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Poly (acrylic acid) (PAA), an anionic polymer was used to prepare ion pair self-assembly (IPSAM) with 4-(methylthio)aniline (MTA), a hydrophobic counter ion, which is responsive to temperature and oxidation. The IPSAM was formed when the carboxylic to amino group molar ratio was 7/3-5/5. The structure of the IPSAM nanoparticle was spherical whose diameter was 30-40 nm on the TEM images. The PAA/MTA ion pair showed the upper critical solution temperature (UCST) that hiked with increasing MTA content. When the MTA of the ion pair was oxidized by H2O2, the UCST was also increased. The amphiphilic property of the ion pair was responsible for interface activity which declined upon the oxidation of the MTA. The surface tension was low for the ratio of PAA/MTA (5/5), which made the 5/5 ratio suitable for further studies. The interaction between PAA and MTA, which was ionic, and the oxidation of MTA was confirmed by FT-IR spectroscopy. The release of payload (i.e. Nile red) in IPSAM was restrained below the UCST but it was triggered above the phase transition temperature possibly due to the disintegration of the IPSAM whereas on MTA oxidation the release was shielded due to more hydrophobicity. The release was found to be higher in tumor environment temperature which could be controlled with the input concentration of H2O2 giving a stable IPSAM. The cell viability results showed that IPSAM has no significant cytotoxicity and can serve as a drug carrier for stimulus-response. [ABSTRACT FROM AUTHOR]

[Display omitted] Schizophrenic copolymers are one type of the popular smart polymers that show invertible colloidal structures in response to temperature stimulus. However, the lack of principles to predict the phase transition temperature of a schizophrenic copolymer from its corresponding parent thermo-responsive polymers limits their development. Additionally, studies on their applications remain scarce. Herein, a series of schizophrenic copolymers were synthesized by polymerization of a RAFT-made polymer precursor poly(acrylamide- co - N -acryloxysuccinimide- co -acrylic acid) (P(AAm- co -NAS- co -AAc)) with the mixture of N -isopropylmethacrylamide (NIPAm) and acrylamide (AAm) in varying molar ratios. In aqueous solution, the block P(AAm- co -NAS- co -AAc) and the block poly(NIPAm- co -AAm) exhibited upper and lower critical solution temperature (UCST and LCST) behavior, respectively. The schizophrenic copolymers featured either UCST-LCST, LCST-UCST, or only LCST thermo-responsive transition. A preliminary correlation of phase transition between the schizophrenic copolymers and their parent polymers was summarized. Furthermore, the co-assembly of the schizophrenic copolymers and proteins were conducted and the kinetics of protein loading and protein activity were investigated, which showed that the schizophrenic copolymers were efficient platforms for protein co-assembly with ultra-high protein loading while preserving the protein bioactivities. Additionally, all the materials were non-toxic towards NIH 3T3 and MCF-7 cells. This work offers the prospects of the schizophrenic polymers in soft colloidal and assembly systems, particularly in guiding the design of new materials and their use in biomedical applications. [ABSTRACT FROM AUTHOR]

Swelling is ubiquitous for conventional hydrogels but is not favorable for many situations, especially underwater applications. In this study, an anti‐swelling and mechanically robust polyacrylic acid (PAAc)/gelatin composite hydrogel is reported with a rapid gelation process (101 s) under mild conditions via the synergy of MXene‐activated initiation and zirconium ion (Zr4+)‐induced cross‐linking, without the requirement of external energy input. The MXene is found efficient to activate the chain initiation, while the Zr4+ is prone indispensable for facilitating the cross‐linking of formed polymer chains. The resulting hydrogel exhibits integration of exceptional anti‐swelling properties and high mechanical performance at room temperature, thanks to the dense hydrogen bonds between PAAc and gelatin chains that enable an upper critical solution temperature above room temperature. Also, desirable electrical conductivity emerges in the hydrogel due to the simultaneous contribution of MXene and Zr4+, allowing stable electrical signal output of the gel upon deformation underwater. As a demonstration, an underwater communicator by harnessing the gel as a sensing module is assembled, which is capable of wirelessly delivering messages to the decoder on the ground via Morse codes. This study provides an exemplary way for the rapid gelation of tough and anti‐swelling hydrogels for durable underwater applications. [ABSTRACT FROM AUTHOR]

