Design of Stretchable and Conductive Self-Adhesive Hydrogels as Flexible Sensors by Guar-Gum-Enabled Dynamic Interactions.

The limited elasticity and inadequate bonding of hydrogels made from guar gum (GG) significantly hinder their widespread implementation in personalized wearable flexible electronics. In this study, we devise GG-based self-adhesive hydrogels by creating an interpenetrating network of GG cross-linked with acrylic, 4-vinylphenylboronic acid, and Ca2+. With the leverage of the dynamic interactions (hydrogen bonds, borate ester bonds, and coordination bonds) between -OH in GG and monomers, the hydrogel exhibits a high stretchability of 700%, superior mechanical stress of 110 kPa, and robust adherence to several substrates. The adhesion strength of 54 kPa on porcine skin is obtained. Furthermore, the self-adhesive hydrogel possesses stable conductivity, an elevated gauge factor (GF), and commendable durability. It can be affixed to the human body as a strain sensor to obtain precise monitoring of human movement behavior. Our research offers possibilities for the development of GG-based hydrogels and applications in wearable electronics and medical monitoring.

The Effect of Temperature and Shear on the Gelation of Cellulose Nanocrystals in Deep Eutectic Solvents.

With the flourishing development of 3D printing technology, the demand for printing materials has been increasing rapidly in recent years. In particular, physical gels formed by cellulose nanocrystals (CNCs) exhibit suitable shear-thinning behavior, high storage moduli, and high yield stresses for extrusion-based printing. While most studies use water as the dispersing medium to form CNC percolated gels, the dispersing behavior of CNCs in alternative solvents, such as deep eutectic solvents (DESs), has not been fully explored. Especially, DESs have low volatility and good ionic conductivity to form functional ionogels. Precise control of the rheological properties and selection of suitable dispersion processes continue to pose significant challenges. In light of this, we have devised a novel dispersion process employing thermal and shear treatments to facilitate the gelation of CNCs within DESs. A crude dispersion of CNCs in the DES underwent thermal treatment to partially remove the surface sulfate ester on CNCs. As a result, the repulsive force between CNCs decreases. A second shear then significantly increases the strength of CNC/DES gels potentially because of the increased rod-rod contacts. This approach enables the formation of high-strength gels at low concentrations of CNCs. Both thermal treatment and a second shear are crucial to forming strong percolated CNC gels. In short, we showed a simple strategy to facilitate the dispersion and gelation of CNCs for direct ink writing.

A Fluorescent Hydrogel with AIE Emission for Dehydration-Visualizable Wearable Sensors.

Hydrogel-based wearable sensors eventually experience dehydration, which negatively impacts their function, leading to decreased sensitivity. Monitoring the real-time water retention rate and sensing performance of wearable flexible sensors without dismantling them remains a significant difficulty. In this study, a molecule having aggregation-induced emission (AIE) properties in an aqueous environment has been developed and produced, which can combine with anionic guar gum and acrylic acid to create an AIE hydrogel. Wearable sensing electronic devices have the capability to track motion signals at various joints of the human body. Additionally, they can effectively and visually monitor dehydration status during extended periods of operation. The fluorescence intensity of the hydrogel is primarily influenced by the level of aggregation of luminous monomers inside the network. This level of aggregation is predominantly governed by the hydrogel's water retention rate. Hence, the extended duration of hydrogel dehydration can be manifested through alterations in their fluorescence characteristics, which are employed for strain sensing. This approach enables users to assess the water retention of hydrogels with greater efficiency, eliminating the requirement for disassembling them from the completed electrical gadget. In summary, the use of AIE-based fluorescent hydrogels will advance the progress of intelligent wearable electronics.

USP39 interacts with SIRT7 to promote cervical squamous cell carcinoma by modulating autophagy and oxidative stress via FOXM1.

