Highly Conductive, Ultrastrong, and Flexible Wet-Spun PEDOT:PSS/Ionic Liquid Fibers for Wearable Electronics.

Conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) fibers with high electrical conductivity, flexibility, and robustness are urgently needed for constructing wearable fiber-based electronics. In this study, the highly conductive (4288 S/cm), ultrastrong (a high tensile strength of 956 MPa), and flexible (a low Young's modulus of 3.8 GPa) PEDOT:PSS/1-ethyl-3-methylimidazolium dicyanamide (EMIM:DCA) (P/ED) fiber was prepared by wet-spinning and a subsequent H2SO4-immersion-drawing process. As far as we know, this is the best performance of the PEDOT:PSS fiber reported so far. The structure and conformation of the P/ED fiber were characterized by FESEM, XPS, Raman spectroscopy, UV-vis-NIR spectroscopy, and WAXS. The results show that the high performances of the P/ED fiber are mainly attributed to the massive removal of PSS and high degree of crystallinity (87.9%) and orientation (0.71) of PEDOT caused by the synergistic effect of the ionic liquid, concentrated sulfuric acid, and high stretching. Besides, the P/ED fiber shows a small bending radius of 0.1 mm, and the conductivity of the P/ED fiber is nearly unchanged after 1000 repeated cycles of bending and humidity changes within 50-90%. Based on this, various P/ED fiber-based devices including the circuit connection wire, thermoelectric power generator, and temperature sensor were constructed, demonstrating its wide applications for constructing flexible and wearable electronics.

Construction Strategy for Flexible and Breathable SiO2/Al/NFs/PET Composite Fabrics with Dual Shielding against Microwave and Infrared-Thermal Radiations for Wearable Protective Clothing.

Microwave and infrared-thermal radiation-compatible shielding fabrics represent an important direction in the development of wearable protective fabrics. Nevertheless, effectively and conveniently integrating compatible shielding functions into fabrics while maintaining breathability and moisture permeability remains a significant challenge. Here, we take hydrophilic PVA-co-PE nanofibrous film-coated PET fabric (NFs/PET) as a flexible substrate and deposit a dielectric/conductive (SiO2/Al) bilayer film via magnetron sputtering. This strategy endows the fabric surface with high electrical conductivity, nanoscale roughness comparable to visible and infrared waves, and a dielectric-metal contact interface possessing localized plasmon resonance and Mie scattering effects. The results demonstrate that the optimized SiO2/Al/NFs/PET composite conductive fabric (referred to as S4-1) possesses favorable X-band electromagnetic interference (EMI) shielding effectiveness (50 dB) as well as excellent long-wave infrared (LWIR) shielding or IR stealth performance (IR emissivity of 0.60). Notably, the S4-1 fabric has a cooling effect of about 12.4 °C for a heat source (80 °C) and an insulating effect of about 17.2 °C for a cold source (-20 °C), showing excellent shielding capability for heat conduction and heat radiations. Moreover, the moisture permeability of the S4-1 fabric is about 300 g/(m2·h), which is better than the requirement concerning moisture permeability for wearable fabrics (≥2500-5000 g/(m2·24 h)), indicating excellent heat and moisture comfort. In short, our fabrics have lightweight, thin, moisture-permeable and excellent shielding performance, which provides novel ideas for the development of wearable multi-band shielding fabrics applied to complex electromagnetic environments.

Elastic Nanofibrous Membranes for Medical and Personal Protection Applications: Manufacturing, Anti-COVID-19, and Anti-Colistin Resistant Bacteria Evaluation.

