Temperature-responsive Hydrogel Research Articles

Hierarchical spontaneous self-assembly of polyethylenimine-poly(propylene glycol) copolymer into cationic polyelectrolyte pH-responsive thermogel

Temperature-responsive hydrogels, otherwise known as thermogels, are promising biomaterials which undergo phase change from liquid to a solid-like gel state when warmed. Although poly (ethylene glycol) (PEG) is employed extensively as the hydrophilic segment in thermogelling polymer design, recent years has witnessed development of new families of PEG-free thermogelling copolymers which offer new opportunities in expanding material property profiles for new biomedical applications. Herein, we study the supramolecular self-assembly process of PEG-free amphiphilic branched graft copolymer containing polyethylenimine (PEI) and poly (propylene glycol) (PPG), which shows both thermogelling ability and pH-responsive gelation behaviour. Additionally, we demonstrate the ease of post-synthetic modulation of thermogel properties by amine functionalisation on the PEI copolymer segments through convenient nucleophilic substitution and amide formation reactions. The synthetic platform offered by PEI-PPG thermogels allow facile customisation of these versatile materials for targeted biomedical applications.

A Sustainable Retinal Drug Co-Delivery for Boosting Therapeutic Efficacy in wAMD: Unveiling Multifaceted Evidence and Synergistic Mechanisms.

Sustainable retinal codelivery poses significant challenges technically, although it is imperative for synergistic treatment of wet age-related macular degeneration (wAMD). Here, a microemulsion-doped hydrogel (Bor/PT-M@TRG) is engineered as an intravitreal depot composing of temperature-responsive hydrogel (TRG) and borneol-decorated paeoniflorin (PF) & tetramethylpyrazine (TMP)-coloaded microemulsions (Bor/PT-M). Bor/PT-M@TRG, functioning as the "ammunition depot", resides in the vitreous and continuously releases Bor/PT-M as the therapeutic "bullet", enabling deep penetration into the retina for 21 days. A single intravitreal injection of Bor/PT-M@TRG yields substantial reductions in choroidal neovascularization (CNV, a hallmark feature of wAMD) progression and mitigates oxidative stress-induced damage in vivo. Combinational PF&TMP regulates the "reactive oxygen species/nuclear factor erythroid-2-related factor 2/heme oxygenase-1" pathway and blocks the "hypoxia inducible factor-1α/vascular endothelial growth factor" signaling in retina, synergistically cutting off the loop of CNV formation. Utilizing fluorescence resonance energy transfer and liquid chromatography-mass spectrometry techniques, they present compelling multifaceted evidence of sustainable retinal codelivery spanning formulations, ARPE-19 cells, in vivo eye balls, and ex vivo section/retina-choroid complex cell levels. Such codelivery approach is elucidated as the key driving force behind the exceptional therapeutic outcomes of Bor/PT-M@TRG. These findings highlight the significance of sustainable retinal drug codelivery and rational combination for effective treatment of wAMD.

Comparative Analysis of Temperature-Responsive Hydrogel (PF 72) for Postoperative Pain After Bimaxillary Surgery: A Retro-spective Study.

Bimaxillary surgery is a painful invasive procedure in plastic surgery. Pain control is typically achieved using intravenous analgesics. We aimed to investigate the efficacy of a novel temperature-responsive hydrogel, PF72, mixed with ropivacaine, as a local pain management solution when applied directly to the surgical site following orthognathic surgery. The study was conducted from October 2022 to July 2023 and included a cohort of 40 candidates for orthognathic surgery, encompassing LeFort I maxillary ostectomy and sagittal split ramus osteotomy. The participants were divided into an Injection group (n=20), where PF72 was administered at the surgical site before the orthognathic surgery, and a Control group (n=20), which relied solely on intravenous analgesics. Pain was evaluated at 3, 6, 24, 48, and 72 h after surgery using a numerical rating scale (NRS). The mean NRS scores at 24 h were 6.35 and 4 for the Control and Injection groups, respectively. The mean NRS scores at 72 h were 3.4 and 2.55 for the Control and Injection groups, respectively. Patients who received PF72 experienced less pain than those who received intravenous analgesics. These findings underscore the potential of PF72 as an effective alternative for enhancing pain management in patients undergoing orthognathic surgery.Level of Evidence III Therapeutic study. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

3D printed heterogeneous bilayer temperature-responsive hydrogel with multi-curvature deformation