BACKGROUND: Sirtuin 7 (SIRT7) is an oncogene that promotes tumor progression in various malignancies, however, its role and regulatory mechanism in cervical squamous cell carcinoma (CSCC) is unknown. Herein, we attempted to investigate the functional role and molecular mechanism of SIRT7 underlying CSCC progression. METHODS: SIRT7 expression was evaluated in CSCC cells using various assays. We then used a series of function gain-and-loss experiments to determine the role of SIRT7 in CSCC progression. Furthermore, mechanism experiments were conducted to assess the interaction between SIRT7/USP39/FOXM1 in CSCC cells. Additionally, rescue assays were conducted to explore the regulatory function of USP39/FOXM1 in CSCC cellular processes. RESULTS: SIRT7 was highly expressed in CSCC patient tissues and cell lines. SIRT7 deficiency showed significant repression on the proliferation, and autophagy of CSCC cells in vitro and tumorigenesis in vivo. Similarly, apoptosis and ROS production in CSCC cells were accelerated after the SIRT7 knockdown. Moreover, SIRT7 and USP39 were found colocalized in the cell nucleus. Interestingly, SIRT7 was revealed to deacetylate USP39 to promote its protein stability in CSCC cells. USP39 protein was also verified to be upregulated in CSCC tissues and cells. USP39 silencing showed suppressive effects on CSCC cell growth. Mechanistically, USP39 was revealed to upregulate SIRT7 by promoting the transcriptional activity of FOXM1. Rescue assays also indicated that SIRT7 promoted autophagy and inhibited ROS production in CSCC cells by regulating USP39/FOXM1. CONCLUSION: The SIRT7/USP39/FOXM1 positive feedback network regulates autophagy and oxidative stress in CSCC, thus providing a new direction for CSCC-targeted therapy.

Bioinspired simultaneous regulation in fluorescence of AIEgen-embedded hydrogels.

The development of stimuli-responsive functional fluorescent hydrogels is of great significance for the realization of artificial intelligence. In the present work, we design and synthesize a stimulus-responsive hydrogel embedded with an aggregation-induced emission (AIE) monomer, in which the fluorescence brightness and intensity can be tuned. The hydrogel embedded with tetraphenylethene-grafted-poly[3-sulfopropyl methacrylate potassium salt] (TPE-PSPMA) as the functional element is prepared by the radical polymerization method. Among them, the TPE core exhibits adaptive fluorescence ability through the AIE effect, while the PSPMA chain provides tunable hydrophilic properties under an external stimulus. The effect of different cationic surfactants with different lengths of hydrophobic tails on the fluorescence properties of TPE-PSPMA in solution is systematically investigated. With cationic surfactants, such as cetyltrimethylammonium bromide (CTAB), the fluorescence intensity is gradually tuned from 1059 to 4623. And the fluorescence intensities increase with the growth of hydrophobic tails of surfactants, which results from hydrophobicity-induced electrostatic interactions among surfactants and polymer chains. Furthermore, an obvious tunable fluorescence feature of hydrogel copolymerized TPE-PSPMA is realized, resulting from the change of brightness and the dynamic increase of fluorescence intensity (from 1031 to 3138) for the hydrogel immersed in CTAB solution with different soaking times. Such a typical fluorescence-regulated behavior can be attributed to the AIE of the TPE-PSPMA chain and the electrostatic interaction between the surfactant and the anionic polymer chain. The designed TPE-PSPMA-based hydrogel is responsive to stimuli, inspiring the development of intelligent systems such as soft robots and smart wearables.

Stimuli-Responsive Supramolecular Chirality Switching and Nanoassembly Constructed by n-Shaped Amphiphilic Molecules in Aqueous Solution.

Self-assembled nanomaterials composed of amphiphilic oligomers with functional groups have been applied in the fields of biomimetic chemistry and on-demand delivery systems. Herein, we report the assembly behavior and unique properties of an emergent n-shaped rod-coil molecule containing an azobenzene (AZO) group upon application of an external stimulus (thermal, UV light). The n-shaped amphiphilic molecules comprising an aromatic segment based on anthracene, phenyl linked with azobenzene groups, and hydrophilic oligoether (chiral) segments self-assemble into large strip-like sheets and perforated-nanocage fragments in an aqueous environment, depending on the flexible oligoether chains. Interestingly, the nano-objects formed in aqueous solution undergo a morphological transition from sheets and nanocages to small one-dimensional nanofibers. These molecules exhibit reversible photo- and thermal-responsiveness, accompanied by a change in the supramolecular chirality caused by the conformational transitions of the rod backbone. The architecture of n-shaped amphiphilic molecules with a photosensitive group makes them ideal candidates for intelligent materials for applications in advanced materials science.

