org/10.1039/b813827c.

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Glazer, P. J., J. Leuven, H. An, S. G. Lemay, and E. Mendes. "Multi-Stimuli Responsive Hydrogel Cilia." Advanced Functional Materials 23, no. 23 (January 18, 2013): 2964–70. http://dx.doi.org/10.1002/adfm.201203212.

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Bates, Jeffrey S., and Jules J. Magda. "Time Interval and Continuous Testing of Stimuli Responsive Hydrogels." MRS Proceedings 1622 (2014): 153–59. http://dx.doi.org/10.1557/opl.2014.7.

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ABSTRACTResearchers have investigated hydrogels as potential materials for biological monitoring. Hydrogel compositions have been designed to respond to changes in temperature, pH, glucose concentration and ionic strength concentration. Hydrogels designed to respond to changes in environmental conditions have demonstrated their ability to respond via a swelling or shrinking action. This swelling behavior can be exploited using a variety of signal transduction methods. While this technology shows promise, the degradation of hydrogel materials has not yet been characterized with respect to the shelf life of hydrogel samples or to their use in continuous testing. A series of experiments were performed to test hydrogels stored for extended periods of time then subjected to oscillatory testing, and the results have been analyzed to determine whether hydrogels can be used for extended periods of time for biological sensing applications.

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Naddaf, A. A., H. J. Bart, and I. Tsibranska. "Diffusion Kinetics of BSA Protein in Stimuli Responsive Hydrogels." Defect and Diffusion Forum 297-301 (April 2010): 664–69. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.664.

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A two-dimensional diffusion mathematical model with moving boundary conditions was developed to evaluate the diffusion kinetics of bovine serum albumin (BSA) through the network of poly(N-isopropylacrylamide) hydrogel (poly(NIPAAm)). These thermosensitive hydrogels were experimentally tested for their response to BSA by exposing the hydrogel disc-shaped geometry to different temperatures and varied protein concentration. The BSA release, which is coupled with hydrogel shrinking when reaching the low critical solution temperature (LCST) of poly(NIPAAm), could be satisfactory described by the model. During the early course of hydrogel shrinking, the hydrogel outermost surface layer collapses to form a dense layer in comparison to the interior bulk matrix. Due to the hydrophobic interaction between polymer chains and polymer protein, the formed layer is thick and dense enough to restrict the outward permeation of entrapped BSA molecules from the hydrogel interior, which greatly slows down the release rate. A good agreement between experimental and calculated data was achieved.

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Jian, Yukun, Baoyi Wu, Xuxu Yang, Yu Peng, Dachuan Zhang, Yang Yang, Huiyu Qiu, Huanhuan Lu, Jiawei Zhang, and Tao Chen. "Stimuli-responsive hydrogel sponge for ultrafast responsive actuator." Supramolecular Materials 1 (December 2022): 100002. http://dx.doi.org/10.1016/j.supmat.2021.100002.

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Madivoli, Edwin Shigwenya, Justine Veronique Schwarte, Patrick Gachoki Kareru, Anthony Ngure Gachanja, and Katharina M. Fromm. "Stimuli-Responsive and Antibacterial Cellulose-Chitosan Hydrogels Containing Polydiacetylene Nanosheets." Polymers 15, no. 5 (February 21, 2023): 1062. http://dx.doi.org/10.3390/polym15051062.

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Herein, we report a stimuli-responsive hydrogel with inhibitory activity against Escherichia coli prepared by chemical crosslinking of carboxymethyl chitosan (CMCs) and hydroxyethyl cellulose (HEC). The hydrogels were prepared by esterification of chitosan (Cs) with monochloroacetic acid to produce CMCs which were then chemically crosslinked to HEC using citric acid as the crosslinking agent. To impart a stimuli responsiveness property to the hydrogels, polydiacetylene-zinc oxide (PDA-ZnO) nanosheets were synthesized in situ during the crosslinking reaction followed by photopolymerization of the resultant composite. To achieve this, ZnO was anchored on carboxylic groups in 10,12-pentacosadiynoic acid (PCDA) layers to restrict the movement of the alkyl portion of PCDA during crosslinking CMCs and HEC hydrogels. This was followed by irradiating the composite with UV radiation to photopolymerize the PCDA to PDA within the hydrogel matrix so as to impart thermal and pH responsiveness to the hydrogel. From the results obtained, the prepared hydrogel had a pH-dependent swelling capacity as it absorbed more water in acidic media as compared to basic media. The incorporation of PDA-ZnO resulted in a thermochromic composite responsive to pH evidenced by a visible colour transition from pale purple to pale pink. Upon swelling, PDA-ZnO-CMCs-HEC hydrogels had significant inhibitory activity against E. coli attributed to the slow release of the ZnO nanoparticles as compared to CMCs-HEC hydrogels. In conclusion, the developed hydrogel was found to have stimuli-responsive properties and inhibitory activity against E. coli attributed to zinc nanoparticles.

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Işikver, Yasemin, and Dursun Saraydin. "Stimuli Responsive Hydrogels: NIPAM/AAm/Carboxylic Acid Polymers." Acta Chemica Iasi 27, no. 2 (December 1, 2019): 155–84. http://dx.doi.org/10.2478/achi-2019-0012.