Near-infrared light (NIR) triggered transdermal drug delivery systems are of great interest due to their on-demand drug release, which enable to enhance drug treatment efficiency as well as reduce side effect. Herein, a NIR-triggered microneedle (MN) patch array has been fabricated through depositing the photothermal conversion agent and anti-diabetic drug-loaded polymer vesicles with upper critical solution temperature (UCST) into dissolvable polymer matrix. The UCST-type polymer has a clearing point temperature of 41 °C and the drug-loaded polymer vesicles present excellent NIR-triggered and temperature responsive drug release behavior in vitro due to the disassociation of polymer vesicles upon NIR irradiation. After applying MNs to diabetic rats, significant hypoglycemic effect is achieved upon interval NIR irradiation and the blood glucose concentration can decrease to normal state for several hours, which enables to achieve the goal of on-demand drug release. This work suggests that the NIR-triggered MN drug release device has a potential application in the treatment of diabetes, especially for those requiring an active drug release manner. [ABSTRACT FROM AUTHOR]

Cucurbit[6]uril‐derivatized vinyl monomer (cucurbit[6]uril methacrylate) was synthesized. Acrylic acid (AA) was used as the comonomer for copolymerization with the cucurbit[6]uril‐derivatized monomer. A series of copolymers of poly(acrylic acid‐co‐cucurbit[6]uril methacrylate) (PAA‐co‐CB[6]MA) were synthesized by free radical polymerization. The cucurbit[6]uril‐derivatized monomer and PAA‐co‐CB[6]MA copolymers were characterized by 1H NMR spectra, high‐resolution mass spectroscopy and gel permeation chromatography. The solution behavior was examined using UV–visible spectroscopy and dynamic light scattering. The PAA‐co‐CB[6]MA showed an upper critical solution temperature (UCST) in water. The UCST‐type thermoresponsive behavior of these CB[6]‐derivatized copolymers was highly dependent on the composition of the copolymer. For the same type of copolymer, changes in its composition gave rise to different UCSTs. Additionally, the PAA‐co‐CB[6]MA copolymers were successful in trapping azocarmine B. The stimuli‐responsive release of encapsulated azocarmine B was achieved by a combination of temperature and pH value stimuli. According to the results, the novel PAA‐co‐CB[6]MA copolymers can be used as carriers. © 2021 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Water‐soluble and thermoresponsive macrocycles with stable inclusion toward guests are highly valuable to construct stimuli‐responsive supramolecular materials for versatile applications. Here, we develop such macrocycles – ureido‐substituted cyclodextrins (CDs) which exhibit unprecedented upper critical solution temperature (UCST) behavior in aqueous media. These novel CD derivatives showed good solubility in water at elevated temperature, but collapsed from water to form large coacervates upon cooling to low temperature. Their cloud points are greatly dependent on concentration and can be mediated through oxidation and chelation with silver ions. Significantly, the amphiphilicity of these CD derivatives is supportive to host‐guest binding, which affords them inclusion abilities to guest dyes. The inclusion complexation remained nearly intact during thermally induced phase transitions, which is in contrast to the switchable inclusion behavior of lower critical solution temperature (LCST)‐type CDs. Moreover, ureido‐substituted CDs were exploited to co‐encapsulate a pair of guest dyes whose fluorescence resonance energy transfer process can be switched by the UCST phase transition. We therefore believe these novel thermoresponsive CDs may form a new strategy for developing smart macrocycles and allow for exploring smart supramolecular materials. [ABSTRACT FROM AUTHOR]

This study focuses on analyzing the noncovalent interaction patterns between three lipid‐nanodisc‐forming polymers and nitroxide radicals which are used as small organic tracer molecules. Besides the negatively charged polymers diisobutylene/maleic acid (DIBMA) and styrene/maleic acid (SMA) (2:1), the solvation behavior of a newly synthesized zwitterionic styrene/maleic amide sulfobetaine copolymer named SMA‐sulfobetaine (SB) is characterized. The applied spin probes vary in their respective chemical structure, allowing the report of different local micropolarities and nanoscopic regions by recording temperature‐dependent continuous‐wave electron paramagnetic resonance (CW EPR) spectra. In combination with light scattering experiments, a nanoscopic interpretation of the dominant polymer/guest molecule interaction patterns is provided. The results indicate that in SMA and DIBMA, ionic interactions dominate the interaction patterns with other molecules. In SMA‐SB, the zwitterionic side chains mainly induce a dynamic assembly with guest molecules due to weaker noncovalent interactions. Depending on the applied spin probe, temperature‐dependent CW EPR measurements reveal nanoscopic cloud points depending on the interaction patterns with SMA‐SB which can occur more than 20 °C below its macroscopically observed upper critical solution temperature. Finally, the detailed dissection of interaction patterns may provide a better understanding that may even allow tuning the polymers' properties for use in lipid nanodisc formation. [ABSTRACT FROM AUTHOR]

