Ultrasensitive Flexible Temperature Sensors Based on Thermal-Mediated Ions Migration Dynamics in Asymmetrical Polymer Bilayers.

Accurately acquiring crucial data on the ambient surroundings and physiological processes delivered via subtle temperature fluctuation is vital for advancing artificial intelligence and personal healthcare techniques but is still challenging. Here, we introduce an electrically induced cation injection mechanism based on thermal-mediated ion migration dynamics in an asymmetrical polymer bilayer (APB) composed of nonionic polymer and polyelectrolyte layers, enabling the development of ultrasensitive flexible temperature sensors. The resulting optimized sensor achieves ultrahigh sensitivity, with a thermal index surpassing 10,000 K-1, which allows identifying temperature differences as small as 10 mK with a sensitivity that exceeds 1.5 mK. The mechanism also enables APB sensors to possess good insensitivity to various mechanical deformations─features essential for practical applications. As a proof of concept, we demonstrate the potential impact of APB sensors in various conceptual applications, such as mental tension evaluation, biomimetic thermal tactile, and thermal radiation detection.

High-compact MXene-based coatings by controllable interfacial structures.

Titanium carbide (Ti3C2Tx) MXenes have been regarded as important functional fillers of organic coatings for anticorrosion. Various MXene-based composite coatings have been fabricated and investigated via a material modification strategy, enhancing the corrosion protection performance. However, the anticorrosion reliabilities of MXene-based composite coatings were thwarted by their disordered interfaces. Significantly, few reports discuss the influence of interface structures on the protection performance for the coatings. In this work, we confirm the exceptional anticorrosion performance of ordered MXene/epoxy composite (OMC) coatings via a reasonable interface strategy. The ordered interfacial structure can synergistically enhance the coating compactness while maximizing the infiltration paths of aggressive species. The obtained OMC coating is compact and shows a high impedance of 6.84 × 109 Ohm cm2, a high coating resistance of 6.08 × 109 Ohm cm2, an extremely low porosity of 0.77% and an extremely low breakpoint frequency of 0.18 Hz, at a low filler content of 0.5 wt%. Besides, the concept of specific impedance (SZ) is proposed to attest the superiority of the OMC coating. Furthermore, the galvanic corrosion effects of MXenes in epoxy coatings are systematically explored and confirmed for the first time. The highly ordered structure eliminates the corrosion promotion activity of the conductive MXene, and thus, endows the superior anticorrosion stability for the coating. This work provides an inspiration for constructing outstanding long-term MXene-based anticorrosion coatings via regulating the coating interface.

Wearable Temperature Sensor with High Resolution for Skin Temperature Monitoring.

Flexible temperature sensors with high resolution and good reliability under deformation are a major research focus for wearable electronic devices for skin temperature monitoring. In this study, a fiber-like temperature sensor is fabricated by in situ growing poly(3,4-ethylenedioxythiophene) (PEDOT) on the surface of thermoplastic polyurethane (TPU) fiber. The temperature sensor achieves a high sensitivity of 0.95%·°C-1 with a high linearity between 20 and 40 °C. Most importantly, the sensor achieves a high temperature resolution of 0.2 °C. Due to its structure, the temperature-sensitive fiber is easily embedded into textiles. By sewing the fiber into normal textiles in an S-shape, the interference of strain can be nearly avoided, even when the textile is stretched to 140%. Also, the obtained sensors can monitor skin temperature during exercise, which demonstrates the potential of the sensor's application in healthcare and disease diagnosis.

High Glucose Aggravates Retinal Endothelial Cell Dysfunction by Activating the RhoA/ROCK1/pMLC/Connexin43 Signaling Pathway.