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Abstract Stimuli-responsive hydrogels (SRH) were prepared by using monomers (i.e. N-isopropyl acrylamide; NIPAM and acrylamide; AAm), co-monomers (i.e. methacrylic acid; MPA or mesaconic acid; MFA) and a crosslinker (N, N’-methylene bisacrylamide; N-Bis). SRH have been prepared by thermal free radical polymerization reaction in aqueous solution. Spectroscopic and thermal analyses such as Fourier Transform Infrared Spectroscopy, thermogravimetric analysis and differential scanning calorimetry analysis were performed for SRH characterization. The equilibrium swelling studies by gravimetrically were carried out in different solvents, at the solutions, temperature, pH, and ionic strengths to determine their effect on swelling characteristic of the hydrogels. In addition, cycles equilibrium swelling studies were made with the solutions at different temperatures and at different pH. NIPAM/AAm hydrogel exhibits a lover critical solution temperature (LCST) at 28 oC, whereas NIPAM/AAm-MPA and NIPAM/AAm-MFA hydrogels exhibit a LCST at 31 C and 35 oC, respectively, and the LCST of NIPAM/AAm-MFA hydrogel is close to the body temperature.

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Yeingst, Tyus J., Julien H. Arrizabalaga, and Daniel J. Hayes. "Ultrasound-Induced Drug Release from Stimuli-Responsive Hydrogels." Gels 8, no. 9 (September 1, 2022): 554. http://dx.doi.org/10.3390/gels8090554.

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Stimuli-responsive hydrogel drug delivery systems are designed to release a payload when prompted by an external stimulus. These platforms have become prominent in the field of drug delivery due to their ability to provide spatial and temporal control for drug release. Among the different external triggers that have been used, ultrasound possesses several advantages: it is non-invasive, has deep tissue penetration, and can safely transmit acoustic energy to a localized area. This review summarizes the current state of understanding about ultrasound-responsive hydrogels used for drug delivery. The mechanisms of inducing payload release and activation using ultrasound are examined, along with the latest innovative formulations and hydrogel design strategies. We also report on the most recent applications leveraging ultrasound activation for both cancer treatment and tissue engineering. Finally, the future perspectives offered by ultrasound-sensitive hydrogels are discussed.

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Meleties, Michael, Priya Katyal, Bonnie Lin, Dustin Britton, and Jin Kim Montclare. "Self-assembly of stimuli-responsive coiled-coil fibrous hydrogels." Soft Matter 17, no. 26 (2021): 6470–76. http://dx.doi.org/10.1039/d1sm00780g.

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A pH-sensitive coiled-coil hydrogel is presented. A pH of 6 results in nanoparticles that are unable to undergo gelation, while pH levels closer to the isoelectric point allow for the formation of fibers that physically crosslink and form hydrogels.

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Zhou, Huaijuan, Guozhao Dong, Ge Gao, Ran Du, Xiaoying Tang, Yining Ma, and Jinhua Li. "Hydrogel-Based Stimuli-Responsive Micromotors for Biomedicine." Cyborg and Bionic Systems 2022 (October 10, 2022): 1–12. http://dx.doi.org/10.34133/2022/9852853.

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The rapid development of medical micromotors draws a beautiful blueprint for the noninvasive or minimally invasive diagnosis and therapy. By combining stimuli-sensitive hydrogel materials, micromotors are bestowed with new characteristics such as stimuli-responsive shape transformation/morphing, excellent biocompatibility and biodegradability, and drug loading ability. Actuated by chemical fuels or external fields (e.g., magnetic field, ultrasound, light, and electric field), hydrogel-based stimuli-responsive (HBSR) micromotors can be utilized to load therapeutic agents into the hydrogel networks or directly grip the target cargos (e.g., drug-loaded particles, cells, and thrombus), transport them to sites of interest (e.g., tumor area and diseased tissues), and unload the cargos or execute a specific task (e.g., cell capture, targeted sampling, and removal of blood clots) in response to a stimulus (e.g., change of temperature, pH, ion strength, and chemicals) in the physiological environment. The high flexibility, adaptive capacity, and shape morphing property enable the HBSR micromotors to complete specific medical tasks in complex physiological scenarios, especially in confined, hard-to-reach tissues, and vessels of the body. Herein, this review summarizes the current progress in hydrogel-based medical micromotors with stimuli responsiveness. The thermo-responsive, photothermal-responsive, magnetocaloric-responsive, pH-responsive, ionic-strength-responsive, and chemoresponsive micromotors are discussed in detail. Finally, current challenges and future perspectives for the development of HBSR micromotors in the biomedical field are discussed.

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Tholen, Haley, and Ryan L. Harne. "Multi-material stimuli-responsive hydrogels with optically induced actuation." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A179. http://dx.doi.org/10.1121/10.0011023.

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A vision for soft, autonomous materials entails synthesis of multiple senses in multifunctional materials where material response requires sensitivity to external stimuli. Stimuli-responsive hydrogels are of particular interest for optically induced mechanical response due to the ability to transform external stimuli into large, reversible shape change. Specifically, temperature-responsive hydrogels are broadly used and can be designed to achieve deformation through the photothermal effect as a result of surface plasmonic resonance of gold nanoparticles. Here, a multi-material stimuli-responsive hydrogel network with embedded gold nanoparticles is demonstrated in a unit cell pattern with anisotropic swelling behavior in response to visible light. Reversible, anisotropic swelling leads to bending motion that contributes to the development of soft, autonomous materials.

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Erfkamp, Jan, Margarita Guenther, and Gerald Gerlach. "Detection of Ammonia Based on Stimuli-Responsive Hydrogels." Proceedings 2, no. 13 (December 7, 2018): 1109. http://dx.doi.org/10.3390/proceedings2131109.

