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Ribonucleic acid (RNA) therapeutics offer a broad prospect in cancer treatment. However, their successful application requires overcoming various physiological barriers to effectively deliver RNAs to the target sites. Currently, a number of RNA delivery systems based on polymeric nanoparticles are developed to overcome these barriers in RNA delivery. This work provides an overview of the existing RNA therapeutics for cancer gene therapy, and particularly summarizes those that are entering the clinical phase. This work then discusses the core features and latest research developments of tumor microenvironment‐responsive polymer‐based RNA delivery carriers which are designed based on the pathological characteristics of the tumor microenvironment. Finally, this work also proposes opportunities for the transformation of RNA therapies into cancer immunotherapy methods in clinical applications. [ABSTRACT FROM AUTHOR]

Breath ammonia is an essential biomarker for patients with many chronic illnesses, such as chronic kidney disease (CKD), chronic liver disease (CLD), urea cycle disorders (UCD), and hepatic encephalopathy. However, existing breath ammonia sensors fail to compensate for the impact of breath humidity and complex breathing motions associated with a human breath sample. Here, a multimodal breath sensing system is presented that integrates an ammonia sensor based on a thermally cleaved conjugated polymer, a humidity sensor based on reduced graphene oxide (rGO), and a breath dynamics sensor based on a 3D folded strain‐responsive mesostructure. The miniaturized construction and module‐based configuration offer flexible integration with a broad range of masks. Experimental results present the capabilities of the system in continuously detecting diagnostic ranges of breath ammonia under real, humid breath conditions with sufficient sensing accuracy and selectivity over 3 weeks. A machine‐learning algorithm based on K‐means clustering decodes multimodal signals collected from the breath sensor to differentiate between healthy and diseased breath concentrations of ammonia. The on‐body test highlights the operational simplicity and practicality of the system for noninvasively tracing ammonia biomarkers. [ABSTRACT FROM AUTHOR]

Responsive polymers can be combined with clay particles to form adaptable, or "tunable," clay–polymer composites. The purpose of this study is to investigate the potential for "tunability" of a nanocomposite at the mesoscale through changes in material properties—swelling behavior, Atterberg limits, hydraulic conductivity, and shear strength—with varying pH and ionic concentration of the surrounding fluid. The composite was synthesized from a nonionic form of the polymer polyacrylamide and an expansive clay, montmorillonite. An attempt was made to induce changes in behavior of the composite by exposing the material to a selected range of pH and ionic concentration conditions, thereby influencing the conformation (shape and size) of the responsive polymer molecules under different stress levels and solid contents. Behavior was compared for the cases of predicted coiled, partially extended, and extended conformation. The test results demonstrate that conformation of responsive polymer and tunability of composite depends primarily on solution type, stress levels, and solid content. The "tuning" response of a nanocomposite is maximized with a significant change in ionic concentration of the surrounding fluid. Nanocomposite swelling was 30% less than pure clay and had a friction angle 12° greater than pure clay at high ionic concentration. At low or high pH conditions, nanocomposite tunability was limited. [ABSTRACT FROM AUTHOR]

There are a limited number of thermoplastics with intrinsic shape memory effect (SME) that are four-dimensional (4D) printable. Development of other shape memory polymers (SMPs) entails synthesis with a complicated chemical experimental lab effort. In this paper, for the first time, a novel layered multi-material structure is developed based on a deep comprehension of SMEs’ macromolecular requisites. The fused deposition modeling (FDM) method is used for the four-dimensional printing of layered structures whose base materials show no SME. Commercial acrylonitrile butadiene styrene (ABS), toughened ABS-thermoplastic polyurethane (TPU) blend, and TPU, all with no SME, are used to fabricate bi-layers of ABSTPU blends and TPU with different volumetric proportions. Different thermo-mechanical tests, including dynamic mechanical thermal analysis (DMTA), and constrained and free shape recovery, are conducted. Also, the interfacial properties of the layered 4D printed structure are assessed by the mean of shear testing and scanning electron microscopy (SEM). Experimental results reveal that the 4D printed bi-layer composites possess a high level of programmability, SME (90–96%), and perfect interfaces without any porosity and detachment between layers. The results of this research can potentially eliminate the desperate need for SMPs for 4D printing and broaden the opportunity to have smart parts using commercial thermoplastics.

