Highly catalytic Prussian blue analogues and their application on the three-dimensional origami paper-based sweat sensors

Prussian blue analogues (PBAs) are promising materials due to their rich active sites and straightforward synthesis. However, their limited conductivity and electron transfer inefficiency hinder practical applications. This study utilizes a simple one-pot synthesis approach to produce a tungsten-disulfide (WS2) and iron-cobalt Prussian blue analogue composite (WS2-PBA), enhancing conductivity and electron transfer rate performance. Through the inclusion of sodium citrate into the solution, the S-edge site concentration of WS2 increases. This augmentation introduces additional active sites and defects into the catalyst, enhancing its catalytic activity. The effectiveness of the WS2-PBA 3D-Origami paper device for lactate detection in sweat is also evaluated for biomedical applications. The device demonstrated a robust relationship between the lactate concentration and current intensity (R2 = 0.997), with a detection limit of 1.83 mM. Additionally, this platform has successfully detected lactate in clinical sweat, correlating with the high-performance liquid chromatography test results, suggesting promising prospects for clinical diagnosis. In the future, the excellent catalytic and Rct performance of the WS2-PBA will enable its use in biomedical applications.

Transparent biodegradable composite plastic packaging film from TEMPO-oxidized cellulose nanofibers

In this research, we develop a method to create biodegradable food packaging films. Initially, TEMPO-oxidized cellulose nanofiber (TOCNF) undergoes sonication to produce well-dispersed single-strain nanofibers. These nanofibers are then blended with waterborne polyurethane (WPU) to enhance their extensibility. To further enhance compatibility between these two components, a non-ionic surfactant, Tween 80, is introduced into the TOCNF/WPU mixture to improve the dispersion of the WPU within the blend. The addition of Tween 80 significantly increases the transparency of the resulting film (Transmittance: 89.4 %, Haze: 2.2 %). Furthermore, the incorporation of the surfactant effectively reduces the formation of wrinkles and cracks during the film drying process, preventing adverse impacts on the film's barrier properties. The thin film further undergoes esterification crosslinking with citric acid to remove its hydrophilic groups for better water vapor barrier properties. The resulting bio-based packaging film exhibits remarkable transparency, strong biodegradability, and superior gas-barrier properties (water vapor and oxygen) compared to commonly used food packaging.

Origami-Inspired Conductive Paper-Based Folded Pressure Sensor with Interconnection Scaling at the Crease for Novel Wearable Applications

Drawing inspiration from origami structures, a pressure sensor was developed with unique interconnection scaling at its creases crafted on a conductive paper substrate, paving the way for advanced wearable technology. Two screen-printed conductive paper substrates were combined face-to-face, and specific folds were introduced to optimize the sensor structure. The Electrical Contact Resistance (ECR) was systematically analyzed across different fold numbers and crease gaps, revealing a notable trade-off: while increasing the number of folds expanded the sensing area, it also influenced the ECR, reaching a performance plateau. Strategic modifications in the sensor's design, including refining interconnections at the crease, enhanced its sensitivity and stability, culminating in a remarkable sensitivity of 3.75 kPa-1 at subtle pressure levels (0-0.05 kPa). This sensor's real-world applications proved to be transformative, from detecting bruxism and aiding in neck posture correction to remotely sensing trigger finger locking phenomena, highlighting its potential as a pivotal tool in upcoming medical diagnostics and treatments.

FT895 Impairs Mitochondrial Function in Malignant Peripheral Nerve Sheath Tumor Cells

Neurofibromatosis type 1 (NF1) stands as a prevalent neurocutaneous disorder. Approximately a quarter of NF1 patients experience the development of plexiform neurofibromas, potentially progressing into malignant peripheral nerve sheath tumors (MPNST). FT895, an HDAC11 inhibitor, exhibits potent anti-tumor effects on MPNST cells and enhances the cytotoxicity of cordycepin against MPNST. The study aims to investigate the molecular mechanism underlying FT895's efficacy against MPNST cells. Initially, our study unveiled that FT895 disrupts mitochondrial biogenesis and function. Post-FT895 treatment, reactive oxygen species (ROS) in MPNST notably increased, while mitochondrial DNA copy numbers decreased significantly. Seahorse analysis indicated a considerable decrease in basal, maximal, and ATP-production-coupled respiration following FT895 treatment. Immunostaining highlighted FT895's role in promoting mitochondrial aggregation without triggering mitophagy, possibly due to reduced levels of XBP1, Parkin, and PINK1 proteins. Moreover, the study using CHIP-qPCR analysis revealed a significant reduction in the copy numbers of promoters of the MPV17L2, POLG, TFAM, PINK1, and Parkin genes. The RNA-seq analysis underscored the prominent role of the HIF-1α signaling pathway post-FT895 treatment, aligning with the observed impairment in mitochondrial respiration. In summary, the study pioneers the revelation that FT895 induces mitochondrial respiratory damage in MPNST cells.

A Multimodality Electrochemical and Impedance Spectroscopy System-on-a-Chip With Temperature Sensing and Impedance-Boosting Techniques

This article presents a multimodal electrochemical sensing system-on-chip (SoC), including the functions of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and temperature sensing. CV readout circuitry achieves an adaptive readout current range of 145.5 dB through an automatic range adjustment and resolution scaling technique. EIS has an impedance resolution of 9.2 m Ω/√ Hz at a sweep frequency of 10 kHz and an output current of up to 120 μA. With an impedance boost mechanism, the maximum detectable load impedance is extended to 22.95 k Ω, while the total harmonic distortion is less than 1%. A resistor-based temperature sensor using a swing-boosted relaxation oscillator can achieve a resolution of 31 mK in 0-85 °C. The design is implemented in a 0.18 μm CMOS process. The total power consumption is 1 mW.