Purpose: This research aims to explore the mechanism underlying the relationship between RhoA/ROCK signaling and Connexin43 (Cx43) in retinal endothelial cell dysfunction and to evaluate the protective effect of ROCK inhibitors against retinal endothelial cell dysfunction in diabetic retinopathy (DR) models. Methods: TUNEL staining, hematoxylin and eosin staining, a retinal digestion assay, and Evans blue assay were conducted to explore the effect of fasudil in alleviating retinal dysfunction induced by DR. ELISA, the CCK-8 assay, and flow cytometry were conducted to study inflammation, viability, and apoptosis of mouse retinal microvascular endothelial cells treated with high glucose and ROCK inhibitors. The qRT-PCR and Western blotting were used to evaluate the expression of RhoA, ROCK1, ROCK2, MLC, pMLC, and Cx43. Co-immunoprecipitation was used to verify the interaction between pMLC and Cx43. Immunofluorescence and scrape-loading and dye transfer were used to evaluate the expression and function of Cx43. Results: Marked endothelial cell dysfunction resulting from the activation of RhoA/ROCK1 signaling was found in in vivo and in vitro models of DR. Via interaction with pMLC, which is downstream of RhoA/ROCK1, a significant downregulation of Cx43 was observed in retinal endothelial cells. Treatment with ROCK inhibitors ameliorated retinal endothelial dysfunction in vitro. The ROCK inhibitor, fasudil, significantly alleviated retinal dysfunction as shown by a decrease of retinal acellular capillaries, an improvement of vascular permeability, and a reduction of cell apoptosis in vivo. Conclusions: Our study highlights a novel mechanism that high glucose could activate RhoA/ROCK1/pMLC signaling, which targets the expression and localization of Cx43 and is responsible for cell viability, apoptosis, and inflammation, resulting in retinal endothelial cell injury. ROCK inhibitors markedly ameliorate endothelial cell dysfunction, suggesting their therapeutic potential for diabetic retinopathy.

All-Nanofibrous Ionic Capacitive Pressure Sensor for Wearable Applications.

Currently, with the development of electronic skins (e-skins), wearable pressure sensors with low energy consumption and excellent wearability for long-term physiological signal monitoring are urgently desired but remain a challenge. Capacitive-type devices are desirable candidates for wearable applications, but traditional capacitive pressure sensors are limited by low capacitance and sensitivity. In this study, an all-nanofibrous ionic pressure sensor (IPS) is developed, and the formation of an electrical double layer at the electrode/electrolyte contact interface significantly enhances the capacitance and sensing properties. The IPS is fabricated by sandwiching a nanofibrous ionic gel sensing layer between two thermoplastic polyurethane nanofibrous membranes with graphene electrodes. The IPS has a high sensitivity of 217.5 kPa-1 in the pressure range of 0-5 kPa, which is much higher than that of conventional capacitive pressure sensors. Combined with the rapid response and recovery speed (30 and 60 ms), the IPS is suitable for real-time monitoring of multiple physiological signals. Moreover, the nanofiber network endows the IPS with excellent air permeability and heat dissipation, which guarantees comfort during long-term wearing. This work provides a viable strategy to improve the wearability of wearable sensors, which can promote healthcare and human-machine interaction applications.

Targeted P2X7/NLRP3 signaling pathway against inflammation, apoptosis, and pyroptosis of retinal endothelial cells in diabetic retinopathy.

Retinal endothelial cells (RECs) are the primary target cells for diabetes-induced vascular damage. The P2X7/NLRP3 pathway plays an essential role in amplifying inflammation via an ATP feedback loop, promoting the inflammatory response, pyroptosis, and apoptosis of RECs in the early stages of diabetic retinopathy induced by hyperglycemia and inflammation. 3TC, a type of nucleoside reverse transcriptase inhibitor, is effective against inflammation, as it can targeting formation of the P2X7 large pore formation. Hence, our aim was to evaluated the anti-inflammatory effects and potential mechanisms of action of 3TC in vitro in retinal microvascular endothelial cells treated with high-glucose (HG) and lipopolysaccharide (LPS), as well as in vivo in the retinas of C57BL/6J male mice with streptozotocin-induced diabetes. The expression of inflammasome-related proteins P2X7 and NLRP3, and apoptosis in the retinas of 3TC-treated diabetic mice were compared to those of untreated diabetic mice. Furthermore, the anti-inflammatory, anti-apoptotic, and anti-pyroptotic effects of 3TC were evaluated in vitro in cultured mice retinal endothelial cells. Co-application of HG and LPS significantly increased the secretion of IL-6, IL-1ß, and TNF-α, and ATP levels, whereas 3TC decreased cell inflammation, apoptosis, and pyroptosis. Inhibition of P2X7R and NLRP3 inflammasome activation decreased NLRP3 inflammasome-mediated injury. 3TC prevented cytokine and ATP release following co-application of HG and LPS/BzATP. Our findings provide new insights regarding the mechanisms of action of 3TC in diabetic environment-induced retinal injury, including apoptosis and pyroptosis.

