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Contact-electrification is a universal effect for all existing materials, but it still lacks a quantitative materials database to systematically understand its scientific mechanisms. Using an established measurement method, this study quantifies the triboelectric charge densities of nearly 30 inorganic nonmetallic materials. From the matrix of their triboelectric charge densities and band structures, it is found that the triboelectric output is strongly related to the work functions of the materials. Our study verifies that contact-electrification is an electronic quantum transition effect under ambient conditions. The basic driving force for contact-electrification is that electrons seek to fill the lowest available states once two materials are forced to reach atomically close distance so that electron transitions are possible through strongly overlapping electron wave functions. We hope that the quantified series could serve as a textbook standard and a fundamental database for scientific research, practical manufacturing, and engineering.

Triggered by the endogenous chemical energy in the tumor microenvironment (TME), chemodynamic therapy (CDT) as an emerging non-exogenous stimulant therapeutic modality has received increasing attention in recent years. The chemodynamic agents can convert internal hydrogen peroxide (H 2 O 2 ) into the lethal reactive oxygen species (ROS) hydroxyl radicals ( • OH) for oncotherapy. Compared with other therapeutic modalities, CDT possesses many notable advantages, such as tumor-specific, highly selective, fewer systemic side effects, and no need for external stimulation. Nevertheless, mild acid pH, low H 2 O 2 content, and overexpressed reducing substance in TME severely suppressed the CDT efficiency. With the rapid development of nanotechnology, some kinds of nanomaterials have been utilized with improved CDT efficiency. In particular, the excellent photo-, ultrasound-, magnetic-, and other stimuli-response properties of nanomaterials make it possible for combination cancer therapy of CDT with other therapeutic modalities, and it has shown superior anti-cancer activity than monotherapies. Therefore, it is necessary to summarize the application of nanomaterial-based chemodynamic cancer therapy. In this review, the various nanomaterials-based nanoplatforms for CDT and its combinational therapies are summarized and discussed, aiming to provide inspiration for the design of better-quality agents to promote the CDT development and lay the foundation for its future conversion to clinical applications.

Quantum dots (QDs) with fluorescence in the second near-infrared window (NIR-II, 1000-1400 nm) are ideal fluorophores for in vivo imaging of deep tissue with high signal-to-noise ratios. Ag₂Se (bulk band gap 0.15 eV) is a promising candidate for preparing NIR-II QDs. By using 1-octanethiol as ligand to effectively balance the nucleation and growth, tuning the fluorescence of Ag₂Se QDs was successfully realized in the NIR-II window ranged from 1080 to 1330 nm. The prepared Ag₂Se QDs can be conveniently transferred to the aqueous phase by ligand exchange, showing great potential for multicolor NIR-II fluorescence imaging in vivo.

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Transdermal drug delivery (TDD) systems with feedback control have attracted extensive research and clinical interest owing to their unique advantages of convenience, self‐administration, and safety. Here, a self‐powered wearable iontophoretic TDD system that can be driven and regulated by the energy harvested from biomechanical motions is proposed for closed‐loop motion detection and therapy. A wearable triboelectric nanogenerator (TENG) is used as the motion sensor and energy harvester that can convert biomechanical motions into electricity for iontophoresis without stored‐energy power sources, while a hydrogel‐based soft patch with side‐by‐side electrodes is designed to enable noninvasive iontophoretic TDD. Proof‐of‐concept experiments on pig skin with dyes as model drugs successfully demonstrate the feasibility of the proposed system. This work not only extends the application of TENG in the biomedical field, but may also provide a cost‐effective solution for noninvasive, electrically assisted TDD with closed‐loop sensing and treatment.

distributed mechanical energy, such as wind energy, body motion energy, and vibration energy, into electrical output by coupling triboelectric effect and electrostatic induction. [1] The converted electrical energy can be used not only as a power source but also as a signal for biochemical sensing, because the electrical output signals can be significantly affected by molecules adsorbed on the contact surface of TENG. To date, many different types of self-powered biochemical sensors based on TENG for the detection of catechin, dopamine, phenol, thrombin, heavy metal ions, etc. have been demonstrated. [2] However, most of these sensors relied on the solid-solid contact electrification, which have some issues such as durability and output stability due to the cross-contamination that resulted from adsorption of chemicals during the contact of triboelectric layers. Moreover, the humidity and surface roughness may also affect the output of TENG, [3] thus affects the accuracy of analysis as a biochemical sensor.Recently, liquid-solid contact TENG has also been successfully designed for harvesting water wave energy and developed as self-powered sensors for solution temperature, polarity, and chemical concentration. [4] As a chemical sensor, the liquid-solid contact TENG has many advantages over solid-solid contact TENG. It not only overcomes the issues existing in solid-solid contact TENG as mentioned above, but also is more flexible for the development of various miniaturized chemical sensors, such as microfluidic chips sensors and capillary tube sensors. [5] However, as one of the most important kinds of TENG, the current study of liquid-solid contact TENG is only based on a single liquid phase, and there are no reports focusing on the liquid-solid contact TENG in oil/water multiphase systems. Oil/water mixtures are ubiquitous in nature and the oil/water interfacial charges are particularly important in chemistry, physics, engineering, biology, and life sciences. [6] It has long been known that the oil/water interface can acquire negative charges, [7][8][9] which is a potential energy source that can be harvested by TENG.Here, a single-electrode liquid-solid contact TENG has been fabricated with poly(tetrafluoroethylene) (PTFE) film, a copper A liquid-solid contact triboelectric nanogenerator (TENG) based on poly(tetrafluoroethylene) (PTFE) film, a copper electrode, and a glass substrate for harvesting energy in oil/water multiphases is reported. There are two distinctive signals being generated, one is from the contact electrification and electrostatic induction between the liquid (water/oil) and the PTFE film (V TENG and I TENG ); and the other is from the electrostatic induction in the copper electrode by the oil/water interfacial charges (ΔV interface and I interface ), which is generated only when the liquid-solid contact TENG is inserted across the oil/water interface. The two signals show interesting opposite changing trends that the V TENG and I TENG decrease while the oil/water interfacial signals of ΔV i...

The growth of licorice in arid areas faces nutritional and environmental stresses. Arbuscular mycorrhizal (AM) fungi have been shown to increase the abilities of plants to develop. However, little is known regarding the role of AM fungi in licorice (Glycyrrhiza uralensis) growth. In the present study, by inoculation with two AM fungi, Glomus mosseae (Nicolson & Gerdemann) Gerd. & Trappe and Glomus veriforme (P. Karst.), the effects on licorice growth in sand were examined by measuring plant height, number of leaves, shoot and root fresh weight, and by analyzing morphological parameters of the root system in sand. The influence of the two microorganisms on the accumulation of mineral nutritions and bioactive components in licorice were also investigated. The results showed that mycorrhyzae were of the Arum-type and their colonization frequency (F %), colonization intensity (M %) and colonization intensity (m %) of AM fungi inoculation were found to be 80.0-84.6%, 49.4-60.0% and 58.4-71.9%, respectively. The inoculation significantly improved plant growth during early and late growth stages in comparison with the control. Moreover, inoculation of G. mosseae and G. versiforme, alone or in combination, improved plant phosphorus acquisition in the leaf over noninoculation plants. In addition, mycorrhiza formation enhanced the glycyrrhizin concentration in roots, but resulted in a considerable reduction of the root oxidase activity. The results indicate that the inoculation with AM fungi could be a useful approach to increase the licorice pharmic quality.