Polyurethane, a prevalent polymer, has garnered considerable attention owing to its exceptional overall performance within various applications. However, even minor damages can significantly curtail the service life of polyurethane. Consequently, a promising approach to address this challenge involves conferring self-healing properties upon polyurethane. Among the various healing mechanisms found in self-healing polyurethane, the intrinsic driving force stands out as the most common. This mechanism entails the spontaneous re-entanglement of polyurethane molecular chains through meticulous molecular structure design, obviating the necessity for external healing agents. Intrinsic driving force encompasses reversible covalent bonds (e.g., disulfide bonds, Diels-Alder reactions, and boronic ester bonds) as well as dynamic non-covalent interactions (e.g., hydrogen bonds, ionic bonds, metal coordination bonds, and host-guest interactions). The polyurethane main chain can possess a single intrinsic driving force or multiple intrinsic driving forces concurrently. Nevertheless, while self-healing polyurethane alone presents advantages in terms of extending service life and reducing maintenance costs through damage repair, it still falls short of meeting the usage requirements in certain specialized applications. To further enable the versatile application of self-healing polyurethane while preserving its self-healing properties, the incorporation of new functional groups becomes an enticing prospect. These functional groups can bestow specific properties upon polyurethane, such as shape memory, degradability, antibacterial properties and biocompatibility, thereby achieving functional integration within self-healing polyurethane. Importantly, these functionalized self-healing polyurethanes possess the potential to supplant traditional materials as dielectric materials, substrate materials, or encapsulation materials in the realm of flexible sensors. Consequently, they contribute to enhancing the reliability and durability of flexible sensors. Therefore, this article primarily focuses on elucidating the self-healing mechanism of self-healing polyurethane. Subsequently, it delves into the integration of functionality within self-healing polyurethane and its application within the field of flexible sensors. Lastly, based on these insights, the paper provides a glimpse into the future prospects for the development of self-healing polyurethane.

Polyolefin is thermoplastic universal plastic widely used in daily life. However, the overuse of polyolefin plastic and lack of degradability has led to a large amount of plastic waste, as well as growing land and marine pollution problems. The overwhelming majority of post-consumer polyolefin plastic is not recycled. Obstacles to the recycling of waste plastic include high energy consumption, low utilization rate of recycled products, low added value, and other wastes generated in the recycling process. Polyolefins degrade very slowly in the environment, and the addition of co-degraders can also cause environmental pollution. A feasible alternative is to redesign and synthesize degradable polyolefins, which can solve waste plastic problem from the source. The synthesis of degradable polyolefins has been extensively studied over the past half century. This paper summarizes the degradation mechanism of polyolefins, including oxidative degradation and co-degradation technology. Meanwhile we review four approaches to synthesizing degradable polyolefins, which cover condensation of long-chain bifunctional monomers, copolymerization with polar monomers, acyclic diene metathesis, and ring-opening polymerization. Among them, olefin metathesis polymerization has significantly expanded the types of degradable polyolefins due to the superior tolerance of the catalysts to functional groups, such as polyester, polyacetal, polycarbonate, polyphosphoester. We discuss the forward-looking synthetic approaches offered by current research and the challenges that these degradable materials face in truly replacing polyolefin materials. Finally, we propose our perspective on the opportunities and challenges in this field.

In recent years, hydrogels have been widely used in biomedical fields such as contact lenses and medical dressings. In these fields, oxygen permeability is a key index to evaluate the application performance of hydrogel materials. In this paper, the application of traditional hydrogels and silicone hydrogels in the field of corneal contact lenses and medical dressings is sketched. The research progress of traditional hydrogels and silicone hydrogels in structural design and oxygen permeability mechanism is summarized, and various factors affecting the oxygen permeability of silicone hydrogels are analyzed emphatically. It is hoped that the relationship between hydrogel microstructure and oxygen permeability can be further understood by summarizing and sorting out the recent related research work, so as to provide help for the regulation of material properties and the design of materials to meet the requirements.