RNA-Binding Proteins and Alternative Splicing Genes Are Coregulated in Human Retinal Endothelial Cells Treated with High Glucose.

To explore the relevant RNA-binding proteins (RBPs) and alternative splicing events (ASEs) in diabetic retinopathy (DR). We devised a comprehensive work to integrate analyses of the differentially expressed genes, including differential RBPs, and variable splicing characteristics related to DR in human retinal endothelial cells induced by low glucose and high glucose in dataset GSE117238. A total of 2320 differentially expressed genes (DEGs) were identified, including 1228 upregulated genes and 1092 downregulated genes. Further analysis screened out 232 RBP genes, and 42 AS genes overlapped DEGs. We selected high expression and consistency six RBP genes (FUS, HNRNPA2B1, CANX, EIF1, CALR, and POLR2A) for coexpression analysis. Through analysis, we found eight RASGs (MDM2, GOLGA2P7, NFE2L1, KDM4A, FAM111A, CIRBP, IDH1, and MCM7) that could be regulated by RBP. The coexpression network was conducted to further elucidate the regulatory and interaction relationship between RBPs and AS. Apoptotic progress, protein phosphorylation, and NF-kappaB cascade revealed by the functional enrichment analysis of RASGs regulated by RBPs were closely related to diabetic retinopathy. Furthermore, the expression of differentially expressed RBPs was validated by qRT-PCR in mouse retinal microvascular endothelial cells and retinas from the streptozotocin mouse model. The results showed that Fus, Hnrnpa2b1, Canx, Calr, and Polr2a were remarkedly difference in high-glucose-treated retinal microvascular endothelial cells and Fus, Hnrnpa2b1, Canx, and Calr were remarkedly difference in retinas from streptozotocin-induced diabetic mice compared to control. The regulatory network between identified RBPs and RASGs suggests the presence of several signaling pathways possibly involved in the pathogenesis of DR. The verified RBPs should be further addressed by future studies investigating associations between RBPs and the downstream of AS, as they could serve as potential biomarkers and targets for DR.

A flexible electrochemical biosensor based on functionalized poly(3,4-ethylenedioxythiophene) film to detect lactate in sweat of the human body.

Conductive polymers with good flexibility, conductivity and film-forming ability attract a lot of attention. In this work, a large-area and ordered structure poly(3,4-ethylenedioxythiophene) (PEDOT) film is fabricated at the air-water interface through interface synthesis method. The PEDOT film can be directly placed on a flexible screen-printed electrode, but also has good adhesion between them. The surface of the PEDOT film is relatively smooth, and has good electrical conductivity and flexibility. Lactate oxidase is immobilized on the surface of PEDOT film through a combination of cross-linking and adsorption method to enhance the lactate sensitive performances. The results show that the PEDOT film sensor has excellent stability and reproducibility. The PEDOT film sensor shows a good response to lactate, the working range is 0.25-40 mmol L-1, and the detection limit is 0.083 mmol L-1 (S/N = 3). Moreover, the electrochemical sensor has potential application in detecting lactate in sweat of the human body.

A dual-functional polyaniline film-based flexible electrochemical sensor for the detection of pH and lactate in sweat of the human body.