Conformal Conductive Features on Curvilinear Surfaces with Self-Assembled Silver Nanoplate Thin Films

In this study, a water transfer method was developed to fabricate conducive thin-film patterns on 3D curvilinear surfaces. Crystalline silver nanoplates (AgNPLs) with a dimension of 700 nm and a thickness of 35 nm were suspended in ethanol with an anionic surfactant, sodium dodecyl sulfate, to improve the suspension stability. The prepared AgNPL suspension was then spread over the water surface via the Langmuir-Blodgett approach to generate a self-assembled thin film. By dipping an accepting object with a robotic arm, the floating AgNPL thin film with nanometer thickness can be effectively transferred to the object surfaces and exhibited a superior conductivity up to 15% of bulk silver without thermal sintering. Besides good conductivity, the AgNPL conductive thin films can also be transferred efficiently on any curvilinear (concave and convex) surface. Moreover, with the help of masks, conductive patterns can be produced on water surfaces and transferred to curvilinear surfaces for electronic applications. As a proof of concept, several examples were demonstrated to display the capability of this approach for radiofrequency identification and other printed circuit applications.

A Brief Review of Graphene-Based Biosensors Developed for Rapid Detection of COVID-19 Biomarkers

The prevalence of mutated species of COVID-19 antigens has provided a strong impetus for identifying a cost-effective, rapid and facile strategy for identifying the viral loads in public places. The ever-changing genetic make-up of SARS-CoV-2 posts a significant challenfge for the research community to identify a robust mechanism to target, bind and confirm the presence of a viral load before it spreads. Synthetic DNA constructs are a novel strategy to design complementary DNA sequences specific for antigens of interest as in this review's case SARS-CoV-2 antigens. Small molecules, complementary DNA and protein-DNA complexes have been known to target analytes in minimal concentrations. This phenomenon can be exploited by nanomaterials which have unique electronic properties such as ballistic conduction. Graphene is one such candidate for designing a device with a very low LOD in the order of zeptomolar and attomolar concentrations. Surface modification will be the significant aspect of the device which needs to have a high degree of sensitivity at the same time as providing a rapid signaling mechanism.

Skin-Inspired Tactile Sensor on Cellulose Fiber Substrates with Interfacial Microstructure for Health Monitoring and Guitar Posture Feedback

Skin-inspired flexible tactile sensors, with interfacial microstructure, are developed on cellulose fiber substrates for subtle pressure applications. Our device is made of two cellulose fiber substrates with conductive microscale structures, which emulate the randomly distributed spinosum in between the dermis and epidermis layers of the human skin. The microstructures not only permit a higher stress concentration at the tips but also generate electrical contact points and change contact resistance between the top and bottom substrates when the pressure is applied. Meanwhile, cellulose fibers possessing viscoelastic and biocompatible properties are utilized as substrates to mimic the dermis and epidermis layers of the skin. The electrical contact resistances (ECR) are then measured to quantify the tactile information. The microstructures and the substrate properties are studied to enhance the sensors' sensitivity. A very high sensitivity (14.4 kPa^-1) and fast recovery time (approx. 2.5 ms) are achieved in the subtle pressure range (approx. 0-0.05 kPa). The device can detect subtle pressures from the human body due to breathing patterns and voice activity showing its potential for healthcare. Further, the guitar strumming and chord progression of the players with different skill levels are assessed to monitor the muscle strain during guitar playing, showing its potential for posture feedback in playing guitar or another musical instrument.

Enhancing Stability of High-Concentration β-Tricalcium Phosphate Suspension for Biomedical Application

We propose a novel process to efficiently prepare highly dispersed and stable Tricalcium Phosphate (β-TCP) suspensions. TCP is coupled with a polymer to enhance its brittleness to be used as an artificial hard tissue. A high solid fraction of β-TCP is mixed with the polymer in order to improve the mechanical strength of the prepared material. The high solid fractions led to fast particle aggregation due to Van der Waals forces, and sediments appeared quickly in the suspension. As a result, we used a dispersant, dispex AA4040 (A40), to boost the surface potential and steric hindrance of particles to make a stable suspension. However, the particle size of β-TCP is too large to form a suspension, as the gravity effect is much more dominant than Brownian motion. Hence, β-TCP was subjected to wet ball milling to break the aggregated particles, and particle size was reduced to ~300 nm. Further, to decrease sedimentation velocity, cellulose nanocrystals (CNCs) are added as a thickening agent to increase the overall viscosity of suspension. Besides the viscosity enhancement, CNCs were also wrapped with A40 micelles and increase the stability of the suspension. These CNC/A40 micelles further facilitated stable suspension of β-TCP particles with an average hydration radius of 244.5 nm. Finally, β-TCP bone cement was formulated with the suspension, and the related cytotoxicity was estimated to demonstrate its applicability for hard tissue applications.

A Wireless Soil pH and Conductance Monitoring Chip Powered by Soil Microbial and Photovoltaic Energy Cells

This paper presents an energy-autonomous wireless soil pH and electrical conductance measurement IC powered by soil microbial and photovoltaic energy. The chip integrates highly efficient dual-input, dual-output power management units, sensor readout circuits, a wireless receiver, and a transmitter. The design scavenges ambient energy with a maximal power point tracking mechanism while achieving a peak efficiency of 81.3% and the efficiency is more than 50% over the 0.05-14 mW load range. The sensor readout IC achieves a sensitivity of -8.8 kHz/pH and 6 kHz·m/S, a noise floor of 0.92 x 10^-3 pH value, and 1.4 mS/m conductance. To avoid interference, a 433 MHz transceiver incorporates chirp modulation and on-off keying (OOK) modulation for data uplink and downlink communication. The receiver sensitivity is -80 dBm, and the output transmission power is -4 dBm. The uplink data rate is 100 kb/s using burst chirp modulation and gated Class E PA, while the downlink data rate is 10 kb/s with a self-frequency tracking mixer-first receiver.

Total Liquid Transfer with Enhanced Contact Line Slippage

A new surface treatment method is developed to achieve total liquid transfer. The transfer process of a liquid droplet is recorded through high-speed photography and analyzed via image analysis to investigate the hydrodynamic interactions. For a pristine PMMA surface, a viscous and viscoelastic liquid facilitates transfer by increased viscous and inertial forces and delayed liquid bridge breakage but is limited by slow contact line slippage. Hydrophobic surface treatments can increase contact line slippage and the receding angle to achieve transfer ratios up to 98%. However, pinning and contact angle hysteresis from surface roughness features limit liquid transfer, especially for smaller droplets and higher separation velocities. A lubricant-infused surface treatment with PDMS and a thin layer of less viscous silicone oil provides a smooth, homogeneous surface with fast slippage, low contact angle hysteresis, and only a slight oil wetting ridge. Liquid could then transfer at high ratios (∼99.9%), regardless of droplet size and separation velocity. Finally, complete transfer liquid from indented cells is demonstrated to show the potential of this surface modification method for gravure printing.