The construction of an artificial light-harvesting system with two-step sequential energy transfer based on supramolecular polymers.

An artificial light-harvesting system with two-step sequential energy transfer was constructed in aqueous media based on cyano-substituted p-phenylenevinylene derivative (PPTA) and bis-(p-sulfonatocalix[4]arenes) (BSC4) supramolecular polymers formed through host-guest interactions, in which two different fluorescent dyes, eosin Y (EY) and sulforhodamine (SR101), were employed as energy acceptors. The obtained artificial light-harvesting system can achieve an efficient two-step energy transfer process from PPTA-BSC4 to EY and then to SR101 with high energy-transfer efficiencies of up to 36.6% and 40.8%, respectively. More importantly, the harvested energy from the PPTA-BSC4 + EY + SR101 system can be used to promote the dehalogenation of α-bromoacetophenone with a yield of 89% in aqueous solution.

The effect of temperature on the kinetics of enhanced amide bond formation from lactic acid and valine driven by deep eutectic solvents.

Deep eutectic solvents have been found to facilitate the copolymerization of hydroxy acids and amino acids through an ester-amide exchange reaction, and to drive the formation of amino acid-enriched oligomers with peptide backbones. The complexity of oligomer distribution is significantly reduced in deep eutectic solvents and amide-linked oligomers can be selectively produced. In the present study, we investigated the kinetics of amide bond formation in deep eutectic solvents to understand how the solvents regulate the pathways of complex copolymerization. A mathematical model successfully simulated the reaction of a lactic acid/valine mixture in deep eutectic solvents at different temperatures and provided insight into the activation energy of each step. Our findings indicated that the esterification and the evaporation of hydroxy acids were greatly suppressed in deep eutectic solvents because of the strong interaction between the quaternary ammonium salts and the hydroxy acids. In contrast, the ester-amide exchange reaction in deep eutectic solvents was significantly enhanced by lowering the activation entropies. The synergic effect of reduced esterification and increased exchange leads to amino acid-enriched oligomers with high yield and high selectivity. Furthermore, the reduced evaporation of hydroxy acids in deep eutectic solvents may preserve limited reactants in the prebiotic scenario. These results reveal deep eutectic solvents as sustainable media for the simple synthesis of amide bonds.

Health-care resource utilization associated with peanut allergy management under allergen avoidance among commercially insured individuals.

Background: Until recently, the standard approach to care for individuals with peanut allergy (PA) was limited to allergen avoidance and treatment of reactions with emergency medicines. Objectives: To assess health-care resource utilization (HRU) and costs associated with PA management under allergen avoidance and to identify risk factors associated with peanut reactions that resulted in inpatient (IP) and/or emergency department (ED) visits. Methods: Privately insured individuals with PA diagnosis codes were identified from a large U.S. administrative claims data base (January 1, 1999, to March 31, 2017). PA-related HRU, indicated by a PA diagnosis and/or diagnostic procedure codes and by epinephrine autoinjectors (EAI) prescription fills in medical and pharmacy claims, respectively, and all-cause costs were described per patient-year (PPY). Risk factors associated with peanut reactions in an IP and/or ED setting were identified by using a multivariable logistic regression model. Results: A total of 86,483 patient-years from 14,136 individuals with PA were included. At the patient-year level, 28.1% were ages 0-3 years, 43.6% were ages 4-11 years, 13.7% were ages 12-17 years, and 14.5% were ages ≥ 18 years; 35.6% had PA-related outpatient visits; 50.6% had EAI fills; and 2.4% had PA-related IP and/or ED visits PPY. Younger individuals had more PA-related outpatient visits and EAI fills, with peak intensive use at ages 4-11 years. The proportion of individuals with PA-related IP and/or ED visits was highest among those aged ≥ 18 years. Mean all-cause costs were $3084 PPY; individuals with PA-related IP and/or ED visits incurred $8902 PPY ($17,451 for those with one or more IP visits). Risk factors associated with peanut reactions that resulted in IP and/or ED visits included young adults (odds ratio [OR] 3.19 [95% confidence interval {CI}, 2.66-3.83]), previous peanut reaction(s) (OR 1.66 [95% CI, 1.23-2.24]), asthma (OR 1.33 [95% CI, 1.18-1.51]), and male sex (OR 1.14 [95% CI, 1.01-1.28]). Conclusion: Individuals with PA and under allergen avoidance had significant HRU that varied across all age groups, with more PA-related outpatient visits during preschool and/or school age and PA-related urgent care among adults. Individuals with previous peanut reaction(s), asthma, and males had a higher risk of peanut reactions that resulted in IP and/or ED visits.