Poly (N-isopropylacrylamide) (PNIPAM) hydrogel are increasingly used in soft actuators and soft robotics due to their distinctive temperature-responsive properties. To realize the multi-curvature bending of the bilayer hydrogel, the PAM-based hydrogel with different properties is arranged in different positions of the PNIPAM based hydrogel through multi-material 3D printing technology to form different restriction areas, which in turn makes the bilayer hydrogel have different restrictions at different positions when bending and deforming. By studying the mechanical properties of different PAM-based hydrogel and the swelling properties of the hydrogel, several homogeneous passive layer bilayer hydrogel were prepared, which showed that the bending curvature of the homogeneous passive layer bilayer hydrogel has a certain relationship with the material properties and the thickness ratio between the two layers. Finally, some typical cases of heterogeneous passive layer bilayer hydrogel were fabricated to realize the multi-curvature bending deformation of bilayer hydrogel, which further broadened the application of bilayer hydrogel.

Temperature-responsive microcapsule hydrogel fabricated by pickering emulsion polymerization for pheromones application

Insect pheromone is a natural effective biological pesticide. To improve the utilization efficiency of pheromone pesticides and reduce labor costs, a sustained and controlled release preparation coordinating with the circadian rhythm of insects has been proposed by our previous report. However, that preparation has some deficiencies, such as the loading capacity of pheromone and sustained time. In order to overcome the existent shortcomings, a temperature-responsive release microcapsule hydrogel loaded with myrcene (as a pheromone model) was fabricated by Pickering emulsion polymerization using modified SiO2 nanoparticles as a stabilizer of microcapsule wall, octadecane and Poly(N-isopropylacrylamide) (PNIPAM) separately as temperature responders of microcapsule core and wall in the present study. The morphological structure and thermal performance of the microcapsule hydrogel were characterized. The release behaviors of myrcene at different environmental temperatures and alternating temperature cycles were also tested. The results indicated that myrcene was successfully loaded in the Myrcene/Octadecane@SiO2-PNIPAM (MOSP) microcapsule hydrogel with encapsulation efficiency and loading capacity of 80.3 % and 13.3 %, respectively. The results of the myrcene release under simulated diurnal temperature cycles revealed that the cumulative release amount was only about 43 % during 15 cycles and release rates respectively were about 0.79 μg/h at 35 °C and 0.058 μg/h at 25 °C, which demonstrated the persistent temperature sensitivity and good temperature rhythm remained after 15 cycles. These results suggested that the MOSP microcapsule hydrogel had a good controlled release effect on myrcene and could adapt well to the circadian rhythm activity of some insects. Therefore, this study provided a promising strategy to improve the utilization efficiency of pheromones through the combination of octadecane and PNIPAM as pheromones release controllers.

Effectiveness of a Novel Temperature-Responsive Hydrogel (PF72) for Postoperative Pain Relief in Breast Augmentation.

Breast augmentation can cause severe postoperative pain, leading to an increased length of hospital stay. Postoperative pain management following breast surgery has traditionally involved intravenous and oral analgesics. However, the misuse of opioids can cause severe complications. As a result, several alternative methods have been suggested. Fifty patients were included in this study. All the patients underwent dual-plane pocket dissection using the transaxillary approach and received smooth-type breast implants. The intervention group included 25 patients who received PF72 combined with ropivacaine, and the control group included 25 patients who received only bupivacaine. The Numerical Rating Scale (NRS) score was used to evaluate each patient's pain. Three hours after the surgery, the average NRS scores of the control and intervention groups were 3.75 and 2.48, respectively. Six hours after the operation, the NRS scores of the control and intervention groups increased to 4.77 and 3.02, respectively. PF72 combined with ropivacaine was more effective than only bupivacaine for pain control in patients who underwent breast augmentations.

Multi-stimuli responsive, shape deformation, and synergetic biomimetic actuator

Hydrogel actuators with controllable deformation and excellent biocompatibility are widely used in soft robot, valve, drug delivery and lenses. However, the stimulation response performance of existing hydrogel actuators mostly focuses on a single active layer, which greatly affects its driving performance and service life. In this work, we integrate temperature-responsive hydrogel (Poly (N-isopropyl acrylamide), PNIPAM) and pH-responsive hydrogel (polyacrylic acid, PAAc) into one system to fabricate a dual active layer composite hydrogel actuator with high performance. Based on the PAAc hydrogels achieving contract or expand at different pH values, the obtained actuator exhibits admirable bidirectional bending characteristics. In addition, the anisotropic bamboo sheet endows the hydrogel actuator with programmable 3 D complex deformation. Benefitting from the synergy and different responsiveness between the two active layers, the hydrogel actuator not only has multiple response performance, but also greatly improves its deformation degree and response speed. More importantly, these promising properties of the actuator have broad application prospects in the development of pattern design and intelligent switch. This work proposes a promising strategy for the structural design of hydrogel actuators with excellent performance, and encourages more exploration of the application range of the actuator.

