Thermoresponsive drug controlled release from chitosan‐based hydrogel embedded with poly(N‐isopropylacrylamide) nanogels

A facile synthetic strategy was developed for the preparation of thermoresponsive nanocomposite hydrogels comprising crosslinked chitosan (CS) networks and poly(N‐isopropylacrylamide) [p(NIPAAm)] nanogels. First, thermoresponsive p(NIPAAm) nanogels were synthesized via emulsion polymerization. The p(NIPAAm) nanogels were introduced into methacrylamide CS (MC) solution and the free‐radical initiated crosslinking reaction of MC produced nanogel‐embedded hydrogels. The last step involves the loading of the antibacterial model drug levofloxacin (LFX) into the prepared nanocomposite hydrogels by allowing the preformed hydrogels to swell to equilibrium in the drug's aqueous solution. The integration of p(NIPAAm) nanogel into CS networks facilitates thermoresponsive release of LFX with an enhancement of the drug‐loading capacity within the hydrogel. Notably, thermoresponsive drug‐release was achieved without unwarranted modification of the hydrogel's dimension and shape, although an increase in temperature caused the collapse of the p(NIPAAm) nanogels. The thermoresponsive property of the investigated nanocomposite hydrogel is beneficial and may offer broad opportunities for drug temperature‐triggered release for clinical applications. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1907–1914     

PVA改性PAMPS-PAM超高力学性能双网络水凝胶的制备

采用紫外光引发聚合制备了聚乙烯醇(PVA)改性的聚(2-丙烯酰胺基-2-甲基丙磺酸)-聚丙烯酰胺(PAMPS-PAM)双网络(DN)水凝胶.测定并比较了PVA改性前后PAMPS-PAM双网络水凝胶的溶胀动力学;通过扫描电子显微镜(SEM)观察了单网络水凝胶的结构;测定PVA改性前后PAMPS-PAM双网络水凝胶的压缩及拉伸性能.结果表明,经PVA改性后的PAMPS-PAM双网络水凝胶有较高的溶胀比;0.82%PVA用量的PAMPS-PAM双网络水凝胶在90%压缩形变率下仍保持完整、最大拉伸应力达到0.5 MPa,大幅提高PAMPS-PAM双网络水凝胶的力学性能.     

Synthesis and Characterization of Hydrogels Based on Gamma Radiation Copolymerization of N‐isopropylacrylamide and Ethylene Glycol Dimethacrylate Monomers

Hydrogels based essentially on N‐isopropylacrylamide (NIPAAm) and different ratios of ethylene glycol dimethacrylate (EGDMA) monomer were synthesized by gamma radiation copolymerization. The thermal decomposition behavior of NIPAAm/EGDMA hydrogels was determined by thermogravimetric analysis (TGA). The effect of temperature and pH on the swelling behavior was also studied. The results showed that the ratio of EGDMA in the comonomer feeding solution has a great effect on the yield product, gel fraction and water content in the final hydrogel. In this regard, it was observed that the increase of EGDMA ratio decreased these properties. The TGA study showed that all the compositions of NIPAAm/EGDMA hydrogels displayed higher thermal stability than the hydrogel based on pure PNIPAAm hydrogel. The swelling kinetics in water showed that pure PNIPAAm and NIPAAm/EGDMA hydrogels reached equilibrium after 6 h. However, NIPAAm/EGDMA hydrogels show swelling in water lower than pure PNIPAAm. The results showed that the swelling character of pure PNIPAAm and NIPAAm/EGDMA hydrogels was affected by the change in temperature within the temperature range 25–40°C, and showed a reversible change in swelling in the pH range 4–7 depending on composition.     