Herein, in the present work two series of thermoplastic polyurethane (TPU) nanofibers were manufactured using the electrospinning techniques with ZnO and CuO nanoparticles for a potential use as an elastic functional layer in antimicrobial applications. Percentages of 0%, 2 wt%, and 4 wt% of the nanoparticles were used. The morphological characterization of the electrospun TPU and TPU/NPs composites nanofibers were observed by using scanning electron microscopy to show the average fiber diameter and it was in the range of 90-150 nm with a significant impact of the nanoparticle type. Mechanical characterization showed that TPU nanofiber membranes exhibit excellent mechanical properties with ultra-high elastic properties. Elongation at break reached up to 92.5%. The assessment of the developed nanofiber membranes for medical and personal protection applications was done against various colistin resistant bacterial strains and the results showed an increment activity by increasing the metal oxide concentration up to 83% reduction rate by using TPU/ZnO 4% nanofibers against K. pneumoniae strain 10. The bacterial growth was completely eradicated after 8 and 16 h incubation with TPU/ZnO and TPU/CuO nanofibers, respectively. The nanofibers SEM study reveals the adsorption of the bacterial cells on the metal oxides nanofibers surface which led to cell lysis and releasing of their content. Finally, in vitro study against Spike S-protein from SARS-CoV-2 was also evaluated to investigate the potent effectiveness of the proposed nanofibers in the virus deactivation. The results showed that the metal oxide concentration is an effective factor in the antiviral activity due to the observed pattern of increasing the antibacterial and antiviral activity by increasing the metal oxide concentration; however, TPU/ZnO nanofibers showed a potent antiviral activity in relation to TPU/CuO.

Synergistically Improving Flexibility and Thermoelectric Performance of Composite Yarn by Continuous Ultrathin PEDOT:PSS/DMSO/Ionic Liquid Coating.

Combining fabrics with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) coating is the most promising method to fabricate wearable thermoelectric (TE) devices. However, the high modulus, low strain, and low TE performance of PEDOT:PSS coating lead to poor flexibility and low power generation efficiency. In this study, dimethyl sulfoxide (DMSO) and ionic liquids (ILs) were selected as a modifier to enhance the flexibility and TE performance of PEDOT:PSS. Different from the penetrating structure and coil conformation of pristine PEDOT:PSS coating, a flexible continuous ultrathin layer of PEDOT:PSS/DMSO/1-ethyl-3-methylimidazolium dicyanamide (P/D/ED) with a linear conformation forms on the surface of cotton yarn. The morphology and structure of PEDOT:PSS and P/D/ED coating were characterized by FESEM, XPS, and Raman spectroscopy. Compared with the pristine PEDOT:PSS film, the P/D/ED film shows significantly reduced modules and enhanced strain and bending stability. Moreover, the TE performance of P/D/ED-coated yarn is significantly enhanced with nearly half mass loading. Based on this, a large-area wearable TE fabric with enhanced flexibility and TE performance was prepared. The output power density is 136.1 mW/m2 at ΔT = 40.8 K, which is a typically high value compared with the former reported composite TE fabrics. This study provides a new way to synergistically enhance the flexibility and TE performance of composite yarn, and the prepared TE fabric has great potential as a wearable power source.

Fiber organic electrochemical transistors based on multi-walled carbon nanotube and polypyrrole composites for noninvasive lactate sensing.

Multi-walled carbon nanotubes (MWCNT) play a synergistic role with conducting polymer in practical applications such as biological sensing. In this paper, multi-walled carbon nanotube and polypyrrole (PPy) composites were prepared on a fiber surface for the first time, and their morphology and electrical properties were characterized. Compared with PPy-coated fiber, the presence of carbon nanotubes induced the growth of large areas of PPy nanowires. In addition, fiber organic electrochemical transistors (FECTs) based on PPy and MWCNT were assembled, showing a higher on/off ratio, better stability, and greater flexibility. The lactate biosensor based on FECTs exhibits high sensitivity, with a correlation coefficient of R = 0.9889, quick response time of 0.6-0.8 s, a wide linear response range of 1 nM-1 mM, and excellent selectivity for lactate. Furthermore, the lactate concentration in human sweat was successfully detected by a FECT-based sensor. The hybrid fibers can be easily woven and placed on fabric simply by stitching. This favorable performance of the FECT-based sensor makes it suitable for noninvasive sensing of lactate. Therefore, it provides a promising platform for future use in healthcare and detection applications. Graphical abstract.