Amphoteric diblock copolymers (S10Vn, n = 5, 10, and 20) composed of anionic poly(sodium p-styrenesulfonate) and cationic poly(vinylbenzyl trimethylammonium chloride) blocks were prepared via a controlled radical polymerization method. S10V10 was insoluble in pure water owing to its electrostatic interactions, but S10V5 and S10V20 were soluble in pure water. S10V5 and S10V10 exhibited upper critical solution temperature behaviors, and the transition temperature decreased with increasing sodium chloride concentration. [ABSTRACT FROM AUTHOR]

Synthesis of a new family of polymers having a polydisulfide structure can be conducted from sulfobetaine-based derivative of natural (R)-lipoic acid. A polydisulfide backbone of polymer can be depolymerized by response to external stimuli and sulfobetaine pendant groups ensure the upper critical solution temperature (UCST) behaviour temperatures that can be modulated according to the nature of the solvent and concentration. Sulfobetaine-bearing polydisulfides were synthesized from dithiolane derivatives and then characterized. UCST behavior of the polymers in water and in mixtures containing different alcohols (methanol, ethanol, isopropanol) was investigated. The regeneration of monomers from the polymers in response to external stimuli was examined using UV–vis and circular dichroism (CD) spectroscopy. Tunable surface wettability were shown on the grafted polymers. Decreasing polarity and/or increasing alcohol percentage in the water mixtures induced an increase in the cloud points of the polymers in the solutions. Thermoresponsive behaviour were repeatable and fully reversible with negligible hysteresis from aggregate to unimer state. The regeneration of monomers by depolymerization was tunable by temperature and sunlight. A thickness dependence on surface wettability was observed on wafers covalently modified with polydisulfides. This is the first report of sulfobetaine-based polydisulfides showing tunable UCST behavior and surface wettability. [ABSTRACT FROM AUTHOR]

The synthesis of thermo‐responsive polymers from non‐responsive and water‐soluble monomers has great practical advantages but significant challenges. Herein, the authors report a novel aqueous copolymerization strategy to prepare polymers with tunable upper critical solution temperature (UCST) or lower critical solution temperature (LCST) from non‐responsive monomers. Acrylic acid (AAc), N‐vinylpyrrolidone (NVP), and acrylamide (AAm) are copolymerized in water, yielding copolymers with UCST behavior. Interestingly, by simply replacing AAm with its methylated homologue, dimethyl acrylamide (DMA), the thermo‐responsiveness of the copolymers is converted into LCST‐type. The cloud points of the copolymers can be tuned rationally with their monomer ratios and the condition of the solvent. The UCST property of the poly(AAc–NVP–AAm) comes from the AAc–AAm and AAc–NVP hydrogen‐bonds, while the LCST property of poly(AAc–NVP–DMA) originates from the hydrophobic aggregation of AAc–NVP complex and DMA, as indicated by temperature‐dependent 1H NMR and dynamic light scattering. [ABSTRACT FROM AUTHOR]

Nonionic double thermoresponsive diblock copolymers with both upper critical solution temperature (UCST) and lower critical solution temperature (LCST) phase transitions are synthesized via eco‐friendly photoiniferter reversible addition–fragmentation chain transfer polymerization. While the biocompatible random copolymer of di(ethylene glycol) methyl ether methacrylate and oligo(ethylene glycol) methacrylate accounts for the LCST transition, the block of polymethacrylamide from an easily accessible monomer with low health hazard is responsible for the UCST transition. Temperature‐dependent dynamic light scattering measurements confirm the formation of micellar aggregates in water at the temperatures below UCST‐ and above LCST‐type cloud points. Additionally, the temperature interval between UCST and LCST, where both blocks are dissolved, can be tailored by varying the comonomer ratio in the random copolymer block. With these unique advantages, the presented work introduces a new polymer system for the design of schizophrenic polymers. [ABSTRACT FROM AUTHOR]

Polyetherimide (PEI) nanoparticles with the size range from about 200 nm to 1 μm were successfully prepared from a PEI/DMSO solution by a simplified cooling-down method. The formation of PEI nanoparticles is caused by the temperature drop. The particle size is related to the temperature, cooling time, and PEI concentration. At low concentrations, well-separated PEI nanoparticles appear, and the lower the concentration is, the narrower the particle size distribution is. At high concentrations, a membrane structure appears, meaning that evaporation at room temperature rather than centrifugation would be a better way to separate the PEI nanoparticles from the PEI/DMSO suspension. [ABSTRACT FROM AUTHOR]