A High Strength Self‐Healable Antibacterial and Anti‐Inflammatory Supramolecular Polymer Hydrogel

There is a significant cost to mitigate the infection and inflammation associated with the implantable medical devices. The development of effective antibacterial and anti‐inflammatory biomaterials with novel mechanism of action has become an urgent task. In this study, a supramolecular polymer hydrogel is synthesized by the copolymerization of N‐acryloyl glycinamide and 1‐vinyl‐1,2,4‐triazole in the absence of any chemical crosslinker. The hydrogel network is crosslinked through the hydrogen bond interactions between dual amide motifs in the side chain of N‐acryloyl glycinamide. The prepared hydrogels demonstrate excellent mechanical properties—high tensile strength (≈1.2 MPa), large stretchability (≈1300%), and outstanding compressive strength (≈11 MPa) at swelling equilibrium state. A simulation study elaborates the changes of hydrogen bond interactions when 1‐vinyl‐1,2,4‐triazole is introduced into the gel network. It is demonstrated that the introduction of 1‐vinyl‐1,2,4‐triazole endowes the supramolecular hydrogels with self‐repairability, thermoplasticity, and reprocessability over a lower temperature range for 3D printing of different shapes and patterns under simplified thermomelting extrusion condition. In addition, these hydrogels exhibit antimicrobial and anti‐inflammatory activities, and in vitro cytotoxicity assay and histological staining following in vivo implantation confirm the biocompatibility of the hydrogel. These hydrogels with integrated multifunctions hold promising potential as an injectable biomaterial for treating degenerated soft supporting tissues.

     

Synthesis and properties of a novel double network nanocomposite hydrogel

A novel polyacrylamide/polyacrylic acid (PAAm/PAA) double network (DN) nanocomposite (NC) hydrogel had been synthesized by two‐step solution polymerization. The PAAm network was crosslinked by inorganic clay while the PAA network was crosslinked by a chemical crosslinker. The chemical structure of the network was confirmed by Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and transmission electron microscopy (TEM). The swelling and mechanical strength properties of PAAm/PAA hydrogels were examined. The results showed that a DN hydrogel achieved both a high swelling capacity of 1219 g/g in deionized water and 124 g/g in 0.9 wt% NaCl solution and high compressive stress of 21.5 kPa in a high water content of 99.58%. Copyright © 2008 John Wiley & Sons, Ltd.     

“Click” chemistry for in situ formation of thermoresponsive P(NIPAAm‐co‐HEMA)‐based hydrogels

The strategy for in situ chemical gelation of poly(N‐isopropylacrylamide‐co‐hydroxylethyl methacrylate) [P(NIPAAm‐co‐HEMA)]‐based polymers was demonstrated. Two types of new P(NIPAAm‐co‐HEMA) derivatives with alkyne and azide pendant groups, respectively, were prepared. When the solutions of the two derivatives were mixed together, a crosslinking reaction, a type of Huisgen's 1,3‐dipolar azide‐alkyne cycloaddition, in the presence of Cu(I) catalyst occurs. The morphology, equilibrium swelling ratio, swelling kinetics, and temperature response kinetics of the in situ gelated hydrogels were studied. In comparison with the conventional PNIPAAm hydrogel, because of the spatial hindrance of polymeric chains, the resulted hydrogels had a macroporous structure as well as a fast shrinking rate. The strategy described here presents a potential alternative to the traditional synthesis techniques for the in situ formation of thermoresponsive hydrogels. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5263–5277, 2008     

Dextran Hydrogels Containing Poly(N‐isopropylacrylamide) as Grafts and Cross‐Linkers Exhibiting Enzymatic Regulation in a Specific Temperature Range

Summary: Specific temperature‐responsive biodegradable hydrogels were synthesized and characterized in terms of their regulation of enzymatic accessibility based on the physical properties of the temperature‐responsive polymers. The hydrogels consist of glycidyl methacrylate‐modified dextran grafted with the poly(N‐isopropylacrylamide) (PNIPAAm) homopolymer, and cross‐linked by co‐polymerization with NIPAAm and N,N‐dimethylacrylamide (DMAAm). The coil‐globule change in the grafted poly(NIPAAm) chains and only a slight dehydration of the poly(NIPAAm‐co‐DMAAm) cross‐linkers are effective in controlling the enzymatic degradation over a specific temperature range.

The thermo‐responses of the graft chains (steric hindrance) and the crosslinkers (slight deswelling of the hydrogel networks) control the enzymatic degradation of the hydrogel.     