Microfluidic wearable electrochemical sweat sensors for health monitoring

Research on remote health monitoring through wearable sensors has attained popularity in recent decades mainly due to aging population and expensive health care services. Microfluidic wearable sweat sensors provide economical, non-invasive mode of sample collection, important physiological information, and continuous tracking of human health. Recent advances in wearable sensors focus on electrochemical monitoring of biomarkers in sweat and can be applicable in various fields like fitness monitoring, nutrition, and medical diagnosis. This review focuses on the evolution of wearable devices from benchtop electrochemical systems to microfluidic-based wearable sensors. Major classification of wearable sensors like skin contact-based and biofluidic-based sensors are discussed. Furthermore, sweat chemistry and related biomarkers are explained in addition to integration of microfluidic systems in wearable sweat sensors. At last, recent advances in wearable electrochemical sweat sensors are discussed, which includes tattoo-based, paper microfluidics, patches, wrist band, and belt-based wearable sensors.

A novel HDAC11 inhibitor potentiates the tumoricidal effects of cordycepin against malignant peripheral nerve sheath tumor through the Hippo signaling pathway

Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous disorder. Clinically, the hallmarks of NF1 include skin pigmentation and cutaneous neurofibroma. Some NF1 patients develop plexiform neurofibroma (PN) since early childhood. Pathologically, PN contains abundant Schwann cells, blood vessels and connective tissues, which may transform into a malignant peripheral nerve sheath tumor (MPNST). MPNST is a highly invasive sarcoma without any effective therapy. Recently, both in vitro and in vivo studies showed that cordycepin can inhibit the growth of MPNST cells. Cordycepin causes cell cycle arrest at G2/M phase and downregulates the protein levels of α-tubulin, p53 and Sp1. Herein, the present study revealed that the HDAC11 inhibitor, FT895, can synergistically enhance the tumoricidal effect of cordycepin against MPNST cells in vitro. Treatment with the combination of cordycepin and FT895 reduced the size of MPNST in the xenograft mouse model. The combined treatment decreased the protein levels of α-tubulin and KIF18A, which may disrupt the microtubule organization leading to the mis-segregation of chromosomes and aneuploidy. Moreover, the expression levels of TEAD1 and its co-activator TAZ, the candidate proteins in hippo signaling pathway, were suppressed after combined treatment. Sequence analysis found a few binding sites for the transcription factor, TEAD1 in the promoter regions of TUBA1B, KIF18A, TEAD1, TAZ, YAP, TP53 and SP1 genes. ChIP-qPCR assay showed that the combined treatment decreases the binding of TEAD1 to the promoters of TUBA1B, KIF18A, TEAD1, TAZ and YAP genes in STS26T cells. The reduced binding to TP53 and SP1 promoters was also found in S462TY cells, which was further confirmed by immunoblotting. The down-regulation of these important transcriptional factors may contribute to the vulnerability of MPNST. In summary, HDAC11 inhibitor, FT895 can potentiate the tumoricidal effect of cordycepin to suppress the MPNST cell growth, which was probably mediated by the dysfunction of hippo-signaling pathway.

Exploring the mechanical properties of nanometer-thick elastic films through micro-drop impinging on large-area suspended graphene

In this work, the dependence of effective Young's modulus on the thickness of suspended graphene was confirmed through a drop impingement method. Large area suspended graphene (LSG) layers with a diameter of up to 400 μm and a nanometer thickness were prepared through transferring chemical vapor deposition grown graphene from copper substrates. 4, 8, and 12-layer LSG samples were found to be crumpled yet defect-free. The mechanical properties of LSG were first studied by observing its interaction with impinging droplets from an ink-jet nozzle. First, the effective Young's modulus was calculated by fitting the instant deformation captured by high speed photography within microseconds. Next, droplets deposited on LSG caused deformation and generated wrinkles and the effective Young's modulus was calculated from the number of wrinkles. The above methods yielded effective Young's modulus values ranging from 0.3 to 3.4 TPa. The results from these methods all indicated that the effective Young's modulus increases with the decreasing thickness or size of suspended graphene layers. Moreover, the crumpled LSG yields higher effective Young's modulus than ideal flat graphene. These comprehensive results from complementary methodologies with precise LSG thickness control down to the nanometer scale provide good evidence to resolve the debate on the thickness dependence of mechanical strength for LSG.

Microwave-Assisted Synthesis for Silver Nanoplates with a High Aspect Ratio

In this work, a simple and rapid synthesis method was developed to prepare silver nanoplates (AgNPLs) with a high aspect ratio. A microwave heating process with a high heating rate and uniform heating was used to promote the silver reduction reaction. Silver nitrate (AgNO₃) was used as the precursor of AgNPLs, and N,N-dimethylformamide (DMF) played the role of a solvent and reducing agent. Poly(vinylpyrrolidone) (PVP) with a molecular weight of 29,000 and a PVP/AgNO₃ ratio of 10 were used to control the shape of synthesized AgNPLs. By adjusting the optimal microwave heating parameters, temperature ramping rate, reaction time, and reaction temperature, triangular AgNPLs with high aspect ratios could be produced. The synthesized AgNPLs had an edge length up to 700 nm and a thickness of 35 nm with aspect ratios up to 20. The AgNPLs were also used to produce conductive patterns via pen writing with a conductivity of 2 × 10⁶ S/m to demonstrate the feasibility of applying the synthesized nanomaterials for electronic applications.

