The health effect of atmospheric fine particulate matters(PMs) is now being increasingly concerned, and a growing number of epidemiological studies have reported the adverse impacts of PMs on the respiratory system, cardiovascular system, etc. However, whether PMs can enter the brain and cause neurotoxicities or not remains unknown, which has been an important research direction for the health risk evaluation of atmospheric smog in recent years. Based on the relevant epidemiological studies and experimental evidences in vitro and in vivo, this paper summarizes the potential pathways regulating the neurotoxicity of atmospheric PMs, their detrimental effects on the adult, elderly, and developmental nervous systems, as well as the underlying molecular mechanisms. Atmospheric PMs were reported to affect the nervous system through the blood-brain barrier pathway, the olfactory nerve pathway, the microbiota-gut-brain axis, etc. Herein, oxidative stress, mitochondrial damage, inflammation, DNA damage, epigenetic regulation, hematological homeostasis, and several key signaling pathways were found to be involved in the observed neurotoxicities caused by atmospheric PM exposure. This review aims to reveal the neurotoxicities of atmospheric PMs, especially their neurodevelopmental effects on special populations such as children. On this basis, this article points out the future research directions in this field, providing a theoretical basis for the evaluation of neurotoxicities and public health hazards of atmospheric PMs.

In recent years, metal-organic framework materials(MOFs) have attracted the attention of many researchers because of their excellent framework structure, rich porosity and versatility. A variety of MOFs materials and MOF-based composites have been developed. However, since most MOFs exist in the form of crystals and powders, their rigidity and fragility limit its practical application. Meanwhile, the instability of MOFs in solution can cause the decomposition of the material. Some high-crystallinity MOFs are also very fragile and difficult to process, so researchers combine MOFs with hydrogels and develop many MOF-based hydrogel materials with excellent properties. This review presents current developments of MOF-based hydrogels with emphasis on the specific categories and the synergistic effects of MOF-derived hydrogels between MOFs and additional materials. Particular emphasis is placed on discussing the advantages of MOF-based hydrogels in applications such as sensors, catalysts, water treatment, wound dressings, drug carriers, etc. MOF-based hydrogels can provide valuable guidance for the investigation of MOFs towards practical applications with processability, stability, and easy handling. Specifically, the recent progress of pure MOF hydrogels, MOF@bioorganic macromolecule hydrogels, MOF@biocompatible hydrogels, other MOF-based composite hydrogels, and the applications of these composite materials are summarized.

MXenes are general term for two-dimensional transition metal carbides, nitrides and carbonitrides, which have been widely used in energy storage, catalysis, electromagnetics and other fields due to their unique physical and chemical properties. As an important member of MXenes, V₂C MXene has high conductivity, low transport barrier and pseudocapacitve performance ascribed to the multiple oxidation states of vanadium. Consequently, it has highlighted performances in many aspects, especially in electrochemical energy storage. However, the difficulty of synthesis caused by its high formation energy and the structural instability of V₂C MXene have restricted its development. This article reviews the progress of V₂C MXene in synthesis, structure, properties and applications, focusing on synthesis methods and applications in electrochemical energy storage and electrocatalytic hydrogen evolution reaction. Meanwhile, the challenges and future perspective in the application of V₂C MXene are outlined.

As a novel kind of two dimensional material, MXene refers to the family of two-dimensional transition metal carbides, nitrides or carbonitrides. The general formula of this material is M_n+1X_nT_x(n=1~3) where M is transitional metal, X is carbon or nitrogen and T is active functional groups such as fluorine, hydroxyl or oxygen-containing group. The ultra-thin structure and fascinating physical and chemical(electronic, optical, magnetic, etc.) properties of this material has attracted wide interest in mechanical engineering, optics, energy, and electronics areas. Currently, MXenes are broadening their applications in the biomedical field. This is mainly originated from their large surface area and strong absorbance in near-infrared region, combining with their facile surface modifications with various molecular or nanoparticles. This review introduces the very recent progress and novel paradigms of MXenes for state-of-the-art biomedical applications. Firstly, the preparation methods and surface modifications of MXenes designed for biomedical applications is introduced. Then their applications in the biomedical areas are emphasized, including structural- and dose-dependent antimicrobial activity, bioimaging, photothermal cancer therapy, precise biosensors and so on. Finally, the current challenges and future opportunities of applying MXene-based nanomaterials and nanocomposites in biomedical field are summarized and discussed. It is highly expected that the ultrathin MXenes and their elaborately designed nanocomposites will become one of the most attractive biocompatible inorganic nano-platforms for multiple and extensive biomedical applications.