Preparation of interpenetrating polymer network composed of poly(ethylene glycol) and poly(acrylamide) hydrogels as a support of enzyme immobilization

Poly(ethylene glycol)(PEG)‐based interpenetrating polymeric network (IPN) hydrogels were prepared for the application of enzyme immobilization. Poly(acrylamide)(PAAm) was chosen as the other network of IPN hydrogel and different concentration of PAAm networks were incorporated inside the PEG hydrogel to improve the mechanical strength and provide functional groups that covalently bind the enzyme. Formation of IPN hydrogels was confirmed by observing the weight per cent gain of hydrogel after incorporation of PAAm network and by attenuated total reflectance/Fourier transform infrared (ATR/FTIR) analysis. Synthesis of IPN hydrogels with higher PAAm content produced more crosslinked hydrogels with lower water content (WC), smaller M_c and mesh size, which resulted in enhanced mechanical properties compared to the PEG hydrogel. The IPN hydrogels exhibited tensile strength between 0.2 and 1.2 MPa while retaining high levels of hydration (70–81% water). For enzyme immobilization, glucose oxidase (GOX) was immobilized to PEG and IPN hydrogel beads. Enzyme activity studies revealed that although all the hydrogels initially had similar enzymatic activity, enzyme‐immobilizing PEG hydrogels lost most of the enzymatic activity within 2 days due to enzyme leaching while IPN hydrogels maintained a maximum 80% of the initial enzymatic activity over a week due to the covalent linkage between the enzyme and amine groups of PAAm. Copyright © 2008 John Wiley & Sons, Ltd.     

Interpenetrating thermophobic and thermophilic dual responsive networks

Poly(N‐acryloyl glycinamide) (PNAGA)/poly(N‐isopropyl acrylamide) (PNIPAAm) interpenetrating network (IPN) hydrogels were made by UV‐light initiated radical polymerization in two‐steps. The IPN hydrogels showed a double thermoresponsive behavior due to the combination of PNIPAAm (thermophobic) and PNAGA (thermophilic) networks. Increasing the content of the thermophobic PNIPAAm network leads to a change from a broad thermophilic volume phase transition temperature of PNAGA to a thermophilic–thermophobic‐type dual transition for the prepared IPN. Due to the double thermoresponsive character of the IPN gels, the mechanical properties are dependent upon temperature as demonstrated by performing tensile tests in water at 15 and 50 °C. Furthermore, the IPN hydrogels were characterized using turbidity measurements, SEM, and the determination of the equilibrium swelling ratio. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 539–544     

Zr(IV)‐Crosslinked Polyacrylamide/Polyanionic Cellulose Composite Hydrogels with High Strength and Unique Acid Resistance

Recently, metal coordination has been widely utilized to fabricate high‐performance hydrogels, but conventional metal‐based hydrogels face some drawbacks, such as staining or acid lability. In the present study, a novel kind of colorless Zr(IV)‐crosslinked polyacrylamide/polyanionic cellulose (PAM/PAC) composite hydrogel with unique acid resistance was constructed via acrylamide polymerization in a PAC solution, followed by posttreatment in a zirconium oxychloride (ZrOCl₂) solution. The prepared gels were characterized in terms of Fourier transform infrared spectroscopy, scanning electron microscopy, and tensile and compressive mechanics, as well as acid resistance. Inside the gels, the synergistic action of hydrogen bonding and Zr(IV) coordination is responsible for their improved mechanical properties and good energy dissipation ability. One hydrogel with nearly 90 wt % of water content can sustain approximately 5 MPa of compression stress at 90% strain without damage. Both microscopic network structures and macroscopic mechanics demonstrate facile adjustability via changing the PAC dosages in polymerization and/or ZrOCl₂ concentrations in posttreatment. Moreover, the gels present unexpected acid resistance due to the strong Zr(IV) coordination with PAC, demonstrating their potential application as hydrogel electrolytes in supercapacitors. The current work provides a new approach to fabricate metal coordination‐based high strength, colorless hydrogels with acid resistance. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 981–991     

Kinetic Study of Bovine Serum Albumin (BSA) Released from Alginate-Ca2+/PNIPAAm Hydrogels