Direct Printed Silver Nanowire Strain Sensor for Early Extravasation Detection

In this study, we presented a wearable sensor patch for the early detection of extravasation by using a simple, direct printing process. Silver nanowire (AgNW) ink was first formulated to provide necessary rheological properties to print patterns on flexible plastic sheets. By adjusting printing parameters, alignments of AgNWs in the printed patterns were controlled to enhance the resistance change under stretching conditions. A resistive strain-sensing device was then fabricated by printing patterned electrodes on a stretchable film for skin attachment. The designed sensor pattern was able to detect forces from a specific direction from the resistance change. Moreover, the sensor showed excellent sensitivity (gauge factor (GF) = 100 at 50% strain) and could be printed in small dimensions. Sensors of millimeter size were printed in an array and were used for multiple detection points in a large area to detect extravasation at small volumes (<0.5 mL) at accurate bump location.

Bio-inspired fractal textile device for rapid sweat collection and monitoring

In this study, a new design concept in sweat collection was developed to achieve rapid and intact sweat sampling for analytical purposes. Textiles with fast water wicking properties were first selected and laser engraved into tree-like bifurcating channels for sweat collection. The fractal framework of the bifurcating textile channels was theoretically derived to minimize the flow resistance for fast sweat absorption. The optimized collector with designed fractal geometry exhibited thorough coverage of emerging droplets without overflow. Great collection efficiency was achieved with a short induction time (<1 minute after perspiration begins) and a maximum sweat collection flux up to 4.0 μL cm-2 min-1 without leakage. After being combined with printed sensors and microchips, the assembled sweat collection/sensing device can simultaneously provide measurements of salt concentration and sweat rate for wireless hydration state monitoring. The collection/sensing system also exhibited fast response times to abrupt changes in sweat rates or concentrations and thus can be used to detect instant physical conditions in exercise. Finally, field tests were performed to demonstrate the reliability and practicality of the device in real-time sweat monitoring under vigorous activities.

A chemical milling process to produce water-based inkjet printing ink from waste tire carbon blacks

In this study, a chemical milling process is developed to convert carbon residues from pyrolyzed waste tires into valuable water-based inkjet printing inks. The residues after waste tire pyrolysis were first sieved to remove ash components and ground into powder (~80 μm). The resulting waste tire carbon blacks (TCB) processed by regular dry or wet milling with the help of compatible solvent can only produce particle sizes around 250 nm. To further reduce particle size under the same mechanical energy, aqueous potassium hydroxide was used in the milling process to leach silica in TCB to create loose and vulnerable structure. Moreover, an ionic surfactant, poly (sodium 4-styrenesulfonate) (PSS), was used to decorate the TCB surface and to inhibit particle aggregation. After chemical milling, the PSS/TCB had a primary particle size around 50 nm and a hydraulic diameter around 110 nm. The PSS/TCB suspension possessed a high zeta potential of -73 mV to stably disperse in water for more than 30 days. To help adhesion of the ink on substrates, the PSS/TCB particles were further mixed with waterborne polyurethane (WPU). The WPU/PSS/TCB ink could be inkjet printed into various black patterns, which showed a higher blackness (jetness value = 342.83) than commercial black inks. Moreover, the printed patterns were water-proof and had a pencil scratch hardness of 4H. In summary, this study provides a guideline to convert waste carbon materials into useful printing supplies, and offers a potential application for waste tire recycling.

Multifunctionalized Cellulose Nanofiber for Water-Repellent and Wash-Sustainable Coatings on Fabrics

A new synthetic route was developed to modify cellulose nanofiber for water-repellent coatings with great sustainability after multiple washing cycles. Multiple functional groups were grafted on 2,2,6,6-tetramethylpiperidine 1-oxyl radical (TEMPO)-oxidized cellulose nanofibers (TOCN) to achieve superhydrophobic performance and strong adhesion on cotton cloth. First, hexadecylamine (HDA) was used to modify TOCN surface into hydrophobic derivatives via amidation. The amidation-modified TOCN (AMT) were then grafted with a polyisocyanate cross-linking agent (PCA). The final multimodified TOCN (MMT) had hydrophobic alkyls and isocyanate groups on the surface. These surface functional groups were confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). After spraying the MMT suspension on cotton fabrics, the isocyanate groups would react with hydroxyl groups on cotton fibers, leading to a uniform conformal layer of MMT on fabric surfaces. The MMT coating showed great water repellence and washing sustainability. A large contact angle of 150° and a small sliding angle of ∼10° were observed. The superhydrophobic performance retained even after 10 laundry washing cycles. Several examples were also demonstrated to show the capability and the possibility of applying this coating material for water-repellent applications.

Stretchable Polydimethylsiloxane Composites with Emulsified Ionic Materials and Thermochromic Applications

In this study, a new preparation method is developed to include thermochromic complex ions in polydimethylsiloxane (PDMS) as a stretchable composite. Ethylene glycol (EG) droplets down to the nanometer scale were dispersed using a reverse micelle method to form a stable suspension in PDMS precursor solution. After curing, the EG nanodroplets were well encapsulated in the cured PDMS elastomer. The EG/PDMS composite exhibited great stability after thermal heating at 100 °C for 2 hours. The deformable liquid droplets helped maintaining the composite structures under severe stretching conditions, and thus the stretched composite exhibited great transparency without any fractures or delamination. Ionic dyes, such as methylene blue and Congo red, can be added in the EG droplets to color the composite. Moreover, complex ions with thermochromic properties can also be used in the composite. Upon thermal heating, the reconfiguration of the complex ions in the liquid dispersed phase led to obvious color changes, and the color remained unchanged up to 50% tensile strain after more than 1000 stretch cycles.

P5644Hypoglycemic episodes increase the risk of ventricular arrhythmias and sudden cardiac arrest in patients with type 2 diabetes - a nationwide cohort study

Background

Hypoglycemic episode (HE) increases the risk of cardiovascular mortality. The impact of HE on the risk of sudden death remains unclear. We hypothesized that HE increases the risks of ventricular arrhythmia (VA) and sudden cardiac arrest (SCA), and that anti-diabetic agents (ADAs) causing hypoglycemia also increase the risks of VA and SCA.

