Reversible Interactions Research Articles

Structural Analysis and Characterization of an Antiproliferative Lectin from Canavalia villosa Seeds.

Cells use glycans to encode information that modulates processes ranging from cell-cell recognition to programmed cell death. This information is encoded within a glycocode, and its decoding is performed by carbohydrate-binding proteins. Among these, lectins stand out due to their specific and reversible interaction with carbohydrates. Changes in glycosylation patterns are observed in several pathologies, including cancer, where abnormal glycans are found on the surfaces of affected tissues. Given the importance of the bioprospection of promising biomolecules, the current work aimed to determine the structural properties and anticancer potential of the mannose-specific lectin from seeds of Canavalia villosa (Cvill). Experimental elucidation of the primary and 3D structures of the lectin, along with glycan array and molecular docking, facilitated the determination of its fine carbohydrate-binding specificity. These structural insights, coupled with the lectin's specificity, have been combined to explain the antiproliferative effect of Cvill against cancer cell lines. This effect is dependent on the carbohydrate-binding activity of Cvill and its uptake in the cells, with concomitant activation of autophagic and apoptotic pathways.

Exceptional n-type thermoelectric ionogels enabled by metal coordination and ion-selective association.

Ionic liquid-based ionogels emerge as promising candidates for efficient ionic thermoelectric conversion due to their quasi-solid state, giant thermopower, high flexibility, and good stability. P-type ionogels have shown impressive performance; however, the development of n-type ionogels lags behind. Here, an n-type ionogel consisting of polyethylene oxide (PEO), lithium salt, and ionic liquid is developed. Strong coordination of lithium ion with ether oxygen and the anion-rich clusters generated by ion-preferential association promote rapid transport of the anions and boost Eastman entropy change, resulting in a huge negative ionic Seebeck coefficient (-15 millivolts per kelvin) and a high electrical conductivity (1.86 millisiemens per centimeter) at 50% relative humidity. Moreover, dynamic and reversible interactions among the ternary mixtures endow the ionogel with fast autonomous self-healing capability and green recyclability. All PEO-based ionic thermoelectric modules are fabricated, which exhibits outstanding thermal responses (-80 millivolts per kelvin for three p-n pairs), demonstrating great potential for low-grade energy harvesting and ultrasensitive thermal sensing.

DNA Chimeras as Electrochemical Biosensors for Host-Guest Measurements in Blood.

Few sensing platforms have become ubiquitous to enable rapid and convenient measurements at the point-of-care. Those, however, are "one-off" technologies, meaning that they can only detect a single target and are hardly adaptable. In response, we plan to develop a sensing platform that can be extended to detect other classes of molecules and that affords rapid, convenient, continuous measurements directly in undiluted complex matrices. For this, we decided to rely on a host molecule that presents reversible interactions toward specific guest molecules to develop a new class of sensors that we coined "Electrochemical DNA-host chimeras". As a proof-of-concept for our sensor, we decided to use cyclobis(paraquat-p-phenylene) ("blue box") that we attached on an electrode-bound DNA to allow measurements of electron-rich guests such as dopamine and aspirin. Doing so allows to promote host-guest complex that could be quantified using blue box's electrochemistry. Because of this unique sensor architecture, we achieve, to our knowledge, the first reagentless, continuous and rapid (< 5 min) host-guest measurements in undiluted whole blood. We envision that given the library of electroactive host molecules that this will allow the development of a sensing platform for measurements of several classes of molecules in complex matrices at the point-of-care.

In-situ phase separation constructing robust hydrophobic ionogels with multifunction