Summary: In this work the releasing of Bovine Serum Albumin (BSA) from thermosensitive hydrogels of alginate-Ca²⁺/PNIPAAm was investigated. The hydrogels are constituted of PNPAAm network interpenetrated in alginate-Ca²⁺ network, so the hydrogels are IPN-typed. The PNIPAAm network was synthesized in the first step in which the sodium alginate remained soluble. The alginate-Ca²⁺ network was formed in the second step by immersion the membrane obtained on the first step in aqueous calcium chloride. It was changed the amount of NIPAAm in the feed solution of the first step. The fractions of BSA released as a function of time were treated according to the mathematical model recently published by our lab [J. Coll. Interf. Sci. 2007 , 310, 128] that allows predicting the whole profile of solute released from polymer networks. This mathematical model is based in the partition phenomena. The amount of BSA released from alginate-Ca²⁺/PNIPAAm hydrogels changes inversely to both amount of PNIPAAm and temperature. Thus, the IPN-typed matrixes of alginate-Ca²⁺/PNIPAAm may be considered as smart hydrogels for release the BSA because the amount and rate of released BSA can be tailored by the amount of PNIPAAm in the hydrogel and by the control of temperature. Finally, the whole profile of released BSA can be adequately fitted by the model based in the partition phenomenon. From that model the kinetic parameter t_1/2 and rate constant of releasing, k_R, were calculated for the different hydrogels investigated in this work.     

A simple FTIR spectroscopic method for the determination of the lower critical solution temperature of N‐isopropylacrylamide copolymers and related hydrogels

Linear and crosslinked polymers based on N‐isopropylacrylamide (NIPAAm) exhibit unusual thermal properties. Aqueous solutions of poly(N‐isopropylacrylamide) (PNIPAAm) phase‐separate upon heating above a lower critical solution temperature (LCST), whereas related hydrogels undergo a swelling–shrinking transition at an LCST. A linear copolymer made of NIPAAm/acryloxysuccinimide (98/2 mol/mol) and two hydrogels with different hydrophilicities were prepared. Fourier transform infrared (FTIR) spectroscopy was employed to determine the transition temperature and provide insights into the molecular details of the transition via probing of characteristic bands as a function of temperature. The FTIR spectroscopy method described here allowed the determination of the transition temperature for both the linear and crosslinked polymers. The transition temperatures for PNIPAAm and the gel resulting from the crosslinking with polylysine or N,N′‐methylenebisacrylamide (MBA) were in the same range, 30–35 °C. For the gels, the transition temperature increased with the hydrophilicity of the polymer matrix. The spectral changes observed at the LCST were similar for the free chains and the hydrogels, implying a similar molecular reorganization during the transition. The C H stretching region suggests that the N‐isopropyl groups and the backbone both underwent conformational changes and became more ordered upon heating above the LCST. An analysis of the amide I band suggests that the amide groups of the linear polymer were mainly involved in hydrogen bonding with water molecules below the LCST, the chain being flexible and disordered in a water solution. During the transition, around 20% of these intermolecular hydrogen bonds between the polymer and water were broken and replaced by intramolecular hydrogen bonds. Similar changes were also observed at the LCST of a gel crosslinked with MBA. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 907–915, 2000     

Synthesis and mechanical strength of a novel double network nanocomposite hydrogel with core‐shell structure

A novel poly[(dimethylimino)(2‐hydroxy‐1,3‐propanedily)chloride]/Laponite/polyacrylic acid (PDMIHPC/Clay/PAA) hydrogel was synthesized by two‐step solution polymerization combining the strategies of both nanocomposite (NC) gels and double network (DN) gels. The chemical composition and core‐shell structure of the hydrogels were confirmed by Fourier transform infrared (FTIR) and transmission electron microscopy (TEM). The mechanical strength was examined by varying the reaction temperature, PDMIHPC/Clay composite dose, N,N′‐methylenebisacrylamide (MBAM) dose and water content. When the reaction temperature was 35°C, PDMIHPC/Clay composite/AA is 1:10 and MBAM dose was 0.050 wt% (based on the weight of AA), the novel hydrogel achieved a best compressive strength of 100.05 KPa with a water content of 98.8%. Copyright © 2011 John Wiley & Sons, Ltd.     