Methods

Patients aged ≥20 years with newly diagnosed diabetes were identified from the Taiwan National Insurance Database. HE was defined as the presentation of hypoglycemic coma or specified/unspecified hypoglycemia. For control group, we included diabetic patients without HE, and they were frequency-matched to the HE group at a 4:1 ratio. The primary outcome was the occurrence of any event of VA (including ventricular tachycardia and fibrillation) and SCA during the defined follow-up periods. Multivariate Cox hazards regression model was used to evaluate the hazard ratio (HR) for VA or SCA.

Results

A total of 54,303 diabetic patients were screened with 1,037 of them in the HE group, and 4,148 in the control group. During a mean follow-up period of 3.3±2.5 years, 29 VA/SCA events had occurred. Compared to the control group, the HE group had a higher incidence of VA/SCA (adjusted HR: 2.42, p=0.04). Diabetic patients medicated with insulin for glycemic control increased the risk of VA/SCA compared to those without insulin (adjusted HR: 3.05, p=0.01).

Kaplan-Meier survival curves

Conclusions

HEs in patients with diabetes increased the risks of VA and SCA compared to those without. Their use of insulin also independently increased the risk of VA/SCA.

P2564Levosimendan shortens action potential duration, decreases alternans threshold and prevents ventricular arrhythmia during therapeutic hypothermia in isolated rabbit hearts

Background

Therapeutic hypothermia (TH) increases the susceptibility to ventricular arrhythmias (VA) by prolonging action potential duration (APD) and facilitating arrhythmogenic spatially discordant alternans (SDA). The calcium sensitizer levosimendan has been reported to shorten APD by enhancing ATP-sensitive K current. We hypothesize that levosimendan might shorten the already prolonged APD during TH, decreasing SDA threshold, and prevent the occurrence of VA.

Methods

Langendorff-perfused isolated rabbit hearts were subjected to 15-min TH (30°C) followed by 30-min treatment with levosimendan (0.5 μM, n=9) or vehicle (n=8). Using an optical mapping system, epicardial APD was evaluated by S1 pacing. SDA threshold was defined as the longest pacing cycle length (PCL) that induced SDA phenomenon. Ventricular fibrillation (VF) inducibility was evaluated by burst pacing for 30 s using the shortest PCL that achieved 1:1 ventricular capture.

Results

Levosimendan shortened the ventricular APD (at PCL 300 ms, from 229±9 ms to 211±18 ms, p=0.02) and decrease the SDA threshold (from 327±88 ms to 311±68 ms, p=0.001) during TH. The VF inducibility was decreased by levosimendan from 39±30% at 30°C to 14±12% after levosimendan infusion. In control hearts, the APD (p=0.75), SDA threshold (p=ns) and VF inducibility (p=0.12) were not changed by vehicle during TH.

Conclusions

Levosimendan protects the hearts against VA during TH by shortening APD and decreasing SDA threshold. Enhancing ATP-sensitive K current with levosimendan might be a novel approach to prevent VA during TH.

Facile Preparation of Cu/Ag Core/Shell Electrospun Nanofibers as Highly Stable and Flexible Transparent Conductive Electrodes for Optoelectronic Devices

Novel transparent conductive electrodes (TCEs) with copper (Cu)/silver (Ag) core/shell nanofibers (NFs) containing random, aligned, and crossed structures were prepared using a combination of electrospinning (ES) and chemical reduction. The ES process was used to prepare continuous copper nanofibers (Cu-NFs), which were used as core materials and were then immersed in silver ink (Ag ink) to form a protective layer of Ag to protect the Cu-NFs from oxidation. The Ag shell layer protected the Cu-NFs against oxidation and enhanced their conductivity. Such Cu/Ag core/shell webs can be easily transferred on the flexible matrix and can be applied in TCEs. The metal NF webs of different structures exhibited various degrees of conductivity and followed the order random type > crossed type > aligned type; however, the order with respect to transmittance ( T) was inverse. The aligned nanowire networks exhibited a high T of over 80%, and the random ones exhibited a low sheet resistance of less than 10² Ω/sq (the best value is 7.85 Ω/sq). The present study demonstrated that TCEs based on Cu/Ag core/shell NF webs have considerable flexibility, transparency, and conductivity and can be applied in novel flexible light-emitting diode devices and solar cells in the future.

Highly Responsive PEG/Gold Nanoparticle Thin-Film Humidity Sensor via Inkjet Printing Technology

In this study, a highly responsive humidity sensor is developed by printing gold nanoparticles (GNPs) grafted with a hygroscopic polymer. These GNPs are inkjet-printed to form a uniform thin film over an interdigitated electrode with a controllable thickness by adjusting the printing parameters. The resistance of the printed GNP thin film decreases significantly upon exposure to water vapor and exhibits a semi-log relationship with relative humidity (RH). The sensor can detect RH variations from 1.8 to 95% with large resistance changes up to 4 orders of magnitude with no hysteresis and small temperature dependence. In addition, with a small thickness, the sensor can reach absorption equilibrium quickly with response and recovery times of ≤1.2 and ≤3 s, respectively. The fast response to humidity changes also allows the GNP thin-film sensor to distinguish signals from intermittent humidification/dehumidification cycles with a frequency up to 2.5 Hz. The printed sensors on flexible substrates show little sensitivity to bending deformation and can be embedded in a mask for human respiratory detection. In summary, this study demonstrates the feasibility of applying printing technology for the fabrication of thin-film humidity sensors, and the methodology developed can be further applied to fabricate many other types of nanoparticle-based sensor devices.

Facile and Green Synthesis of Graphene-Based Conductive Adhesives via Liquid Exfoliation Process

In this study, we report a facile and green process to synthesize high-quality and few-layer graphene (FLG) derived from graphite via a liquid exfoliation process. The corresponding characterizations of FLG, such as scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM) and Raman spectroscopy, were carried out. The results of SEM show that the lateral size of as-synthesized FLG is 1–5 μm. The results of TEM and AFM indicate more than 80% of graphene layers is <10 layers. The most surprising thing is that D/G ratio of graphite and FLG are 0.15 and 0.19, respectively. The result of the similar D/G ratio demonstrates that little structural defects were created via the liquid exfoliation process. Electronic conductivity tests and resistance of composite film, in terms of different contents of graphite/polyvinylidene difluoride (PVDF) and FLG/PVDF, were carried out. Dramatically, the FLG/PVDF composite demonstrates superior performance compared to the graphite/PVDF composite at the same ratio. In addition, the post-sintering process plays an important role in improving electronic conductivity by 85%. The composition-optimized FLG/PVDF thin film exhibits 81.9 S·cm⁻¹. These results indicate that the developed FLG/PVDF composite adhesives could be a potential candidate for conductive adhesive applications.