Large-Area, Wearable, Self-Powered Pressure-Temperature Sensor Based on 3D Thermoelectric Spacer Fabric.

The rapid development of wearable devices puts forward higher requirements for mass-produced integrated smart systems that incorporate multiple electric components, such as energy supplying, multisensing, and communicating. To synchronously realize continuously self-powering, multifunctional sensing, distinguish signals from different stimuli, and productively design and fabricate a large-area sensing array, an all-fabric-based self-powered pressure-temperature-sensing electronic skin (e-skin) was prepared in this study by assembling highly flexible and compressible 3D spacer fabric (SF) and the thermoelectric poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT:PSS). The all-fabric-based e-skin can efficiently and accurately sense the temperature with a detection resolution of 0.1 K and a response time of 1 s, as well as pressure within a wide range of 200 Pa to 200 kPa and a fast response time of 80 ms. The electricity necessary for driving the sensor can be provided by the temperature difference between the body and environment. Notably, independent voltage and current signals can be generated and read out under the simultaneous temperature-pressure stimuli. For the first time, a real waistcoat-like e-skin with electricity-generating and pressure-temperature-sensing functions on the whole area was designed and prepared by a simple and easy to scale-up production method. All of these features make the developed all-fabric self-powered sensor have very promising applications.

Strategy of Constructing Light-Weight and Highly Compressible Graphene-Based Aerogels with an Ordered Unique Configuration for Wearable Piezoresistive Sensors.

Three-dimensional (3D) graphene aerogels (GAs) have attracted huge attention from researchers due to their great potential in vast applications. The hydrothermal reaction combined with freeze-drying using graphene oxide (GO) as a precursor has proven to be an effective method for obtaining relatively well-structured pure GAs. However, insufficient mechanical strength and low compressibility of the materials still limit their practical applications. Here, we report the microstructure-induced strong mechanical anisotropy of these monolithic GAs in transverse direction (TD) and longitudinal direction (LD), which has never been considered to be related to structural vulnerability. To overcome this anisotropy and enhance the structure, we hereby introduce our self-made poly(vinyl alcohol)- co-polyethylene (PVA- co-PE) nanofibers and low-molecular weight PVA as structural enhancers into the original 3D network to form a novel nanofiber-graphene composite aerogel. Intriguingly, a unique configuration is formed in the GA, in which the highly aligned stacked reduced GO sheets serve as the framework (cellular walls) and the nanofibers act as cross-linking columns anchored between the walls to support the structure along the TD, whereas the micro/nanosized PVA lamellae serve as binders. The resulting aerogel (referred to as graphene-PVA- co-PE nanofibers-PVA aerogel (GNPA)) has excellent compressive resilience along the TD and exhibits an ultrahigh gauge factor (14387%) at a very subtle strain (0.23%) in piezoresistive properties. The GNPA-TD has also been assembled into a variety of wearable sensors and demonstrates great potential for wireless human pressure sensing. In short, this study offers an extremely simple and effective method for developing graphene aerogels with a strong mechanical structure and paves the way for the application of 3D graphene in wearable sensors.

Selective inhibition of intestinal 5-HT improves neurobehavioral abnormalities caused by high-fat diet mice.