Copolymers of acrylamide (AAm) and hydrophobic monomers are known as non‐ionic polymers to show an upper critical solution temperature (UCST) in aqueous solution. By utilizing cyclic ketene acetals and carrying out the radical ring opening polymerization along with copolymerization with AAm, a UCST polymer, poly(acrylamide‐co‐2‐methylene‐1,3‐dioxepane) (P(AAm‐co‐MDO)), is obtained. The AAm/MDO content results in the shift of UCST phase transition temperature. The present work shows how the combination of water‐soluble PAAm and polycaprolactone‐like structured PMDO develops a new type of thermoresponsive polymer which can be expected for bio‐related applications. [ABSTRACT FROM AUTHOR]

The influence of temperature on the miscibility of the {methanol + p-xylene + isooctane} and {methanol + benzene + isooctane} ternary systems at atmospheric pressure are investigated. The effect of temperature on the phase equilibrium is discussed for each system. All chemicals are verified using gas chromatograph, density, viscosity and refractive index. Phase equilibrium are reached using a modified version of measurement equipment used previously. Some ternary systems and binary subsystems are taken from the literature at different temperatures to determine the influence of the temperature on the systems. The upper critical solution temperature for the methanol + isooctane binary system was determined by the constant-composition method with an accuracy of ± 0.1 K. Experimental data are compared with the literature. Calculated values by the non-random two liquids (NRTL) and universal quasi-chemical (UNIQUAC) equations are contrasted with experimental data for the ternary systems. Deviations from the experimental binodal curve have good adjustment of less than one per cent for all systems. [ABSTRACT FROM AUTHOR]

Thermoresponsive polypeptides bearing amide pendants with an upper critical solution temperature (UCST) under physiologically relevant solution conditions are developed. A series of poly(γ‐propanyl‐l‐glutamate)s bearing amide pendants (PPLGn‐Am) with different molecular weight (or degree of polymerization, DP) is prepared by copper mediated 1,3‐dipolar cycloaddition. While fourier transform infra‐red and CD analysis reveal random coil conformation of the PPLGn‐Am in the solid‐state and in aqueous solutions, respectively, PPLGn‐Am shows reversible UCST‐type phase behaviors in deionized water (DI) water and phosphate‐buffered saline. Variable temperature UV–vis spectroscopy indicates that the UCST‐type cloud point temperature (Tcp) in the range of 25–75 °C can be readily tuned by molecular weight (or DP), polymer concentration, and incorporation of hydrophobic (i.e., n‐hexyl) pendants. Moreover, PPLGn‐Am is readily degraded by proteinase K within 48 h. The results indicate that UCST‐type thermoresponsive and biodegradable polypeptides in aqueous solutions can be constructed by conjugation of amide pendants which shall provide guidance for future UCST polymer designs. [ABSTRACT FROM AUTHOR]

Currently, the phase transition of aqueous binary systems containing thermoresponsive (co)polymers, and exhibiting upper critical solution temperature (UCST), is exclusively investigated in dilute solutions, which can limit the knowledge of their UCST‐type phase transition. Herein, a photo‐RAFT polymerization approach, using acrylamide (AAm) and acrylonitrile (AN) as monomer models, is used to prepare well‐controlled poly(AAm‐co‐AN) copolymers "in situ" in highly concentrated dispersions (60 wt%). The impact of the copolymer concentration and the chemical composition (as a variation of AN fraction in the copolymers) on the cloud point temperature (TCP) are investigated using turbidity measurements. Importantly, the results show that upon increasing the polymer concentration, a sharp increase of TCP up to a maximum point is observed, representing the UCST, before the decrease of TCP at higher polymer concentrations. Finally, a model equation is developed to fit the UCST values of poly(AAm‐co‐AN), which can be useful to design new poly(AAm‐co‐AN) copolymers with a desired UCST for a specific application. [ABSTRACT FROM AUTHOR]