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This article describes an ammonia-responsive hydrogel based on acrylic acid (AAc) and 2-(dimethylamino)ethyl methacrylate (DMAEMA). The influence of the hydrogel composition on swelling behavior in the alkaline range was shown. Furthermore, the hydrogel swelling in ammonia solutions was tested and a detection limit in the range of 1 mmol/L ammonia in dependence of the buffer solution was determined.

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Tao, Yufeng, Chengchangfeng Lu, Chunsan Deng, Jing Long, Yunpeng Ren, Zijie Dai, Zhaopeng Tong, et al. "Four-Dimensional Stimuli-Responsive Hydrogels Micro-Structured via Femtosecond Laser Additive Manufacturing." Micromachines 13, no. 1 (December 27, 2021): 32. http://dx.doi.org/10.3390/mi13010032.

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Rapid fabricating and harnessing stimuli-responsive behaviors of microscale bio-compatible hydrogels are of great interest to the emerging micro-mechanics, drug delivery, artificial scaffolds, nano-robotics, and lab chips. Herein, we demonstrate a novel femtosecond laser additive manufacturing process with smart materials for soft interactive hydrogel micro-machines. Bio-compatible hyaluronic acid methacryloyl was polymerized with hydrophilic diacrylate into an absorbent hydrogel matrix under a tight topological control through a 532 nm green femtosecond laser beam. The proposed hetero-scanning strategy modifies the hierarchical polymeric degrees inside the hydrogel matrix, leading to a controllable surface tension mismatch. Strikingly, these programmable stimuli-responsive matrices mechanized hydrogels into robotic applications at the micro/nanoscale (<300 × 300 × 100 μm3). Reverse high-freedom shape mutations of diversified microstructures were created from simple initial shapes and identified without evident fatigue. We further confirmed the biocompatibility, cell adhesion, and tunable mechanics of the as-prepared hydrogels. Benefiting from the high-efficiency two-photon polymerization (TPP), nanometer feature size (<200 nm), and flexible digitalized modeling technique, many more micro/nanoscale hydrogel robots or machines have become obtainable in respect of future interdisciplinary applications.

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Chen, Yujie, Runjing Zhang, Baiqin Zheng, Chao Cai, Zhen Chen, Hua Li, and Hezhou Liu. "A Biocompatible, Stimuli-Responsive, and Injectable Hydrogel with Triple Dynamic Bonds." Molecules 25, no. 13 (July 3, 2020): 3050. http://dx.doi.org/10.3390/molecules25133050.

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Injectable hydrogels have attracted growing interests as promising biomaterials for clinical applications, due to their minimum invasive implanting approach and easy-handling performance. Nevertheless, natural biomaterials-based injectable hydrogels with desirable nontoxicity are suffering from limited functions, failing to fulfill the requirements of clinical biomaterials. The development of novel injectable biomaterials with a combination of biocompatibility and adequate functional properties is a growing urgency toward biomedical applications. In this contribution, we report a simple and effective approach to fabricate multi-functional CMC-OSA-DTP hydrogels. Two kinds of natural polysaccharide derived polymers, carboxymethyl chitosan (CMC) and oxidized alginate (OSA) along with 3,3′-dithiopropionic acid dihydrazide (DTP) were utilized to introduce three dynamic covalent bonds. Owing to the existence of triple dynamic bonds, this unique CMC-OSA-DTP hydrogel possessed smart redox and pH stimuli-responsive property, injectability as well as self-healing ability. In addition, the CCK-8 and live/dead assays demonstrated satisfying cytocompatibility of the CMC-OSA-DTP hydrogel in vitro. Based on its attractive properties, this easy-fabricated and multi-functional hydrogel demonstrated the great potential as an injectable biomaterial in a variety of biomedical applications.

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Nakajima, Shunsuke, Ryuji Kawano, and Hiroaki Onoe. "Stimuli-responsive hydrogel microfiber with internal patterns." Proceedings of the Symposium on Micro-Nano Science and Technology 2017.8 (2017): PN—77. http://dx.doi.org/10.1299/jsmemnm.2017.8.pn-77.

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Dadsetan, Mahrokh, Zen Liu, Matthias Pumberger, Catalina Vallejo Giraldo, Terry Ruesink, Lichun Lu, and Michael J. Yaszemski. "A stimuli-responsive hydrogel for doxorubicin delivery." Biomaterials 31, no. 31 (November 2010): 8051–62. http://dx.doi.org/10.1016/j.biomaterials.2010.06.054.

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Dong, Chang-Ming, and Yi Chen. "Stimuli-responsive polypeptide-based reverse micellar hydrogel." Journal of Controlled Release 152 (November 2011): e13-e14. http://dx.doi.org/10.1016/j.jconrel.2011.08.092.

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Biswas, Subharanjan, Lakshmi Priya Datta, and Soumyajit Roy. "A Stimuli-Responsive Supramolecular Hydrogel for Controlled Release of Drug." Journal of Molecular and Engineering Materials 05, no. 03 (September 2017): 1750011. http://dx.doi.org/10.1142/s2251237317500113.

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An inexpensive, facile, and environmentally benign method has been developed for the preparation of stimuli-responsive and self-healing polyacrylic acid–chitosan-based supramolecular hydrogels. Guanidine hydrochloride is used as the supramolecular crosslinker to form an interconnected network with polyacrylic acid–chitosan complex. Because of the dynamic equilibrium between the hydrogen-bonding sites of the components, the hydrogels were found to be self-healable and sensitive to biochemical-stimulus, such as pH. Controlled loading of drug like doxorubicin and its significant anticancer activity of such hydrogels is worth mentioning.