Intelligent polymers responsive to the environment have aroused widespread interest in many applications of materials and interfaces. However, sensitive control of the oil-water interface remains a major challenge, using reversible self-assembly of macromolecules induced by external stimuli. Here, we synthesized a new amphiphilic triblock copolymer responsive to pH and UV light via reversible addition–fragmentation chain transfer (RAFT) aqueous polymerization. Poly(methacrylic acid) (PMAA) acts as the hydrophilic block; poly(N, N-dimethyl aminoethyl methacrylate) (PDMAEMA) and poly(methacrylamide azobenzene) (PMAAAB) are the hydrophobic blocks with responsiveness. The as-synthesized polymer was measured regarding UV–vis transmittance and contact angle to verify the tunable amphiphilicity and wettability by the double stimulation. The newly developed dual-responsive polymer was applied for oil/water separation and controlled dye release, where methylene red (MR) was chosen as the representative adsorbate. With the synergic stimulation of pH and UV light, efficient separation for oil-in-water emulsions (separation efficiency: 66.8% in 15 min) and excellent desorption for adsorbed dyes (desorption efficiency: 93.8% in 15 min) are achieved. [ABSTRACT FROM AUTHOR]

In comparison to conventional actuated techniques, the utilization of a Flexible Biomimetic Artificial Muscle (FBAM) incorporating calcium alginate hydrogel, a type of responsive polymer, offers numerous benefits including reduced weight, lower actuated voltage requirements, enhanced specific energy density, and minimal acoustic disturbances, among others. This paper presents the fabrication of the FBAM through calcium alginate gelation utilizing six calcium salts with identical Ca2+ molar mass. Subsequently, the electrically actuated characteristics and electrochemical mechanism of the FBAM were investigated, employing four evaluation indexes: peak force density (D, mN/g), operating life (Tt, s), response speed (Vr, mN/g·s), and rise time (Ts, s). The findings of this study hold significant implications for the advancement of novel responsive polymers for artificial muscles. The findings of the study indicate that the electrically actuated characteristics of FBAM were most optimal when calcium alginate gelation with CaH8I2O4 was employed. This was evidenced by the D value of 22.807 mN/g, Tt value of 1066 s, Vr value of 98 s, and Ts value of 0.1046 mN/g·s. The sufficient degree of calcium alginate gelation between sodium alginate molecule and Ca2+ cations resulted in the formation of intermolecular bridges within the calcium alginate hydrogel, which consisted of polymer β-D-mannuronic and α-L-guluronic. Notably, this gelation process was found to be inversely related to the pH level in the aqueous solution of the electrically actuated membrane.

Peptide drugs have been successfully used for the treatment of various diseases. However, it is still challenging to develop therapeutic peptides working on intracellular targets due to their poor membrane permeability. Here, we proposed a type of dual-responsive bioconjugates bearing a heterobifunctional adaptor containing both aldehyde and catechol moieties for efficient cytosolic peptide delivery. Hydrazine-terminated cargo peptides were tagged to a boronated dendrimer with the help of the adaptor via dynamic acylhydrazone and catechol‑boronate linkages. The bioconjugates efficiently delivered peptides with distinct physicochemical properties into various cells, and could release the cargo peptides triggered by intracellular reactive oxygen species and endolysosomal acidity, restoring the biofunctions of delivered peptides. In addition, the designed complexes efficiently delivered a pro-apoptotic peptide into osteosarcoma cancer cells and successfully inhibited the tumor growth both in vitro and in vivo. This study provides a universal and efficient platform for cytosolic therapeutic peptide delivery to intracellular targets for treating various diseases. [Display omitted] • Bioconjugates bearing a adaptor containing both aldehyde and catechol moieties were proposed for cytosolic peptide delivery. • The cargo peptides could maintain the bioactivity after ROS- and acid-responsive release. • The designed bioconjugates efficiently deliver antitumor peptide to inhibit the tumor growth in mice bearing osteosarcomas. [ABSTRACT FROM AUTHOR]