Ionogels, as the promising alternative to hydrogels, have garnered great attention due to their excellent ionic conductivity, thermal stability, and non-volatility. However, the design and construction of robust hydrophobic ionogel still is a significant challenge at present, especially with a facile method. Herein, inspired by the two-phase structure of the dermis in human skin (stiff collagen fiber scaffold embedded in soft elastin matrix), a one-pot in-situ phase separation design strategy is proposed to construct the robust hydrophobic ionogel through the random copolymerization of hydrophobic monomers with the solubility difference in hydrophobic ionic liquid (IL). The resultant ionogel forms a homogeneously dual phase network containing solvent-rich soft domains and solvent-poor hard domains. The mechanical robustness can be synergistically achieved by the hard domain strong skeleton and the soft domain elastic matrix. Benefiting from multiple reversible interactions including hydrogen bonding, ion–dipole and ion-ion interactions, and physical entanglement, the ionogel shows strong IL retention, excellent self-healing, and regenerating abilities, while can adhere to different substrates. The unique phase separation structure brings temperature-dependent transparency and high-damping features. The ionogel also presents high ionic conductivity due to the abundance of movable ions. As application demonstrations, the ionogel is successfully used for dynamic pattern encryption, shock attenuation, and strain sensing. What’s more, this strategy can be also applied to improve the mechanical properties of hydrophobic ionogels based on other monomers. Hence, this work establishes an effective and general design strategy for hydrophobic ionogels demanding versatility.

Metallic-Polyphenolic Nanoparticles Reinforced Cationic Guar Gum Hydrogel for Effectively Treating Burn Wound.

The development of injectable hydrogel dressings which are long-term moisturizing, easy-to-apply, and effectively inhibiting infection and inflammatory is essential to promote burn wound repairing. Herein, an injectable hydrogel with moisturizing, antibacterial, and anti-inflammation abilities via multiple reversible interactions between cation guar gum (CG) and metallic-polyphenolic nanoparticles (PA-ZnII NPs) is developed. Specifically, PA-ZnII NPs is formed by synergistic complexation of protocatechualdehyde (PA) and zinc ion (Zn2+ ), provides CGPZ hydrogel with plentiful reversible interactions to inhibit the loss of moist. By interacting with PA-ZnII NPs, the CGPZ hydrogel can provide enhanced moisturization for more than 3 days. Moreover, the CGPZ hydrogel can maintain good adhesion for a period of time with injection and self-healing capabilities due to reversible interactions between CG and PA-ZnII NPs. In addition, CGPZ hydrogel exhibits outstanding broad spectrum antibacterial performance, as its killing efficiency against Escherichia coli and Staphylococcus aureus is all greater than 99.99%. Importantly, compared with commercial dressing, the CGPZ hydrogel can promote wound healing faster by inhibiting tissue damage from dysregulated inflammation and accelerating neovascularization. It is believed that the moisturizing CGPZ hydrogel with antibacterial and anti-inflammation performance can serve as a promising dressing for the effective treatment of burn wound.

Branched poly-l-lysine for cartilage penetrating carriers.

Joint diseases, such as osteoarthritis, often require delivery of drugs to chondrocytes residing within the cartilage. However, intra-articular delivery of drugs to cartilage remains a challenge due to their rapid clearance within the joint. This problem is further exacerbated by the dense and negatively charged cartilage extracellular matrix (ECM). Cationic nanocarriers that form reversible electrostatic interactions with the anionic ECM can be an effective approach to overcome the electrostatic barrier presented by cartilage tissue. For an effective therapeutic outcome, the nanocarriers need to penetrate, accumulate, and be retained within the cartilage tissue. Nanocarriers that adhere quickly to cartilage tissue after intra-articular administration, transport through cartilage, and remain within its full thickness are crucial to the therapeutic outcome. To this end, we used ring-opening polymerization to synthesize branched poly(l-lysine) (BPL) cationic nanocarriers with varying numbers of poly(lysine) branches, surface charge, and functional groups, while maintaining similar hydrodynamic diameters. Our results show that the multivalent BPL molecules, including those that are highly branched (i.e., generation two), can readily adhere and transport through the full thickness of cartilage, healthy and degenerated, with prolonged intra-cartilage retention. Intra-articular injection of the BPL molecules in mouse knee joint explants and rat knee joints showed their localization and retention. In summary, this study describes an approach to design nanocarriers with varying charge and abundant functional groups while maintaining similar hydrodynamic diameters to aid the delivery of macromolecules to negatively charged tissues.