Fabrication of Strain Gauges via Contact Printing: A Simple Route to Healthcare Sensors Based on Cross-Linked Gold Nanoparticles

In this study, we developed a novel and efficient process for the fabrication of resistive strain gauges for healthcare-related applications. First, 1,9-nonanedithiol cross-linked gold nanoparticle (GNP) films were prepared via layer-by-layer (LbL) spin-coating and subsequently transferred onto flexible polyimide foil by contact printing. Four-point bending tests revealed linear response characteristics with gauge factors of ∼14 for 4 nm GNPs and ∼26 for 7 nm GNPs. This dependency of strain sensitivity is attributed to the perturbation of charge carrier tunneling between neighboring GNPs, which becomes more efficient with increasing particle size. Fatigue tests revealed that the strain-resistance performance remained nearly the same after 10.000 strain/relaxation cycles. We demonstrate that these sensors are well suited to monitor muscle movements. Furthermore, we fabricated all-printed strain sensors by directly transferring cross-linked GNP films onto soft PDMS sheets equipped with interdigitated electrodes. Due to the low elastic modulus of poly(dimethylsiloxane) (PDMS), these sensors are easily deformed and, therefore, they respond sensitively to faint forces. When taped onto the skin above the radial artery, they enable the well-resolved and robust recording of pulse waves with diagnostically relevant details.

Impedimetric analysis on the mass transfer properties of intact and competent E. coli cells

Competent Escherichia coli cells are commonly used in bacterial transformation owing to its high permeability for bioorganic macromolecules like plasmid DNA. However, the mass transfer property of competent E. coli cell has not fully investigated. In the present study, mass transfer coefficients of competent and intact E. coli cells in deionized water were evaluated by impedimetric analysis of the release of cytoplasmic compounds. Because competent cells have a higher permeability after chemical treatment, the lumped mass transfer coefficient of a competent cell was approximately 6.5 times larger than that of an intact cell at room temperature. Release of cytoplasmic components was accelerated at an elevated temperature of 42 °C, which is the heat shock temperature used during bacterial transformation. At this elevated temperature, assessed lumped mass transfer coefficients of intact and competent E. coli cells were 9.28 × 10^-4 min^-1 and 97.10 × 10^-4 min^-1, respectively. Significant increase in the mass transfer coefficient of the competent cell is caused by cytolysis of cells. The double layer capacitances were also assessed from the electrochemical spectra confirming the enhanced ion release from E. coli cells and rupture of the competent cell under prolonged exposure at the elevated temperature. Impedimetric detection of the ion release with analyses using an equivalent circuit model provides a method to evaluate mass transfer properties of biomolecules.

Healable and Foldable Carbon Nanotube/Wax Conductive Composite

In this study, a composite material with healable and foldable features is formulated to print conductive patterns on rough surfaces, such as paper, cloth, and three-dimensional (3D) printed objects. Carbon nanotubes (CNTs) are mixed with wax to formulate a solid composite for pen writing. The composite has a low percolation threshold of 2.5 wt % CNTs and can be written on various rough substrates, such as paper and cloth, to create conductive patterns for electronic conductors. Because of the strong infrared (IR) absorption of CNTs, the printed patterns can be selectively sintered by noncontact IR radiation efficiently to show great electrical conductivity. The electrical resistance of the written patterns on paper also show an insignificant increase after bending, folding, and crumpling. Furthermore, the conductive composite exhibits great healability after destructive damages. The conductivity of the damaged patterns after severe folding or knife cutting recovers to its original value with thermal or IR heating. Several examples, such as conductive tracks on paper, cloth, or 3D printed objects, are also demonstrated to show the potential of this healable conductive composite for electronic applications.

The Establishment of a Lung Colonization Assay for Circulating Tumor Cell Visualization in Lung Tissues

Metastasis is the major cause of cancer death. The role of circulating tumor cells (CTCs) in promoting cancer metastasis, in which lung colonization by CTCs critically contributes to early lung metastatic processes, has been vigorously investigated. As such, animal models are the only approach that captures the full systemic process of metastasis. Given that problems occur in previous experimental designs for examining the contributions of CTCs to blood vessel extravasation, we established an in vivo lung colonization assay in which a long-term-fluorescence cell-tracer, carboxyfluorescein succinimidyl ester (CFSE), was used to label suspended tumor cells and lung perfusion was performed to clear non-specifically trapped CTCs prior to lung removal, confocal imaging, and quantification. Polymeric fibronectin (polyFN) assembled on CTC surfaces has been found to mediate lung colonization in the final establishment of metastatic tumor tissues. Here, to specifically test the requirement of polyFN assembly on CTCs for lung colonization and extravasation, we performed short term lung colonization assays in which suspended Lewis lung carcinoma cells (LLCs) stably expressing FN-shRNA (shFN) or scramble-shRNA (shScr) and pre-labeled with 20 μM of CFSE were intravenously inoculated into C57BL/6 mice. We successfully demonstrated that the abilities of shFN LLC cells to colonize the mouse lungs were significantly diminished in comparison to shScr LLC cells. Therefore, this short-term methodology may be widely applied to specifically demonstrate the ability of CTCs within the circulation to colonize the lungs.

Welding Silver Nanowire Junctions for Transparent Conducting Films by a Rapid Electroplating Method

A simple electrochemical method is developed in this study to weld the contact points in silver nanowire (AgNW) thin films. The AgNW thin film is first fabricated by spray coating and then submerged in a silver plating solution. By applying electrical potential over the AgNW thin films, silver ions in the plating solution are reduced into silver nanoparticles preferentially over nanowires and solder the nanomesh structures. Due to the large current density between silver nanowires, nanoparticles generated in the electroplating reaction mainly appeared at the junction. The electroplated AgNW network not only shows better conductivity with a negligible loss of transmittance, but also exhibit much better mechanical strength in the bending test.

