Thermoresponsive Materials Research Articles

Highly stable and near-infrared responsive phase change materials for targeted enzyme delivery toward cancer therapy

Natural enzyme-based catalytic cascades have garnered increasing attention in cancer therapy, but their clinical utility is greatly limited due to loss of function during in vivo delivery. Here, we developed an enzyme delivering nanoplatform (GCI@RPCM) with great in vivo stability and achieve NIR-triggered enzyme dynamic therapy. This nanoplatform is created with encapsulation of nature enzymes (glucose oxidase and chloroperoxidase) and photothermal agent (indocyanine green) within tumor targeting and thermo-responsive phase change materials (RPCMs). With NIR irradiation for 10 min, GCI@RPCM can release 41 % of the enzymes and generate abundant reactive oxygen species (ROS), which showed significant tumor cell inhibition. After intravenous injection, GCI@RPCM can efficiently accumulate at the tumor site and local NIR treatment resulted in complete tumor eradication without detectable systemic toxicity. This study provides a highly stable and NIR-controllable smart delivery system and achieve enzyme dynamic therapy for enhanced breast cancer therapy.

In Vitro Assessment of Thermo-Responsive Scaffold as a 3D Synthetic Matrix for CAR-T Potency Testing Against Glioblastoma Spheroids.

Chimeric antigen receptor (CAR) T cell immunotherapy has demonstrated exceptional efficacy against hematological malignancies, but notably less against solid tumors. To overcome this limitation, it is critical to investigate antitumor CAR-T cell potency in synthetic 3D microenvironments that can simulate the physical barriers presented by solid tumors. The overall goal of this study was the preliminary assessment of a synthetic thermo-responsive material as a substrate for invitro co-cultures of anti-disialoganglioside (GD2) CAR-T cells and patient-derived glioblastoma (GBM) spheroids. Independent co-culture experiments demonstrated that the encapsulation process did not adversely affect the cell cycle progression of glioma stem cells (GSCs) or CAR-T cells. GSC spheroids grew over time within the terpolymer scaffold, when seeded in the same ratio as the suspension control. Co-cultures of CAR-T cells in suspension with hydrogel-encapsulated GSC spheroids demonstrated that CAR-T cells could migrate through the hydrogel and target the encapsulated GSC spheroids. CAR-T cells killed approximately 80% of encapsulated GSCs, while maintaining effective CD4:CD8 T cell ratios and secreting inflammatory cytokines after interacting with GD2-expressing GSCs. Importantly, the scaffolds also facilitated cell harvesting for downstream cellular analysis. This study demonstrated that a synthetic 3D terpolymer hydrogel can serve as an artificial scaffold to investigate cellular immunotherapeutic potency against solid tumors.

Dual-Responsive PIL Films with Gold Nanoparticles: Tailoring Electrical Responses to pH and Thermal Stimuli.

In recent years, stimuli-responsive poly(ionic liquids) (PILs) have attracted great attention. The stimuli-dependent properties, particularly the electrical properties, of multiresponsive PILs incorporating functionalized nanoparticles, however, have been less investigated. In this work, we present the synthesis, characterization, and application of PIL films incorporating pH- and thermoresponsive hybrid materials composed of gold nanoparticles functionalized with poly(2-(dimethylamino)ethyl methacrylate) (Au@PDMAEMA). The Au@PDMAEMA nanoparticles exhibit distinct responsiveness to changes in environmental pH and temperature, thereby altering the electrical properties of the PIL films blended with responsive gold nanoparticles (PIL w/Au). This research not only fills a gap in the study of electrical properties of multiresponsive nanoparticle-incorporated PILs but also extends the potential applications of PILs in various fields, including smart sensors and electronic devices.

Four-Dimensional Printing of Multi-Material Origami and Kirigami-Inspired Hydrogel Self-Folding Structures.