As an important part of intelligent wearable device, flexible pressure/strain sensors are widely used in human motion detection, health monitoring, robot and electronic skin. Among them, 3D conductive materials(such as aerogels, sponges and foams) have 3D interconnection microstructures and have excellent compressibility and conductivity, which bring a breakthrough that enables sensors to have high sensitivity and wide range. According to the raw materials for the preparation of 3D conductive materials, this article divides them into five types: biomass materials, carbon materials, polymer materials, metal nanomaterials, and MXene materials. Then, the preparation methods of 3D conductive materials and their innovation and development in the field of sensor applications are summarized. Finally, the prospect of flexible strain/pressure sensors based on 3D materials is discussed.

In recent years, inorganic CsPbX₃(X=Cl, Br, I) perovskite has attracted much attention in the application of perovskite solar cell(PSC) due to its advantages such as high absorption coefficient, low exciton binding energy and long carrier diffusion length. Efficient synthesis methods and accurate morphology control are crucial to the optical properties, the photoelectric performance and stability of solar cells. In this paper, the synthesis methods of inorganic perovskite materials with different dimensions including zero-dimensional quantum dots, one-dimensional nanowire/nanorod, two-dimensional nanoplate and three-dimensional nanoflower are systematically introduced. Among them, hot-injection, solvothermal and vapor deposition are widely used. The advantages of various synthesis methods are compared. The methods of controlling the morphologies and optical properties of inorganic perovskite, as well as the optimization strategies for the photoelectric performance of the corresponding solar cells are systematically emphasized. In particularly, temperature and reaction time and ligand are main factors that influence the morphology control. Finally, the application of inorganic perovskites with different dimensions towards harmless and high-performance solar cell is prospected.

Due to the consuming upgrade and development of 5G technology, the future display technology focuses on ultra-high resolution, large-area, light weight, flexibility and low-cost. Organic light-emitting diodes(OLEDs) have attracted considerable attention as one of the most promising next-generation display technologies due to the advantages of self-emitting, ultra-thin thickness, low electric power consumption, large-area, and high flexibility. Flexible transparent conducting electrodes(TCEs) are primary to achieve the flexible, foldable and wearable OLEDs. However, novel TCEs are required to replace traditional indium tin oxide(ITO), due to its inherent brittle nature and steadily rising price. Carbon-based materials are the most promising alternate flexible TCEs because of their abundant resources and simple, cost-effective fabrication processes. Among the carbon-based materials, one-dimensional(1D) carbon nanotubes, 2D graphene and 3D interpenetrating network conducting polymers are drawing extensive interest owning to the excellent optical transparency, conductivity, flexibility and chemical functionalization characteristics, leading to remarkable achievements in optoelectronic devices as TCEs. In this review, carbon-based flexible TCEs, including carbon nanotubes, graphene and conducting polymers, are introduced, including the basic optoelectronic properties, preparation methods, and pattern technologies. Furthermore, a comprehensive overview of recent research progress for the flexible OLEDs using carbon-based TCEs are presented and summarized. Finally, we address the key challenges in current scale production and applications, and provide some potential proposals for future flexible OLEDs.

Organic-based materials which have been explored for use as electrodes in rechargeable devices have the potential to utilize changes in charge-state of the electroactive sites to realize intrinsic redox reactions. As outlined in this review, organic electrode materials are not strictly limited to conventional Li-ion batteries, they may also be used in other metal ion batteries with larger ionic radius(such as Na⁺, K⁺, Mg²⁺, Zn²⁺). Organic electrode materials have been shown to have great application potential in rechargeable devices due to a range of advantages which include high molecular structure diversity, low cost, abundant resource, and environmental sustainability. The properties of organic electrode materials can also be readily tailored with appropriate material design. However, there are still critical issues which need to be addressed in order to facilitate the practical application of organic electrode materials, including their poor electrical conductivity and dissolution in conventional organic electrolyte systems. This review addresses organic electrode materials with various redox centers, including organosulfur compounds, organic radicals, imide-based compounds, azo compounds and carbonyl compounds through first providing an overview of their working principles. We then focus on approaches towards enhancing the electrochemical performance of carbonyl-based electrode materials. We also review the last five years of advancements relating to applications of carbonyl-based electrode materials in the field rechargeable devices. Finally, the challenges and opportunities for organic electrode materials towards practical application are outlined.