Colloidal stability of oleic- and ricinoleic-acid-coated magnetic nanoparticles in organic solvents

Polyacrylic acid (PAA) and polyacrylamide (PAAm) double network (DN) hydrogels with high mechanical strength (about 1.5 MPa) are obtained when two kinds of monomer solutions of 4M AA with 5 mol% crosslinker and 4M AAm with 0.1 mol% crosslinker are used for the optimal preparation. Their high mechanical strength can be maintained even at high water content (above 50%) and at external stimuli (solvent and pH). This optimized DN hydrogel is used to develop the PAA/PAAm inverse opal hydrogel with DN structure by twice infiltration-polymerization and colloidal templating. Its photonic stop band can be tuned by controlling the solvent and pH. It first shows a small red-shift (about 20 nm), and then a large blue-shift (about 180 nm) with the increased ethanol content. For pH response, the DN inverse opal hydrogel has a large stop-band shift of about 140 nm when the pH increases from 1.2 to 5.6. Moreover, the DN inverse opal hydrogel also shows rapid recovery ability without hysteresis phenomenon in strong acidic environment, good reproducibility and durability. The interaction between the independently crosslinked PAA network and PAAm network plays a significant role in determining the response performance.     

Dynamics studies on thermoresponsive poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) hydrogel in tetrahydrofuran/water mixtures

The properties of thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) hydrogel in tetrahydrofuran/H₂O mixtures were studied. Scanning electron microscopic (SEM) images demonstrate that the hydrogel changes from homogeneous to heterogeneous microstructure upon the addition of tetrahydrofuran to water. This heterogeneous PNIPAAm hydrogel in the mixture solvent exhibits a very slow response rate at temperatures above its lower critical solution temperature. The decreased response rate is attributed to the formation of special ternary complexes including the polymer and the two solvents in the tetrahydrofuran/H₂O mixture. Factors controlling the thermoresponse rate are discussed further and several suggestions are provided for designing and developing fast-response PNIPAAm hydrogels in the future.     

A Double Network Hydrogel with High Mechanical Strength and Shape Memory Properties

Double network (DN) hydrogels as one kind of tough gels have attracted extensive attention for their potential applications in biomedical and load-bearing fields. Herein, we import more functions like shape memory into the conventional tough DN hydrogel system. We synthesize the PEG-PDAC/P(AAm-co-AAc) DN hydrogels, of which the first network is a well-defined PEG (polyethylene glycol) network loaded with PDAC (poly(acryloyloxyethyltrimethyl ammonium chloride)) strands, while the second network is formed by copolymerizing AAm (acrylamide) with AAc (acrylic acid) and cross-linker MBAA (N, N'-methylenebisacrylamide). The PEG-PDAC/P(AAm-co-AAc) DN gels exhibits high mechanical strength. The fracture stress and toughness of the DN gels reach up to 0.9 MPa and 3.8 MJ/m³, respectively. Compared with the conventional double network hydrogels with neutral polymers as the soft and ductile second network, the PEG-PDAC/P(AAm-coAAc) DN hydrogels use P(AAm-co-AAc), a weak polyelectrolyte, as the second network. The AAc units serve as the coordination points with Fe³⁺ ions and physically crosslink the second network, which realizes the shape memory property activated by the reducing ability of ascorbic acid. Our results indicate that the high mechanical strength and shape memory properties, probably the two most important characters related to the potential application of the hydrogels, can be introduced simultaneously into the DN hydrogels if the functional monomer has been integrated into the network of DN hydrogels smartly.     

PVA-PAMPS-PAA三元互穿网络型水凝胶的合成及其性能研究

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酸(AA)以及聚乙烯醇(PVA)为原料,制备了PVA-PAMPS-PAA三元互穿网络型(T-IPN)水凝胶.红外分析表明,PVA与PAA以及PAMPS之间形成了较强的氢键,使得PVA分子上的C—O伸缩震动吸收峰移向了低波数处.X射线衍射以及电镜分析表明,当PVA用量较低时,PVA能均匀的穿插于凝胶网络中,形成完善的互穿网络结构,当PVA用量过高时,部分的PVA结晶而使得凝胶出现相分离.研究了该三元互穿网络型水凝胶的溶胀性能,结果表明,该水凝胶的平衡溶胀比在200至340之间,并且随着AA以及AMPS用量的增加,凝胶的溶胀速率以及平衡溶胀比均升高.该三元互穿网络型水凝胶在酸性溶液中和在碱性溶液中表现出截然不同的消溶胀性能;并且随着溶液pH的升高,凝胶在pH=9.0附近出现体积突变,表现出pH敏感性.通过研究T-IPN水凝胶的抗压缩性能发现,利用线型高分子、柔性高分子网络以及刚性高分子网络制备的三元互穿网络型水凝胶能在高溶胀比下保持较高的强度.溶胀比为180的T-IPN水凝胶,其最大抗压缩强度可达12.1 MPa.进一步研究发现,凝胶的组成以及溶胀比均对凝胶的抗压缩强度和压缩应变均存在较大的影响.     