Four-dimensional printing refers to a process through which a 3D printed object transforms from one structure into another through the influence of an external energy input. Self-folding structures have been extensively studied to advance 3D printing technology into 4D using stimuli-responsive polymers. Designing and applying self-folding structures requires an understanding of the material properties so that the structural designs can be tailored to the targeted applications. Poly(N-iso-propylacrylamide) (PNIPAM) was used as the thermo-responsive material in this study to 3D print hydrogel samples that can bend or fold with temperature changes. A double-layer printed structure, with PNIPAM as the self-folding layer and polyethylene glycol (PEG) as the supporting layer, provided the mechanical robustness and overall flexibility to accommodate geometric changes. The mechanical properties of the multi-material 3D printing were tested to confirm the contribution of the PEG support to the double-layer system. The desired folding of the structures, as a response to temperature changes, was obtained by adding kirigami-inspired cuts to the design. An excellent shape-shifting capability was obtained by tuning the design. The experimental observations were supported by COMSOL Multiphysics® software simulations, predicting the control over the folding of the double-layer systems.

Effect of N-isopropylacrylamide and graphene oxide on the microstructure and performance of thermo-responsive membranes by Ce (IV)-induced redox radical polymerization

In this study, a series of novel thermo-responsive materials were synthesized using polyvinylidene fluoride, N-isopropylacrylamide (NIPAM) and graphene oxide (GO) via Ce (IV)-induced redox radical polymerization name as PNG. Thermo-responsive membranes were prepared by non-solvent induced phase separation. The results demonstrated that the CO and N-H stretching absorption intensities increased with the addition of NIPAM. XPS analysis demonstrated that the PNG1 membrane exhibited abundant functional group structure under the dosage of NIPAM at 1 g. The finger-like porous structure of membrane became longer and wider with the addition of NIPAM at 1 g, leading to a maximum porosity of 45.5 %. The CA decreased from 62.4 ° to 49.0 ° at 35 °C under the adding dosage of NIPAM at 1 g. The temperature-sensitive of PNG1 membrane was 35 °C. In addition, The PNG1 membrane had the lower Rir and higher flux recover than the others under the BSA rejection. According to the XDLVO theory analysis, the total interaction energy for PNG1 membrane achieved the maximum absolute values of −33.850 mJ/m2 and −19.956 mJ/m2 than the others under the temperature at 25 °C and 35 °C. This interaction influenced the adsorption between the pollutant and membrane surface, resulting in reversible fouling.

Preparation of Ultra-Sensitive flexible temperature sensors with thermal responsive waterborne polyurethane for enhanced temperature sensing performance

Flexible temperature sensors with superior resolution and reliable repeatability are crucial in the burgeoning field of electronic skins (e-skins). In this study, we synthesized thermo-responsive materials with mechanical flexibility by incorporating multi-wall carbon nanotubes (MWCNT) into waterborne polyurethane (WPU) matrix via covalent bonding. The thermal movement of WPU chain segments serves as the driving force, endowing the resultant material with excellent temperature response properties and stability. The MWCNT@WPU sensor demonstrates ultra-high sensitivity (−5.63 % K−1), high accuracy (0.1 °C), rapid response (mere 4.5 s), and long-term durability (up to 30 days) for temperature sensing within the range of 30 to 60 °C. Importantly, the temperature coefficient of resistance (TCR) can be tailored by adjusting the molecular weight of WPU soft segments and the ratio of hard segment to soft segment in WPU. Moreover, the developed sensor exhibits outstanding detection accuracy and stability in practical applications such as continuous water temperature monitoring, breathing rate measurement, and human skin temperature sensing, highlighting its immense potential in the e-skins field, catering to applications in healthcare monitoring, intelligent robotic platforms, and environmental surveillance.