Multifunctional enhanced energy density integrated supercapacitor based on self-healing redox-mediated gel polymer electrolyte

Flexible supercapacitors have undergone rapid development, however, there is still a serious challenge in integrating multiple functions into a single supercapacitor. Therefore, higher requirements are put forward for electrolytes and assembled technology. Herein, a redox-mediated physically crosslinked double network polyacrylic acid/polyisodecyl methacrylate/K3[Fe(CN)6] gel polymer electrolyte (GPE) has been synthesized. The double network structure and reversible interactions, including hydrophobic association, hydrogen bond and ion coordination, endow the GPE with exceptional strength, toughness and self-healability. In particular, Fe2+/Fe3+ ions play a dual role as charge carriers and crosslinking agents, simultaneously increasing the electrochemical and mechanical capabilities of the GPE (3.76 S/m and 1.99 MPa, respectively). Subsequently, a flexible integrated supercapacitor has been developed through in situ polymerization of aniline on the surface of GPE. Thanks to the seamless construction and reversible redox reactions of Fe2+/Fe3+, the supercapacitor exhibits significantly enhanced capacitance and energy density (271.6 mF/cm2 and 98.1 μWh/cm2, respectively). Moreover, the supercapacitor demonstrates promising self-healability with a 99.3 % capacitance retention rate after 10 cutting/healing cycles. Due to the mutual fusion of the electrode and electrolyte layers, the outstanding electrochemical durability is obtained even under severe deformations. Overall, the redox-mediated double network GPE and the unique integrated configuration provide an effective strategy for multifunctional energy storage devices.

Does MPK4/12-HT1 function as a CO2/bicarbonate sensor to regulate the stomatal conductance under high CO2 levels?

Recently, a HT1 protein has been identified which causes continuous opening of stomata because of its kinase activity.However, reversible interaction between MAP4/12 and HT1 protein acts as a CO2/bicarbonate sensor and causes the closing of stomata by inhibiting HT1 kinase activity.

Injectable, tough and adhesive zwitterionic hydrogels for 3D-printed wearable strain sensors

3D printing of high-strength hydrogel remains a great challenge owing to trade-off between strength and printability. Herein, a zwitterionic strategy was proposed through electrostatic reversible interaction to improve the rheology of shear-thinning based on an agarose-based network. Therefore, this mechanism of dual network (DN) ultimately imparts the hydrogel with remarkable strength (with a tensile strength of 0.79 MPa and a compressive strength of 14.18 MPa) and ductility (with a toughness of 766%), while simultaneously possessing multiple functionalities, such as high transparency, excellent biocompatibility, and adhesion. Furthermore, the developed agarose/poly([2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium -co-N- hydroxyethylacrylamide) (A/D-H) DN hydrogel exhibited impressive strain sensitivity with a strain gauge factor GF of 4.33 even under large deformations. Various forms of flexible sensors based on this printed gel were successfully utilized in human motion sensing and remote heartbeat monitoring, thereby opening up new perspectives for the further expansion of injectable materials.

3D-exosomes laden multifunctional hydrogel enhances diabetic wound healing via accelerated angiogenesis

Impaired vascular networks, local insufficiency of neovascularization, and tissue inflammation caused by the accumulation of reactive oxygen species (ROS) and bacterial infections contribute to the delayed healing of wounds in patients with diabetes. Thus, an urgent need is to develop effective diabetic wound treatments that promote angiogenesis, inhibit bacterial infections, and reduce oxidative damage and tissue inflammation. Exosome therapy promotes angiogenesis and wound healing. However, traditional exosomes have limitations such as low yield and rapid release. Compared with two-dimensional (2D) cell culture, three-dimensional (3D) cell culture results in a higher yield of exosomes and better healing effects. In this study, we designed a multifunctional hydrogel with 3D-exosome-sustained release features to improve diabetic wound healing. Chitosan-grafted-dihydrocaffeic acid (CS-DA) and benzaldehyde-terminated Pluronic®F127 (PF127-CHO) were combined using a dynamic Schiff base bond to form a dynamic hydrogel network and simultaneously fused tannic acid (TA) and 3D adipose-derived mesenchymal stem cells-derived exosomes (3D ADSCs-Exos, referred to in this study as 3D-Exo). The phosphoric acid groups of 3D-Exo combine with the polyphenol groups of DA/TA through reversible interactions, enabling the sustained release of 3D-Exo. The CS-DA/PF/TA/3D-Exo hydrogel exhibited tissue-adhesive, self-healing, antibacterial, anti-inflammatory, and antioxidant properties. The CS-DA/PF/TA/3D-Exo hydrogel significantly accelerated the recovery of diabetic wounds by promoting angiogenesis and collagen deposition in vivo. Furthermore, rapid hemostasis was achieved owing to the wet tissue adhesion and platelet activation of the hydrogel. In general, this multifunctional hydrogel could be used as a wound dressing for diabetic wound management.