A flexible dual functional electrochemical sensor based on macroscopic polyaniline (PANI) film is reported. The PANI film is prepared by interfacial synthesis without any additional templates and surfactants, and is easily transferred from the water surface to any substrate. The surface of PANI film is flat and has a certain degree of crystallization. The PANI film exhibits good electrochemical properties, which is attributed to the order structure of PANI. The flexible sensor based on PANI film exhibits good electrochemical performances to pH and lactate. And the flexible PANI sensor has good reproducibility, selectivity and long-term stability. Meanwhile, the PANI sensor is also applied to detect the actual sample (such as food and human sweat), and the results are in accordance with the commercial pH meter, indicating the reliability of the PANI sensor.

Bio-inspired Multifunctional Graphene-Epoxy Anticorrosion Coatings by Low-Defect Engineered Graphene.

Although graphene has been regarded as the most ideal anticorrosion filler, to date, some vital problems including poor dispersion, disordered arrangement, structure defects, and galvanic corrosion remain unresolved,, thus blocking its potential application in metal protection. In this work, a bio-inspried multilayered graphene-epoxy composite coating was fabricated through a scalable spraying approach with well-dispersed low-defect engineered graphene as the functional filler. Polydopamine served as an enforcer to improve the dispersity and repair the structure defects of graphene (π-π interaction) and bridged the dense graphene layers and epoxy layers (strong adhesion) for forming "interlock" structures to ensure complete coating systems. Electrochemical tests confirmed that the bio-inspired composite coating showed elevated coating resistance from 4.2 × 106 Ω cm2 for blank coating and 2.5 × 108 Ω cm2 for blending composite coating to 3.0 × 109 Ω cm2. The highly anisotropic graphene layers endowed the bio-inspried coating with highly anisotropic thermal and electrical conductivities, with the in-plane and through-plane thermal conductivities being 0.78 and 0.21 W/mK, respectively. Besides, the good anisotropic conductivities make the bio-inspired coating achieve self-monitoring of structural safety and health. This bio-inspired strategy provides a fascinating method for constructing high-performance graphene composite coatings with functional properties.

Biocompatible Multifunctional E-Skins with Excellent Self-Healing Ability Enabled by Clean and Scalable Fabrication.

Electronic skins (e-skins) with an excellent sensing performance have been widely developed over the last few decades. However, wearability, biocompatibility, environmental friendliness and scalability have become new limitations. Self-healing ability can improve the long-term robustness and reliability of e-skins. However, self-healing ability and integration are hardly balanced in classical structures of self-healable devices. Here, cellulose nanofiber/poly(vinyl alcohol) (CNF/PVA), a biocompatible moisture-inspired self-healable composite, was applied both as the binder in functional layers and the substrate. Various functional layers comprising particular carbon materials and CNF/PVA were patterned on the substrate. A planar structure was beneficial for integration, and the active self-healing ability of the functional layers endowed self-healed e-skins with a higher toughness. Water served as both the only solvent throughout the fabrication process and the trigger of the self-healing process, which avoids the pollution and bioincompatibility caused by the application of noxious additives. Our e-skins could achieve real-time monitoring of whole-body physiological signals and environmental temperature and humidity. Cross-interference between different external stimuli was suppressed through reasonable material selection and structural design. Combined with conventional electronics, data could be transmitted to a nearby smartphone for post-processing. This work provides a previously unexplored strategy for multifunctional e-skins with an excellent practicality.

Highly sensitive and chemically stable NH3 sensors based on an organic acid-sensitized cross-linked hydrogel for exhaled breath analysis.

Due to interference by the high moisture content and complicated compositions of human exhaled breath, the trace-level detection of ammonia (NH3) with desirable selectivity and stability is a large challenge for exhaled breath analysis. Carboxyl-sensitized hydrogels can be activated by moisture to exhibit a significant response and excellent selectivity to NH3. However, the high activity of carboxyl groups in hydrogels is a double-edged sword, resulting in poor chemical stability during NH3 detection. Herein, organic acids were embedded into a cross-linked poly(ethylene glycol) diacrylate (PEGDA) hydrogel via thiol-ene photochemistry to form stable hydrogels for NH3 detection in a humid atmosphere. As a result, under high humidity conditions (80% RH), the optimal sensors exhibited superior selectivity to NH3 among various interfering gas species, a remarkably high NH3 response (Za/Zg=6.20) towards 20 ppm NH3, and an extremely low actual detection limit (50 ppb) at room temperature. Moreover, the sensors exhibited excellent chemical stability due to the moderate equilibrium water content of the hydrogel composites and acid dissociation constant of the acid groups. The moisture-activated NH3 sensing mechanism was thoroughly investigated by complex impedance spectroscopy (CIS), quartz crystal microbalance (QCM) measurements, Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). To explore the application prospects of cross-linked hydrogel sensors for detecting NH3 in exhaled breath, a simulated exhaled breath test was also performed.