Exploring pNIPAM lyogels: Experimental study on swelling equilibria in various organic solvents and mixtures, supported by COSMO-RS analysis

Stimuli-responsive lyogels are considered to be smart materials due to their capability of undergoing significant macroscopic changes in response to external triggers. Due to their versatile and unique properties, smart lyogels exhibit great potential in various applications such as drug delivery or actuation processes. While Poly-N-isopropylacrylamide (pNIPAM) is widely known as a thermo-responsive material, it also shows significant solvent-responsive swelling behavior. For the systems tested, polar solvents induce strong swelling due to hydrogen bonding with the amide group, nonpolar solvents lead to significant shrinkage of the lyogels. The aim of this study is to investigate and to model this behavior for future application in chemical or biochemical reactors. As a current area of research, incorporating smart lyogel technology into (bio-)chemical reactors facilitates the development of smart reactor systems. Applying thermodynamic modelling with the gE model COSMO-RS on the monomer or oligomers of pNIPAM, the correlation between solvent-polymer interactions and the degree of swelling can be observed. pNIPAM derivatives exhibit low infinite dilution activity coefficients (IDACs) in polar solvents with large degrees of swelling, while displaying an increase of IDACs in nonpolar solvents. Hydrogen bonds dominate the swelling behavior of lyogels not only in pure solvents but also in mixtures of solvents with varying polarity. Even in mixtures containing high amounts of nonpolar solvents, large degrees of swelling were observed due to the uptake of the polar solvent in the lyogel matrix. This effect can be observed in binary solvent mixtures but also in representative mixtures along an esterification reaction with varying carboxylic chain length of alcohol and carboxylic acids.

Design of Thermosensitive Niosomes by Eutectic Mixture of Natural Fatty Acids.

In the current study, a smart release system responsive to temperature was developed to improve the efficiency of tetracycline (TC) in antibacterial therapy. The nanovesicles designed consist of a non-ionic surfactant, SPAN60, cholesterol and a phase change material (PCM) as a thermoresponsive gating material. Niosomes were prepared using an increasing amount of PCM and characterized in terms of size, zeta potential, colloidal stability and thermoresponsive properties. The vesicles that developed were homogenous in size, had good biocompatibility and stability for up to 3 months and demonstrated thermoresponsive behavior. A low drug leakage was observed at 37 °C, while a rapid release occurred at 42 °C, due to the faster diffusion rate of the drug trough the melted PCM. This controllable drug release capacity allows us to avoid premature drug release, minimizing unwanted and toxic effects and ensuring a long retention time in the nanodevice so that it reaches the infected sites. In addition, TC-loaded niosomes were screened to investigate their antibacterial activity against various Gram-positive and Gram-negative bacteria by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. An interesting temperature-dependent antibacterial activity was observed against some bacterial strains: the niosomes activity against S. epidermis, for example, was improved by the temperature increase, as suggested by a reduction in MIC values from 112.81 to 14.10 μM observed at 37 and 42 °C, respectively. Taken together, the thermoresponsive platform developed allows us to use lower antibiotic amounts while ensuring therapeutic efficacy and, so, will advance the development of a novel antibacterial agent in clinical practice.

A “Hand‐In‐Hand” Thermal‐Responsive Cyclodextrin Material Designed for Liquid Smart Windows

AbstractThermochromic smart windows have emerged as a focal point in energy research. In this study, a novel approach is introduced for developing thermoresponsive materials for smart windows, utilizing microscopic agglomeration of molecules to regulate incident light. The groundbreaking material, β‐CD‐Val‐IBAm4, is constructed by grafting four isobutylated valines onto natural β‐cyclodextrins. This material exhibits a unique “hand‐in‐hand” effect, resulting from the interaction of isobutylated valine side chains, which leads to molecular aggregation and reduced light transmission at elevated temperatures. The hydration–dehydration process is related to molecular aggregation rather than crosslinking, ensuring the structural integrity and uniformity of the smart windows. Molecular dynamics simulations and 2D NOESY confirm the thermal response mechanism of β‐CD‐Val‐IBAm4. When dissolve in a glycerol‐water binary solvent system, the material forms a thermochromic liquid with outstanding optical performance (ΔTsol of 1 mm liquid can reach 69.8%) and long‐term stability. This innovative approach opens new avenues for the advancement of next‐generation smart window technologies.