Recent literature reported the adverse effects of high-fat diet (HFD) on animal's emotional and cognitive function. An HFD-induced obesity/hyperlipidemia is accompanied by hormonal and neurochemical changes that can lead to depression. The important roles of gut-derived serotonin (5-Hydroxytryptamine, 5-HT) during this processing have been increasingly focused. Hence, to determine the potential role of gut-derived serotonin, HFD model was established in C57BL/6 mice. At the 4th week of feeding, a pharmacologic inhibitor of gut-derived 5-HT synthesis LP533401 (12.5 mg/kg/day), simvastatin (SIM) (5 mg/kg/day) and benzafibrate (BZ) (75 mg/kg/day) were administered for two weeks by oral gavage. Then, intraperitoneal glucose tolerance test (IPGTT), open field test (OFT), tail suspension test (TST), forced swim test (FST), sucrose preference test (SPT) were used to evaluate metabolic and neurobehavioral performances. Immunohistochemical staining, real-time quantitative PCR and other methods were to explore possible mechanisms. It was found that HFD feeding and drug treatments had some significant effects on neurobehaviors and brain: (1) All administrations reduced the total cholesterol (TC) and triglyceride (TG) parametric abnormality caused by HFD. LP533401 and SIM could significantly improve the impaired glucose tolerance, while BZ had no significant effect. (2) LP533401, SIM and BZ alleviated depression-like behavior of HFD mice in OFT, TST, FST and SPT. (3) LP533401 and SIM reversed the inhibition of Tryptophan Hydroxylase 2, Tph2 gene expression and the activation of Indoleamine 2,3-dioxy-Genase, IDO expression in HFD-treated brain, whereas BZ did not. (4) LP533401, SIM and BZ restored the inhibitory expression of 5-HT1A receptor in HFD hippocampus. Conclusions: Selective inhibition of intestinal 5-HT can attenuate depressive-like behavior, reduce 5-HT1AR impairment in hippocampus and correct abnormal 5-HT pathway in brain while ameliorating HFD-induced glucose intolerance. Further experiments are warranted to define the adequate strategy of targeting peripheral 5-HT for the treatment of such co-morbidity.

Wearable Fiber-Based Organic Electrochemical Transistors as a Platform for Highly Sensitive Dopamine Monitoring.

Fiber-based organic electrochemical transistors (FECTs) provide a new platform for the realization of an ultrafast and ultrasensitive biosensor, especially for the wearable dopamine (DA)-monitoring device. Here, we presented a fully filament-integrated fabric, it exhibited remarkable mechanical compatibility with the human body, and the minimum sensing unit was an organic electrochemical transistor (OECT) based on PVA- co-PE nanofibers (NFs) and polypyrrole (PPy) nanofiber network. The introduction of NFs notably increased the specific surface area and hydrophilicity of the PA6 filament, resulting in the formation of a large area of intertwined PPy nanofiber network. The electrical performance of PPy nanofiber network-modified fibers improved considerably. For the common FECTs, the typical on/off ratio was up to two orders of magnitude, and the temporal recovery time between on and off states was shortened to 0.34 s. Meanwhile, the device exhibited continuous cycling stability. In addition, the performances of FECT-based dopamine sensors depending on different gate electrodes have also been investigated. The PPy/NFs/PA6 filament-based dopamine sensor was more superior to the gold and platinum (Pt) wires, and the sensor presented long-term sensitivity with a detection region from 1 nM to 1 µM, rapid response time to a set of DA concentrations, remarkable selectivity in the presence of sodium chloride, uric acid, ascorbic acid and glucose, and superior reproducibility. Moreover, it could also be woven into the fabric product. The novel and wearable FECT device shows the potential to become the state-of-the-art DA-monitoring platform.

Simvastatin therapy in adolescent mice attenuates HFD-induced depression-like behavior by reducing hippocampal neuroinflammation.