Exceptionally Fast Temperature-Responsive, Mechanically Strong and Extensible Monolithic Non-Porous Hydrogels: Poly(N-isopropylacrylamide) Intercalated with Hydroxypropyl Methylcellulose.

Exceptionally fast temperature-responsive, mechanically strong, tough and extensible monolithic non-porous hydrogels were synthesized. They are based on divinyl-crosslinked poly(N-isopropyl-acrylamide) (PNIPAm) intercalated by hydroxypropyl methylcellulose (HPMC). HPMC was largely extracted after polymerization, thus yielding a 'template-modified' PNIPAm network intercalated with a modest residue of HPMC. High contents of divinyl crosslinker and of HPMC caused a varying degree of micro-phase-separation in some products, but without detriment to mechanical or tensile properties. After extraction of non-fixed HPMC, the micro-phase-separated products combine superior mechanical properties with ultra-fast T-response (in 30 s). Their PNIPAm network was highly regular and extensible (intercalation effect), toughened by hydrogen bonds to HPMC, and interpenetrated by a network of nano-channels (left behind by extracted HPMC), which ensured the water transport rates needed for ultra-fast deswelling. Moreover, the T-response rate could be widely tuned by the degree of heterogeneity during synthesis. The fastest-responsive among our hydrogels could be of practical interest as soft actuators with very good mechanical properties (soft robotics), while the slower ones offer applications in drug delivery systems (as tested on the example of Theophylline), or in related biomedical engineering applications.

Development of a Temperature-Responsive Hydrogel Incorporating PVA into NIPAAm for Controllable Drug Release in Skin Regeneration.

Melanoma, a highly malignant and aggressive form of skin cancer, poses a significant global health threat, with limited treatment options and potential side effects. In this study, we developed a temperature-responsive hydrogel for skin regeneration with a controllable drug release. The hydrogel was fabricated using an interpenetrating polymer network (IPN) of N-isopropylacrylamide (NIPAAm) and poly(vinyl alcohol) (PVA). PVA was chosen for its adhesive properties, biocompatibility, and ability to address hydrophobicity issues associated with NIPAAm. The hydrogel was loaded with doxorubicin (DOX), an anticancer drug, for the treatment of melanoma. The NIPAAm-PVA (N-P) hydrogel demonstrated temperature-responsive behavior with a lower critical solution temperature (LCST) around 34 °C. The addition of PVA led to increased porosity and faster drug release. In vitro biocompatibility tests showed nontoxicity and supported cell proliferation. The N-P hydrogel exhibited effective anticancer effects on melanoma cells due to its rapid drug release behavior. This N-P hydrogel system shows great promise for controlled drug delivery and potential applications in skin regeneration and cancer treatment. Further research, including in vivo studies, will be essential to advance this hydrogel system toward clinical translation and impactful advancements in regenerative medicine and cancer therapeutics.

PH and temperature responsive UV curable lignin-based hydrogels with controllable and outstanding compressive properties

Functional hydrogels have been widely researched in various fields. However, preparing bio-hydrogels with several functionalities, such as desirable mechanical properties, high swelling ability, and stimuli-responsive properties, still presents a challenge. In this study, a UV-curable lignin-based bio-hydrogel was produced via methacrylation using glycidyl methacrylate, followed by cross-linking with acrylamide. The synthesized lignin hydrogel showed outstanding compressive performance, durability properties, and rheological behaviors, which could be engineered by changing the lignin content. With the increase in lignin concentration, the crosslinking density and storage/loss modulus were increased, whereas tan δ was decreased. Additionally, the hydrogels exhibited excellent swelling ratios (up to several thousand %), meanwhile their swelling behavior and dimensional changes varied with the lignin concentration, and strongly depended on temperature and pH. Finally, a smart strip-shaped hydrogel was designed to explore an actuator behavior, showing a fast and reversible swelling-deswelling response between pH 3 and 9. This can indicate that the lignin-based hydrogel could be a promising material for biomedical applications and 4D printing materials.