Investigating oligo(ethylene glycol) methacrylate thermoresponsive copolymers

Methacrylate-based polymers are frequently used in the development of thermoresponsive smart materials for biomedical applications. Among all the routes to such polymers, reversible addition fragmentation chain transfer (RAFT) copolymerisation is one of the most widely used. This paper reports the synthesis of thermoresponsive copolymers comprising oligo(ethylene glycol) methyl ether methacrylate with Mn of 300 (OEGMA300) and di(ethylene glycol) methyl ether methacrylate (DiEGMA). Polymers of molecular weight up to 100 kDA were obtained via RAFT polymerisation, mediated by a dithiobenzoate chain transfer agent (CTA) at 70 °C. An appropriate solvent, ratio of initiator to monomers, and minimum reaction polymerisation time were essential to provide optimum polymers. The synthesis of homogenous p(OEGMA300-co-DIEGMA) polymers with PDI of 1.1–1.2 was achieved in toluene with ≥10 h of reaction. Increasing the molecular weight of the p(OEGMA300-co-DiEGMA) polymers decreases the polydispersity index. p(OEGMA300-co-DiEGMA) polymers with Mw of 50,000 Da were successfully synthesised with lower critical solution temperatures (LCSTs) of 41.3 °C, 43.0 °C and >45 °C for OEGMA300:DiEGMA molar ratios of 2:8, 3:7 and 4:6, respectively. Further, the LCST was not found to be affected by the polymer molecular weight. The p(OEGMA300-co-DiEGMA) polymers showed no cytotoxicity to Caco-2 cells at a concentration of 1 mg mL−1, whereas a decrease of HDF cell viability by up to 26.5 % was seen. These polymers could be beneficial for several biomedical applications, such as developing formulations for temperature-triggered drug delivery.

A Thermo-Responsive MOFs for X-Ray Scintillator.

Thermo-responsive smart materials have aroused extensive interest due to the particular significance of temperature sensing. Although various photoluminescent materials are explored in thermal detection, it is not applicable enough in X-ray radiation environment where the accuracy and reliability will be influenced. Here, a strategy is proposed by introducing the concept of radio-luminescent functional building units (RBUs) to construct thermo-responsive lanthanide metal-organic frameworks (Ln-MOFs) scintillators for self-calibrating thermometry. The rational designs of RBUs (including organic ligand and Tb3+/Eu3+) with appropriate energy levels lead to high-performance radio-luminescence. Ln-MOFs scintillators exhibit perfect linear response to X-ray, presenting low dose rate detection limit (min ≈156.1 nGyairs-1). Self-calibrating detection based on ratiometric XEL intensities is achieved with good absolute and relative sensitivities of 6.74 and 8.1%K-1, respectively. High relative light yield (max ≈39000 photons MeV-1), imaging spatial resolution (max ≈18 lpmm-1), irradiation stability (intensity ≈100% at 368 K in total dose up to 215 Gyair), and giant color transformation visualization benefit the applications, especially the in situ thermo-responsive X-ray imaging. Such strategy provides a promising way to develop the novel smart photonic materials with excellent scintillator performances.

Cellulose nanocrystal thermal smart molecular brushes with upper critical aggregation temperature

Grafting thermo-responsive polymers onto cellulose nanocrystals (CNCs) and achieving critical temperature regulation has drawn significant research interest. The thermal transition behavior of CNCs can be controlled by adjusting the polymer molecular brushes on the CNCs surface. We synthesized poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA) grafted CNCs via surface-initiated reversible addition–fragmentation chain transfer, followed by modifying PDMAEMA brushes into poly-3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate (PDMAPS) brushes via quaternization. The critical temperature was regulated by modifying and grafting of poly (ethylene glycol) methacrylate. Found the thermal stimulus-responsive type and transition point of CNCs can be controlled by adjusting the surface molecular brushes. Ultraviolet-visible spectroscopy and dynamic light scattering analyses indicated that CNC–PDMAEMA aggregated above 70 °C, whereas CNC–PDMAPS aggregated below 31 °C. The thermo-responsive materials based on CNCs exhibited a conversion from a lower critical aggregation temperature to an upper critical aggregation temperature (UCAT) type. CNC–PDMAPS–mPEG was obtained by modifying and grafting for UCAT to be regulated to approximately 37 °C, which is close to the human body temperature. CNC–PDMAPS and CNC–PDMAPS–mPEG exhibited only microscopic alterations and could encapsulate and release substances. Therefore, they demonstrate considerable potential for biomedical applications.