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Tao, Xiaosheng, Fujian Jiang, Kang Cheng, Zhenzhen Qi, Vamsi K. Yadavalli, and Shenzhou Lu. "Synthesis of pH and Glucose Responsive Silk Fibroin Hydrogels." International Journal of Molecular Sciences 22, no. 13 (July 1, 2021): 7107. http://dx.doi.org/10.3390/ijms22137107.

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Silk fibroin (SF) has attracted much attention due to its high, tunable mechanical strength and excellent biocompatibility. Imparting the ability to respond to external stimuli can further enhance its scope of application. In order to imbue stimuli-responsive behavior in silk fibroin, we propose a new conjugated material, namely cationic SF (CSF) obtained by chemical modification of silk fibroin with ε-Poly-(L-lysine) (ε-PLL). This pH-responsive CSF hydrogel was prepared by enzymatic crosslinking using horseradish peroxidase and H2O2. Zeta potential measurements and SDS-PAGE gel electrophoresis show successful synthesis, with an increase in isoelectric point from 4.1 to 8.6. Fourier transform infrared (FTIR) and X-ray diffraction (XRD) results show that the modification does not affect the crystalline structure of SF. Most importantly, the synthesized CSF hydrogel has an excellent pH response. At 10 wt.% ε-PLL, a significant change in swelling with pH is observed. We further demonstrate that the hydrogel can be glucose-responsive by the addition of glucose oxidase (GOx). At high glucose concentration (400 mg/dL), the swelling of CSF/GOx hydrogel is as high as 345 ± 16%, while swelling in 200 mg/dL, 100 mg/dL and 0 mg/dL glucose solutions is 237 ± 12%, 163 ± 12% and 98 ± 15%, respectively. This shows the responsive swelling of CSF/GOx hydrogels to glucose, thus providing sufficient conditions for rapid drug release. Together with the versatility and biological properties of fibroin, such stimuli-responsive silk hydrogels have great potential in intelligent drug delivery, as soft matter substrates for enzymatic reactions and in other biomedical applications.

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Dai, Wanting, Xiaoyan Zhou, and Huilong Guo. "A Metal Ion and Thermal-Responsive Bilayer Hydrogel Actuator Achieved by the Asymmetric Osmotic Flow of Water between Two Layers under Stimuli." Polymers 14, no. 19 (September 26, 2022): 4019. http://dx.doi.org/10.3390/polym14194019.

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Shape-morphing hydrogels have drawn great attention due to their wide applications as soft actuators, while asymmetric responsive shape-morphing behavior upon encountering external stimuli is fundamental for the development of hydrogel actuators. Therefore, in this work, bilayer hydrogels were prepared and the shrinkage ratios (LA/LN) of the AAm/AAc layer to the NIPAM layer immersed in different metal ion solutions, leading to bending in different directions, were investigated. The difference in the shrinkage ratio was attributed to the synergistic effect of the osmolarity difference between the inside and outside of the hydrogels and the interaction difference between the ion and hydrogel polymer chains. Additionally, under thermal stimuli, the hydrogel actuator would bend toward the NIPAM layer due to the shrinkage of the hydrogel networks caused by the hydrophilic–hydrophobic phase transition of NIPAM blocks above the LCST. This indicates that metal ion and thermal-responsive shape-morphing hydrogel actuators with good mechanical properties could be used as metal ion or temperature-controllable switches or other smart devices.

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Long, Shijun, Jiacheng Huang, Jiaqiang Xiong, Chang Liu, Fan Chen, Jie Shen, Yiwan Huang, and Xuefeng Li. "Designing Multistimuli-Responsive Anisotropic Bilayer Hydrogel Actuators by Integrating LCST Phase Transition and Photochromic Isomerization." Polymers 15, no. 3 (February 3, 2023): 786. http://dx.doi.org/10.3390/polym15030786.

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Stimuli-responsive hydrogel actuators have attracted tremendous interest in switches and microrobots. Based on N-isopropylacrylamide (NIPAM) monomers with LCST phase separation and photochromic molecule spiropyran which can respond to ultraviolet light and H+, we develop a novel multistimuli-responsive co-polymer anisotropic bilayer hydrogel, which can undergo complex deformation behavior under environmental stimuli. Diverse bending angles were achieved based on inhomogeneous swelling. By controlling the environmental temperature, the bilayer hydrogels achieved bending angles of 83.4° and −162.4° below and above the critical temperature of PNIPAM. Stimulated by ultraviolet light and H+, the bilayer hydrogels showed bending angles of −19.4° and −17.3°, respectively. In addition, we designed a strategy to enhance the mechanical properties of the hydrogel via double network (DN). The mechanical properties and microscopic Fourier transform infrared (micro-FTIR) spectrum showed that the bilayer hydrogel can be well bonded at the interfaces of such bilayers. This work will inspire the design and fabrication of novel soft actuators with synergistic functions.

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Wang, Rong, Xinhua Wan, and Jie Zhang. "Multi-stimuli-responsive induced chirality of polyoxometalates in natural polysaccharide hydrogels." Chemical Communications 55, no. 32 (2019): 4711–14. http://dx.doi.org/10.1039/c9cc01981b.

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Multi-stimuli-responsive induced circular dichroism of polyoxometalates was realized in natural polysaccharide hydrogels. The extrinsic chiral factors rather than the intrinsic chirality of the polyoxometalates were dominant in κ-carrageenan hydrogel hybrids.