Color reproduction is an important aspect of three-dimensional (3D) printing in terms of creating a colored visual appearance with high fidelity and stability. To this end, structural color is an ideal coloring mechanism, which processes unique nonfading ability and tunable optical features. In this study, we propose a printable structural color ink composed of cholesteric cellulose liquid crystals together with gelatin and a thermal-responsive hydrogel. The ink maintains a cholesteric liquid crystalline state that gives rise to the structural color, and the rheology properties of the ink are optimized by gelatin, which allows the ink to flow during printing and form self-supporting structures after printing. The incorporation of the hydrogel further enables shape maintenance of the ink after printing via in situ ultraviolet-crosslinking. Based on this, we print a series of graphics and 3D objects with angle-independent color appearances and demonstrate the versatility of the printing system in different substrates. Moreover, the printed objects possess dual thermal responsiveness, which results in visible color changes around body temperature. These performances, together with the biocompatibility of the constituents, indicate that the present ink represents a leap forward to the next-generation 3D printing and would unlock a wide range of real-life applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Photo-responsive polymers have attracted increasing attention due to the unique advantages that light stimulus provides, such as high sensitivity, precise selectivity, temporal and spatial control as well as its non-aggressive nature. Photo-responsivity can be divided into different categories including fluorescence and phosphorescence emission, photochromism, variable wettability and polarity changes, photocatalysis, photodynamic therapy, photo fluidization, photothermal function, photo-induced shape memory effects, and photo-locomotion. The chemical integration or physical doping of the photo-responsive compounds to a polymer matrix could induce such photo-responsivity to the host polymers. In recent years, electrospinning has been used as an effective method to fabricate photo-responsive electrospun nanofibrous mats with improved photo-responsive functionalities due to their porous structure with a high surface-to-volume ratio. This review focuses on the recent developments in photo-responsive electrospun polymer nanofibers. The preparation methods and electrospinning parameters, incorporated photo-responsive compounds, photo-responsive mechanisms, and the application areas of the photo-responsive electrospun nanofibrous mats are covered in detail. In this review, the recent studies on photo-responsive polymer nanofibers will be discussed and arranged based on their application types, such as monitoring and sensing, food packaging, anticounterfeiting, drug delivery, wound healing, bioactivity, membranes, and self-cleaning. Moreover, new strategies are proposed for each application field for the future studies to prepare multi-functional electrospun nanofibers with different morphologies, such as layer-by-layer, core-shell, and Janus nanofibers. It is believed that this review may provide new horizons in the preparation of new photo-responsive electrospun polymer nanofibers with smart applications. [ABSTRACT FROM AUTHOR]

Forisomes are giant self‐assembling mechanoproteins that undergo reversible structural changes in response to Ca2+ and various other stimuli. Artificial forisomes assembled from the monomer MtSEO‐F1 can be used as smart biomaterials, but the molecular basis of their functionality is not understood. To determine the role of protein polymerization in forisome activity, we tested the Ca2+ association of MtSEO‐F1 dimers (the basic polymerization unit) by circular dichroism spectroscopy and microscale thermophoresis. We found that soluble MtSEO‐F1 dimers neither associate with Ca2+ nor undergo structural changes. However, polarization modulation infrared reflection absorption spectroscopy revealed that aggregated MtSEO‐F1 dimers and fully‐assembled forisomes associate with Ca2+, allowing the hydration of poorly‐hydrated protein areas. A change in the signal profile of complete forisomes indicated that Ca2+ interacts with negatively‐charged regions in the protein complexes that only become available during aggregation. We conclude that aggregation is required to establish the Ca2+ response of forisome polymers. [ABSTRACT FROM AUTHOR]

