Eco-friendly triboelectric nanogenerator based on degradable rape straw powder for monitoring human movement.

Green energy from the surrounding environment has great potential for reducing environmental pollution and sustainable development. Triboelectric nanogenerators (TENGs) are of great interest as they can easily harvest mechanical energy from the environment. Here, we present a triboelectric nanogenerator (RS-TENG) based on rape straw (RS), which was developed from a film composed of waste RS and polyvinyl alcohol (PVA). Due to the high content of carbonyl, hydroxyl and amino acid functional groups in RS, the ability of RS/PVA to lose electrons is increased. The proposed RS-TENG device with a size of 6.25 cm2exhibits open circuit voltage (78 V), short circuit current (5.3µA) performance under uniform external stress at a frequency of 3.5 Hz and 10 N in the cylinder motor. 104.5µW was obtained with a load resistance of 25 MΩ. Results obtained from degradability tests revealed that the RS/PVA film was able to degrade over a period of 30 d (In PBS solution). The RS-TENG produces a significantly high current signal under conditions of finger bending, elbow movements, and foot tapping. Practical tests of the RS-TENG have shown that it is a promising sensing device that will be widely used in the future.

Ultrastretchable, Antifreezing, and High-Performance Strain Sensor Based on a Muscle-Inspired Anisotropic Conductive Hydrogel for Human Motion Monitoring and Wireless Transmission.

Integrating structural anisotropy, excellent mechanical properties, and superior sensing capability into conductive hydrogels is of great importance to wearable flexible electronics yet challenging. Herein, inspired from the aligned structure of human muscle, we proposed a facile and universal method to construct an anisotropic hydrogel composed of polyacrylamide and sodium alginate by pre-stretching in a confined geometry and subsequent ionic cross-linking. The designed hydrogels showed extraordinary mechanical performances, such as ultrahigh stretchability, a comparable modulus to that of human tissues, and good toughness, ascribed to their anisotropically aligned polymer networks. Additionally, the hydrogel possessed anisotropic conductivity due to the anisotropy in ion transport channels. The hydrogel along the vertical direction was further cut and assembled into a flexible strain sensor, exhibiting a low detection limit (0.1%), wide strain range (1585%), rapid response (123 ms), distinct resilience, good stability, and repeatability, thereby being capable of monitoring and discriminating different human movements. In addition, the relatively high ionic conductivity and superior sensitivity enabled the anisotropic hydrogel sensor to be used for wireless human-machine interaction. More interestingly, the Ca2+-cross-linking strategy also endowed the hydrogel sensor with antifreezing ability, further broadening their working temperature. This work is expected to speed up the development of hydrogel sensors in the emerging wearable soft electronics.

Breathable Strain/Temperature Sensor Based on Fibrous Networks of Ionogels Capable of Monitoring Human Motion, Respiration, and Proximity.

Wearable strain and temperature sensors are desired for human-machine interfaces, health monitoring, and human motion monitoring. Herein, the fibrous mat with aligned nanofibers of ionic liquid (IL)/thermoplastic polyurethane (TPU) ionogels is fabricated via an electrospinning technique. The resultant fibrous mat is cut into a rectangle specimen and electrodes are loaded along the direction perpendicular to the nanofiber orientation to design a high-performance multimodal sensor based on an ionic conducting mechanism. As a strain sensor, the obtained sensor exhibits a wide strain working range (0-200%), a fast response and recovery (119 ms), a low detection limit (0.1%), and good reproducibility because of the reversible and deformable ionic conductive pathways of the sensor. Moreover, the sensor also exhibits excellent temperature-sensing behaviors, including a monotonic thermal response, high sensitivity (2.75% °C-1), high accuracy (0.1 °C), a fast response time (2.46 s), and remarkable repeatability, attributable to the negative temperature coefficient behavior of the IL/TPU fibrous mat. More interestingly, the IL/TPU fibrous sensor possesses good breathability, which is desired for wearable electronics. Because of these excellent sensing capabilities in strain and temperature, the sensor can not only monitor tiny and large human motions but also detect respiration and proximity, exhibiting enormous potential in wearable electronics.

Micelles modified with a chitosan-derived homing peptide for targeted intracellular delivery of ginsenoside compound K to liver cancer cells.

Ginsenoside compound K (CK), a major metabolite of protopanaxadiol ginsenosides, exhibits significant anticancer activities against various cancer cells. However, CK has poor water solubility and low bioavailability, which have limited its application. In this study, A54 peptide was utilized to fabricate CK-loaded micelles (APD-CK) for liver targeting, using deoxycholic acid-O-carboxymethyl chitosan as the vehicle. The average particle size of APD-CK micelles was about 171.4 nm by dynamic light scattering in the hydrated state and their morphology were spherical with good dispersion. An in vitro release assay indicated pH-responsive and sustained release behavior through a mechanism of non-Fickian diffusion. Moreover, the in vitro cytotoxicity of the APD-CK micelles against HepG2 and Huh-7 cells was significantly stronger than that of CK up to 20 µg/mL. Enhanced cellular uptake of micelles in both cell types was established using confocal fluorescence scanning microscopy and flow cytometry. In addition, western blot analysis revealed that APD-CK micelles could promote the protein expression levels of caspase-3, caspase-9, and poly (ADP-ribose) polymerase. Therefore, APD-CK micelles are a potential vehicle for delivering hydrophobic drugs in liver cancer therapy, enhancing drug targeting and anticancer activity.

More ordered, convex ganglioside-enriched membrane domains: the effects of GM1 on sphingomyelin bilayers containing a low level of cholesterol.

The special physical state of the sphingolipid-enriched membranes with characteristic lipid composition, presently one of the most controversial foci in cell biology, provides the essential environment for the proteins inside to be involved in the related physiological processes. The role of gangliosides, an important component of the membranes, deserves attention. The present investigation using several biophysical techniques indicates that ganglioside GM(1) induces the phase separation in the sphingomyelin membrane with 5 mol% cholesterol and regulates the membrane structure. The results of differential scanning calorimetry show that a higher T(m), GM(1)-rich phase emerges behind the lower T(m), sphingomyelin-rich phase with the incorporation of GM(1) into the sphingomyelin/cholesterol bilayers; and the GM(1)-rich phase dominates the membrane when the proportion of GM(1) reaches about 20 mol%. Fluorescence quenching further shows that the separation of the two domains is independent of temperature, occurring both in the gel phase and in the liquid phase. Laser Raman spectroscopy and fluorescence polarization suggest that the order of hydrocarbon chains increases and membrane fluidity decreases with increase in GM(1) content. Use of the fluorescence probe merocyanine-540 and electron microscopy reveals that the insertion of GM(1) leads to an increase in the spatial density of the lipid headgroups and a decrease in the curvature of the sphingomyelin/cholesterol bilayers. In sums, both the hydrophilic sugar heads and the hydrophobic hydrocarbon chains of GM(1) contribute to the regulation of membrane architecture. We suggest that the convex curvature of ganglioside-enriched membrane could be involved in forming and maintaining the characteristic flask-shaped invagination of caveolae.