As a unique class within the versatile family of microporous materials, compared with ordinary conjugated polymers or porous materials, conjugated microporous polymers(CMPs) not only have π-conjugated framework but also have many micropores. Since their discovery in 2007, CMPs have been intensively studied as an important subclass of porous materials, and various interesting properties and possible applications have been discovered and described. A wide range of chemical reactions, building blocks and synthetic method offer a tremendous number of CMPs with different properties and specific structures, which drives the rapid growth of the field. CMPs have shown great potential in solving energy and environmental problems, in particular, they have demonstrated huge application prospect in gas adsorption, heterogeneous catalysis, light emittance, sensing, energy storage and biological applications. Since first discovered, CMPs are unparalleled among porous materials because they possess extended π-conjugated backbones along with the chemical and thermal stability. Nowadays, the possibility to produce solvent processable CMPs or to generate thin films on electrodes all makes CMPs an exciting field for further research. In this review, we present the recent significant breakthroughs and the conventional functions and practices in the field of CMPs to find useful applications. We start with an initial historical look at origins of porous materials and a briefly contrast between CMPs and other porous materials. Then, we present an exhaustive analysis of the design strategies with special emphasis on the topologies of amorphous porous organic materials. As following, we discuss the chemical synthesis of CMPs that gives access to a range of potential applications, with a focus on the up-to-date overview of the main fields. Finally, we give an outlook of the challenges and restrictions which CMPs research in the future. We also draw some comparisons between CMPs and the growing range of conjugated crystalline covalent organic frameworks(COFs).

As a kind of green rechargeable battery with high energy density and power density, lithium-ion batteries are the first choice of portable electronic products and are gradually applied in the field of power vehicles. In order to better meet application requirements, it is necessary to further improve the energy density of current lithium-ion batteries. Different from the rapid development of high-voltage anode materials, traditional electrolyte is easy to decompose under high working voltage, which greatly hinders the commercial application of high energy density lithium-ion batteries. As an important component of lithium-ion batteries, electrolyte has an important impact on performance of lithium-ion batteries in many aspects. Therefore, it is urgent to improve the working voltage of electrolyte to solve the problem of low energy density of lithium-ion batteries. In this paper, the research progress of high-voltage electrolyte at home and abroad in recent years is summarized from two aspects of new organic solvent and high-voltage additive, the effect of theoretical calculation on the design of high-voltage electrolyte is introduced, and the development and prospect of high-voltage electrolyte are summarized and forecast.

Small molecular biothiols, including cysteine(Cys), homocysteine(Hcy), and glutathione(GSH), play an import role in physiological and pathological processes. The abnormal levels of biothiols in cells and organisms are closely relevant to various kinds of diseases. Therefore, the detection of biothiols is of great importance. In recent years, the fluorescent probe has shown favorable advantages compared to various other detecting techniques, owing to its facile operation, high temporal-spatial resolution, low destructiveness and visualization. Among the numerous reported thiol fluorescent probes, the probes with red/near-infrared(NIR) emission signal are especially concerned, because of the low background interferences, less disturbance by Raman scattering, deeper penetration depth and less photodamage to biological tissues. All these features endow the thiol fluorescent probes with better properties in cell imaging and great potential in in vivo imaging. Here, we mainly review the paper published in recent three years concerning a variety of thiol fluorescent probes with red or NIR emission. The probes are classified according to their fluorogens, with six kinds described here: rhodamine, BODIPY, cyanine, natural pigment(anthocyanidins and curcumin), donor-acceptor(D-A) conjugated molecules and fluorophores with aggregation induced-emission(AIE). We discuss the molecular design, fluorescent property, recognition mechanism and bioimaging application of each probe. At the same time, the unsolved problems and the prospect of biothiol fluorescent probes with long wavelength emission are also presented.

Cancers seriously threaten human health due to their relatively high mortality. Early diagnosis and treatment play key roles in improving the cancers cure rate and saving people’s lives. With the development of science and nanotechnology, the advent of micro/nanomotors with self-propelled capabilities has enabled exciting opportunities for the diagnosis and therapy of cancers. The micro/nanomotors can effectively convert diverse energy sources(light, ultrasound, magnetic, electrical, heat, etc.) into their own driving forces, and show encouraging potential for performing various complex and precise tasks in the micrometer or nanometer space. Compared with nanomaterials with passive Brownian motion, micro/nanomotors with active propulsion capabilities endow more flexibility in intelligent cancer diagnosis and treatment. With the development of fabrication strategies, various shapes of micro/nanomotors that can be driven in various modes have been successfully fabricated, such as Janus microspheres, microtubular microrockets and nanowires, etc. These micro/nanomotors have been widely used in different fields of cancer research, as evidenced by significant breakthroughs in the development of a series of intracellular delivery systems, novel diagnosis methods and imaging strategies. In this review, we mainly focus on the tremendous inspiration and opportunities offered by micro/nanomotors in intelligent cancer diagnosis and therapy. Firstly, we demonstrate the recent progress of micro/nanomotors in the fields of cancer diagnostics(ranging from isolation of circulating tumor cells to detection of cancer related biomarkers, such as protein and microRNA), cancer-target delivery(such as drug, interfering RNA, etc.), as well as tumor phototherapy. The challenges and outlooks of micro/nanomotors for future development are also discussed.