Highly Deformable Origami Paper Photodetector Arrays

Flexible electronics will form the basis of many next-generation technologies, such as wearable devices, biomedical sensors, the Internet of things, and more. However, most flexible devices can bear strains of less than 300% as a result of stretching. In this work, we demonstrate a simple and low-cost paper-based photodetector array featuring superior deformability using printable ZnO nanowires, carbon electrodes, and origami-based techniques. With a folded Miura structure, the paper photodetector array can be oriented in four different directions via tessellated parallelograms to provide the device with excellent omnidirectional light harvesting capabilities. Additionally, we demonstrate that the device can be repeatedly stretched (up to 1000% strain), bent (bending angle ±30°), and twisted (up to 360°) without degrading performance as a result of the paper folding technique, which enables the ZnO nanowire layers to remain rigid even as the device is deformed. The origami-based strategy described herein suggests avenues for the development of next-generation deformable optoelectronic applications.

Printed Combinatorial Sensors for Simultaneous Detection of Ascorbic Acid, Uric Acid, Dopamine, and Nitrite

In this study, an effective and simple direct printing method was developed to create sensing devices on screen-printed carbon electrodes (SPCEs) to detect multiple species simultaneously. Two sensing materials, graphene oxide nanoribbons (GONRs) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), were printed on one SPCE for detection of multiple biochemical substances. Printed layers of the GONRs and PEDOT:PSS mixture (GONRs & PEDOT:PSS) on SPCE showed embedment of GONRs in the PEDOT:PSS layer and diminished the electrochemical activity of GONRs. In contrast, by printing the GONRs and PEDOT:PSS at separate locations (GONRs + PEDOT:PSS) on the same SPCE, the electrochemical activities of both GONRs and PEDOT:PSS can be preserved. Thus, without synthesizing new materials, the modified electrode is able to simultaneously detect ascorbic acid (AA), uric acid (UA), dopamine (DA), and nitrite (NO₂^-), with high anodic oxidation currents and well-separated voltammetric peaks, in differential pulse voltammetry measurements. The detection limits for the four analytes are 41 nM (AA), 30 nM (DA), 11 nM (UA), and 18 nM (NO₂^-), respectively. The electrode can either detect single species separately or simultaneously determine specific concentrations of the four species in aqueous mixtures, and this can be further extended for many other electrochemical sensing applications.

Effect of decomposition and organic residues on resistivity of copper films fabricated via low-temperature sintering of complex particle mixed dispersions

Mixtures of a copper complex and copper fine particles as copper-based metal-organic decomposition (MOD) dispersions have been demonstrated to be effective for low-temperature sintering of conductive copper film. However, the copper particle size effect on decomposition process of the dispersion during heating and the effect of organic residues on the resistivity have not been studied. In this study, the decomposition process of dispersions containing mixtures of a copper complex and copper particles with various sizes was studied. The effect of organic residues on the resistivity was also studied using thermogravimetric analysis. In addition, the choice of copper salts in the copper complex was also discussed. In this work, a low-resistivity sintered copper film (7 × 10⁻⁶ Ω·m) at a temperature as low as 100 °C was achieved without using any reductive gas.

Stability Analysis of Printed Liquid Elbows

In this study, a theoretical model was developed to analyze the stability of liquid elbow patterns and validated by experiments. An exemplar system of ethylene glycol continuously deposited on polyethylene terephthalate (PET) was used to study the effects of printing parameters on bulge formation near the elbow corners. In the elbow region, because of the capillary pressure differences, liquids flowed into the concave elbow corner and formed bulges easily after being printed. However, the bulge formation disappeared when the elbow angle is >90°. A simple model based on surface energy analysis was proposed to explain the bulging phenomenon and can successfully predict bulge sizes at steady state. A stability diagram was also calculated to map out the stable regimes. With the guidance of the stability diagram, stable elbow lines without any bulges can be printed with various angles by controlling the thickness of liquids. In summary, this stabilization strategy in this study is effective to maintain the fidelity of printed liquid patterns and provides useful guidelines for printed electronic applications.

Stabilization of the thermal decomposition process of self-reducible copper ion ink for direct printed conductive patterns

An alkylamine is added to stabilize the thermal decomposition process and to improve the surface morphology of printed patterns. The adhesion and mechanical stability of the copper thin films are also investigated.

Selective metallic coating of 3D-printed microstructures on flexible substrates

In this work, a simple method was developed to fabricate micron scale three-dimensional (3D) conductive objects on a flexible PDMS substrate.

Accelerated Sedimentation Velocity Assessment for Nanowires Stabilized in a Non-Newtonian Fluid

In this work, the long-term stability of titanium oxide nanowire suspensions was accessed by an accelerated sedimentation with centrifugal forces. Titanium oxide (TiO₂) nanoparticle (NP) and nanowire (NW) dispersions were prepared, and their sizes were carefully characterized. To replace the time-consuming visual observation, sedimentation velocities of the TiO₂ NP and NW suspensions were measured using an analytical centrifuge. For an aqueous TiO₂ NP suspension, the measured sedimentation velocities were linearly dependent on the relative centrifugal forces (RCF), as predicted by the classical Stokes law. A similar linear relationship was also found in the case of TiO₂ NW aqueous suspensions. However, NWs preferred to settle parallel to the centrifugal direction under high RCF because of the lower flow resistance along the long axis. Thus, the extrapolated sedimentation velocity under regular gravity can be overestimated. Finally, a stable TiO₂ NW suspension was formulated with a shear thinning fluid and showed great stability for weeks using visual observation. A theoretical analysis was deduced with rheological shear-thinning parameters to describe the nonlinear power-law dependence between the measured sedimentation velocities and RCF. The good agreement between the theoretical predictions and measurements suggested that the sedimentation velocity can be properly extrapolated to regular gravity. In summary, this accelerated assessment on a theoretical basis can yield quantitative information about long-term stability within a short time (a few hours) and can be further extended to other suspension systems.

