Nature-Inspired Molecular-Crowding Enabling Wide-Humidity Range Applicable, Anti-Freezing, and Robust Zwitterionic Hydrogels for On-Skin Electronics.

Hydrogels are currently in the limelight for applications in soft electronics but they suffer from the tendency to lose water or freeze when exposed to dry environments or low temperatures. Molecular crowding is a prevalent occurrence in living cells, in which molecular crowding agents modify the hydrogen bonding structure, causing a significant reduction in water activity. Here, a wide-humidity range applicable, anti-freezing, and robust hydrogel is developed through the incorporation of natural amino acid proline (Pro) and conductive MXene into polyvinyl alcohol (PVA) hydrogel networks. Theoretical calculations reveal that Pro can transform "free water" into "locked water" via the molecular-crowding effect, thereby suppressing water evaporation and ice forming. Accordingly, the prepared hydrogel exhibits high water retention capability, with 77% and 55% being preserved after exposure to 20 °C, 28% relative humidity (RH) and 35 °C, 90% RH for 12 h. Meanwhile, Pro lowers the freezing temperature of the hydrogel to 34 °C and enhances its stretchability and strength. Finally, the PVA/Pro/MXene hydrogels are assembled as multifunctional on-skin strain sensors and conductive electrodes to monitor human motions and detect tiny electrophysiological signals. Collectively, this work provides a molecular crowding strategy that will motivate researchers to develop more advanced hydrogels for versatile applications.

Sustainable Dielectric Films with Ultralow Permittivity from Soluble Fluorinated Polyimide.

In the rapidly growing area of high-frequency communications, polyimide films with ultralow dielectric constant and dielectric loss, adequate insulating strength, and recyclability are in high demand. Using a synthesized soluble fluorinated polyimide, a series of recyclable porous dielectric films with varying porosities were fabricated in this study through nonsolvent-induced phase separation. By manipulating the mass ratio of the binary solvent used to dissolve the polyimide, the shape, size, and size distribution of the pores generated throughout the polyimide matrix can be accurately regulated. The porosity and average pore size of the as-prepared porous films were adjustable between 71% and 33% and between 9.31 and 1.00 µm, respectively, which resulted in a variable dielectric constant of 1.51-2.42 (100 kHz) and electrical breakdown strength of 30.3-119.7 kV/mm. The porous sPI film with a porosity rate of 48% displayed a low dielectric constant of 2.48 at 10 GHz. Coupled with their superior thermal stability, mechanical characteristics, and recyclability, these porous polyimide films are highly promising for constructing high-frequency microelectronic devices.

Direct Writing of Silver Nanowire Patterns with Line Width down to 50 µm and Ultrahigh Conductivity.

Direct writing of one-dimensional nanomaterials with large aspect ratios into customized, highly conductive, and high-resolution patterns is a challenging task. In this work, thin silver nanowires (AgNWs) with a length-to-diameter ratio of 730 are employed as a representative example to demonstrate a potent direct ink writing (DIW) strategy, in which aqueous inks using a natural polymer, sodium alginate, as the thickening agent can be easily patterned with arbitrary geometries and controllable structural features on a variety of planar substrates. With the aid of a quick spray-and-dry postprinting treatment at room temperature, the electrical conductivity and substrate adhesion of the written AgNWs-patterns improve simultaneously. This simple, environment benign, and low-temperature DIW strategy is effective for depositing AgNWs into patterns that are high-resolution (with line width down to 50 µm), highly conductive (up to 1.26 × 105 S/cm), and mechanically robust and have a large alignment order of NWs, regardless of the substrate's hardness, smoothness, and hydrophilicity. Soft electroadhesion grippers utilizing as-manufactured interdigitated AgNWs-electrodes exhibit an increased shear adhesion force of up to 15.5 kPa at a driving voltage of 3 kV, indicating the strategy is very promising for the decentralized and customized manufacturing of soft electrodes for future soft electronics and robotics.

Stellate Ganglion Block Improves Postoperative Cognitive Dysfunction in aged rats by SIRT1-mediated White Matter Lesion Repair.

Postoperative cognitive dysfunction (POCD) is a common complication of the central nervous system after surgery, especially in elderly patients. Many factors can influence POCD, one of which is white matter lesion. Nowadays, stellate ganglion block (SGB) is considered as an effective intervention for postoperative cognitive dysfunction and SIRT1 may play a role in that, but the exact mechanism remains unclear. Therefore, the underlying mechanisms that SGB improves postoperative cognitive dysfunction through SIRT1 in aged rats and its association with white matter lesion are yet to be elucidated. The role of SIRT1 in the process that stellate ganglion block improves the cognitive impairment, and its association with white matter lesion was investigated using splenectomy-induced POCD model. To investigate this result further, we performed transection of the cervical sympathetic trunk on the basis of POCD model, and the role of SIRT1 was then verified again by intraperitoneal injection of EX527 (5 mg/kg) five min before surgery. Data show that SGB treatment has neuroprotective effects in POCD rats. SGB treatment can ameliorate cognitive impairment, neuroinflammation and neuronal apoptosis in white matter. Moreover, SGB treatment enhanced the expression of SIRT1 in the hippocampus and white matter, decreased NF-κB activity in the hippocampus and white matter. It also increased the levels of inflammatory factor in serum and white matter, primarily at the level of anti-inflammatory factor. These findings indicated that SIRT1-mediate white matter repair could be a new therapeutic target for neurodegenerative illnesses.

Optimizing energy harvesting performance of silicone elastomers by molecular grafting of azobenzene to the macromolecular network.