Thermo-Responsive Hydrogels Encapsulating Targeted Core-Shell Nanoparticles as Injectable Drug Delivery Systems.

As therapeutic agents that allow for minimally invasive administration, injectable biomaterials stand out as effective tools with tunable properties. Furthermore, hydrogels with responsive features present potential platforms for delivering therapeutics to desired sites in the body. Herein, temperature-responsive hydrogel scaffolds with embedded targeted nanoparticles were utilized to achieve controlled drug delivery via local drug administration. Poly(N-isopropylacrylamide) (pNIPAM) hydrogels, prepared with an ethylene-glycol-based cross-linker, demonstrated thermo-sensitive gelation ability upon injection into environments at body temperature. This hydrogel network was engineered to provide a slow and controlled drug release profile by being incorporated with curcumin-loaded nanoparticles bearing high encapsulation efficiency. A core (alginate)-shell (chitosan) nanoparticle design was preferred to ensure the stability of the drug molecules encapsulated in the core and to provide slower drug release. Nanoparticle-embedded hydrogels were shown to release curcumin at least four times slower compared to the free nanoparticle itself and to possess high water uptake capacity and more mechanically stable viscoelastic behavior. Moreover, this therapy has the potential to specifically address tumor tissues over-expressing folate receptors like ovaries, as the nanoparticles target the receptors by folic acid conjugation to the periphery. Together with its temperature-driven injectability, it can be concluded that this hydrogel scaffold with drug-loaded and embedded folate-targeting nanoparticles would provide effective therapy for tumor tissues accessible via minimally invasive routes and be beneficial for post-operative drug administration after tumor resection.

MOF-Thermogel Composites for Differentiated and Sustained Dual Drug Delivery.

In recent years, multidrug therapy has gained increasing popularity due to the possibility of achieving synergistic drug action and sequential delivery of different medical payloads for enhanced treatment efficacy. While a number of composite material release platforms have been developed, few combine the bottom-up design versatility of metal-organic frameworks (MOFs) to tailor drug release behavior, with the convenience of temperature-responsive hydrogels (or thermogels) in their unique ease of administration and formulation. Yet, despite their potential, MOF-thermogel composites have been largely overlooked for simultaneous multidrug delivery. Herein, we report the first systematic study of common MOFs (UiO-66, MIL-53(Al), MIL-100(Fe), and MOF-808) with different pore sizes, geometries, and hydrophobicities for their ability to achieve simultaneous dual drug release when embedded within PEG-containing thermogel matrices. After establishing that MOFs exert small influences on the rheological properties of the thermogels despite the penetration of polymers into the MOF pores in solution, the release profiles of ibuprofen and caffeine as model hydrophobic and hydrophilic drugs, respectively, from MOF-thermogel composites were investigated. Through these studies, we elucidated the important role of hydrophobic matching between MOF pores and loaded drugs in order for the MOF component to distinctly influence drug release kinetics. These findings enabled us to identify a viable MOF-thermogel composite containing UiO-66 that showed vastly different release kinetics between ibuprofen and caffeine, enabling temporally differentiated yet sustained simultaneous drug release to be achieved. Finally, the MOF-thermogel composites were shown to be noncytotoxic in vitro, paving the way for these underexploited composite materials to find possible clinical applications for multidrug therapy.

Photo and temperature responsive novel surface active ionic liquid-based polymeric hydrogel

Integrating more than two properties into a single polymeric hydrogel to introduce the multi-functionality has been a challenge for the scientific community in recent times. In order to impart photo and temperature responsive characteristics added with adjustable mechanical properties into the polymeric hydrogel, herein we have added newly synthesized photo-responsive ionic liquid (IL) into the polymeric (κ-carrageenan) hydrogel. The IL used is having morpholine-based ester functionalized long chain cation and azobenzene based anion that exhibited trans to cis transformation when irradiated by light of 465 nm for 50 min and show surface-active properties with CMC of 6.83 mM. IL with such photo and temperature responsive properties when mixed with the hydrogel of κ-carrageenan in KCl solution gives the photo and thermo-responsive hybrid hydrogel. The three-dimensional network structure of hydrogel made up of the ellipsoidal aggregates with major and minor axis radius of 9.3 A0 and 1.6 A0, respectively is made up of a fibrous porous structure and gets disrupted through the light irradiation and initiated the gel to sol transition, studied through the SEM images, DLS data and rheological measurements. The (IL) based hydrogel gets disrupted after light irradiation as the anion of the IL starts transforming from trans to cis isomerization. Also, the thermo-reversible transition of hydrogel within room temperature to 54 °C is also shown by rheology. Kinetics of the trans to cis transformation, controlled strain and stress measurement and thermal stability of the hydrogel are assessed here. The studied photo and temperature responsive hydrogel could start a new range of smart materials.