Porous alginate-Ca hydrogels interpenetrated with PNIPAAm networks: Interrelationship between compressive stress and pore morphology

Thermo-sensitive porous hydrogels composed of interpenetrated networks (IPN) of alginate-Ca²⁺ and PNIPAAm have been obtained. The hydrogels were prepared by cross-linking alginate-Na⁺ with Ca²⁺ ions inside PNIPAAm networks. Compressive tests and scanning electron microscopy were used to evaluate gel strength and pore morphology, respectively. IPN hydrogels displayed two distinct pore morphologies under thermal stimuli. Below 30-35 °C, the LCST of PNIPAAm in water, IPN hydrogels were highly porous. The pore size of hydrogel heated above LCST became progressively smaller. Alginate-Ca²⁺ and PNIPAAm hydrogels, used as references, did not present such behaviour, indicating that the porous effect is due to IPN hydrogel. It was verified that higher strength is achieved when the hydrogel presents small pore size and the temperature is increased. It is suggested that at temperatures above LCST, the PNIPAAm chains shrink and pull the alginate-Ca²⁺ networks back. During shrinking, the polymer chains occupy the open spaces (pores from which water is expelled), and therefore, the hydrogel becomes less deformable when subjected to compressive stress. The results presented in this work indicate that the mechanical properties as well as the pore morphologies of these IPN hydrogels can be tailored by thermal stimulus.     

Controlled synthesis of responsive hydrogel nanostructures via microcontact printing and ATRP

Surfaces that are spatially functionalized with intelligent hydrogels, especially at the micro‐ and nanoscale, are of high interest in the diagnostic and therapeutic fields. Conventional methods of the semiconductor industry have been successfully employed for the patterning of hydrogels for various applications, but methods for fabricating precise 3 D patterns of hydrogels at the micro‐ and nanoscale over material surfaces remain limited. Herein, microcontact printing (µCP) followed by atom transfer radical polymerization (ATRP) was applied as a platform to synthesize temperature responsive poly(N‐isopropylacrylamide) hydrogels with varied network structures (e.g. different molecular weight crosslinkers) over gold surfaces. The XY control of the hydrogels was achieved using µCP, and the Z (thickness) control was achieved using ATRP. The controlled growth and the responsive behavior of hydrogels to temperature stimuli were characterized using Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM). The results demonstrate that this platform allows for the controlled growth of hydrogel nanostructures using the controlled ATRP mechanism. It is also shown that the molecular weight of the crosslinker affects the rate of hydrogel growth. These PNIPAAm‐based crosslinked hydrogel patterns were also demonstrated to have a temperature‐dependent swelling response. Using this technique, it is possible to synthesize responsive hydrogel patterns over various surfaces for potential applications in the biomedical field. Copyright © 2009 John Wiley & Sons, Ltd.     

Novel Biodegradable and Thermosensitive Dex‐AI/PNIPAAm Hydrogel

The dextran‐allyl isocyanate/poly(N‐isopropylacrylamide) (Dex‐AI/PNIPAAm) hydrogel was designed and prepared by copolymerization of the modified dextran with N‐isopropylacrylamide (NIPAAm). This novel Dex‐AI/PNIPAAm hydrogel is biodegradable and intelligent due to its biodegradable dextran linkage and thermosensitive PNIPAAm moiety. With an increase in dextran content, it exhibits the increased lower critical solution temperature (LCST) and decreased porous microstructure. Also, the thermosensitivity of this hydrogel is also controllable and adjustable depending on the different compositions.

SEM micrographs of the Dex‐AI/PNIPAAm hydrogels.