Humidity sensors based on metal organic frameworks derived polyelectrolyte films.

Application of metal organic frameworks (MOFs) on sensors is of great interest for researchers. Film forming ability of the sensing material is very important for both the preparation process and sensing properties of the devices. Humidity sensors based on UIO-66 derived polyelectrolyte films were well prepared by in situ thiol-ene click cross-linking polymerization in this work. The hydrophilicity of the sensing film could be controlled by the feed ratios. The optimized humidity sensor shows a fast response to RHs change (Res/Rec time is 3.1 s/1.5 s, respectively) with ∼1.2% RH of humidity hysteresis. The water molecules adsorption behavior of the film and the sensing mechanism were also be investigated. The humidity sensor with good water and thermal stability and repeatability was applied in breath monitoring, which can well distinguish different breath states.

Correction: An ultrahigh thermal conductive graphene flexible paper.

Correction for 'An ultrahigh thermal conductive graphene flexible paper' by Jiheng Ding et al., Nanoscale, 2017, 9, 16871-16878, DOI: 10.1039/C7NR06667H.

Study on a quartz crystal microbalance sensor based on chitosan-functionalized mesoporous silica for humidity detection.

Chitosan-functionalized mesoporous silica MCM-41 (Chi/M41) was prepared by a mild method. In the composite materials, the spherical MCM-41 particles were regarded as supporting skeletons, which reduced the effect of chitosan swelling on the repeatability and reliability of quartz crystal microbalance (QCM) sensors at high relative humidity (RH), and chitosan provided good film-forming properties of the final composite. The composite structure effectively improved the sensitivity of the QCM sensors compared to that of chitosan and MCM-41 sensors. The QCM sensor based on the Chi/M41 composites showed excellent sensitivity (58.4 ± 0.3 Hz/% RH). In addition, the optimal sensor exhibited excellent reliability, such as negligible humidity hysteresis (0.8 ± 0.1% RH), a small variation coefficient (1.1 ± 0.1), short response and recovery times (18 s/15 s) and good long-term stability. Furthermore, the Langmuir adsorption isotherm model and the Gibbs free energy were used to investigate the adsorption mechanism of water molecules on the sensitive films in this work.

A Case Report of Sweet's Syndrome with Panuveitis and Rhegmatogenous Retinal Detachment.

Purpose: To report a case of a patient who suffered from Sweet's syndrome with panuveitis in both eyes.Materials & Methods: Retrospective interventional case report.Results: A 54-year-old Chinese male patient complained of fever, painful skin lesions and blurry vision in both eyes lasting for 4 days. His visual acuity was hand motion in both eyes. Slit-lamp examination showed the hypopyon and severe vitreous opacification in both eyes. A skin pathology from head skin lesion demonstrated diffuse neutrophilic infiltration in the dermis with karyorrhexis. Based on the inspection above, the patient was diagnosed with Sweet's syndrome and given systemic corticosteroids therapy. However, he developed secondary rhegmatogenous retinal detachment in the right eye during his treatment.Conclusion: The association of bilateral uveitis with Sweet's syndrome has been described in this report.

Superior to graphene: super-anticorrosive natural mica nanosheets.