Spidroin-based multifunctional microneedles with controlled drug release for efficient wound management

Wound healing remains a serious challenge in the biomedical field due to its complex physiological processes. To address this issue, microneedle patches are proposed as an effective strategy for wound management. Herein, we propose novel breathable microneedle patches containing therapeutic drugs and functional materials for wound healing, which are fabricated using extrusion 3D printing technology. The microneedle patch is composed of needle tips and a breathable scaffold backing layer made of spidroin hydrogel, polyurethane, and aloe vera gel, providing excellent biocompatibility and self-healing ability. Furthermore, eutectic Galium-Indium (EGaIn) was incorporated into the dressing, enabling the near-infrared light response function. The highly efficient photothermal conversion allowed for superfast self-healing in seconds. The microneedle dressing was sensitive enough to monitor large-scale movements at different joints and small-scale motions of the throat during swallowing. Combining biocompatible microneedles with a temperature-responsive hydrogel (pNIPAM), stable controllable drug delivery is achieved using near-infrared (NIR) light. The stable photothermal performance enabled the device to release a controlled dose of the drug over multiple light triggers. With NIR-triggered pulse drug release, VEGF-mediated treatment on wound healing was significantly improved in mouse models by accelerating tissue repair and reducing the inflammatory response.

A dual pH- and temperature-responsive hydrogel produced in situ crosslinking of cyclodextrin-cellulose for wound healing

Cellulose hydrogels have gained attention in the field of wound healing due to their biodegradability, biocompatibility, and the capacity to sustain a humid environment that promotes healing. Conventional cellulose hydrogels were usually lacked responsiveness to changing wound conditions, and limited capacity for controlled release of active substances. The composite hydrogels with Berberine (BBR) loading were prepared from bamboo parenchymal cellulose and in situ crosslinking carboxylated-β-cyclodextrin (BPCH-B) via dissolution. The inclusion of BBR enhanced the antibacterial properties of cellulose hydrogel while maintaining biocompatibility and drug delivery capabilities. The dual-responsive dressing was demonstrated to modulate drug release kinetics in accordance with the pH and temperature conditions prevailing within the wound site. Specifically, study exhibited a significant increase in drug release (over 70 %) under alkaline pH (7.6) and temperature (40 °C) conditions. Full-thickness wound healing experiments indicated that BPCH-B had better healing ability, and the wound healing area of BPCH-B treated was 80 % within 12 days, while the control group was only 50 %. This strategy for generating functional wound healing can be further control release of drug compounds for treatment of wounds, enabling development of practical wound care materials.

Self-Healing of Pluronic® F127 Hydrogels in the Presence of Various Polysaccharides.

Thermoresponsive Pluronic® F127 (PL) gels in water were investigated through rheological tests in different shear conditions. The gel strength was tuned with the addition of 1% polysaccharide solution. In the presence of xanthan gum (XG), the viscoelastic behavior of PL-based hydrogels was improved in aqueous environment, but the rheological behavior was less changed with the addition of XG in PBS solutions, whereas in the presence of 0.1 M NaCl, the viscoelastic parameters decreased. PL micellar networks exhibited a self-healing ability, recovering their initial structure after applying cycles of high strain. The rheological characteristics of the PL hydrogel changed with the addition of 1% polysaccharides (xanthan gum, alginate, κ-carrageenan, gellan, or chitosan). PL/polysaccharide systems form temperature-responsive hydrogels with shear thinning behavior, yield stress, and self-healing ability, being considered a versatile platform for injectable biomaterials or bioinks. Thus, in the presence of xanthan gum in aqueous medium, the gel strength was improved after applying a high strain (the values of elastic modulus increased). The other investigated natural polymers induced specific self-healing behaviors. Good performances were observed with the addition of gellan gum, alginate, and κ-carrageenan, but for high values of strain, the ability to recover the initial structure decreased. A modest self-healing behavior was observed in the presence of chitosan and xanthan gum dissolved in NaCl solution.

Swarming Multifunctional Heater-Thermometer Nanorobots for Precise Feedback Hyperthermia Delivery.