BACKGROUND: A high-fat diet (HFD)-induced obesity/hyperlipidemia is accompanied by hormonal and neurochemical changes that can be associated with depression. Emerging studies indicate that simvastatin (SMV, decreasing cholesterol levels) has therapeutic effects on neurological and neuropsychiatric diseases through hippocampal-dependent function. However, the studies on the HFD exposure in adolescent animals, which investigate the neuroprotective effects of SMV on the hippocampal morphology, serotonin (5-HT) system and inflammation, are limited. Hence, the aim of this study was to determine whether SMV attenuates HFD-induced major depressive disorders in adolescent animals and, more specifically, acts as an anti-neuroinflammatory response. METHODS: Twenty-four male C57BL/6 mice were fed a control (n = 8), HFD (n = 8) and HFD + SMV (n = 8) for 14 weeks. In HFD + SMV group, SMV (10 mg/kg) was administrated from the 10th week of HFD feeding. The open field test (OFT) and the tail suspension test (TST) were used to examine the effect of SMV on behavioral performance. HE and Nissl staining were conducted to detect hippocampal morphology and neural survival. Expression of the inflammatory cytokine genes was assayed by quantitative polymerase chain reaction (Q-PCR). RESULTS: Firstly, alterations in lipid parameters were minimized after SMV treatment. HFD-induced depression-like behavior, which was evidenced by an increase in immobility time in TST along with considerable decrease in locomotion activity, was significantly attenuated by SMV therapy for 4 weeks. Additionally, SMV could reduce HFD-induced structural abnormality, neuronal injury, serotonergic system disturbance and pro-inflammatory cytokine over-expression in the hippocampus. Neuroimmunological changes in central hippocampus displayed a similar characteristic (only IL-1ß, IL-6, TNF-α) with that in periphery spleen, whereas they appeared in an entirely opposite trend with that in cerebral cortex. CONCLUSION: Our results suggest that SMV may be a promising treatment for HFD-induced depression-like behavior during adolescent period through brain region-specific neuroninflammatory mechanisms.

Ultrasensitive Wearable Pressure Sensors Assembled by Surface-Patterned Polyolefin Elastomer Nanofiber Membrane Interpenetrated with Silver Nanowires.

Wearable pressure sensors with ultrahigh sensitivity and flexibility have garnered tremendous attention because of their abilities to mimic the human somatosensory system and perceive surrounding pressure distribution. Herein, an ultrasensitive pressure sensor was fabricated with surface-patterned nanofibrous membranes (SPNMs) via a facile replica method from available plain-weaved nylon textiles. The SPNMs were composed of internal three-dimensional interpenetrating polyolefin elastomer nanofibers and silver nanowires (Ag NWs). The effects of the geometry of surface patterns and the density of the Ag NW network on the sensing performance of the assembled pressure sensor were systematically investigated. The results indicated that clavate groove-shaped surface patterns improved the sensitivity and a larger groove spacing contributed to higher sensitivities, whereas denser Ag NWs would reduce the sensing performance. The optimal pressure sensor assembled with SPNMs-45 and a Ag NW fraction of 3.8% showed high sensitivity (19.4 kPa-1) below the pressure of 2.76 kPa, a low detection limit (<1.6 Pa), fast response (30 and 42 ms), as well as excellent durability. These outstanding performances demonstrated its promising potential for wearable electronic applications, like detecting the spatial pressure distribution and monitoring human muscle motions.

Normal diet Vs High fat diet - A comparative study: Behavioral and neuroimmunological changes in adolescent male mice.

Recent evidence has established that consumption of High-fat diet (HFD)-induced obesity is associated with deficits in hippocampus-dependent memory/learning and mood states. Nevertheless the link between obesity and emotional disorders still remains to be elucidated. This issue is of particular interest during adolescence, which is important period for shaping learning/memory and mood regulation that can be sensitive to the detrimental effects of HFD. Our present study is focused to investigate behavioral and metabolic influences of short-term HFD intake in adolescent C57BL/6 mice. HFD caused weight gain, impaired glucose tolerance (IGT) and depression-like behavior as early as after 3 weeks which was clearly proved by a decrease in number of groomings in the open field test (OFT) and an increase in immobility time in the tail suspension test (TST). In the 4th week HFD induced obese model was fully developed and above behavioral symptoms were more dominant (decrease in number of crossings and groomings and increase in immobility time in both FST and TST). At the end of 6th week hippocampal analysis revealed the differences in morphology (reduced Nissl positive neurons and decreased the 5-HT1A receptor expression), neuronal survival (increased cleaved caspase-3 expression), synaptic plasticity (down regulation of p-CREB and BDNF), and inflammatory responses (increase in expression of pro-inflammatory cytokines and decrease in expression of anti-inflammatory cyokines) in HFD mice. Our results demonstrate that, high-fat feeding of adolescent mice could provoke "depression-like" behavior as early as 3 weeks and modulate structure, neuron survival and neuroinflammation in hippocampus as early as 6 weeks proving that adolescent age is much prone to adverse effects of HFD, which causes obesity, behavioral differences, memory and learning deficiencies.