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Cho, Heejoo, Sumin Jeon, Junghyeok Yang, Song Yi Baek, and Doeun Kim. "Hydrogel Nanoparticle as a Functional Coating Layer in Biosensing, Tissue Engineering, and Drug Delivery." Coatings 10, no. 7 (July 10, 2020): 663. http://dx.doi.org/10.3390/coatings10070663.

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The development of functional coating materials has resulted in many breakthroughs in the discovery of energy, environmental, and biomedical applications. Responsive polymeric hydrogels are an example of smart coating materials due to their stimuli-responsive characteristics upon changes in their local environment. This review focuses on the introduction of hydrogel nanoparticles and their applications in functional layers as responsive coating materials. Hydrogels are explained by the composition of cross-links and monomers used for preparation. In particular, an important class of responsive hydrogels, that is, nanosized hydrogel particles (nanogels), are described for thee synthesis, modification, and application in assembly of functional coating layers. Finally, nanogel functional layers for biological applications will be discussed with recent advances in biosensing, tissue engineering, and drug delivery.

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Solano-Delgado, Leidy C., César A. Bravo-Sanabria, Carolina Ardila-Suárez, and Gustavo E. Ramírez-Caballero. "Stimuli-Responsive Hydrogels Based on Polyglycerol Crosslinked with Citric and Fatty Acids." International Journal of Polymer Science 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/3267361.

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Polyglycerol-based hydrogels from biodegradable raw materials were synthesized by crosslinking reactions of polyglycerol with citric and fatty acids. Three hydrogels were studied varying molar ratios of crosslinking agent. It was found that crosslink amount, type, and size play a crucial role in swelling, thermal, mechanical, and stimuli-responsive properties. The hydrogels absorption capacity changed in response to temperature and pH external stimuli. The hydrogel with the highest swelling capacity absorbed more than 7 times its own weight at room temperature and pH 5. This material increased 14 times its own weight at pH 10. Creep-recovery tests were performed to study the effect of crosslinking agent on mechanical properties. Deformation and percentage of recovery of synthesized hydrogels were obtained. Formation of hydrogels was confirmed using FTIR, and physicochemical properties were analyzed by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetric (DSC), and Dynamic Mechanical Analysis (DMA). This paper aims to give a contribution to biobased hydrogel knowledge from chemical, physicochemical, and mechanical point of view.

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Chatterjee, Sudipta, and Patrick Chi-leung Hui. "Review of Applications and Future Prospects of Stimuli-Responsive Hydrogel Based on Thermo-Responsive Biopolymers in Drug Delivery Systems." Polymers 13, no. 13 (June 24, 2021): 2086. http://dx.doi.org/10.3390/polym13132086.

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Some of thermo-responsive polysaccharides, namely, cellulose, xyloglucan, and chitosan, and protein-like gelatin or elastin-like polypeptides can exhibit temperature dependent sol–gel transitions. Due to their biodegradability, biocompatibility, and non-toxicity, such biomaterials are becoming popular for drug delivery and tissue engineering applications. This paper aims to review the properties of sol–gel transition, mechanical strength, drug release (bioavailability of drugs), and cytotoxicity of stimuli-responsive hydrogel made of thermo-responsive biopolymers in drug delivery systems. One of the major applications of such thermos-responsive biopolymers is on textile-based transdermal therapy where the formulation, mechanical, and drug release properties and the cytotoxicity of thermo-responsive hydrogel in drug delivery systems of traditional Chinese medicine have been fully reviewed. Textile-based transdermal therapy, a non-invasive method to treat skin-related disease, can overcome the poor bioavailability of drugs from conventional non-invasive administration. This study also discusses the future prospects of stimuli-responsive hydrogels made of thermo-responsive biopolymers for non-invasive treatment of skin-related disease via textile-based transdermal therapy.

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Zhan, Ziheng, Lei Chen, Huigao Duan, Yiqin Chen, Min He, and Zhaolong Wang. "3D printed ultra-fast photothermal responsive shape memory hydrogel for microrobots." International Journal of Extreme Manufacturing 4, no. 1 (December 3, 2021): 015302. http://dx.doi.org/10.1088/2631-7990/ac376b.

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Abstract Hydrogels with stimuli-responsive capabilities are gaining more and more attention nowadays with prospective applications in biomedical engineering, bioelectronics, microrobot, etc. We develop a photothermal responsive hydrogel based on N-isopropylacrylamide that achieved a fast and reversible deformation manipulated only by near-infrared (NIR) light. The hydrogel was fabricated by the projection micro stereolithography based 3D printing technique, which can rapidly prototype complex 3D structures. Furthermore, with the variation of the grayscale while manufacturing the hydrogel, the deformation of the hydrogel structure can be freely tuned within a few seconds by losing and absorbing water through adjusting the intensity and the irradiation direction of the NIR light, showing a potential application in ultra-fast object grabbing and transportation. The present study provides a new method for designing ultrafast photothermal responsive hydrogel based microrobot working in water.

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Tang, James D., Cameron Mura, and Kyle J. Lampe. "Stimuli-Responsive, Pentapeptide, Nanofiber Hydrogel for Tissue Engineering." Journal of the American Chemical Society 141, no. 12 (March 4, 2019): 4886–99. http://dx.doi.org/10.1021/jacs.8b13363.