Micro-/nanorobots (MNRs) are envisioned to act as "motile-targeting" platforms for biomedical tasks due to their ability to propel and navigate in challenging, hard-to-reach biological environments. However, it remains a great challenge for current swarming MNRs to accurately report and regulate therapeutic doses during disease treatment. Here we present the development of swarming multifunctional heater-thermometer nanorobots (HT-NRs) and their application in precise feedback photothermal hyperthermia delivery. The HT-NRs are designed as photothermal-responsive photonic nanochains consisting of magnetic Fe3O4 nanoparticles arranged periodically in one dimension and encapsulated in a temperature-responsive hydrogel shell. The HT-NRs exhibit energetic and controllable swarming motions under a rotating magnetic field, while simultaneously functioning as motile nanoheaters and nanothermometers, utilizing their photothermal conversion and (photo)thermal-responsive structural color changes (photothermochromism). Consequently, the HT-NRs can be quickly deployed to a remote target area (e.g., a superficial tumor lesion) using their collective motion and selectively eliminate diseased cells in a specific targeted region by utilizing their self-reporting photothermochromism as visual feedback for precisely regulating external light irradiation. This work may inspire the development of intelligent multifunctional theranostic micro-/nanorobots and their practical applications in precise disease treatment.

Delivery Systems in Ocular Retinopathies: The Promising Future of Intravitreal Hydrogels as Sustained-Release Scaffolds.

Slow-release delivery systems are needed to ensure long-term sustained treatments for retinal diseases such as age-related macular degeneration and diabetic retinopathy, which are currently treated with anti-angiogenic agents that require frequent intraocular injections. These can cause serious co-morbidities for the patients and are far from providing the adequate drug/protein release rates and required pharmacokinetics to sustain prolonged efficacy. This review focuses on the use of hydrogels, particularly on temperature-responsive hydrogels as delivery vehicles for the intravitreal injection of retinal therapies, their advantages and disadvantages for intraocular administration, and the current advances in their use to treat retinal diseases.

Temperature-Responsive Hydrogel for Silver Sulfadiazine Drug Delivery: Optimized Design and In Vitro/In Vivo Evaluation.

Response surface methodology (RSM) was applied to optimise a temperature-responsive hydrogel formulation synthesised via the direct incorporation of biocellulose, which was extracted from oil palm empty fruit bunches (OPEFB) using the PF127 method. The optimised temperature-responsive hydrogel formulation was found to contain 3.000 w/v% biocellulose percentage and 19.047 w/v% PF127 percentage. The optimised temperature-responsive hydrogel provided excellent LCST near to the human body surface temperature, with high mechanical strength, drug release duration, and inhibition zone diameter against Staphylococcus aureus. Moreover, in vitro cytotoxicity testing against human epidermal keratinocyte (HaCaT) cells was conducted to evaluate the toxicity of the optimised formula. It was found that silver sulfadiazine (SSD)-loaded temperature-responsive hydrogel can be used as a safe replacement for the commercial SSD cream with no toxic effect on HaCaT cells. Last, but not least, in vivo (animal) dermal testing-both dermal sensitization and animal irritation-were conducted to evaluate the safety and biocompatibility of the optimised formula. No sensitization effects were detected on the skin applied with SSD-loaded temperature-responsive hydrogel indicating no irritant response for topical application. Therefore, the temperature-responsive hydrogel produced from OPEFB is ready for the next stage of commercialisation.

Temperature-responsive hydrogel prepared from carboxymethyl cellulose-stabilized N-vinylcaprolactam with potential for fertilizer delivery

The growth of plants is highly dependent on sufficient water and suitable fertilizer nutrients, but the soil often loses moisture and the fertilizers are low efficiency. To address this issue, the temperature-responsive hydrogels were developed using the N-vinylcaprolactam (NVCL) dispersed in water through the emulsification of carboxymethyl cellulose (CMC) and acrylamide (AM), and urea was loaded into the hydrogel as a fertilizer. The amount of CMC and monomer have an effect on the structure, mechanical properties, swelling ability, and temperature sensitivity of the hydrogel. Therefore, the maximum swelling ratio of the hydrogel can reach 2056 % with the increasing hydrophilic groups, and the hydrogel exhibits a deswelling behavior as the temperature rises to higher than LCST due to the temperature responsiveness. Moreover, the fertilizer can rapidly release when the temperature is higher than LSCT, and exhibits similar release behavior in water and soil. Thus, the temperature-responsive hydrogel shows a great potential application for the controlled release of water and fertilizer in agriculture and forestry.