Thermoresponsive polymers can endow membranes with tunable separation and self-cleaning performance. However, up to now, there have been only very limited choices of thermoresponsive polymers for the fabrication of smart membranes. Herein, thermoresponsive membranes based on UCST-type organoboron polymer (Poly(CPBA)) were fabricated for the first time. Poly(CPBA) synthesized via a nucleophilic ring-opening reaction with Poly(GMA) and 3-carboxyphenylboronic acid has shown typical thermoresponsive behavior in water and water/ethanol mixture. Under vacuum conditions, Poly(CPBA) formed the cross-linked boroxine network on the membrane surface via a dehydration-induced condensation reaction. The reversible conformational change of Poly(CPBA) near UCST acted as a smart "gating" to regulate both pore size and surface properties of the membrane. When the temperature exceeded UCST, the fully extended polymer chains provided a strong washing force to remove contaminants, resulting in effective self-cleaning performance (FRR up to 99.2 %). In particular, due to the presence of the boroxine network, the polymer chains were firmly "stuck" on the membrane surface, providing stable performance and superior repeatability of the composite membrane. Illustration of thermoresponsive PAN/Poly(CPBA)/x membranes fabrication and the mechanism of self-cleaning and smart gating. [Display omitted] • Thermoresponsive membranes based on UCST-type organoboron polymers were fabricated via simple surface impregnation. • Membrane thermoresponsive as a smart gating modulation of pore size and surface properties. • The boroxine network endows membranes with excellent stability and repeatability. • Membranes exhibit tunable separation and efficient self-cleaning performance. [ABSTRACT FROM AUTHOR]

This study was undertaken to investigate the extraction of In3+ and Ga3+ by 7-(4-ethyl-1-methyloctyl)-8-hydroxy-quinoline (Kelex100), which has been found to be a slow extraction process. Homogeneous liquid-liquid extraction utilizing upper critical solution temperature of 4-methyl-1,3-dioxolan-2-one (propylene carbonate, abbreviated as PC) was used to eliminate the interface and speed up the extraction, since distribution between two phases was thought to be the rate-determining step. The effect of contact time on the percentage of metal extraction was examined at 80ºC using Kelex100 dissolved in toluene and PC solutions and the difference between two solvents was evaluated. The results clearly show that the use of homogeneous liquid-liquid extraction using PC with Kelex100 is faster than traditional two phase extraction. [ABSTRACT FROM AUTHOR]

Aqueous two-phase system (ATPS) formation is the macroscopic completion of liquid-liquid phase separation (LLPS), a process by which aqueous solutions demix into 2 distinct phases. We report the temperature-dependent kinetics of ATPS formation for solutions containing a monoclonal antibody and polyethylene glycol. Measurements are made by capturing dark-field images of protein-rich droplet suspensions as a function of time along a linear temperature gradient. The rate constants for ATPS formation fall into 3 kinetically distinct categories that are directly visualized along the temperature gradient. In the metastable region, just below the phase separation temperature, Tph, ATPS formation is slow and has a large negative apparent activation energy. By contrast, ATPS formation proceeds more rapidly in the spinodal region, below the metastable temperature, Tmeta, and a small positive apparent activation energy is observed. These region-specific apparent activation energies suggest that ATPS formation involves 2 steps with opposite temperature dependencies. Droplet growth is the first step, which accelerates with decreasing temperature as the solution becomes increasingly supersaturated. The second step, however, involves droplet coalescence and is proportional to temperature. It becomes the rate-limiting step in the spinodal region. At even colder temperatures, below a gelation temperature, Tgel, the proteins assemble into a kinetically trapped gel state that arrests ATPS formation. The kinetics of ATPS formation near Tgel is associated with a remarkably fragile solid-like gel structure, which can form below either the metastable or the spinodal region of the phase diagram. [ABSTRACT FROM AUTHOR]

A novel class of aqueous biphasic systems (ABS) formed by zwitterions (ZI) has been investigated in the present work. A series of water soluble ZIs have been synthesized using triethylamine, N-Methylimidazole, N-Vinylimidazole, pyridine, N-Methylpyrrolidine, N-Ethylpiperidine and 1,4 butane sultone. The synthesized ZIs were explored for their ability to form biphasic systems in combination with aqueous inorganic salt solutions of K3PO4, K2HPO4 and K2CO3. The phase diagrams for all systems have been constructed through cloud point titration method at 298.15 K and atmospheric pressure. The phase behavior of ZI based ABS have been analyzed to understand the structural effects of ZIs as well as the effect of nature of salt used on the overall phase formation. Further the temperature dependence of the ZI based ABS was also explored by studying the phase behavior at variable temperatures of 298.15, 308.15 and 318.15 K. In order to estimate the applicability of proposed ZI based ABS, extraction experiments have been performed for an alkaloid i.e. caffeine for all synthesized ZIs with K3PO4 and at 298.15 K. ZI based ABS have been found to be capable of single step extraction of caffeine similar to IL based ABS thus providing the possibilities to explore these ZI based ABS as efficient extraction and separation systems. [ABSTRACT FROM AUTHOR]