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32

Wang, Jun, Daniel D. N. Sun, Yoshitsune Shin-ya, and Kam W. Leong. "Stimuli-Responsive Hydrogel Based on Poly(propylene phosphate)." Macromolecules 37, no. 2 (January 2004): 670–72. http://dx.doi.org/10.1021/ma035453d.

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33

Chan, Ariel W., Ralph A. Whitney, and Ronald J. Neufeld. "Semisynthesis of a Controlled Stimuli-Responsive Alginate Hydrogel." Biomacromolecules 10, no. 3 (March 9, 2009): 609–16. http://dx.doi.org/10.1021/bm801316z.

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34

Tokarev, Ihor, Venkateshwarlu Gopishetty, Jian Zhou, Marcos Pita, Mikhail Motornov, Evgeny Katz, and Sergiy Minko. "Stimuli-Responsive Hydrogel Membranes Coupled with Biocatalytic Processes." ACS Applied Materials & Interfaces 1, no. 3 (February 12, 2009): 532–36. http://dx.doi.org/10.1021/am800251a.

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35

Jeon, Seog-Jin, Adam W. Hauser, and Ryan C. Hayward. "Shape-Morphing Materials from Stimuli-Responsive Hydrogel Hybrids." Accounts of Chemical Research 50, no. 2 (February 9, 2017): 161–69. http://dx.doi.org/10.1021/acs.accounts.6b00570.

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36

Yoon, ChangKyu, Rui Xiao, JaeHyun Park, Jaepyeong Cha, Thao D. Nguyen, and David H. Gracias. "Functional stimuli responsive hydrogel devices by self-folding." Smart Materials and Structures 23, no. 9 (August 11, 2014): 094008. http://dx.doi.org/10.1088/0964-1726/23/9/094008.

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37

Niibe, Kenta, and Hiroaki Onoe. "Stimuli-responsive hydrogel sensors integrated with microfluidic device." Proceedings of the Symposium on Micro-Nano Science and Technology 2017.8 (2017): PN—85. http://dx.doi.org/10.1299/jsmemnm.2017.8.pn-85.

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38

Ehrick, J. D., S. Stokes, S. Bachas-Daunert, E. A. Moschou, S. K. Deo, L. G. Bachas, and S. Daunert. "Chemically Tunable Lensing of Stimuli-Responsive Hydrogel Microdomes." Advanced Materials 19, no. 22 (November 19, 2007): 4024–27. http://dx.doi.org/10.1002/adma.200601969.

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Kurnia, Jundika Candra, Erik Birgersson, Arun Sadashiv Mujumdar, and Lee Ching Quah. "Mathematical Modeling of Hydrogels for Microfluidic Flow Control." Advanced Materials Research 74 (June 2009): 33–36. http://dx.doi.org/10.4028/www.scientific.net/amr.74.33.

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A mathematical model of a microfluidic controller comprising a hydrogel in a typical T- and Y-junction is derived and presented. The model takes into account conservation of momentum, mass and ions for laminar incompressible flow and the deformation/sensing of a pH-sensitive hydrogel. The response of the pH-responsive hydrogel is validated with experimental equilibrium swelling curves for which good agreement is found. The model is employed to study the behavior of the hydrogel and its impact on the overall fluid flow in different microfluidic flow channel/hydrogel configurations, e.g. in a T-junction, where the hydrogel can act autonomously and without external power supply to regulate the flow. Finally, we discuss how the model can be generalized for other types of stimuli-responsive hydrogels.

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40

Roshan Deen, G., Yee Lin Tan, M. Rajkumar Yalini, Chin Hao Mah, and Tee Wei Teo. "Synthesis, Swelling Characteristics, and Dye Adsorption Mechanism of a New Stimuli-Responsive Cationic Hydrogel." European Journal of Advanced Chemistry Research 3, no. 1 (January 23, 2022): 12–24. http://dx.doi.org/10.24018/ejchem.2022.3.1.86.

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In this study, a new multi-stimulus cationic copolymer hydrogel was developed by bulk photo-polymerization of N-acryloyl-N’-propyl piperazine (AcrNPP) and poly (ethylene glycol) methacrylate (PEGMA) with ethylene glycol dimethacrylate (EGDMA) as crosslinker. The effect of multiple external stimuli, concentration of monomers, and equilibrium swelling of the hydrogels was studied in detail. The gels swelled in acidic solutions due to protonation of tertiary amine in the piperazine ring, and de-swelled in basic solutions. The presence of PEGMA in the hydrogel enhanced the swelling and imparted water-responsive property, leading to disintegration at high concentration of 49.85%. The hydrogel was evaluated as an adsorbent for the removal of an anionic dye, Congo red (CR) from water. The dye uptake capacity of the hydrogel increased with increase in the initial dye concentration. Interestingly, the swelling ratio of the hydrogel decreased at high dye concentration due to the formation of additional physical crosslinks within the hydrogel matrix. The dye uptake capacity of the hydrogel decreased with increasing temperature due to the negative-temperature responsive property of the hydrogel. The time-dependent adsorption data was fitted with seven kinetic models. Pseudo second-order model best described the kinetics of adsorption process, and the adsorption of CR onto the hydrogel could be very well described with phase-boundary controlled models. The adsorption was a multistep process with surface adsorption followed by intraparticle diffusion.

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Jervis, Peter J., Loic Hilliou, Renato B. Pereira, David M. Pereira, José A. Martins, and Paula M. T. Ferreira. "Evaluation of a Model Photo-Caged Dehydropeptide as a Stimuli-Responsive Supramolecular Hydrogel." Nanomaterials 11, no. 3 (March 11, 2021): 704. http://dx.doi.org/10.3390/nano11030704.