Continuously Producible Ultrasensitive Wearable Strain Sensor Assembled with Three-Dimensional Interpenetrating Ag Nanowires/Polyolefin Elastomer Nanofibrous Composite Yarn.

Fiber-shaped strain sensors with great flexibility and knittability have been tremendously concerned due to the wide applications in health manager devices, especially in human motion detection and physiological signal monitoring. Herein, a novel fiber-shaped strain sensor has been designed and prepared by interpenetrating Ag nanowires (NWs) into polyolefin elastomer nanofibrous yarn. The easy-to-obtain structure and simple roll-to-roll process make the continuous large-scale production of nanofibrous composite yarn possible. The continuous and alternating stretching and releasing reversibly change the contact probability between AgNWs in this interpenetrating network, leading to the variations of electrical resistance of the sensor. The gauge factors of strain sensors are calculated to be as high as 13920 and the minimum detection limit is only 0.065%. In addition, the strain sensor shows excellent durability during 4500 cycles with the strain of 10%. The response times of stretching and releasing strains are 10 and 15 ms, respectively. Furthermore, the strain sensor has been successfully applied in human motion detections both in single yarn and knitted fabrics. The result shows the practicability in applications of monitoring limbs movements, eye motion changes, artificial vocal cords, human pulse, and complex motions, which shows great potential in wearable sensors and electronic skin.

The woven fiber organic electrochemical transistors based on polypyrrole nanowires/reduced graphene oxide composites for glucose sensing.

Novel woven fiber organic electrochemical transistors based on polypyrrole (PPy) nanowires and reduced graphene oxide (rGO) have been prepared. SEM revealed that the introduction of rGO nanosheets could induce the growth and increase the amount of PPy nanowires. Moreover, it could enhance the electrical performance of fiber transistors. The hybrid transistors showed high on/off ratio of 102, fast switch speed, and long cycling stability. The glucose sensors based on the fiber organic electrochemical transistors have also been investigated, which exhibited outstanding sensitivity, as high as 0.773 NCR/decade, with a response time as fast as 0.5s, a linear range of 1nM to 5µM, a low detection concentration as well as good repeatability. In addition, the glucose could be selectively detected in the presence of ascorbic acid and uric acid interferences. The reliability of the proposed glucose sensor was evaluated in real samples of rabbit blood. All the results indicate that the novel fiber transistors pave the way for portable and wearable electronics devices, which have a promising future for healthcare and biological applications.

Amine-functionalized PVA-co-PE nanofibrous membrane as affinity membrane with high adsorption capacity for bilirubin.

