Ultralight and compressible carbon materials have promising applications in strain and pressure detection. However, it is still difficult to prepare carbon materials with supercompressibility, elasticity, stable strain-electrical signal response, and ultrasensitive detection limits, due to the challenge in structural regulation. Herein, a new strategy to prepare a reduced graphene oxide (rGO)-based lamellar carbon aerogels with unexpected and integrated performances by designing wave-shape rGO layers and enhancing the interaction among the rGO layers is demonstrated. Addition of cellulose nanocrystalline and low-molecular-weight carbon precursors enhances the interaction among rGO layers and thus produces an ultralight, flexible, and superstable structure. The as-prepared carbon aerogel displays a supercompressibility (undergoing an extreme strain of 99%) and elasticity (100% height retention after 10 000 cycles at a strain of 30%), as well as stable strain-current response (at least 10 000 cycles). Particularly, the carbon aerogel is ultrasensitive for detecting tiny change in strain (0.012%) and pressure (0.25 Pa), which are the lowest detection limits for compressible carbon materials reported in the literature. Moreover, the carbon aerogel exhibits excellent bendable performance and can detect an ultralow bending angle of 0.052°. Additionally, the carbon aerogel also demonstrates its promising application as wearable devices.

BackgroundThe receptors of Notch family play an important role in controlling the development, differentiation, and function of multiple cell types. The aim of this study is to investigate the role of Notch1 signaling upon immune suppression induced by melanoma cells.MethodsMelanoma cell line B16 cells were transfected by lentivirus containing mouse Notch1 gene or Notch1 shRNA to generate B16 cell line that highly or lowly expressed Notch1. Notch1 in anti-tumor immune response was comprehensively appraised in murine B16 melanoma tumor model in immunocompetent and immunodeficient mice. The ratios of CD3+CD8+ cytotoxic T cells, CD49b+NK cells, CD4+CD25+FoxP3+ Tregs and Gr1+CD11b+ MDSCs in tumor-DLN or spleen were examined by flow cytometry. After the co-culture of B16 cells and CD8+ T cells, the effects of Notch1 on the proliferation and activation of T cells were assessed by CCK8 assay, CFSE dilution and Chromium-release test. The mRNA expression and supernatant secretion of immunosuppressive cytokines, TGF-β1, VEGF, IL-10 and IFN-γ were measured by RT-PCR and ELISA, respectively.ResultsDownregulation or overexpression of Notch1 in B16 melanoma cells inhibited or promoted tumor growth in immunocompetent mice, respectively. Notch1 expression in B16 melanoma cells inhibited the infiltration of CD8+ cytotoxic T lymphocytes and NK cells and reduced IFN-γ release in tumor tissue. It could also enhance B16 cell-mediated inhibition of T cell proliferation and activation, and upregulate PD-1 expression on CD4+ and CD8+ T cells. The percentage of CD4+CD25+FoxP3+ Tregs and Gr1+CD11b+MDSCs were significantly increased in tumor microenvironment, and all these were attributed to the upregulation of TGF-β1.ConclusionThese findings suggested that Notch1 signaling in B16 melanoma cells might inhibit antitumor immunity by upregulation of TGF-β1.

Mechanically stable and foldable air cathodes with exceptional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities are key components of wearable metal-air batteries. Herein, we report a directional freeze-casting and annealing approach for the construction of 3D honeycomb nanostructured, N, P-doped carbon aerogel incorporating in situ grown FeP/Fe 2 O 3 nanoparticles as the cathode for flexible Zn-air battery. The aqueous rechargeable Zn-air batteries assembled with this carbon aerogel exhibit a remarkable specific capacity of 648 mAh g -1 at current density of 20 mA cm -2 with good long-term durability, outperforming those assembled with commercial Pt/C+RuO 2 catalyst. Furthermore, such foldable carbon aerogel with directional channels can serve as freestanding air cathode for flexible solid state Zn-air battery without the use of carbon paper/cloth and additives, giving a specific capacity of 676 mA h g -1 and an energy density of 517 W

Lightweight and elastic carbon materials have attracted great interest in pressure sensing and energy storage for wearable devices and electronic skins. Wood is the most abundant renewable resource and offers green and sustainable raw materials for fabricating lightweight carbon materials. Herein, a facile and sustainable strategy is proposed to fabricate a wood-derived elastic carbon aerogel with tracheid-like texture from cellulose nanofibers (CNFs) and lignin. The flexible CNFs entangle and assemble into an interconnected framework, while lignin with high thermal stability and favorable stiffness prevents the framework from severe structural shrinkage during annealing. This strategy leads to an ordered tracheid-like structure and significantly reduces the thermal deformation of the CNFs network, producing a lightweight and elastic carbon aerogel. The wood-derived carbon aerogel exhibits excellent mechanical performance, including high compressibility (up to 95% strain) and fatigue resistance. It also reveals high sensitivity at a wide working pressure range of 0-16.89 kPa and can detect human biosignals accurately. Moreover, the carbon aerogel can be assembled into a flexible and free-standing all-solid-state symmetric supercapacitor that reveals satisfactory electrochemical performance and mechanical flexibility. These features make the wood-derived carbon aerogel highly attractive for pressure sensor and flexible electrode applications.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201910292. important applications in wearable sensors, electronic skins, and flexible energy storage devices. Although carbon aerogels with good mechanical performances can be achieved from nanocarbon unites, their carbon precursors are nonrenewable, and the synthesis process of CNT, graphene, or their aerogels is high-cost and complicated.Considering the natural abundance, renewability, environmental friendliness, and low cost, biomass has been regarded as a renewable and sustainable carbon precursor for fabricating carbon aerogels. Up to now, several biomass-derived carbon aerogels have been successfully developed from gelatin, [16] winter melon, [17] protein, [18] bacterial cellulose, [19] and raw cotton. [20] However, those carbon aerogels show poor compressibility, elasticity, and fatigue resistance owing to the intrinsic random porous architecture and severe volume shrinkage at annealing or carbonization. Wood, as one of the most abundant biomass resources, demonstrates hierarchical tracheid structure that is composed of CNFs and amorphous matrix (lignin and hemicelluloses). [21] Owing to the compact structure (large amounts of additives and various interaction among tracheids or CNFs), natural wood is rigid and the tracheids are hard to be compressed and easily collapsed. Therefore, fabricating compressible and elastic conductive carbon aerogel from original wood tracheids is challenging. To solve this problem, Hu et al. [22] put forward a "top-down" stra...

Compressible and elastic carbon aerogels (CECAs) hold great promise for applications in wearable electronics and electronic skins. MXenes, as new two-dimensional materials with extraordinary properties, are promising materials for piezoresistive sensors. However, the lack of sufficient interaction among MXene nanosheets makes it difficult to employ them to fabricate CECAs. Herein, a lightweight CECA is fabricated by using bacterial cellulose fiber as a nanobinder to connect MXene (Ti3C2) nanosheets into continuous and wave-shaped lamellae. The lamellae are highly flexible and elastic, and the oriented alignment of these lamellae results in a CECA with super compressibility and elasticity. Its ultrahigh structural stability can withstand an extremely high strain of 99% for more than 100 cycles and long-term compression at 50% strain for at least 100 000 cycles. Furthermore, it has a high sensitivity that demonstrates not only an ultrahigh linearity but also a broad working pressure range (0–10 kPa). In particular, the CECA has a high linear sensitivity in almost the entire workable strain range (0–95%). In addition, it has very low detection limits for tiny strain and pressure. These features enable the CECA-based sensor to be a flexible wearable device to monitor both subtle and large biosignals of the human body.