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Short peptides capped on the N-terminus with aromatic groups are often able to form supramolecular hydrogels, via self-assembly, in aqueous media. The rheological properties of these readily tunable hydrogels resemble those of the extracellular matrix (ECM) and therefore have potential for various biological applications, such as tissue engineering, biosensors, 3D bioprinting, drug delivery systems and wound dressings. We herein report a new photo-responsive supramolecular hydrogel based on a “caged” dehydropeptide (CNB-Phe-ΔPhe-OH 2), containing a photo-cleavable carboxy-2-nitrobenzyl (CNB) group. We have characterized this hydrogel using a range of techniques. Irradiation with UV light cleaves the pendant aromatic capping group, to liberate the corresponding uncaged model dehydropeptide (H-Phe-ΔPhe-OH 3), a process which was investigated by 1H NMR and HPLC studies. Crucially, this cleavage of the capping group is accompanied by dissolution of the hydrogel (studied visually and by fluorescence spectroscopy), as the delicate balance of intramolecular interactions within the hydrogel structure is disrupted. Hydrogels which can be disassembled non-invasively with temporal and spatial control have great potential for specialized on-demand drug release systems, wound dressing materials and various topical treatments. Both 2 and 3 were found to be non-cytotoxic to the human keratinocyte cell line, HaCaT. The UV-responsive hydrogel system reported here is complementary to previously reported related UV-responsive systems, which are generally composed of peptides formed from canonical amino acids, which are susceptible to enzymatic proteolysis in vivo. This system is based on a dehydrodipeptide structure which is known to confer proteolytic resistance. We have investigated the ability of the photo-activated system to accelerate the release of the antibiotic, ciprofloxacin, as well as some other small model drug compounds. We have also conducted some initial studies towards skin-related applications. Moreover, this model system could potentially be adapted for on-demand “self-delivery”, through the uncaging of known biologically active dehydrodipeptides.

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Chen, Jing, Jingli Yang, Guorong Gao, and Jun Fu. "Responsive Bilayered Hydrogel Actuators Assembled by Supramolecular Recognition." MRS Advances 3, no. 28 (2018): 1583–88. http://dx.doi.org/10.1557/adv.2018.222.

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ABSTRACTMacroscopic assembling of responsive hydrogels has been used to construct soft actuators that transform their shape upon external stimuli. It remains a challenge to establish a robust assembling interface between gels. Here, we demonstrate a fabrication of bilayered hydrogel actuators assembled by host-guest recognition at the interface. The supramolecular recognition enabled efficient, rapid, and robust macroscopic assembling of hydrogels, which was utilized to create gel bilayers that were actuated upon unbalanced swelling/deswelling.

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Wang, Ri, Zhongguang Yang, Jiren Luo, I.-Ming Hsing, and Fei Sun. "B12-dependent photoresponsive protein hydrogels for controlled stem cell/protein release." Proceedings of the National Academy of Sciences 114, no. 23 (May 22, 2017): 5912–17. http://dx.doi.org/10.1073/pnas.1621350114.

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Thanks to the precise control over their structural and functional properties, genetically engineered protein-based hydrogels have emerged as a promising candidate for biomedical applications. Given the growing demand for creating stimuli-responsive “smart” hydrogels, here we show the synthesis of entirely protein-based photoresponsive hydrogels by covalently polymerizing the adenosylcobalamin (AdoB12)-dependent photoreceptor C-terminal adenosylcobalamin binding domain (CarHC) proteins using genetically encoded SpyTag-SpyCatcher chemistry under mild physiological conditions. The resulting hydrogel composed of physically self-assembled CarHC polymers exhibited a rapid gel-sol transition on light exposure, which enabled the facile release/recovery of 3T3 fibroblasts and human mesenchymal stem cells (hMSCs) from 3D cultures while maintaining their viability. A covalently cross-linked CarHC hydrogel was also designed to encapsulate and release bulky globular proteins, such as mCherry, in a light-dependent manner. The direct assembly of stimuli-responsive proteins into hydrogels represents a versatile strategy for designing dynamically tunable materials.

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44

Samai, Suman, Christos Sapsanis, Sachin P. Patil, Alaa Ezzeddine, Basem A. Moosa, Hesham Omran, Abdul-Hamid Emwas, Khaled N. Salama, and Niveen M. Khashab. "A light responsive two-component supramolecular hydrogel: a sensitive platform for the fabrication of humidity sensors." Soft Matter 12, no. 11 (2016): 2842–45. http://dx.doi.org/10.1039/c6sm00272b.

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45

Malekmohammadi, Samira, Negar Sedghi Aminabad, Amin Sabzi, Amir Zarebkohan, Mehdi Razavi, Massoud Vosough, Mahdi Bodaghi, and Hajar Maleki. "Smart and Biomimetic 3D and 4D Printed Composite Hydrogels: Opportunities for Different Biomedical Applications." Biomedicines 9, no. 11 (October 26, 2021): 1537. http://dx.doi.org/10.3390/biomedicines9111537.