In this study, poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous membrane was activated by sodium hydroxide and cyanuric chloride, and then the activated membranes were functionalized by 1,3-propanediamine, hexamethylenediamine and diethylenetriamine to be affinity membranes for bilirubin removal, respectively. The chemical structures and morphologies of membranes were investigated by SEM, FTIR and XPS. And the adsorption ability of different amine-functionalized nanofibrous membranes for bilirubin was characterized. Furthermore, the effects of temperature, initial concentration of bilirubin, NaCl concentration and BSA concentration on the adsorption capacity for bilirubin of diethylenetriamine-functionalized nanofibrous membrane were studied. Results indicated that the adsorption capacity for bilirubin of diethylenetriamine-functionalized nanofibrous membrane could reach 85mg/g membrane when the initial bilirubin concentration was 200mg/L while the adsorption capacity could be increased to 110mg/g membrane if the initial bilirubin concentration was more than 400mg/L. The dynamic adsorption of diethylenetriamine-functionalized nanofibrous membrane showed that the ligands of amine groups on the membrane surface could be used as far as possible by recirculating the plasma with certain flow rates. Therefore, the diethylenetriamine-functionalized PVA-co-PE nanofibrous membrane possessed high adsorption capacity for bilirubin and it can be candidate as affinity membrane for bilirubin removal.

Hierarchically Three-Dimensional Nanofiber Based Textile with High Conductivity and Biocompatibility As a Microbial Fuel Cell Anode.

Microbial fuel cells (MFCs) encompass complex bioelectrocatalytic reactions that converting chemical energy of organic compounds to electrical energy. Improving the anode configuration is thought to be a critical step for enhancing MFCs performance. In present study, a hierarchically structured textile polypyrrole/poly(vinyl alcohol-co-polyethylene) nanofibers/poly(ethylene terephthalate) (referred to PPy/NFs/PET) is shown to be excellent anode for MFCs. This hierarchical PPy/NFs/PET anode affords an open porous and three-dimensional interconnecting conductive scaffold with larger surface roughness, facilitating microbial colonization and electron transfer from exoelectrogens to the anode. The mediator-less MFC equipped with PPy/NFs/PET anode achieves a remarkable maximum power density of 2420 mW m(-2) with Escherichia coli as the microbial catalyst at the current density of 5500 mA m(-2), which is approximately 17 times higher compared to a reference anode PPy/PET (144 mW m(-2)). Considering the low cost, low weight, facile fabrication, and good winding, this PPy/NFs/PET textile anode promises a great potential for high-performance and cost-effective MFCs in a large scale.

A nanofiber based artificial electronic skin with high pressure sensitivity and 3D conformability.

Pressure sensors with 3D conformability are highly desirable components for artificial electronic skin or e-textiles that can mimic natural skin, especially for application in real-time monitoring of human physiological signals. Here, a nanofiber based electronic skin with ultra-high pressure sensitivity and 3D conformability is designed and built by interlocking two elastic patterned nanofibrous membranes. The patterned membrane is facilely prepared by casting conductive nanofiber ink into a silicon mould to form an array of semi-spheroid-like protuberances. The protuberances composed of intertwined elastic POE nanofibers and PPy@PVA-co-PE nanofibers afford a tunable effective elastic modulus that is capable of capturing varied strains and stresses, thereby contributing to a high sensitivity for pressure sensing. This electronic skin-like sensor demonstrates an ultra-high sensitivity (1.24 kPa(-1)) below 150 Pa with a detection limit as low as about 1.3 Pa. The pixelated sensor array and a RGB-LED light are then assembled into a circuit and show a feasibility for visual detection of spatial pressure. Furthermore, a nanofiber based proof-of-concept wireless pressure sensor with a bluetooth module as a signal transmitter is proposed and has demonstrated great promise for wireless monitoring of human physiological signals, indicating a potential for large scale wearable electronic devices or e-skin.

Ion sensors based on novel fiber organic electrochemical transistors for lead ion detection.

Fiber organic electrochemical transistors (FECTs) based on polypyrrole and nanofibers have been prepared for the first time. FECTs exhibited excellent electrical performances, on/off ratios up to 10(4) and low applied voltages below 2 V. The ion sensitivity behavior of the fiber organic electrochemical transistors was investigated. It exhibited that the transfer curve of FECTs shifted to lower gate voltage with increasing cations concentration, the sensitivity reached to 446 µA/dec in the 10(-5)-10(-2) M Pb(2+) concentration range. The ion selective properties of the FECTs have also been systematically studied for the detection of potassium, calcium, aluminum, and lead ions. The devices with different cations showed great difference in response curves. It was suitable for selectively monitoring Pb(2+) with respect to other cations. The results indicated FECTs were very effective for electrochemical sensing of lead ion, which opened a promising perspective for wearable electronics in healthcare and biological application. Graphical Abstract The schematic diagram of fiber organic electrochemical transistors based on polypyrrole and nanofibers for ion sensing.