Groundwater Quality and Suitability Assessment for Irrigation Using Hydrogeochemical Characteristics and Pollution Indices: A Case Study of North Al-Quwayiyah Governorate, Central Saudi Arabia

The present work focuses on a comprehensive hydrochemical assessment of groundwater within a shallow aquifer located in the central region of Saudi Arabia. This aquifer serves as the principal source of groundwater supply for agricultural irrigation purposes. A total of twelve groundwater samples were systematically collected and subjected to thorough analysis to determine various physicochemical parameters. These parameters encompassed electrical conductivity (EC), pH, temperature, total dissolved solids (TDS), as well as concentrations of major ions. Analysis of major ion analysis was employed to elucidate the chemical attributes of groundwater within the research area. This approach facilitated an understanding of the geochemical evolution and the potential suitability of the groundwater for agriculture irrigation. The recorded range of electrical conductivity (EC) for the groundwater in this region falls between 3283 and 11,000 µS/cm, with an average value of 6709.4 µS/cm. The pH levels of the groundwater exhibited a slightly alkaline nature, ranging from 7.8 to 8.6. All sampled wells exhibited brackish water conditions (TDS &gt; 1000 mg/L) based on TDS concentrations. The findings of this investigation demonstrated that the average ion concentration followed the order: Na+ &gt; Ca+ &gt; Mg2+ &gt; K+ and Cl− &gt; SO42− &gt; HCO3− &gt; NO32−. Applying Piper’s classification system, the groundwater samples were classified into two predominant categories: Ca-Cl and mix-Ca-Mg-Cl. The predominance of Ca2+ and Mg2+ over alkalis indicated mixed groundwater facies influenced by processes of reverse ion exchange and extensive interactions between water and rock formations. The distinct chemical characteristics of the groundwater were attributed to a combination of factors, including the percolation of irrigation-returned water, chemical transformations within the vadose zone, and extensive interactions with subsurface lithology. Despite major ion concentrations surpassing the permissible limits outlined by the World Health Organization (WHO) for drinking water, the assessment of quality indices was conducted to ascertain the suitability of the groundwater for irrigation purposes. These quality indices encompassed the permeability index (PI), magnesium hazard (MH), Kelly’s ratio (KR), sodium-adsorption ratio (SAR), residual sodium carbonate (RSC), sodium percentage (Na%), and magnesium ratio (MR). A meticulous evaluation of groundwater quality for agricultural utilization indicated that all sampled groundwater sources were deemed suitable for irrigation purposes.

Second law of classical and quantum thermodynamics and its validity for any timescale and system size

We develop a strategy to properly analyse the entropy in a classical system originally envisaged by Maxwell and extended it to quantum systems (molten liquid and water interacting with photons). We exploit the renormalized interaction to evaluate the entropy-change in these systems and have unequivocally identified the following two assumptions to be physically false. The false assumptions are related to (1) time reversibility and (2) reversible physical interaction(s) without any other changes. The second law of thermodynamics is found to be valid for any timescale and system size for as long as these two assumptions are violated, and stay violated. In the presence of any phase transition, or for larger systems with longer timescales, these two assumptions are automatically false. We prove that if we activate these assumptions at certain timescale and size, we are then led to the violation of the second law of thermodynamics.