Responsive self-assembly of nanomaterials: Mechanisms, applications, and future perspectives

In the development of nanotechnology, responsive self-assembly has been an important research theme. Responsive self-assembly is a technique where nanoparticles form structures in response to external stimuli like temperature and light. Thermo-responsive and photo-controlled self-assembly processes are outstanding compared with traditional methods, and theyve been applied in drug delivery and smart surfaces. Yet, the two processes still have their own challenges in practical applications. This review explores both techniques for explaining how these external stimuli work and the role of nanomaterial properties in the processes. Then it dives deep into their applications, specifically focusing on their strengths and challenges. Thermo-responsive and photo-controlled self-assembly are eco-friendly and reversible, ensuring their wide applications in various conditions. However, thermo-responsive materials, notably UCST-based polymers, are limited in scope, sensitive to the environment, and extremely expensive, while the effectiveness of the photo-controlled assembly process is limited by certain light conditions. Future research should focus on exploring their potential and overcoming the challenges.

Combination of Chemical and Physical Cancer Therapeutics Developed with Microcapsules Made of κ-Casein and Gold Nanoparticles in the Presence of Drug-Loaded Phase Change Materials.

Tumor heterogeneity requires development of an anticancer system equipped with both chemical and physical therapeutics to eradicate cancer exhibiting drug resistance and clonal evolution into diverse tumor cells. Assortment of various toxic components into one platform without compromising their individual toxic activity remains a formidable task. Herein, a novel drug delivery system (DDS) exerting potent cytotoxicity toward cancer cells was fabricated with gold nanoparticles (AuNPs) coated with an innocuous self-assembly protein of κ-casein (κC). Pickering emulsions of the κC-AuNP conjugates in the presence of chloroform inside led to the κC-AuNP microcapsules being stabilized via robust β-sheet formation between κC molecules located on the single-layered shell made of κC-AuNPs. Phase change material (PCM) comprising a eutectic mixture of lauric acid and myristic acid with the melting point of 43 °C was encapsulated in the presence of a hydrophilic anticancer drug of doxorubicin (Dox), in which the PCM has played multiple functions such as drug-holding matrix and thermoresponsive gating material for drug release. Once liberated with the heat generated by the AuNPs upon a near-infrared (NIR) irradiation at 808 nm, the PCM by itself exhibited not only chemical cytotoxicity but also physical toxic effects such as membrane destabilization of the cells and a possible cellular fixative effect toward cancer cells by the solidified PCM at body temperature. Moreover, the PCM was shown to facilitate the intranuclear localization of Dox. As a result, the DDS comprising κC-AuNP microcapsules containing Dox-loaded PCM was demonstrated to show a powerful anticancer effect upon the NIR irradiation, which unleashed several toxic agents such as Dox, PCM, heat-generating AuNPs, and tissue-immobilizing solidified PCM. Therefore, the κC-AuNP microcapsules would serve as an anticancer system into which diverse chemical and physical therapeutic agents could be combined to effectively remove the heterogeneous and drug resistant cancer cells.

Publisher Correction: Fast and reversible thermoresponsive polymer switching materials for safer batteries

Publisher Correction: Fast and reversible thermoresponsive polymer switching materials for safer batteries

A Thermoresponsive Lead‐Free Organic‐Inorganic Hybrid Perovskite as a Dielectric Switch

AbstractThermochromic perovskites, renowned for their tunable bandgap, high absorption coefficient, and reversible color changes, emerge as promising candidates for applications in smart windows. These advancements not only have the potential to enhance occupant comfort but also contribute significantly to reducing energy consumption in buildings. Here, we present a two‐dimensional lead‐free organic‐inorganic hybrid perovskite [Cyclobutylammonium]2CuCl4 which shows phase transitions from C2/c to P21/c to P21/c space group at 319.5 K and 348.8 K, respectively. Accompanying these transitions is a fascinating, reversible thermochromic behavior that is dependent on the phase structure. This behavior manifests as a vibrant sequence transitioning from yellow to brown and finally to a slightly dark brown. Most importantly, the demonstrated ability to switch stably between high and low dielectric states indicates the enormous potential of this material as a dielectric switch. This non‐toxic thermoresponsive perovskite, characterized by its appropriate transition temperatures, reversible phase structure‐dependent thermochromism, and stable dielectric switching behavior, is expected to generate significant interest within the fields of thermoresponsive and dielectric switching materials. The integration of these features not only positions this perovskite as a noteworthy subject of scientific inquiry but also opens avenues for practical applications in diverse fields.