Secondary inorganic sulfate and nitrate, as the key chemical components of PM_2.5, play important roles in the formation of severe regional haze events. The deteriorating sulfate and nitrate pollution has brought more serious challenges to the continuous improvement of air quality. Thus, elucidating the formation pathways and key factors of controlling the formation of inorganic sulfate and nitrate is crucial to eliminate PM_2.5 pollution in the atmosphere. The formation of sulfate and nitrate involves complex chemical reactions, including gas- and aqueous-phase reactions and multi-phase reactions. Recent experimental and filed studies have revealed new reaction mechanisms and detailed reaction kinetics for the oxidation of SO₂ and NO₂ to form sulfate and nitrate. Merging new formation pathways of sulfate and nitrate with updating reaction kinetics based on laboratory measurements and field observations, air quality model performance is effectively improved to capture the spatial-temporal variations of sulfate and nitrate and identify their chemical formation pathways. This review provides a synthetic synopsis of recent advances in the fundamental mechanisms of sulfate and nitrate formation. In particular, the mechanisms and reaction kinetic results for a series of individual reaction pathways of current interest for the SO₂ and NO₂ oxidation are emphasized. The key factors affecting the SO₂ and NO₂ oxidation rates and significant challenges in laboratory studies of characterizing the reaction kinetics are also discussed. In addition, the sensitivity of nitrate to emission reductions of nitrogen oxides (NO_x), volatile organic compounds (VOCs) and ammonia (NH₃) is investigated. Finally, suggestions are put forward for the future research directions to improve the understanding of sulfate and nitrate formation.

The traditional electrolyte is flammable, easy to leak, and toxic, which affects the safety performance of batteries working for a long time. In view of the above problems, recently researchers have focused on the development of (quasi) solid electrolyte. Solid composite electrolyte composed of inorganic fillers and polymer has the advantages of high ionic conductivity and mechanical stability of inorganic electrolyte, flexibility and low interface impedance of polymer electrolyte, which has attracted extensive attention of researchers. Inorganic components mainly include active Li⁺-containing fillers and inert Li⁺-free fillers. The inert Li⁺-free fillers possess the benefits of low cost and easy preparation process, so they have greater potential for large-scale industrial applications. In this paper, the performance requirements of composite polymer electrolytes are reviewed. Starting from non-lithium inorganic hybrid components, we summarize the research on improving the performance of composite polymer electrolyte with inert Li⁺-free fillers, including zero-dimensional nanoparticles, one-dimensional nanotubes (nanowires, nanorods), two-dimensional boron nitride nanosheets, and three-dimensional structure of fillers. Different dimensions of analysis and thinking aim to shed light on the design and application of inert fillers-polymer electrolytes, and we also look forward to the broad prospects of non-lithium inorganic components in the industrial application of composite electrolyte.

Strigolactones (SLs) are the most concerned endogenous sesquiterpenoid phytohormones.Recent studies have shown that strigolactones play crucial roles in inhibition of plant hypocotyl elongation and crop tillering, regulating root growth and development, stimulation of parasitic weed seed germination, coordinating the symbiotic interaction between parasitic plants and fungi, as well as regulation of plant response to biotic or abiotic stresses. Therefore, it is considered to be a new type of phytohormone with great development value and application potential in the field of agricultural science and plant protection. In addition, SL derivatives have also attracted much attention in the field of innovative drug research as the studies have found that: (1) SLs exhibit inhibitory activities against several tumor cell lines such as liver cancer, breast cancer, prostate cancer, glioblastoma, and colorectal cancers; (2) they possess anti-inflammation and glucose metabolism inhibitory activity. This paper aims to review the latest research progress of strigolactone and its structural derivatives with brief analysis on their biological activity, mechanism of action and structure-activity relationship. We hope this review provide guidance and directions on molecular design, development and utilization of SL natural products.