Self-healing, ultra-stretchable, and highly sensitive conductive hydrogel reinforced by sulfate polysaccharide from Enteromorpha prolifera for human motion sensing

The synthesis of multifunctional conductive hydrogel has attracted extensive attention worldwide due to their integrated properties of stretchability, self-adhesion, self-healing, and high sensitivity, while it is still a challenge. Although various kinds of polysaccharides and their derivatives are used to achieve the aforementioned objective, there are few researches about hydrogel design introducing sulfated polysaccharide from Enteromorpha prolifera (SPE), which is rich in hydroxyl, sulfate, and carboxyl groups providing amounts of reaction sites for hydrogel synthesis. Herein, conductive hydrogel (PAA-Al3+-SPE3) reinforced by SPE was designed by simple one pot hot polymerization method. This hydrogel demonstrated charming extension ratio (up to 4027.40 %), strain stress (up to 59.94 kPa), compressive strength (19.71 Mpa), and high conductivity sensibility (GF 6.76, 300 % - 700 %). Additionally, PAA-Al3+-SPE3 showed good self-healing property (repaired autonomously after 60 s) and satisfied self-adhesion (31.11 kPa) due to the reversible hydrogen bonds and metal coordination interactions. Furthermore, the PAA-Al3+-SPE3 hydrogel showed great real-time sensing performance to monitor various motions. These findings suggest the potential of PAA-Al3+-SPE3 hydrogel as an affordable and reliable conductive sensing material. Meantime, the first utilization of SPE to construct flexible wearable sensors offers new route for the high-value application of Enteromorpha prolifera.

HIV-1 reverse transcriptase stability correlates with Gag cleavage efficiency: reverse transcriptase interaction implications for modulating protease activation.

Proteolytic processing of human immunodeficiency virus type 1 particles mediated by viral protease (PR) is essential for acquiring virus infectivity. Activation of PR embedded in Gag-Pol is triggered by Gag-Pol dimerization during virus assembly. We previously reported that amino acid substitutions at the RT tryptophan repeat motif destabilize virus-associated RT and attenuate the ability of efavirenz (EFV, an RT dimerization enhancer) to increase PR-mediated Gag cleavage efficiency. Furthermore, a single amino acid change at RT significantly reduces virus yields due to enhanced Gag cleavage. These data raise the possibility of the RT domain contributing to PR activation by promoting Gag-Pol dimerization. To test this hypothesis, we investigated the putative involvement of a hydrophobic leucine repeat motif (LRM) spanning RT L282 to L310 in RT/RT interactions. We found that LRM amino acid substitutions led to RT instability and that RT is consequently susceptible to degradation by PR. The LRM mutants exhibited reduced Gag cleavage efficiencies while attenuating the EFV enhancement of Gag cleavage. In addition, an RT dimerization-defective mutant, W401A, reduced enhanced Gag cleavage via a leucine zipper (LZ) motif inserted at the deleted Gag-Pol region. Importantly, the presence of RT and integrase domains failed to counteract the LZ enhancement of Gag cleavage. A combination of the Gag cleavage enhancement factors EFV and W402A markedly impaired Gag cleavage, indicating a disruption of W402A Gag-Pol dimerization following EFV binding to W402A Gag-Pol. Our results support the idea that RT modulates PR activation by affecting Gag-Pol/Gag-Pol interaction. IMPORTANCE A stable reverse transcriptase (RT) p66/51 heterodimer is required for HIV-1 genome replication in host cells following virus entry. The activation of viral protease (PR) to mediate virus particle processing helps viruses acquire infectivity following cell release. RT and PR both appear to be major targets for inhibiting HIV-1 replication. We found a strong correlation between impaired p66/51RT stability and deficient PR-mediated Gag cleavage, suggesting that RT/RT interaction is critical for triggering PR activation via the promotion of adequate Gag-Pol dimerization. Accordingly, RT/RT interaction is a potentially advantageous method for anti-HIV/AIDS therapy if it is found to simultaneously block PR and RT enzymatic activity.

Phase separation and pathologic transitions of RNP condensates in neurons: implications for amyotrophic lateral sclerosis, frontotemporal dementia and other neurodegenerative disorders.