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In recent years, smart/stimuli-responsive hydrogels have drawn tremendous attention for their varied applications, mainly in the biomedical field. These hydrogels are derived from different natural and synthetic polymers but are also composite with various organic and nano-organic fillers. The basic functions of smart hydrogels rely on their ability to change behavior; functions include mechanical, swelling, shaping, hydrophilicity, and bioactivity in response to external stimuli such as temperature, pH, magnetic field, electromagnetic radiation, and biological molecules. Depending on the final applications, smart hydrogels can be processed in different geometries and modalities to meet the complicated situations in biological media, namely, injectable hydrogels (following the sol-gel transition), colloidal nano and microgels, and three dimensional (3D) printed gel constructs. In recent decades smart hydrogels have opened a new horizon for scientists to fabricate biomimetic customized biomaterials for tissue engineering, cancer therapy, wound dressing, soft robotic actuators, and controlled release of bioactive substances/drugs. Remarkably, 4D bioprinting, a newly emerged technology/concept, aims to rationally design 3D patterned biological matrices from synthesized hydrogel-based inks with the ability to change structure under stimuli. This technology has enlarged the applicability of engineered smart hydrogels and hydrogel composites in biomedical fields. This paper aims to review stimuli-responsive hydrogels according to the kinds of external changes and t recent applications in biomedical and 4D bioprinting.

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46

Zhang, Dong, Baiping Ren, Yanxian Zhang, Lijian Xu, Qinyuan Huang, Yi He, Xuefeng Li, et al. "From design to applications of stimuli-responsive hydrogel strain sensors." Journal of Materials Chemistry B 8, no. 16 (2020): 3171–91. http://dx.doi.org/10.1039/c9tb02692d.

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Stimuli-responsive hydrogel strain sensors that synergize the advantages of both hydrogel and smart functional materials have attracted increasing interest from material design to emerging applications in health monitors and human–machine interfaces.

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47

Šťastná, Julie, Vladislav Ivaniuzhenkov, and Lenka Hanyková. "External Stimuli-Responsive Characteristics of Poly(N,N′-diethylacrylamide) Hydrogels: Effect of Double Network Structure." Gels 8, no. 9 (September 15, 2022): 586. http://dx.doi.org/10.3390/gels8090586.

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Swelling experiments and NMR spectroscopy were combined to study effect of various stimuli on the behavior of hydrogels with a single- and double-network (DN) structure composed of poly(N,N′-diethylacrylamide) and polyacrylamide (PAAm). The sensitivity to stimuli in the DN hydrogel was found to be significantly affected by the introduction of the second component and the formation of the double network. The interpenetrating structure in the DN hydrogel causes the units of the component, which is insensitive to the given stimulus in the form of the single network (SN) hydrogel, to be partially formed as globular structures in DN hydrogel. Due to the hydrophilic PAAm groups, temperature- and salt-induced changes in the deswelling of the DN hydrogel are less intensive and gradual compared to those of the SN hydrogel. The swelling ratio of the DN hydrogel shows a significant decrease in the dependence on the acetone content in acetone–water mixtures. A certain portion of the solvent molecules bound in the globular structures was established from the measurements of the 1H NMR spin–spin relaxation times T2 for the studied DN hydrogel. The time-dependent deswelling and reswelling kinetics showed a two-step profile, corresponding to the solvent molecules being released and absorbed during two processes with different characteristic times.

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48

Zhang, Ziru. "Research progress and clinical application of stimuli-responsive hydrogels in cervical cancer." Highlights in Science, Engineering and Technology 14 (September 29, 2022): 188–98. http://dx.doi.org/10.54097/hset.v14i.1610.

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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.

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Dumitriu, Raluca Petronela, Ana Maria Oprea, and Cornelia Vasile. "Kinetics of Swelling and Drug Release from PNIPAAm/Alginate Stimuli Responsive Hydrogels." Solid State Phenomena 154 (April 2009): 17–22. http://dx.doi.org/10.4028/www.scientific.net/ssp.154.17.

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Stimuli responsive hydrogels are very attractive for applications in sustained and/or targeted drug delivery systems. As the release of drugs is related to the swelling behavior of hydrogels, the swelling kinetic studies become of great importance to appreciate the release kinetics from hydrogel matrices. Hydrogels with high performance properties have been prepared from N-isopropylacryl amide (NIPAAm) and sodium alginate, crosslinked with N,N`-methylene-bis-(acrylamide) (MBAAm). This study is focused on the investigation of swelling and drug release kinetics, coupled by morphological studies. The kinetic parameters of the swelling at different temperatures for hydrogels samples have been evaluated and confirmed their temperature-responsive behavior. The swelling rate constant (ksw) decreases of with increasing temperature and slight increases with the alginate content in the samples. The drug release kinetic study from the prepared hydrogel matrices was performed in twice-distilled water and ethanol for bioactive agents as vanillin and ketoprofen, respectively. An increase of alginate content results in a slower rate and smaller percentage of vanillin and ketoprofen released. It has been established that the ketoprofen occurs according with case II of transport and vanillin release behavior occurs by an anomalous transport mechanism. The values of the release rate constant (kr) decreased by increasing swelling degree in case of 75/25 NIPAAm/alginate hydrogels and decreased also by increasing content of alginate in hydrogels with various compositions. Morphological studies performed by environmental scanning electron microscopy (ESEM) evidenced a relaxed network at high relative humidity, which explain both swelling and release profiles.

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Yu, Dongyang, Yanhua Teng, He Feng, Xiuling Lin, Jianjun Li, Qingping Wang, and Changguo Xue. "Multi-responsive and conductive bilayer hydrogel and its application in flexible devices." RSC Advances 12, no. 13 (2022): 7898–905. http://dx.doi.org/10.1039/d1ra09232d.

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Journal articles on the topic 'Stimuli-responsive hydrogel'

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