The relationship between molecular structure and supramolecular morphology in the self-assembly of rod-coil molecules with oligoether chains.

Controlling the morphology of rod-coil molecular aggregates is crucial for studying and obtaining functional materials with exceptional properties. In this paper, we report the construction of rod-coil molecular nanoaggregates with well-defined structures. The rod-coil molecules, labeled 1a-1d, consist of a rod section, composed of phenyl and biphenyl groups, and oligoether chains with 7 and 12 repeating units. The final assembled structures showed either oblique or hexagonal columnar structures, depending on the length of the coils in the bulk state. Interestingly, in water, molecules 1a and 1c self-assemble into scrolled nanofibers and cylindrical micelles. Instead, molecules 1b and 1d, which have methyl groups decorated at the interface of the rod and coil sections, self-organize into helical nanofibers and nanorings, respectively. Thus, controlling the length of the coil chains and inserting lateral methyl groups is an effective strategy to construct precise rod-coil molecular assemblies in the bulk and in aqueous solution.

Surveying the sequence diversity of model prebiotic peptides by mass spectrometry.

The rise of peptides with secondary structures and functions would have been a key step in the chemical evolution which led to life. As with modern biology, amino acid sequence would have been a primary determinant of peptide structure and activity in an origins-of-life scenario. It is a commonly held hypothesis that unique functional sequences would have emerged from a diverse soup of proto-peptides, yet there is a lack of experimental data in support of this. Whereas the majority of studies in the field focus on peptides containing only one or two types of amino acids, here we used modern mass spectrometry (MS)-based techniques to separate and sequence de novo proto-peptides containing broader combinations of prebiotically plausible monomers. Using a dry-wet environmental cycling protocol, hundreds of proto-peptide sequences were formed over a mere 4 d of reaction. Sequence homology diagrams were constructed to compare experimental and theoretical sequence spaces of tetrameric proto-peptides. MS-based analyses such as this will be increasingly necessary as origins-of-life researchers move toward systems-level investigations of prebiotic chemistry.

Formation and Fate of Formaldehyde in Methanol-to-Hydrocarbon Reaction: In Situ Synchrotron Radiation Photoionization Mass Spectrometry Study.

HCHO has been confirmed as an active intermediate in the methanol-to-hydrocarbon (MTH) reaction, and is critical for interpreting the mechanisms of coke formation. Here, HCHO was detected and quantified during the MTH process over HSAPO-34 and HZSM-5 by in situ synchrotron radiation photoionization mass spectrometry. Compared with conventional methods, excellent time-resolved profiles were obtained to study the formation and fate of HCHO, and other products during the induction, steady-state reaction, and deactivation periods. Similar formation trends of HCHO and methane, and their close correlation in yields suggest that they are derived from disproportionation of methanol at acidic sites. In the presence of Y2 O3 , the amount of HCHO changes, affecting the hydrogen-transfer processes of olefins into aromatics and aromatics into cokes. The yield of HCHO affects the aromatic-based cycle and the formation of ethylene, indicating that ethylene is mainly formed from the aromatic-based cycle.

Supramolecular helical nanostructures from self-assembly of coil-rod-coil amphiphilic molecules incorporating the dianthranide unit.