Homopolypeptide bearing azobenzene and triethylene glycol spacers, and 1-butylimidazolium pendants, namely P(Azo-OEG3-ImX) (X = Cl, I, BF4) are prepared by 1,3-dipolar cycloaddition and subsequent ion-exchange reaction. Both 1H NMR and FTIR confirm the polymer structures and reveal a high grafting efficiency (97%). P(Azo-OEG3-ImI) shows reversible upper critical solution temperature (UCST)-type thermoresponsive property in ethanol while P(Azo-OEG3-ImI/BF4) shows a UCST in ethanol/water solvent mixtures. P(Azo-OEG3-ImI) shows UCST-type phase transitions in ethanol or ethanol/water solvent mixtures. After UV irradiation, the UCST-type cloud point temperature (Tcp) remains constant in ethanol. However, it decreases after UV irradiation and increases after visible light irradiation in ethanol/water solvent mixtures due to the trans-cis isomerization of azobenzene moieties. P(Azo-OEG3-ImCl/I) shows NaI-induced UCST in water. The Tcp of the P(Azo- OEG3-ImCl/I) aqueous solution is highly related to the polymer/salt concentration and nature of counteranions. P(Azo-OEG3-ImCl) also shows reversible light-responsive properties in NaI aqueous solutions. Higher NaI concentration is needed to induce a UCST for P(Azo-OEG3-ImCl) after UV irradiation. Moreover, ciprofloxacin-loaded hydrogel containing P(Azo-OEG3-ImCl) shows more efficient drug release while the UV irradiation leads to slightly low drug release. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Multiphase systems are relevant in many fields of process engineering. For process and product design in connection with multiphase systems, knowledge on the thermophysical properties of the individual phases such as viscosity and on the interfacial tension between these is required but often lacking in literature. In the present study, the applicability of surface light scattering (SLS) for the simultaneous measurement of interfacial tensions and viscosities in multiphase systems in macroscopic thermodynamic equilibrium is demonstrated. For two model systems consisting of n -decane and methanol as well as n -dodecane and methanol forming a vapor-liquid-liquid equilibrium at atmospheric pressure, surface fluctuations which show an oscillatory behavior at the vapor-liquid and liquid-liquid interface could be associated with hydrodynamic modes. From an exact theoretical description of the dynamics of the surface fluctuations, absolute data for the dynamic viscosities of the two liquid phases as well as the vapor-liquid and liquid-liquid interfacial tensions could be determined at temperatures between (333 and 358) K with total measurement uncertainties (k = 2) down to about 2%. For both systems studied at temperatures close to the upper critical solution temperature, the viscosities of the two liquid phases approach each other and the liquid-liquid interfacial tension tends to zero. [ABSTRACT FROM AUTHOR]

Graphical abstract We report the preparation and stimuli-responsive property of a thermo-, light-, and oxidation-responsive homopolypeptide bearing azobenzene, thioether spacers, and oligo(ethylene glycol) tails. After oxidation, the polypeptide showed unusual light-tunable thermoresponsive behaviors namely the UCST-type T cp increased while the LCST-type T cp decreased after UV light irradiation. Highlights • We prepared homopolypeptide bearing azobenzene, thioether spacers, and oligo(ethylene glycol) tails. • We studied the thermo-, light-, and oxidation-responsive properties. • We discovered an unusual light-tunable thermoresponsive behavior. Abstract OEGylated homopolypeptide (i.e., P(Azo-S-OEG 7)) bearing azobenzene, thioether spacers, and oligo(ethylene glycol) OEG tails were prepared via a copper-mediated 1,3-dipolar cycloaddition. P(Azo-S-OEG 7) showed an upper critical solution temperature (UCST)-type thermo-, light-, and oxidation-responsive in ethanol/water solvent mixtures. The UCST-type cloud point temperature (T cp) decreased after UV irradiation and it increased after visible light irradiation due to the trans - cis isomerization of azobenzene moieties. P(Azo-S-OEG 7) can be readily oxidized in the presence of H 2 O 2 , yielding P(Azo-SOX-OEG 7) with sulfone or sulfoxide spacers. P(Azo-SOX-OEG 7) showed an increase of UCST-type T cp after UV irradiation and the T cp decreased after visible light irradiation, which is an opposite trend to the UCST-type phase behavior of P(Azo-S-OEG 7) as well as previous report. P(Azo-S-OEG 7) showed poor water-solubility, yet it underwent H 2 O 2 induced solution phase transition yielding P(Azo-SOX-OEG 7) with lower critical solution temperature (LCST)-type phase behavior in water. The P(Azo-SOX-OEG 7) aqueous solutions showed a decrease of LCST-type T cp after UV irradiation and consequently T cp decreased after visible light irradiation. [ABSTRACT FROM AUTHOR]

