Epoxy-based multifunctional re-bondable polymer with self-healing, shape memory and superb bonding properties.

Thermoset epoxy resin-based materials are widely used, but their permanent cross-linked network limits their processability and reusability, which can lead to environmental burdens. In this work, by exploiting the weak reactivity of aniline to design appropriate reaction ratios, we achieved a linear link between the epoxy resin and the curing agent. This linear link, along with the crosslinking points provided by the flexibly branched polyurethanes, avoids the inherent brittleness associated with the highly crosslinked network of conventional epoxy resins. As a result, the adhesive exhibits extraordinary improvements in extensibility and toughness. The lap shear strength, tensile strength and elongation at break reach 11.9 MPa, 14.4 MPa and 607 %, respectively. The fracture toughness is as high as 109.6 kJ/m2, far beyond the existing epoxy adhesives. The synergistic effect of disulfide bonds and hydrogen bonds confers the adhesive with self-healing and repeatable bonding characteristics. The multi-level hydrogen bonding and appropriate phase separation structure are key to optimizing toughness, resulting in excellent comprehensive performance. The introduction of polyurethane not only improves toughness but also enhances the interfacial bonding force between the adhesive and the substrate, broadening the scope of applications. The prepared high-performance polymers provide new insights into reusable epoxy adhesives.

Asynchronous Ring Opening of Cyclic Carbonate and Glycidyl Ether Induced Phase Evolution Towards Heat-Free and Rapid-Bonding Superior Epoxy Adhesive.

Structural adhesives that do not require heating are in high demand in the automotive and electronics industries. However, it remains a challenge to develop robust adhesives that rapidly achieve super adhesion near ambient temperature. Herein, a room-temperature curable, fast-bonding, and super strong epoxy-based structural adhesive was designed from the perspective of cross-scale structure, which lies in threefold pivotal aspects: (i) high branching topology of glycerol carbonate-capped polyurethane (PUGC) increases the kinetics of the ring-opening reaction, contributing to fast crosslinking and the formation of abundant urethane and hydroxyl moieties; (ii) asynchronous crosslinking of epoxy and PUGC synergistically induces phase separation of PUGC within the epoxy resin and the resulting PUGC domains surrounded by interpenetrated shell serves to efficiently toughen the matrix; (iii) abundant dynamic hydrogen bonds including urethane and hydroxyl moieties, along with the elastomeric PUGC domains, dissipate energy of shearing force. As a result, the adhesive strength rapidly grows to 16 MPa within 4 hours, leveling off to 21 MPa after 7 hours, substantially outperforming commercial room-temperature curable epoxy adhesives. The results of this study could advance the field of high-performance adhesives and provide valuable insights into designing materials for efficient curing at room temperature.

Application of Fluorescent Probes in Reactive Oxygen Species Disease Model.

Reactive oxygen species (ROS) play an important role in living activities as signaling molecules that regulate the living activities of organisms. There are many types of ROS, mainly including hydrogen peroxide (H2O2), hypochlorous acid (HOCl), hydroxyl radical (•OH), peroxyl radical (ROO•), singlet oxygen (1O2), peroxynitrite (ONOO-) and superoxide anion radical (O2-•) etc. Existing studies have shown that changes in ROS levels are closely associated with the development of many diseases, such as inflammation, cancer, cardiovascular disease, and neurodegenerative damage. Small molecule fluorescent probes have been widely used in biology, pathology and medical diagnosis due to their advantages of noninvasive, high sensitivity and in vivo real-time detection. It is extremely important to better apply small-molecule fluorescent probes to detect ROS levels in organisms to achieve early diagnosis of diseases and assessment of therapeutic conditions. This work focuses on summarizing the representative applications of some fluorescent probes in ROS disease models in recent years. This article focuses on summarizing the construction methods of various ROS-related disease models, and classifying and analyzing the basic ideas and methods of fluorescent probes applied to disease models according to the characteristics of various diseases.

Dual-Ratiometric Fluorescent Probe for H2O2 and HClO in Living Cells and Zebrafish and Application in Alcoholic Liver Injury Monitoring.

Reactive oxygen species (ROS) are an important component for maintaining normal physiological activities in organisms, and abnormal changes in their level are often accompanied by many diseases. As the two most representative components of ROS, HClO and H2O2 play vital roles in many physiological and pathological processes and are interdependent and mutually transformable. Although there is a lot of work that has specifically detected HClO or H2O2, there are few reports on the simultaneous differential detection of HClO and H2O2. Here, we report a ratio-based fluorescent probe capable of simultaneously distinguishing HClO and H2O2 based on making the best use of the untapped potential of coumarin derivatives. This probe was triumphantly put into use in the discriminative identification of HClO and H2O2 in aqueous media with high sensitivity and selectivity, and the probe was appropriate in a wide pH range. Furthermore, the imaging experiment for HClO and H2O2 in cells and zebrafish was eventually proven to be feasible. Importantly, this probe was qualified for monitoring the variation of HClO and H2O2 levels in organisms with alcoholic liver injury.

A phenothiazine coumarin based ratiometric fluorescent probe for real-time detection of lysosomal hypochlorite in living cell and zebra fish.

Hypochlorite (ClO-), a type of reactive oxygen species (ROS), plays an essential role in complex biological systems. Real-time detection of the content and distribution of ClO- in cells or subcellular organelle is critically essential. In this paper, a lysosomal-targeted fluorescent probe, Cou-Lyso, was constructed for real-time detection of ClO- in a ratiometric manner, achieving high sensitivity with a low detection limit (0.58 µM). Upon reaction with ClO-, this probe was subjected to a significant fluorescence change from red emission (λmaxem = 610 nm) to green emission (λmaxem = 535 nm) with the ratio of I535 nm/I610 nm displaying a 76-fold enhancement from 0.04 to 3.03. The confocal imaging experiments for Cou-Lyso showed that this probe could detect ClO- in living cell and zebra fish. This probe has been successfully applied to stain lysosome and image lysosomal ClO- based on co-localization imaging experiments.

A bifunctional fluorescent probe for simultaneous detection of GSH and H2Sn (n > 1) from different channels with long-wavelength emission.

In this work, we presented a long-wavelength emission fluorescent probe DCM-Cou-SePh that can discriminatively detect glutathione (GSH) and hydrogen polysulfides (H2Sn, n > 1) from green and red emission channels, respectively. With the addition of GSH, probe DCM-Cou-SePh displayed green fluorescence emission (λex/em = 430/530 nm). In the presence of H2Sn, the probe exhibited a significant fluorescence enhancement in red channel (λex/em = 560/680 nm). We also demonstrated that this probe was suitable to quantitatively detect GSH and H2Sn with low detection limits (0.12 µM for GSH, 0.19 µM for H2Sn). Furthermore, DCM-Cou-SePh can be used for sensing endogenous GSH and H2Sn in living cells by dual-color fluorescence imaging.