Liquid-liquid phase separation results in the formation of dynamic biomolecular condensates, also known as membrane-less organelles, that allow for the assembly of functional compartments and higher order structures within cells. Multivalent, reversible interactions between RNA-binding proteins (RBPs), including FUS, TDP-43, and hnRNPA1, and/or RNA (e.g., RBP-RBP, RBP-RNA, RNA-RNA), result in the formation of ribonucleoprotein (RNP) condensates, which are critical for RNA processing, mRNA transport, stability, stress granule assembly, and translation. Stress granules, neuronal transport granules, and processing bodies are examples of cytoplasmic RNP condensates, while the nucleolus and Cajal bodies are representative nuclear RNP condensates. In neurons, RNP condensates promote long-range mRNA transport and local translation in the dendrites and axon, and are essential for spatiotemporal regulation of gene expression, axonal integrity and synaptic function. Mutations of RBPs and/or pathologic mislocalization and aggregation of RBPs are hallmarks of several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Alzheimer's disease. ALS/FTD-linked mutations of RBPs alter the strength and reversibility of multivalent interactions with other RBPs and RNAs, resulting in aberrant phase transitions. These aberrant RNP condensates have detrimental functional consequences on mRNA stability, localization, and translation, and ultimately lead to compromised axonal integrity and synaptic function in disease. Pathogenic protein aggregation is dependent on various factors, and aberrant dynamically arrested RNP condensates may serve as an initial nucleation step for pathologic aggregate formation. Recent studies have focused on identifying mechanisms by which neurons resolve phase transitioned condensates to prevent the formation of pathogenic inclusions/aggregates. The present review focuses on the phase separation of neurodegenerative disease-linked RBPs, physiological functions of RNP condensates, and the pathologic role of aberrant phase transitions in neurodegenerative disease, particularly ALS/FTD. We also examine cellular mechanisms that contribute to the resolution of aberrant condensates in neurons, and potential therapeutic approaches to resolve aberrantly phase transitioned condensates at a molecular level.

Cytotoxic effect of polyvinyl alcohol-magnetite composite

Polymeric hydrogel is a promising candidate for drug delivery applications due to its ability to encapsulate and release drugs. Incorporating magnetic particles enables controlled and specific release, providing sustained and targeted delivery. This study aimed to assess the cytotoxicity of the magnetite-polyvinyl alcohol (MPVA) hydrogel, specifically its magnetite content, using 3T3 fibroblast cells. The findings indicate that the MPVA hydrogel with magnetite nanoparticles was compatible with the cells and did not induce cell death. Incorporating magnetite nanoparticles into the PVA hydrogel improved its thermal stability and degradation temperature, disrupting the chain order, decreasing melting behavior, and fractional crystallinity of the hydrogel. The MPVA hydrogel demonstrated a higher gel fraction and crosslink density compared to the PVA hydrogel due to the presence of magnetite nanoparticles. The interaction between PVA and magnetite nanoparticles occurred through non-covalent forces, allowing for reversible interactions and dispersion of the nanoparticles within the PVA matrix. Although the cytotoxicity of the MPVA gel was similar to that of the PVA gel, the viability of fibroblast cells within the MPVA gel varied depending on the concentration. The MPVA hydrogel exhibited stronger attachment and induced irregular changes on the cell surface compared to the PVA hydrogel. Furthermore, the MPVA gel displayed paramagnetic behavior and controllable magnetization, as demonstrated by the hysteresis loop. These magnetic properties make the MPVA gel suitable for potential biomedical applications, including drug delivery, tissue engineering, and magnetic resonance imaging (MRI) contrast agents.

MIUIC: A Human-Computer Collaborative Multimodal Intention-Understanding Algorithm Incorporating Comfort Analysis

The naturalness and safety of human-computer interaction have always been primary research focuses in the field of human-computer interaction. This paper proposes a multimodal intention understanding algorithm (MIUIC), which incorporates comfort analysis, as a solution to address the issues of low intention understanding rate, weak interaction, and weak collaboration that are often observed in most massage systems. The algorithm efficiently fuses multimodal data based on objective implicit information to address the challenge of low intention understanding rates caused by non-standard expression of natural behavior. Moreover, this algorithm incorporates comfort reasoning to detect and address intentions related to security threats while providing the ability for robots to make behavioral decisions through inverse active interaction, leading to more equitable human-robot interactions. To test the validity and safety of the MIUIC algorithm, we embedded the algorithm into a mechanical arm massage system. Subsequently, 45 elderly volunteers were invited to participate in experimental tests. Finally, to verify the validity and safety of the MIUIC algorithm, we assessed the algorithm in terms of four aspects, including multimodal intention recognition rate, the ability to reduce data dispersion, the intention enhancement rate under reverse human-machine interaction, and the rate of avoiding dangerous intentions. In conclusion, the MIUIC algorithm enhances the intention understanding rate and promotes.