[Display omitted] Stabilization of water-in-water (W/W) emulsions resulting from the separation of polymeric phases such as dextran (DEX) and poly(ethyleneoxide) (PEO) is highly challenging, because of the very low interfacial tensions between the two phases and because of the interface thickness extending over several nanometers. In the present work, we present a new type of stabilizers, based on bis-hydrophilic, thermoresponsive microgels, incorporating in the same structure poly(N -isopropylacrylamide) (pNIPAM) chains having an affinity for the PEO phase and dextran moieties. We hypothesize that these particles allow better control of the stability of the W/W emulsions. The microgels were synthesized by copolymerizing the NIPAM monomer with a multifunctional methacrylated dextran. They were characterized by dynamic light scattering, zeta potential measurements and nuclear magnetic resonance as a function of temperature. Microgels with different compositions were tested as stabilizers of droplets of the PEO phase dispersed in the DEX phase (P/D) or vice-versa (D/P), at different concentrations and temperatures. Only microgels with the highest DEX content revealed excellent stabilizing properties for the emulsions by adsorbing at the droplet surface, thus demonstrating the fundamental role of bis-hydrophilicity. At room temperature, both pNIPAM and DEX chains were swollen by water and stabilized better D/P emulsions. However, above the volume phase transition temperature (VPTT ≈ 32 °C) of pNIPAM the microgels shrunk and stabilized better P/D emulsions. At all temperatures, excess microgels partitioned more to the PEO phase. The change in structure and interparticle interaction induced by heating can be exploited to control the W/W emulsion stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cyclodextrin-based polymers responsive to ultraviolet light were synthesized by the atom transfer radical polymerization. • Assemblies of the polymer and nanoparticles in aqueous solutions were triggered by the pH & light stimulations. • Adsorption mechanism of the polymer and nanoparticles was investigated via the adsorption experiment and molecular dynamics simulation. • Dual stimulation allowed the polymer and nanoparticles to enhance viscous oil removal and control dye release. Responsive Pickering emulsions are an excellent platform to control the interfacial properties of oil–water systems. However, the removal of viscous crude oil from oily waste by external stimuli is still a challenge. Here, a dual-stimuli supramolecular assembly of the polymer and silica particles (PS) was designed to achieve desirable control of oil–water interfaces for viscous oil removal and controlled molecular release. The β-cyclodextrin-based polymer was fabricated through the atom transfer radical polymerization (ATRP) method for the host molecules responsive to UV light and amine-modified silica particles for the guest molecules responsive to pH. Utilizing their responsive properties, the PS system was demonstrated in this study to significantly enhance the oil washing efficiency (from 18.3% to 74.2%). Moreover, as the acidic condition was replaced by CO 2 injection, it was further enhanced from 74.2% to 88.5%, which is beneficial to greener remediation and production. The responsive PS assembly was also applied for dye release with a slower or faster release of methyl red by tuning the stimuli (pH & UV light). The molecular mechanism was revealed via the molecular dynamics (MD) simulation, which articulates the interaction and motion of the PS system under various stimulations. More importantly, this novel assembly of the cyclodextrin-based polymer and amine-modified silica particles affords a simple and efficient route to enhance the removal of viscous oil waste and precisely control the molecular release. The findings of the molecular self-assembly in this work offer unique opportunities to integrate functional polymers and particles into the liquid–liquid interface, opening an avenue for applications in Pickering emulsions. [ABSTRACT FROM AUTHOR]

Polyphenols are used as antioxidants in various foods and beverages, which are considered to be a health benefit. The measurement of polyphenols contents is of great interest in food chemistry and health science. This work reported a microgels based photonic device (etalon) to detect polyphenols. Dopamine was used as a model compound of polyphenols. Herein, we proposed a “block” concept for dopamine detection. The dopamine was oxidized and formed dopamine films catalyzed by tyrosinase on the surface of etalon. As the etalon was immersed in ZnCl2, the dopamine films blocked the ZnCl2 diffusion into etalon that caused optical property changes. The film thickness is associated with the concentration of dopamine which can be readout via optical signals.

Interaktive Materialien, die auf einen Trigger hin ihre Morphologie ändern, aber sich genauso allmählich in völlig lösliche Komponenten zersetzen, können als attraktive Bausteine für eine neue Generation an Biomaterialien Anwendung finden. In dieser Arbeit stellen wir transient thermoresponsive Polymere vor, die eine obere kritische Lösungstemperatur (UCST) besitzen, aber graduell diese Eigenschaft nach Hydrolyse der Polymerseitenkette verlieren. Dabei können die Polymere ihre Morphologie und Löslichkeit unter physiologisch relevanten Bedingungen (Temperatur, pH, Ionenstärke) ändern. Während solches Verhalten zuvor bereits für Systeme mit einer unteren kritischen Lösungstemperatur (LCST) beschrieben wurde, blieb dies für UCST‐Polymere lange Zeit unerforscht. In dieser Arbeit zeigen wir, dass solche UCST‐Polymere im Gegensatz zu LCST‐Polymeren in wässriger Umgebung unterhalb ihrer kritischen Lösungstemperatur Koazervate ausbilden, in die sowohl ein hydrophiles Modellprotein als auch ein hydrophober Farbstoff eingelagert werden können. Wegen ihrer geringen Toxizität ist uns in vivo der Nachweis für die Einsetzbarkeit der Koazervate als Depots für Proteine, die über einen längeren Zeitraum hin freigesetzt werden, gelungen. [ABSTRACT FROM AUTHOR]