As the largest internal organ in the human body, the liver plays an essential role in the metabolism. The liver or relevant diseases are one of the leading causes of death in the world, with the number of cases surging each year. Therefore, an in-depth understanding of the physiological and biochemical processes and pathological mechanisms of the liver is of great significance for the research, prevention, diagnosis, and treatment of liver-related or metabolism-related diseases. The in vitro liver culture model is an important experimental platform for the study of liver-related biological mechanisms. However, the traditional two-dimensional in vitro cell culture model makes it difficult to reproduce the complex physiological structure and microenvironment of the liver, and lack of disease characteristics. More importantly, the cell structure, gene expression, substance metabolism, and so on in the process of planar culture are significantly different from those in vivo. Microfluidic technology can simulate the physiological structure of liver by designing appropriate micro-structure, providing a microenvironment more like that in vivo by combining with three-dimensional liver tissue culture. Therefore, this paper summarizes the methods and latest progress in constructing 3D liver chips in vitro based on microfluidic technology, including porous membrane culture, hydrogel culture, cell spheroid-based culture, and 3D bioprinting. The applications of 3D cultured liver microchips in remodeling liver physiological structure, exploring mechanism and pathological mechanism, drug screening, and toxicity testing are further summarized. Finally, the potential value and challenges of 3D liver-on-a-chip are discussed.

Catalyst loading is one of the effective strategies for green catalysis. Palladium (Pd) catalysts supported by magnetic nanoparticles (MNPs) have been widely studied and used in organic synthesis due to their good dispersibility, high catalytic activity, rapid separation under the action of an external magnetic field, and efficient recovery. The MNPs-supported polydentate Pd compound catalyst (MNPs@L-Pd) shows better catalytic activity and stability than the MNPs-supported Pd nanoparticle catalyst (MNPs@PdNP). This is mainly because the introduction of the modified ligand in MNPs@L-Pd can regulate the electronic effect and steric hindrance of the catalyst metal center to achieve the regulation of its activity, on the other hand, it makes the stable chemical bond between the catalyst metal center and the magnetic material to achieve the regulation of stability. This paper mainly focuses on MNPs@L-Pd, the preparation of MNPs@L-Pd based on different ligands and coordination methods and its application in C-X(Cl, Br, I) activation reaction in the past 10 years are reviewed from the aspects of catalyst stability and activity, and the prospect of these reactions are also presented.

Enzymes are considered as natural biocatalysts, which catalyze many biochemical reactions with good catalytic efficiency, biocompatibility, and substrate specificity. The intrinsic limitations of natural enzymes such as low stability, high cost, and storage difficulty have led to the introduction of artificial enzymes that imitate the activity of natural enzymes. With the rapid development of nanomaterials in the recent decade, novel enzyme-mimicking nanomaterials (nanozymes) have attracted considerable attention from researchers. Nanozymes are defined as a class of artificial nanomaterials possessing intrinsic enzymes-like activities, which have the advantages of simple preparation processes, low cost and some environmental tolerance. However, most of them are limited by their low activity and relatively poor stability, leading to many difficulties in the application of biochemical analysis. Among them, metal-organic framework nanozymes (MOFs) have demonstrated a wide range of uses because of their evident favorable circumstances, including the large surface area and porosity for functionalization, uniform active sites, high catalytic activity and stability, simple and controllable synthesis and low cost. In this review, we provide a summary of the clinical detection application of MOFs in nucleic acid, protein and small molecules based on their different activity classification (peroxidase, oxidase, catalase, superoxide dismutase, and hydrolase). Finally, we look forward to the opportunities and challenges that MOFs will face in clinical detection, promoting their clinical application transformation.

Due to the excellent optical properties, good biocompatibility, high reactive oxygen species yield and excellent photothermal conversion ability, aggregation-induced emission (AIE) materials show great potential applications in the fields of photodynamic and photothermal therapy. However, traditional fluorescent materials need light with short wavelength for emission, which has the problem of poor tissue penetration, and further restricts the clinical application. To overcome the problem, AIE materials with emission in the range of second near-infrared (NIR-Ⅱ) emission are employed, which promotes the feasibility of the clinical application. This review summarizes the application of NIR-Ⅱ AIEgens with donor-π-acceptor (D-π-A) and donor-acceptor-donor (D-A-D) structure in photodynamic-photothermal dual-mode synergistic therapy.