The dielectric elastomer generator (DEG) has attracted significant attention in the past decade for harvesting energy from reciprocating mechanical motion owing to its variable capacitance under tension. However, the challenge of conceiving novel DEGs with high energy harvesting performance should be addressed. In this work, azobenzene molecules with strong polarity were synthesized and chemically grafted onto a hydroxyl-terminated polydimethylsiloxane (PDMS) network through a simple one-step process, offering a robust, molecularly homogenous silicone rubber. In addition, dimethyl silicone oil (DMSO) plasticizer was simultaneously added to reduce the mechanical modulus of the composite. The loading content of DMSO was firstly optimized in terms of the mechanical and dielectric properties of the resultant azo-g-PDMS/DMSO elastomers. Then, the effects of azobenzene loading on the morphology, and mechanical, dielectric and electric generation performances were thoroughly investigated. Overall, the dielectric permittivity displayed a rising trend with the increase of the azobenzene content while the breakdown strength increased initially and then decreased. The breakdown strength could reach as high as 73 V µm-1 by grafting with 7 phr of azobenzene while maintaining a relatively low mechanical modulus. Meanwhile, the as-prepared azo-g-PDMS/DMSO films exhibited enhanced energy harvesting density (0.69 mJ cm-3) and electromechanical conversion efficiency (5.01%) at a bias voltage of 1500 V, which were 2 and 2.5 times as much as those of the azobenzene-free matrix. This work provides ideas for future applications of DEG with high energy harvesting performance.

Comprehensive analysis of the differential expression profile of microRNAs in rats with spinal cord injury treated by electroacupuncture.

Abnormal microRNA (miRNA) expression has been implicated in spinal cord injury (SCI), but the underlying mechanisms are poorly understood. To observe the effect of electroacupuncture (EA) on miRNA expression profiles in SCI rats and investigate the potential mechanisms involved in this process, Sprague­Dawley rats were divided into sham, SCI and SCI+EA groups (n=6 each). Basso, Beattie and Bresnahan (BBB) scoring and hematoxylin­eosin staining of cortical tissues were used to evaluate spinal cord recovery with EA treatment 21 days post­surgery across the three groups. To investigate miRNA expression profiles, 6 Sprague­Dawley rats were randomly divided into SCI and SCI+EA groups (n=3 in each group) and examined using next­generation sequencing. Integrated miRNA­mRNA­pathway network analysis was performed to elucidate the interaction network of the candidate miRNAs, their target genes and the involved pathways. Behavioral scores suggested that hindlimb motor functions improved with EA treatments. Apoptotic indices were lower in the SCI+EA group compared with the SCI group. It was also observed that 168 miRNAs were differentially expressed between the SCI and SCI+EA groups, with 29 upregulated and 139 downregulated miRNAs in the SCI+EA group. Changes in miRNA expression are involved in SCI physiopathology, including inflammation and apoptosis. Reverse transcription­quantitative PCR measurement of the five candidate miRNAs, namely rno­miR­219a­5p, rno­miR­486, rno­miR­136­5p, rno­miR­128­3p, and rno­miR­7b, was consistent with RNA sequencing data. Integrated miRNA­mRNA­pathway analysis suggested that the MAPK, Wnt and NF­κB signaling pathways were involved in EA­mediated recovery from SCI. The present study evaluated the miRNA expression profiles involved in EA­treated SCI rats and demonstrated the potential mechanism and functional role of miRNAs in SCI in rats.

Identification of functional tRNA-derived fragments in senescence-accelerated mouse prone 8 brain.

Transfer RNA-derived fragments (tRFs) are known to contribute to multiple illnesses, including cancers, viral infections, and age-related neurodegeneration. In this study, we used senescence-accelerated mouse prone 8 (SAMP8) as a model of neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease, and a control, the senescence-accelerated mouse resistant 1 (SAMR1) model, to comprehensively explore differences in tRF expression between them. We discovered 570 tRF transcripts among which eight were differentially expressed. We then obtained 110 potential target genes in a miRNA-like pattern. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation suggest that these target genes participate in a variety of brain functions; e.g., synapse formation (GO: 0045202) and the synaptic vesicle cycle pathway. We further assessed in detail those tRFs whose miRNA-like pattern was most likely to promote the progression of either Alzheimer's or Parkinson's disease, such as AS-tDR-011775 acting on Mobp and Park2. Our findings suggest the eight dysregulated tRFs we uncovered here may be beneficially exploited as potential diagnostic biomarkers and/or therapeutic targets to treat age-related brain diseases.

Characterization of circRNA-Associated-ceRNA Networks in a Senescence-Accelerated Mouse Prone 8 Brain.

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. Although many researchers have attempted to explain the origins of AD, developing an effective strategy in AD clinical therapy is difficult. Recent studies have revealed a potential link between AD and circRNA-associated-ceRNA networks. However, few genome-wide studies have identified the potential circRNA-associated-ceRNA pairs involved in AD. In this study, we systematically explored the circRNA-associated-ceRNA mechanism in a 7-month-old senescence-accelerated mouse prone 8 (SAMP8) model brain through deep RNA sequencing. We obtained 235 significantly dysregulated circRNA transcripts, 30 significantly dysregulated miRNAs, and 1,202 significantly dysregulated mRNAs. We then constructed the most comprehensive circRNA-associated-ceRNA networks in SAMP8 brain. GO analysis revealed that these networks were involved in regulating the development of AD from various angles, for instance, axon terminus (GO: 0043679) and synapse (GO: 0045202). Following rigorous selection, we discovered that the circRNA-associated-ceRNA networks in this AD mouse model were mainly involved in the regulation of Aß clearance (Hmgb2) and myelin function (Dio2). This research is the first to provide a systematic dissection of circRNA-associated-ceRNA profiling in SAMP8 mouse brain. The selected circRNA-associated-ceRNA networks can profoundly affect the diagnosis and therapy of AD in the future.