In comparison to conventional actuated techniques, the utilization of a Flexible Biomimetic Artificial Muscle (FBAM) incorporating calcium alginate hydrogel, a type of responsive polymer, offers numerous benefits including reduced weight, lower actuated voltage requirements, enhanced specific energy density, and minimal acoustic disturbances, among others. This paper presents the fabrication of the FBAM through calcium alginate gelation utilizing six calcium salts with identical Ca2+ molar mass. Subsequently, the electrically actuated characteristics and electrochemical mechanism of the FBAM were investigated, employing four evaluation indexes: peak force density (D , mN/g), operating life (T t , s), response speed (V r , mN/g·s), and rise time (T s , s). The findings of this study hold significant implications for the advancement of novel responsive polymers for artificial muscles. The findings of the study indicate that the electrically actuated characteristics of FBAM were most optimal when calcium alginate gelation with CaH 8 I 2 O 4 was employed. This was evidenced by the D value of 22.807 mN/g, T t value of 1066 s, V r value of 98 s, and T s value of 0.1046 mN/g·s. The sufficient degree of calcium alginate gelation between sodium alginate molecule and Ca2+ cations resulted in the formation of intermolecular bridges within the calcium alginate hydrogel, which consisted of polymer β-D-mannuronic and α-L-guluronic. Notably, this gelation process was found to be inversely related to the pH level in the aqueous solution of the electrically actuated membrane. • A flexible biomimetic artificial muscle is fabricated by a responsive polymer of calcium alginate. • Electrically actuated properties and electrochemical mechanism of FBAM are studied thoroughly. • FBAM is assessed based on peak force density, operating life, response speed, and rise time. • After gelation with CaH 8 I 2 O 4 , FBAM achieves the best microstructure and actuated characteristics. • The degree of calcium alginate gelation is negatively correlated with the pH in membrane solution. [ABSTRACT FROM AUTHOR]

Trigger-responsive materials are capable of controlled drug release in the presence of a specific trigger. Reduction induced drug release is especially interesting as the reductive stress is higher inside cells than in the bloodstream, providing a conceptual controlled release mechanism after cellular uptake. In this work, we report the synthesis of 5-fluorouracil (5-FU) molecularly imprinted polymers (MIPs) based on poly(2-isopropenyl-2-oxazoline) (PiPOx) using 3,3′-dithiodipropionic acid (DTDPA) as a reduction-responsive functional cross-linker. The disulfide bond of DTDPA can be cleaved by the addition of tris(2-carboxyethyl)phosphine (TCEP), leading to a reduction-induced 5-FU release. Adsorption isotherms and kinetics for 5-FU indicate that the adsorption kinetics process for imprinted and non-imprinted adsorbents follows two different kinetic models, thus suggesting that different mechanisms are responsible for adsorption. The release kinetics revealed that the addition of TCEP significantly influenced the release of 5-FU from PiPOx-MIP, whereas for non-imprinted PiPOx, no statistically relevant differences were observed. This work provides a conceptual basis for reduction-induced 5-FU release from molecularly imprinted PiPOx, which in future work may be further developed into MIP nanoparticles for the controlled release of therapeutic agents.

Thermoresponsive polymers have received significant research attention as smart materials with particular interest in biomedical applications. The composition and architecture are known to strongly influence the thermoresponsive properties of the materials. For example, the strong overlap of end-grafted polymer chains in polymer brushes leads to a broader collapse transition relative to linear ungrafted chains as well as temperature dependent adhesion. The temperature response of free polymer has been widely reported to depend on the concentration and identity of ions in solution and is further modified by the composition of the solvent and presence of cosolutes. However, the influence of polymer architecture on these specific ion effects is relatively unknown. Herein, we compare the current understanding of specific ion effects on free polymer chains and gels with recent studies of polymer brushes. Further studies on mixed salt systems are found to be the next step to predicting the behaviour of these materials in biological systems. [ABSTRACT FROM AUTHOR]

Biological stimuli-responsive polymers have increasingly attracted attention in recent years because it can satisfy many requirements of applications related with human body while traditional systems do not meet. Due to the importance of this burgeoning field, great efforts have been devoted and, up to now, polymer chemists have made a remarkable success in this prospective research topic. In this review, we systematically generalize the present state of biological stimuli-responsive polymer systems. We highlight several representative examples to specify the current problems and look ahead a clear sense of direction in this area. [ABSTRACT FROM AUTHOR]