Metal-Organic Framework Colloids: Disassembly and Deaggregation

We demonstrate a high-resolution method as an efficient tool to in situ characterize partially reversible assembly and aggregation of metal-organic framework (MOF) colloids. Based on the gas-phase electrophoresis, the primary size and the degree of aggregation of the MOF-525 crystals are tunable by pH adjustment and mobility selection. These findings allow for the further size control of MOF colloids and prove the capability of semiquantitative analysis for the MOF-based platforms in a variety of aqueous formulations (e.g., biomedical applications).

Designing a stronger interface through graded structures in amorphous/nanocrystalline ZrCu/Cu multilayered films

Many multilayered nano-structures appear to fail due to brittle matter along the interfaces. In order to toughen them, in this study, the microstructure and interface strength of multilayered thin films consisting of amorphous ZrCu and nanocrystalline Cu (with sharp or graded interfaces) are examined and analyzed. The interface possesses a gradient nature in terms of composition, nanocrystalline phase size and volume fraction. The bending results extracted from the nano-scaled cantilever bending samples demonstrate that multilayered films with graded interfaces would have a much higher interface bending strength/strain/modulus, and an overall improvement upgrade of more than 50%. The simple graded interface design of multilayered thin films with improved mechanical properties can offer much more promising performance in structural and functional applications for MEMS or optical coating.

Adhesive Stretchable Printed Conductive Thin Film Patterns on PDMS Surface with an Atmospheric Plasma Treatment

In this study, a plasma surface modification with printing process was developed to fabricate printed flexible conductor patterns or devices directly on polydimethylsiloxane (PDMS) surface. An atmospheric plasma treatment was first used to oxidize the PDMS surface and create a hydrophilic silica surface layer, which was confirmed with photoelectron spectra. The plasma operating parameters, such as gas types and plasma powers, were optimized to obtain surface silica layers with the longest lifetime. Conductive paste with epoxy resin was screen-printed on the plasma-treated PDMS surface to fabricate flexible conductive tracks. As a result of the strong binding forces between epoxy resin and the silica surface layer, the printed patterns showed great adhesion on PDMS and were undamaged after several stringent adhesion tests. The printed conductive tracks showed strong mechanical stability and exhibited great electric conductivity under bending, twisting, and stretching conditions. Finally, a printed pressure sensor with good sensitivity and a fast response time was fabricated to demonstrate the capability of this method for the realization of printed electronic devices.

Inkjet-Printed Porous Silver Thin Film as a Cathode for a Low-Temperature Solid Oxide Fuel Cell

In this work we report a porous silver thin film cathode that was fabricated by a simple inkjet printing process for low-temperature solid oxide fuel cell applications. The electrochemical performance of the inkjet-printed silver cathode was studied at 300-450 °C and was compared with that of silver cathodes that were fabricated by the typical sputtering method. Inkjet-printed silver cathodes showed lower electrochemical impedance due to their porous structure, which facilitated oxygen gaseous diffusion and oxygen surface adsorption-dissociation reactions. A typical sputtered nanoporous silver cathode became essentially dense after the operation and showed high impedance due to a lack of oxygen supply. The results of long-term fuel cell operation show that the cell with an inkjet-printed cathode had a more stable current output for more than 45 h at 400 °C. A porous silver cathode is required for high fuel cell performance, and the simple inkjet printing technique offers an alternative method of fabrication for such a desirable porous structure with the required thermal-morphological stability.

A Fabrication Method for Highly Stretchable Conductors with Silver Nanowires

Stretchable electronics are identified as a key technology for electronic applications in the next generation. One of the challenges in fabrication of stretchable electronic devices is the preparation of stretchable conductors with great mechanical stability. In this study, we developed a simple fabrication method to chemically solder the contact points between silver nanowire (AgNW) networks. AgNW nanomesh was first deposited on a glass slide via spray coating method. A reactive ink composed of silver nanoparticle (AgNPs) precursors was applied over the spray coated AgNW thin films. After heating for 40 min, AgNPs were preferentially generated over the nanowire junctions to solder the AgNW nanomesh, and reinforced the conducting network. The chemically modified AgNW thin film was then transferred to polyurethane (PU) substrates by casting method. The soldered AgNW thin films on PU exhibited no obvious change in electrical conductivity under stretching or rolling process with elongation strains up to 120%.

Printed Multicolor High-Contrast Electrochromic Devices

In this study, electrochemical responses of inkjet-printed multicolored electrochromic devices (ECD) were studied to evaluate the feasibility of presenting multiple colors in one ECD. Metallo-supramolecular polymers (MEPE) solutions with two primary colors were inkjet-printed on flexible electrodes. By digitally controlling print dosages of each species, the colors of the printed EC thin film patterns can be adjusted directly without premixing or synthesizing new materials. The printed EC thin films were then laminated with a solid transparent thin film electrolyte and a transparent conductive thin film to form an ECD. After applying a dc voltage, the printed ECDs exhibited great contrast with a transmittance change (ΔT) of 40.1% and a high coloration efficiency of 445 cm(2) C(-1) within a short darkening time of 2 s. The flexible ECDs also showed the same darkening time of 2 s and still had a high ΔT of 30.1% under bending condition. This study demonstrated the feasibility to fabricate display devices with different color setups by an all-solution process and can be further extended to other types of displays.

Highly stretchable and conductive silver nanowire thin films formed by soldering nanomesh junctions

Silver nanowires (AgNWs) have been widely used for stretchable and foldable conductors due to their percolating network nanostructure. To enhance the mechanical strength of AgNW thin films under extreme stretching conditions, in this study, we utilize a simple chemical reaction to join AgNW network connections. Upon applying a reactive ink over AgNW thin films, silver nanoparticles are preferentially generated over the nanowire junctions and solder the nanomesh structures. The soldered nanostructure reinforces the conducting network and exhibits no obvious change in electrical conductivity in the stretching or rolling process with elongation strains up to 120%. Several examples are also demonstrated to show potential applications of this material in stretchable electronic devices.