Graphene has been generally considered to be the most ideal anticorrosive material based on its extraordinary impermeability, but tends in practical applications to promote metal corrosion because of its inherently high electrical conductivity. Mica nanosheets (MNSs), in contrast, display excellent electrical insulation properties, as well as excellent temperature stability and chemical durability, and show tremendous potential for protecting metals, and hence are a promising substitute for graphene. To date, however, there have been no reports about MNS-based anticorrosive coatings, since it is much more difficult to exfoliate high-quality MNSs than other layered materials. In this work, high-concentration (4.3 mg ml-1) ultrathin MNS (1-5 layers) dispersions were synthesized based on a facile and efficient hydrothermal exfoliation approach. Epoxy (EP) coatings were filled with the as-obtained MNSs to enhance the anticorrosion performance of the coatings, and their corrosion behaviors were studied systemically through a series of measurements. With the addition of only 0.4 wt% MNSs, the corrosion rate was observed to be reduced 6500 fold, and the coating impedance increased by four orders of magnitude compared with the blank EP coating. We believe that this method opens a novel avenue for developing high-performance anticorrosive coatings to replace graphene materials for metal protection.

Capacitive humidity sensors based on mesoporous silica and poly(3,4-ethylenedioxythiophene) composites.

Owing to the outstanding dielectric properties derived from the conjugated π-electron systems, conjugated polymers have been explored and developed in capacitive humidity sensors for a few decades. In this work, a series of composites - mesoporous silica and semiconducting polymers - MCM-41 (MCM, Mesoporous Crystalline Material)/PEDOT (poly(3,4-ethylenedioxythiophene)) were chemically obtained by in-situ polymerization at 0 °C, while the amounts of PEDOT were adjusted by different evaporation times of EDOT (3,4-ethylenedioxythiophene) in the porous MCM-41 film. Additionally, it was able to modulate both the dielectricity and porosity of the composites via this convenient approach. The obtained capacitive humidity sensors based on MCM-41/PEDOT composites exhibit much better sensing performance than their bulk counterparts, with wider humidity sensing range, higher sensitivity and much faster response speed.

Proton-Conductive Gas Sensor: a New Way to Realize Highly Selective Ammonia Detection for Analysis of Exhaled Human Breath.

The analysis of exhaled human breath has great significance for early noninvasive diagnosis. Poor selectivity and strong humidity are two bottlenecks for the application of gas sensors to exhaled breath analysis. In this work, we utilized the adsorption, dissolution, ionization, and migration processes of ammonia in wet nonconjugated hydrophilic polymers to realize effective ammonia detection. The indispensable high-humidity atmosphere of exhaled breath was turned into a favorable condition for ammonia sensing. Nonconjugated polymer sensors can distinguish ammonia from most other gases because of its extremely high solubility and good ionization ability. A sensor based on poly(vinyl pyrrolidone) (PVP) could detect 0.5 ppm ammonia with an extremely high selectivity. The ammonia-sensing mechanism was thoroughly investigated by complex impedance plots (CIPs) and a quartz crystal microbalance (QCM) measurement. Finally, the potential of the PVP sensor for ammonia detection in exhaled breath was evaluated in simulated environments.

Bioinspired Smart Anticorrosive Coatings with an Emergency-Response Closing Function.

Emergency-response closing (ERC) of diffusion pathways for aggressive species in graphene/epoxy (G/EP) coatings was achieved via terpyridine derivative (TDD)-functionalized graphene oxide (tGO). Under stimulation from corrosion produced ferrous (Fe2+) ions, tGO sheets urgently aggregated through complexation reminiscent of leaves closing on a mimosa. Consequently, the coating showed significantly decreased oxygen (ORT) and water vapor transmittance rate (WVTR) changes after immersion in ferrous solution. According to the simulation and electrochemical results, tGO sheets could self-assemble into 3D architectures with Fe2+ ions and efficiently protect metals from aggressive species attack. This tGO/EP coating provided an ERC function via self-adaptability with the Fe2+ ions to achieve long-term anticorrosion. The application of tGO/EP to the protection of metal components is therefore validated as a fascinating route for the enhancement of anticorrosion efficiency on graphene anticorrosive coatings, with great potential in durable anticorrosive coatings application.