Preparation and properties of multiple dynamically crosslinked self-healing poly(siloxane-urethane) flexible sensor

The flexible sensor with self-healing performance can heal itself when the sensor is damaged by the outside world, so it can significantly improve the service life of the sensor and reduce the repair cost, which has attracted widespread attention. However, currently, most flexible sensors with self-healing performance have problems such as single repair conditions and difficulty in balancing mechanical performance and repair efficiency. In this study, polypyrrole modified carbon nanotubes (PPY/CNTs) were first made, and then, inspired by the Chinese traditional myth “Nuwa Fuxi”, a multiple dynamic crosslinking self-healing composite poly(siloxane-urethane) conductive elastomer (CPUSi) was successfully developed. The prepared CPUSi has excellent mechanical properties (11.27 MPa) and total shear repair efficiency (84%) under the excitation of multiple dynamic reversible interactions. At the same time, the surface scratch of CPUSi can be self-healing under multiple conditions such as heating at 60 °C, infrared light and ultraviolet light. The scratch repair efficiency is up to 99.9% under infrared light for 2 h. in addition, CPUSi has cyclic response to temperature and strain, so the material has broad application prospects in sports monitoring, electronic skin, intelligent wear, brain-computer interface and other fields

Phytic acid assist for self-healing nanocomposite hydrogels and their application in flexible strain sensors

Nanocomposite hydrogels have been applied in the field of flexible sensors to monitor human body signals. In this manuscript, phytic acid (PA) was successfully adsorbed on the surface of graphene oxide@polydopamine (GO@PDA). The obtained graphene oxide@polydopamine-phytic acid (GO@PDA-PA) was further implanted to the poly acrylic acid (PAA) hydrogels as flexible strain sensors. Dopamine (DA) was self-polymerized on both two sides of GO by mussel-inspired chemistry to synthetize GO@PDA. PA was decorated on the surface of GO@PDA to obtain GO@PDA-PA nanocomposites with Pickering emulsion in oil-in-water (O/W) emulsion. The GO@PDA-PA hydrogels’ self-healing efficiency (98.6%) and mechanical strength (1.77 MPa) were both improved due to the presence of reversible interaction such as hydrogen bond and metal-ligand coordination. The wearable flexible sensors based on the prepared GO@PDA-PA hydrogels have high sensitivity (gauge factor (GF) = 3.3), stability, durability and high response ability. It can detect the sharp movement signals of human body and tiny movement signals such as breathing. The excellent performance of nanocomposite hydrogels is expected to promote the evolution of flexible sensors.

Constructing Ultrastable Metallo-Cages via In Situ Deprotonation/Oxidation of Dynamic Supramolecular Assemblies.

Coordination-driven self-assembly enables the spontaneous construction of metallo-supramolecules with high precision, facilitated by dynamic and reversible metal-ligand interactions. The dynamic nature of coordination, however, results in structural lability in many metallo-supramolecular assembly systems. Consequently, it remains a formidable challenge to achieve self-assembly reversibility and structural stability simultaneously in metallo-supramolecular systems. To tackle this issue, herein, we incorporate an acid-/base-responsive tridentate ligand into multitopic building blocks to precisely construct a series of metallo-supramolecular cages through coordination-driven self-assembly. These dynamic cagelike assemblies can be transformed to their static states through mild in situ deprotonation/oxidation, leading to ultrastable skeletons that can withstand high temperatures, metal ion chelators, and strong acid/base conditions. This in situ transformation provides a reliable and powerful approach to manipulate the kinetic features and stability of metallo-supramolecules and allows for modulation of encapsulation and release behaviors of metallo-cages when utilizing nanoscale quantum dots (QDs) as guest molecules.