Coil-rod-coil amphipathic oligomers composed of a rigid dianthranide unit and a hydrophilic branched oligoether as the coil segment were synthesized. These amphiphilic molecules self-assemble into clew-like aggregates composed of fibres or helical nanofibers in aqueous solution. Subsequently, supramolecular polymers were produced from the above objects through charge-transfer interactions by adding 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (4F-TCNQ). Interestingly, temperature-sensitive supramolecular chirality was induced by lateral methyl units located at the interface of the rigid and flexible segments. However, upon addition of the electron-acceptor molecule, 4F-TCNQ, strong donor-acceptor interactions restrict any change in supramolecular chirality with temperature.

Kinetics of prebiotic depsipeptide formation from the ester-amide exchange reaction.

In this work, we introduce a kinetic model to study the effectiveness of ester-mediated amide bond formation under prebiotic conditions. In our previous work, we found that a simple system composed of α-hydroxy acids and α-amino acids is capable of forming peptide bonds via esterification followed by the ester-amide exchange reaction. To further understand the kinetic behavior of this copolymerization, we first tracked the growth of initial species from a valine/lactic acid mixture in a closed system reactor. A mathematical model was developed to simulate the reactions and evaluate the rate constants at different temperatures. We found these reactions can be described by the empirical Arrhenius equation even when reaction occurred in the solid (dry) state. Further calculations for activation parameters showed that the ester-mediated pathway facilitates amide bond formation by lowering activation entropies. These results provide a theoretical framework that illustrates why the ester-mediated pathway for peptide bond formation is efficient and why it would have been more favorable on the early Earth, compared to peptide bond formation without the aid of hydroxy acids.

Ester-Mediated Amide Bond Formation Driven by Wet-Dry Cycles: A Possible Path to Polypeptides on the Prebiotic Earth.

Although it is generally accepted that amino acids were present on the prebiotic Earth, the mechanism by which α-amino acids were condensed into polypeptides before the emergence of enzymes remains unsolved. Here, we demonstrate a prebiotically plausible mechanism for peptide (amide) bond formation that is enabled by α-hydroxy acids, which were likely present along with amino acids on the early Earth. Together, α-hydroxy acids and α-amino acids form depsipeptides-oligomers with a combination of ester and amide linkages-in model prebiotic reactions that are driven by wet-cool/dry-hot cycles. Through a combination of ester-amide bond exchange and ester bond hydrolysis, depsipeptides are enriched with amino acids over time. These results support a long-standing hypothesis that peptides might have arisen from ester-based precursors.

Superoxide radical generator based on triphenylamine-based supramolecular organic framework for green light photocatalysis.

Supramolecular organic frameworks (SOFs) mostly require high-energy purple or blue light for photocatalytic reactions, while highly abundant and low-energy light systems have rarely been explored. Therefore, it is necessary to construct 2D SOFs for low-energy light-induced photocatalysis. This study describes the design and synthesis of a water-soluble two-dimensional (2D) supramolecular organic framework (TP-SOF) using the host-guest interaction between a triphenylamine derivative (TP-3Py) and cucurbit[8]uril (CB[8]). The formation of the 2D SOF can be attributed to the synergistic impact resulting from the orientated head-to-tail superposition mode between the vinylpyridine arms of TP-3Py and CB[8], which results in a significant redshift in the UV-vis absorption spectrum, especially displaying a strong absorption band in the green light region. The monomeric TP-3Py can effectively produce singlet oxygen (1O2) and realize the photocatalytic oxidation of thioanisole in the aqueous solution. In comparison to monomeric TP-3Py, the confinement effect of CB[8] results in a notable enhancement in the production efficiency of superoxide anion radicals (O2•-), exhibiting promising prospects in the field of photocatalytic oxidation reaction, which facilitates the application of TP-SOF as a very efficient photosensitizer for the promotion of the oxidative hydroxylation of arylboronic acids under green light in the aqueous solution, giving a high yield of 91%. The present study not only presents a compelling illustration of photocatalysis utilizing a 2D SOF derived from triphenylamine, but also unveils promising avenues for the photocatalytic oxidation of SOF employing low-energy light systems.