Immobilization of Firefly Luciferase on PVA-co-PE Nanofibers Membrane as Biosensor for Bioluminescent Detection of ATP.

The bioluminescent reaction catalyzed by firefly luciferase has become widely established as an outstanding analytical system for assay of adenosine triphosphate (ATP). When in solution, the luciferase is unstable and cannot be reused. The problem can be partially solved by immobilizing the luciferase on solid substrates. The poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibers membrane has abundant active hydroxyl groups on the surface. The PVA-co-PE nanofibers membrane was first activated by cyanuric chloride with triazinyl group. Then the activated PVA-co-PE nanofibers membrane was subsequently reacted with 1,3-propanediamine and biotin. The firefly luciferase was immobilized onto the surface of 1,3-propanediamine- and biotin-functionalized membranes. The surface chemical structure and morphologies of nanofibers membranes were characterized by FTIR-ATR spectra and SEM. The hydrophilicity of membranes was tested by water contact angle measurements. The detection of fluorescence intensity displayed that the firefly-luciferase-immobilized PVA-co-PE nanofibers membranes indicated high catalytic activity and efficiency. Especially, the firefly-luciferase-immobilized nanofiber membrane which was functionalized by biotin can be a promising candidate as biosensor for bioluminescent detection of ATP because of its high detection sensitivity.

5-HT1A/1B receptors as targets for optimizing pigmentary responses in C57BL/6 mouse skin to stress.

Stress has been reported to induce alterations of skin pigmentary response. Acute stress is associated with increased turnover of serotonin (5-hydroxytryptamine; 5-HT) whereas chronic stress causes a decrease. 5-HT receptors have been detected in pigment cells, indicating their role in skin pigmentation. To ascertain the precise role of 5-HT in stress-induced pigmentary responses, C57BL/6 mice were subjected to chronic restraint stress and chronic unpredictable mild stress (CRS and CUMS, two models of chronic stress) for 21 days, finally resulting in abnormal pigmentary responses. Subsequently, stressed mice were characterized by the absence of a black pigment in dorsal coat. The down-regulation of tyrosinase (TYR) and tyrosinase-related proteins (TRP1 and TRP2) expression in stressed skin was accompanied by reduced levels of 5-HT and decreased expression of 5-HT receptor (5-HTR) system. In both murine B16F10 melanoma cells and normal human melanocytes (NHMCs), 5-HT had a stimulatory effect on melanin production, dendricity and migration. When treated with 5-HT in cultured hair follicles (HFs), the increased expression of melanogenesis-related genes and the activation of 5-HT1A, 1B and 7 receptors also occurred. The serum obtained from stressed mice showed significantly decreased tyrosinase activity in NHMCs compared to that from nonstressed mice. The decrease in tyrosinase activity was further augmented in the presence of 5-HTR1A, 1B and 7 antagonists, WAY100635, SB216641 and SB269970. In vivo, stressed mice received 5-HT precursor 5-hydroxy-l-tryptophan (5-HTP), a member of the class of selective serotonin reuptake inhibitors (fluoxetine; FX) and 5-HTR1A/1B agonists (8-OH-DPAT/CP94253), finally contributing to the normalization of pigmentary responses. Taken together, these data strongly suggest that the serotoninergic system plays an important role in the regulation of stress-induced depigmentation, which can be mediated by 5-HT1A/1B receptors. 5-HT and 5-HTR1A/1B may constitute novel targets for therapy of skin hypopigmentation disorders, especially those worsened with stress.