Developing endogenous hyperthermia offers a promising strategy to address challenges with current exogenous hyperthermia techniques in clinics. Herein, a CD44-targeted and thermal-responsive nanocarrier was developed for the simultaneous delivery of 2,4-dinitrophenol and syrosingopine. The objective was to induce endogenous hyperthermia and regulate immunometabolism, ultimately augmenting anti-tumour immune responses. Dinitrophenol as mitochondrial uncoupler can convert electrochemical potential energy of inner mitochondrial membrane into heat, facilitating endogenous hyperthermia. Meanwhile, syrosingopine not only inhibits excessive lactate efflux caused by dinitrophenol but also downregulates tumour cell glycolysis, thus alleviating immunosuppression and heat shock protein (HSP)-dependent thermo-resistance through immunometabolism regulation. The synergistic effects of endogenous hyperthermia and immunometabolism regulation by this nanomedicine have potential to enhance tumor immunogenicity, reshape the tumour immune microenvironment, and effectively suppress the growth of subcutaneous tumours and patient-derived organoids in triple-negative breast cancer. Therefore, the endogenous hyperthermia strategy developed in this study would revolutionize hyperthermia for cancer treatment. [Display omitted] • UCST nanomedicine producing the mild endogenous hyperthermia via mitochondria uncoupling to revolute cancer thermal therapy. • Alleviating heat shock protein (HSP)-dependent thermo-resistance through UCST nanomedicine-induced tumour starvation. • Synergism of endogenous hyperthermia and immunometabolism regulation augmenting anti-tumour immune responses. [ABSTRACT FROM AUTHOR]

Abstract Proteins and synthetic polymers can undergo phase transitions in response to changes to intensive solution parameters such as temperature, proton chemical potentials (pH), and hydrostatic pressure. For proteins and protein-based polymers, the information required for stimulus-responsive phase transitions is encoded in their amino acid sequence. Here, we review some of the key physical principles that govern the phase transitions of archetypal intrinsically disordered protein polymers (IDPPs). These are disordered proteins with repetitive amino acid sequences. Advances in recombinant technologies have enabled the design and synthesis of protein sequences of a variety of sequence complexities and lengths. We summarize insights that have been gleaned from the design and characterization of IDPPs that undergo thermo-responsive phase transitions and build on these insights to present a general framework for IDPPs with pH and pressure responsive phase behavior. In doing so, we connect the stimulus-responsive phase behavior of IDPPs with repetitive sequences to the coil-to-globule transitions that these sequences undergo at the single-chain level in response to changes in stimuli. The proposed framework and ongoing studies of stimulus-responsive phase behavior of designed IDPPs have direct implications in bioengineering, where designing sequences with bespoke material properties broadens the spectrum of applications, and in biology and medicine for understanding the sequence-specific driving forces for the formation of protein-based membraneless organelles as well as biological matrices that act as scaffolds for cells and mediators of cell-to-cell communication. Graphical Abstract Unlabelled Image Highlights • Proteins can undergo phase transitions in response to changes in intensive solution parameters such as temperature, pH, and pressure. • Stimulus-responsive phase transitions are derived from information encoded in amino acid sequences. • Of particular interest are the stimulus-responsive phase transitions of intrinsically disordered protein polymers, which are repeats of intrinsically disordered regions. • We present a conceptual framework for the phase behavior of IDPPs that connects collapse transitions of individual chains to collective phase transitions. • We summarize heuristics that have emerged from recent studies regarding the sequence determinants of stimulus-responsive phase transitions for IDPPs. [ABSTRACT FROM AUTHOR]

Abstract: Phase diagrams of the polyphenylsulfone (PPSU)-polyethylene glycol (PEG)-N-methyl-2-pyrrolidone (NMP) system have been plotted as a function of PEG molecular weight. For 15 wt % PPSU solutions containing 15 wt % of PEG with molecular weight of 6000-40 000 g mol-1, the occurrence of an upper critical solution temperature (UCST, solution-gel transfer (gel point)) and a lower critical solution temperature (LCST) was found. According to the phase diagrams analysis, a method for the preparation of high flux PPSU membranes using the systems with UCST and LCST in an experimentally attainable temperature range has been proposed. The method involves casting solution processing at a temperature of the existence of a one-phase homogeneous solution (UCST < T < LCST), and the use of a coagulation bath at a temperature between UCST (gel point) and LCST. Membranes prepared from 15 wt % PPSU solutions with the addition of PEG-20000 were found to have the highest pure water flux (500-1000 L m-2 h-1 at 0.1 MPa), and a human serum albumin rejection of ca. 90%. [ABSTRACT FROM AUTHOR]