Switchover from singlet oxygen to superoxide radical through a photoinduced two-step sequential energy transfer process.

The competitive nature of type II photosensitizers in the transfer of excitation energy for the generation of singlet oxygen (1O2) presents significant challenges in the design of type I photosensitizers to produce the superoxide anion radical (O2˙-). In this study, we present an efficient method for the direct transformation of type II photosensitizers into type I photosensitizers through the implementation of an artificial light-harvesting system (ALHSs) involving a two-step sequential energy transfer process. The designed supramolecular complex (DNPY-SBE-ß-CD) not only has the ability to generate 1O2 as type II photosensitizers, but also demonstrates remarkable fluorescence properties in aqueous solution, which renders it an efficient energy donor for the development of type I photosensitizers ALHSs, thereby enabling the efficient generation of O2˙-. Meanwhile, to ascertain the capability and practicality of this method, two organic reactions were conducted, namely the photooxidation reaction of thioanisole and oxidative hydroxylation of arylboronic acids, both of which display a high level of efficiency and exhibit significant catalytic performance. This work provides an efficient method for turning type II photosensitizers into type I photosensitizers by a two-step sequential energy transfer procedure.

Photocatalytic selective oxidation of toluene under encapsulated air conditions.

Benzaldehydes are indispensable building blocks in chemistry. However, the selective oxidation of toluene to benzaldehyde remains an ongoing challenge due to the low oxidation potential of benzaldehyde compared to toluene. We report herein a mild protocol that combines hydrogen atom transfer (HAT) with encapsulated air conditions and suitable catalyst loading for selective oxidation of toluene with high selectivity as well as good functional-group tolerance and a broad substrate scope for the synthesis of various high-value aromatic aldehydes. Moreover, the compatibility of this reaction with toluene derivatives of bioactive molecules further demonstrated the practicality of this approach. Mechanism studies have demonstrated that the collaboration between the oxygen quantity and the HAT catalytic system has a major impact on the high selectivity of the reaction. This study not only showcases the effectiveness of HAT strategies toward selective oxidation of toluene to benzaldehyde, but also provides an approach to controlling the selectivity of HAT reactions.

A supramolecular photosensitizer based on triphenylamine and pyrazine with aggregation-induced emission properties for high-efficiency photooxidation reactions.

Recently, there has been a great interest in the study of photocatalysts (PCs) and photosensitizers (PSs) in the field of organic photocatalysis. In the present study, a pure organic thermally activated delayed fluorescence (TADF) molecule 4,4'-(12-(pyridin-4-yl)dibenzo[f,h]pyrido[2,3-b]quinoxaline-3,6-diyl)bis(N,N-diphenylaniline) (DPQ-TPA) was designed and synthesized, which not only have excellent TADF property and small energy splitting (ΔEST), but also can self-assembly in water to form cross-linked nanoparticles with exceptional aggregation-induced emission (AIE) characteristics. DPQ-TPA exhibits excellent remarkable selectivity and notably enhances the production capacity of reactive oxygen species (ROS), particularly 1O2, which was employed as a highly effective photocatalyst in the photooxidation reaction of phosphine and hydroazobenzenes under blue light irradiation with high yields up to 94% and 91%, respectively. This work expands the potential application of (donor-acceptor) D-A type AIE-TADF molecules in photocatalytic organic transformations through supramolecular self-assembly.

Visible-light-mediated direct C3 alkylation of quinoxalin-2(1H)-ones using alkanes.

Due to the high C-H bond dissociation energy of alkanes, the utilization of alkanes as alkyl radical precursors for C-H functionalization of heteroarenes is synthetically captivating but practically challenging, especially under metal- and photocatalyst-free conditions. We report herein a mild and practical visible-light-mediated method for C-H alkylation of quinoxalin-2(1H)-ones using trifluoroacetic acid as a hydrogen atom transfer reagent and air as an oxidant. This mild protocol was performed under metal- and photocatalyst-free circumstances and presented good functional-group tolerance as well as a broad substrate scope.