Zwitterionic hybrid block copolymer based nanocarriers are ideal candidates for drug delivery applications due the higher resistance to nonspecific protein adsorption in complex media compared to nonionic polymers. Especially, zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) p(MPC) based nanocarriers can maintain its stability during circulation in complex media, such as serum. Thus, a series of bioreducible and pH-responsive zwitterionic/amphiphilic block copolymers, poly(2-methacryloyloxyethyl phosphorylcholine) 50 - block -poly( l -aspartic acid) n (p(MPC) 50 – b –p(AA) n ) ( n = 10, 25, 50, 75), bearing a degradable disulfide linker have been synthesized and exploited as dual-stimuli-responsive drug delivery vehicle of the chemotherapeutic drug, doxorubicin (Dox). Dox was successfully loaded into uniform vesicles (∼ 100 nm) fabricated from p(MPC) 50 – b –p(AA) n and the release performance was investigated under different pH conditions and with a range of concentrations of the reducing agent, 1,4-dithiothreitol (DTT). At physiological conditions, increasing concentrations of DTT resulted in faster Dox release from vesicles. Dox release at elevated DTT concentrations was more effective at pH 5.5 than at pH 7.5. Blank vesicles were non-toxic over a wide concentration range when tested in normal cell lines (0.01–100 μg/mL). Vesicles efficiently encapsulated Dox and the dual stimuli-responsive disassembly results demonstrated controlled and sustained release of Dox tin 4T1 cancer cells to confer dose-dependent cytotoxicity. Thus, the bioreducible and pH sensitive vesicles appear to be a promising theranostic platform for drug delivery applications. [ABSTRACT FROM AUTHOR]

Several series of presumed dual thermo-responsive diblock copolymers consisting of one non-ionic and one zwitterionic block were synthesized via consecutive reversible addition-fragmentation chain transfer (RAFT) polymerization. For all copolymers, poly(N-isopropylmethacrylamide) was chosen as non-ionic block that shows a coil-to-globule collapse transition of the lower critical solution temperature (LCST) type. In contrast, the chemical structure of zwitterionic blocks, which all belonged to the class of poly(sulfobetaine methacrylate)s, was varied broadly, in order to tune their coil-to-globule collapse transition of the upper critical solution temperature (UCST) type. All polymers were labeled with a solvatochromic fluorescent end-group. The dual thermo-responsive behavior and the resulting multifarious temperature-dependent self-assembly in aqueous solution were mapped by temperature-resolved turbidimetry, 1 H NMR spectroscopy, dynamic light scattering (DLS), and fluorescence spectroscopy. Depending on the relative positions between the UCST-type and LCST-type transition temperatures, as well as on the width of the window in-between, all the four possible modes of stimulus-induced micellization can be realized. This includes classical induced micellization due to a transition from a double hydrophilic, or respectively, from a double hydrophobic to an amphiphilic state, as well as “schizophrenic” behavior, where the core- and shell-forming blocks are inverted. The exchange of the roles of the hydrophilic and hydrophobic block in the amphiphilic states is possible through a homogeneous intermediate state or a heterogeneous one. [ABSTRACT FROM AUTHOR]

The thermoresponse of poly(di(ethyleneglycol) methyl ether methacrylate) (PMEO 2 MA) brushes has been investigated in the presence of monovalent anions at either end of the Hofmeister series using ellipsometry, neutron reflectometry (NR) and colloid probe atomic force microscopy (AFM). NR measurements in deuterium oxide showed no evidence of vertical phase separation perpendicular to the grafting substrate with a gradual transition between a block-like, dense structure at 45 °C and an extended, dilute conformation at lower temperatures. All three techniques revealed a shift to a more collapsed state for a given temperature in kosmotropic potassium acetate solutions, while more swollen structures were observed in chaotropic potassium thiocyanate solutions. No difference was observed between 250 mM and 500 mM thiocyanate for a 540 Å brush studied by ellipsometry, while the lower molecular weight ∼200 Å brushes used for NR and AFM measurements continued to respond with increasing salt concentration. The effect of thiocyanate on the temperature response was greatly enhanced relative to PNIPAM with the shift in temperature response at 250 mM being five times greater than a PNIPAM brush of similar thickness and grafting density. [ABSTRACT FROM AUTHOR]