Control of phase transition temperature of thermoresponsive poly(ionic liquid) gels and application to a water purification system using these gels with polydopamine

Demand for purified water is increasing as the population grows. Water purification systems combining thermoresponsive materials and adsorbents that can be used in areas without electricity or other energy infrastructure have begun to be reported. The thermoresponsive hydrogel used in this system must be able to adsorb and desorb a large amount of water, react drastically to temperature, and have a phase transition temperature that can be easily changed depending on the environment in which it is used. In this study, thermoresponsive ionic liquid-derived polyelectrolyte gels (poly(IL) gels) were prepared as lower critical solution temperature (LCST)-type thermoresponsive materials. As a result, poly(IL) gel, which exhibits drastic swelling/shrinking and reversible adsorption/desorption of a large amount of water (44 times the amount of water to its own weight), was successfully fabricated. The phase transition temperature can be controlled between 20 °C and 35 °C by copolymerizing ILs with different structures. Then, polydopamine (PDA), which can serve as a photothermal conversion material as well as an adsorbent for contaminants, was polymerized on the surface of the poly(IL) gel. In addition to its role as an adsorbent, PDA can also serve as a photothermal conversion material. First, a poly(IL)-based material with PDA is swollen in contaminated water. Subsequent irradiation with sunlight induces an LCST-type phase transition behavior by converting light energy into heat. Finally, the contaminants remain adsorbed, and only the water is discharged from the material to obtain purified water. Using this material, we were able to show that organic dyes are removed from aqueous solutions with high efficiency using sunlight.

In vitro encapsulation and expansion of T and CAR-T cells using 3D synthetic thermo-responsive matrices.

Suspension cell culture and rigid commercial substrates are the most common methods to clinically manufacture therapeutic CAR-T cells ex vivo. However, suspension culture and nano/micro-scale commercial substrates poorly mimic the microenvironment where T cells naturally develop, leading to profound impacts on cell proliferation and phenotype. To overcome this major challenge, macro-scale substrates can be used to emulate that environment with higher precision. This work employed a biocompatible thermo-responsive material with tailored mechanical properties as a potential synthetic macro-scale scaffold to support T cell encapsulation and culture. Cell viability, expansion, and phenotype changes were assessed to study the effect of two thermo-responsive hydrogel materials with stiffnesses of 0.5 and 17 kPa. Encapsulated Pan-T and CAR-T cells were able to grow and physically behave similar to the suspension control. Furthermore, matrix stiffness influenced T cell behavior. In the softer polymer, T cells had higher activation, differentiation, and maturation after encapsulation obtaining significant cell numbers. Even when terpolymer encapsulation affected the CAR-T cell viability and expansion, CAR T cells expressed favorable phenotypical profiles, which was supported with cytokines and lactate production. These results confirmed the biocompatibility of the thermo-responsive hydrogels and their feasibility as a promising 3D macro-scale scaffold for in vitro T cell expansion that could potentially be used for cell manufacturing process.

Multifunctional thermochromic smart windows for building energy saving

Smart windows based on thermoresponsive materials can modulate solar radiation to save building energy. Next generation smart windows that not only modulate solar transmission, but also convert and store solar energy through new power technologies.

Thermoresponsive and biocompatible poly(N-isopropylacrylamide)–cellulose nanocrystals hydrogel for cell growth

We describe herein a poly(N-isopropylacrylamide) (PNIPAAm)–cellulose nanocrystals (CNC) hydrogel as thermoresponsive and biocompatible material.