Stimuli-responsive nanoparticles are focused to promote the pathological specificity and controlled therapeutic activation in biomedicine, but the multifunctional modulation remains challenging. Herein, size and morphology switchable phototheranostic nanoparticles are developed for photoacoustic (PA) imaging-guided photothermal-chemotherapy. Multifunctional polypyrrole (PPy) nanoparticles with the template of upper critical solution temperature (UCST) polymers are designed to achieve light-controlled pulsatile drug release and concurrent activation of photothermal therapy (PTT). Wherein the UCST-featured inner core is loaded with camptothecin (CPT), the outer corona is tethered with thermo-cleavable doxorubicin (DOX) prodrug and further in-situ coated with PPy, affording the resultant CPT@DOX-UCST/PPy nanoparticles. Upon 808 nm continuous laser illumination, significant heating generated from light-absorbable PPy results in DOX prodrug cleavage and considerable size swelling (∼125-fold), which in turn promotes simultaneous dual drug release, and thus triggering the combined therapeutic activation of PTT and chemotherapy. When laser is switched off, the discontinued photothermal generation makes the nanoparticle shrink back, thereby avoiding the leakage of CPT and DOX. In vivo experiments demonstrate the favorable tumor accumulation and prolonged tumor retention (>24 h) for long-term PA imaging-guided combination therapy. Current multifunctional nanoparticles integrated with light-controlled swelling/shrinking and synergistic therapeutic activation/silence represent a promising platform for precision cancer theranostics. [ABSTRACT FROM AUTHOR]

Abstract: A thermoresponsive lipase catalyst with an upper critical solution temperature (UCST) of about 26 °C was exploited by covalent immobilization of an enzyme, Pseudomonas cepacia lipase (PSL), onto poly(acrylamide‐co‐acrylonitrile) by glutaraldehyde coupling. The experimental conditions for the PSL immobilization were optimized. The immobilized PSL was much more stable for wide ranges of temperature and pH than free PSL. The material was also evaluated as an asymmetric catalyst in the kinetic resolution of racemic α‐methylbenzyl butyrate at 55 °C in an aqueous medium and exhibited high catalytic performance and stability. Up to 50 % conversion and 99.5 % product enantiomeric excess were achieved, thus providing highly pure enantiomers. This biocatalyst could be easily recovered by simple decantation for reuse based on temperature‐induced precipitation. It showed good reusability and retained 80.5 % of its original activity with a well reserved enantioselectivity in the 6th cycle. This work would shed light on the future development of new UCST‐type enzyme catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ionic liquids (ILs) with different kinds of functional group were synthesized. • Phase separation behavior of aqueous solutions of the ILs were investigated. • Enthalpy of mixing water and ILs would strongly affect the phase behavior. • NMR measurement indicated that hydrogen bonding was key factor of the enthalpy. • Hydrogen-bonding properties of the ILs is a vital viewpoint to design the ILs. Ionic liquids (ILs) with an upper critical solution temperature (UCST) are feasible candidates as draw solutions in the forward osmosis process. However, the factors controlling the phase separation of UCST-type ILs in aqueous solutions remain unclear. Here, we focused on the role of hydrogen bonding in the phase separation behavior of UCST-type ILs. The phase separation behavior of aqueous solutions of UCST-type ILs is affected by the hydrogen-bonding functional groups of the ILs. A thermodynamic analysis of the mixing of water and ILs indicated that the phase separation of the aqueous solution of UCST-type ILs is characterized by enthalpy changes of mixing. To investigate the state of hydrogen bond formation in aqueous solutions of ILs, 1H nuclear magnetic resonance spectra were acquired. The data suggest that the hydrophobic parts of the ILs broke the water–water hydrogen bonds, and the hydrogen-bonding functional groups of the IL formed hydrogen bonds in the aqueous IL solution. These hydrogen-bonding states strongly affect the enthalpy changes of mixing. Therefore, water–water and water–IL hydrogen bonds play an important role in the phase separation behavior of UCST-type ILs in aqueous solutions. [ABSTRACT FROM AUTHOR]