Poly(aspartic acid) (PASP) hydrogels were prepared by crosslinking polysuccinimide (PSI) with diaminobutane followed by the mild hydrolysis of the resultant PSI gels to PASP hydrogels. The composition dependence of the gelation time and the stiffness of bulk PASP hydrogels were determined by rheometry and compression tests, respectively. The composition of the prepared PASP nanogels was chosen based on the results on bulk PASP hydrogels. Prior to nanogel preparation stability of DMSO-in-oil (inverse) emulsions was tested as a function of the chemical quality of apolar phase, the concentration of the precursor polymer and the concentration of the surfactant. PASP nanogels in the size of a few hundred nanometers were prepared by the hydrolysis of PSI nanogels synthesized in inverse emulsion. PASP nanogels showed pH-dependent swelling and strongly negative surface charge at physiological pH values, thus they can be further developed to meet the specific criteria of different bio-related applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel coating is fabricated using polymer conjugates complexing an inorganic corrosion inhibitor. • The coating exhibits a remarkable healing efficiency of ∼ 98 %, relying on metal–ligand interactions. • The corrosion rate of the coating is ∼ 31 times lower than the coatings without metal coordination bonds. • The combination of organic and inorganic inhibitors provided an excellent anticorrosion performance. Coatings containing corrosion inhibitors are effective materials for hindering corrosion of metals and alloys structures. However, shortcomings of these coatings include an uncontrolled leaching of inhibitors and susceptibility to mechanical damages, which lead to a shortened anticorrosion property. To overcome these issues, we prepare a new smart coating with the abilities of releasing selectively corrosion inhibitors and repairing autonomously mechanical damages. This dual-function is imparted by a pH-responsive polymer containing a corrosion inhibitor which coordinates cerium ions. Upon corrosion, the polymer releases the corrosion inhibitor and cerium which then forms insoluble cerium oxides or cerium hydroxides on cathodic sites. The corrosion rate of aluminum alloys coated with the polymer conjugate complex is ∼ 31 times lower than for the coating of the polymer conjugate that is not complexed. Self-healing after mechanical damage is enabled by the metal–ligand coordination bond between cerium ions and conjugated 8-hydroxyquinoline (8HQ), leading to a restauration of ∼ 98 % of the anticorrosion properties. [ABSTRACT FROM AUTHOR]

Protein drugs are increasingly used as therapeutics for the treatment of cancer. However, their inherent drawbacks, such as poor stability, low cell membrane and tissue permeability, lack of tumor selectivity, and severe side effects, limit their wide applications in cancer therapy. Herein, screening of a thermo-pH-sensitive polymer-glucose oxidase conjugate that can controllably self-assemble into nanoparticles with improved stability is reported. The size, surface charge, and bioactivity of the conjugate can be tuned by adjustment of the solution temperature and pH. The cellular uptake, intracellular hydrogen peroxide generation, and tumor cell spheroid penetration of the conjugate are greatly enhanced under the acidic tumor microenvironment, leading to increased cytotoxicity to tumor cells. Upon a single intratumoural injection, the conjugate penetrates into the whole tumor tissue but hardly diffuses into the normal tissues, resulting in the eradication of the tumors in mice without perceivable side effects. Simultaneously, the conjugate induces a robust antitumor immunity to efficiently inhibit the growth of distant tumors, especially in combination with an immune checkpoint inhibitor. These findings provide a novel and general strategy to make multifunctional protein-polymer conjugates with responsiveness to the acidic tumor microenvironment for selective tumor therapy., (© 2023 Wiley-VCH GmbH.)

The light-induced self-assembly of gold nanoparticles was studied systematically. A methacrylate type monomer with an azobenzene sidechain was polymerized in a reversible addition–fragmentation chain transfer (RAFT) polymerization. The resulting light responsive polymer was grafted to gold nanoparticles via the RAFT group. UV-light induced trans to cis isomerization of the azobenzene moieties triggers the aggregation of the polymer–gold hybrid particles in toluene dispersion. The thermally induced cis to trans relaxation was found to be significantly slower than for small molecules at gold surfaces. The self-assembly was followed by dynamic light scattering (DLS), UV/vis spectroscopy and transmission electron microscopy (TEM). The density of primary gold particles within the self-assembled aggregates can be tuned by varying the molar mass of the grafted polymer. [ABSTRACT FROM AUTHOR]

Polylactide (PLA) and its copolymers are hydrophobic polyesters used for biomedical applications. Hydrogel medicinal implants have been used as drug delivery vehicles and scaffolds for tissue engineering, tissue augmentation and more. Since lactides are non-functional, they are copolymerized with hydrophilic monomers or conjugated to a hydrophilic moiety to form hydrogels. Copolymers of lactic and glycolic acids with poly(ethylene glycol) (PEG) provide thermo-responsive hydrogels. Physical crosslinking mechanisms of PEG–PLA or PLA-polysaccharides include: lactic acid segment hydrophobic interactions, stereocomplexation of D and L-lactic acid segments, ionic interactions, and chemical bond formation by radical or photo crosslinking. These hydrogels may also be tailored as stimulus responsive (pH, photo, or redox). PLA and its copolymers have also been polymerized to include urethane bonds to fabricate shape memory hydrogels. This review focuses on the synthesis, characterization, and applications of PLA containing hydrogels. [ABSTRACT FROM AUTHOR]

Crosslinked-polymer brushes give rise to new opportunities for functionalizing, protecting, and structuring both organic and inorganic materials. In this study, pH- and temperature-switchable crosslinked-polymer brushes were easily prepared by combining the in situ method with reversible addition–fragmentation chain transfer (RAFT) polymerization. Initially, the RAFT agent was immobilized on an amine-terminated silicon wafer surface and utilized in the surface-initiated RAFT polymerization of 2-N-morpholinoethyl methacrylate (MEMA) as a monomer, and β-cyclodextrin methacrylate (CDMA) was used as a crosslinker on the silicon substrate. Measurements of film thickness, water contact angle, surface morphology, and structural characteristics of the resulting surfaces confirmed the poly(2-N-morpholinoethyl methacrylate) (PMEMA) brush-gels. Reversible capture and release measurements of methylene blue as a model molecule were also performed by UV–vis analysis. The switchable properties of the PMEMA brush-gels were maintained over five cycles. The results indicate that these PMEMA brush-gels with reversible capture and release properties might have widespread potential applications, including improved diagnostic tools as well as bioseparation.

Introduction of new components is an effective way to gain new functionalities and to regulate the properties of responsive polymers. In the present work, a RAFT polymerization approach to terpyridine-containing poly( N -isopropyl acrylamide) (PNIPAAm) copolymers was developed and the dually responsive behavior of the obtained polymer to temperature variation and metal ions in dilute solutions were investigated. By utilizing RAFT polymerization, the molecular weight polydispersity index of the polymer can be reduced compared with the traditional free radical polymerization method. Due to the coexistence of thermosensitive component and terpyridine, the synthesized polymer is thermosensitive and metal ion sensitive. Further titration investigation revealed that this polymer may be utilized as a water-soluble and colorimetric sensor for Fe 2 + and Fe 3 + and the obvious color change from a colorless state to a purple state makes the polymer a potential sensor to detect Fe 2 + and Fe 3 + macroscopically by naked eye. Overall, the terpyridine-containing poly( N -isopropyl acrylamide) copolymers may enrich the family of terpyridine-containing polymers and provide some clues for developing new multi-responsive and multi-functional polymers. [ABSTRACT FROM AUTHOR]

Knowledge of the interactions between polymer and protein is very important to fabricate the potential materials for many bio-related applications. In this regard, the present work investigated the effect of copolymers on the conformation and thermal stability of bovine serum albumin (BSA) with the aid of biophysical techniques such as fluorescence spectroscopy, circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC). In comparison with that of copolymer PGA-1.5, our fluorescence spectroscopy results reveal that the copolymer PGA-1, which has a lower PEGMA/AA ratio, shows greater influence on the conformation of BSA. Copolymers induced unfolding of the polypeptide chain of BSA, which was confirmed from the loss in the negative ellipticity of CD spectra. DSC results showed that the addition of PGA-1 and PGA-1.5 (0.05% (w/v) decreased the transition temperature by 14.8 and 11.5 °C, respectively). The results from the present study on the behavior of protein in response to changes in the chemical composition of synthetic polymers are significant for various biological applications such as enzyme immobilization, protein separations, sensor development and stimuli-responsive systems. [ABSTRACT FROM AUTHOR]