Latest ArticlesExosomes play significant roles in physiological and tumorigenic processes and it is desirable to visualize and track the exosomes. Herein, a novel amphiphilic fluorescent probe HBT-Exo based on excited-state intramolecular proton transfer (ESIPT) mechanism is reported for exosome-labeling. Its ESIPT characteristics were confirmed by both theory calculation and experimental observation, which enable the probe to show a large Stokes shift as well as near-infrared (NIR) keto-form emission. HBT-Exo displayed excellent biocompatibility and remarkable efficiency for exosome-labeling in gastric cancer cells. Furthermore, the labeled exosomes were successfully applied for the real-time in situ imaging in mouse models.
The transport of colloids and radionuclides is sophisticated because of the variety of charge properties between colloidal particles and host subsurface media, which causes great difficulty in establishing a reliable model of radionuclides migration by taking the colloid phase into consideration. In this work, the co-transport of illite colloids (IC) and Eu(Ⅲ) in the quartz sand and iron-coated sand porous media was investigated by column experiments to address the predominant mechanism of charge properties on co-transport. Results showed that Eu(Ⅲ) transport was driven by the illite colloids and electrostatic interaction was critical in governing the co-transport patterns. The promotion of Eu(Ⅲ) transport by IC was attenuated in the iron-coated sand systems; more IC-Eu(Ⅲ) complexes were retained uniformly in the column. The pore throat shrinkage caused by electrostatic attachment between aggregated IC and iron oxides exacerbated the physical straining and size exclusion effect of IC-Eu(Ⅲ) complexes. An aggravated irreversible retention of IC-Eu(Ⅲ) was detected in iron-coated sand column due to the electrostatic attraction of IC-Eu(Ⅲ) to host media. The findings are essential for improving the understanding on the potential transport, retention and release risk of colloids associated radionuclides, and imply that the positively charged permeable reactive barrier is an effective strategy to reduce the transport risk of colloid associated radionuclides.
Flexible electronics technology is considered as a revolutionary technology to unlock the bottleneck of traditional rigid electronics that prevalent for decades, thereby fueling the next-generation electronics. In the past few decades, the research on flexible electronic devices based on organic materials has witnessed rapid development and substantial achievements, and inorganic semiconductors are also now beginning to shine in the field of flexible electronics. As validated by the latest research, some of the inorganic semiconductors, particularly those at low dimension, unexpectedly exhibited excellent mechanical flexibility on top of superior electrical properties. Herein, we bring together a comprehensive analysis on the recently burgeoning low-dimension inorganic semiconductor materials in flexible electronics, including one-dimensional (1D) inorganic semiconductor nanowires (NWs) and two-dimensional (2D) transition metal dichalcogenides (TMDs). The fundamental electrical properties, optical properties, mechanical properties and strain engineering of materials, and their performance in flexible device applications are discussed in detail. We also propose current challenges and predict future development directions including material synthesis and device fabrication and integration.
Macrocyclic supramolecular complexes demonstrate the dynamic potential to solve global biomedical challenges, a promising cancer treatment modality. The macrocyclic system is an important heterocyclic system widely present in natural products and synthetic molecules. The unique structural feature of macrocyclic supramolecular complexes with desirable donor & acceptor characteristics is beneficial for readily binding with various enzymes and receptors in biological systems through diverse weak interactions, thereby exhibiting broad bioactivities. Macrocyclic-related research and macrocyclic moleculesbased medicinal chemistry developments have become rapidly developing areas of study. Numerous macrocyclic-based molecules as clinical drugs have been extensively used in the clinic to treat various diseases with high therapeutic potency. This critically analyzed work systematically reviews current developments of macrocyclic supramolecular complexes-based compounds in the range of medicinal chemistry as anticancer, anti-inflammatory, and other therapeutic agents, together with their potential applications in diagnostics and pathology. This review will be helpful for medicinal chemistry researchers to develop new thoughts in the quest for rational designs of more active and less toxic macrocyclic supramolecular complexes-based medicinal drugs, as well as more effective diagnostic agents and pathologic probes.
The high amount of L-lysine can increase the potential risk of cardiovascular disease. Additionally, 2-methoxy benzaldehyde (2-MB) has high toxicity and can easily pollute the environment. In this work, carbon quantum dots (CQDs) can be encapsulated into Eu-BTB (H3BTB = 1,3,5-tri(4-carboxyphenyl)benzene), forming the multi-emission composite material Eu-BTB@CQDs. It has two emissions peaks (617 nm for Eu and 470 nm for CQDs). Eu-BTB@CQDs can be applied as bi-functional ratiometric “off & on” luminescent sensor for L-lysine and 2-MB with high sensitivity and selectivity, the low limit of detection (LOD) for L-lysine is 3.68 µmol/L and for 2-MB is 0.54 µmol/L, respectively. Additionally, Eu-BTB@CQDs can quantitatively discriminate L-lysine in the mixed D- and L-lysine water solutions (five different concentrations ratio of L/D-lysine has been set) makes the chiral detection of L-lysine are more meaningful. On the other hand, Eu-BTB@CQDs also can detect 2-MB over 4-methoxybenzaldehyde (4-MB) with high selectivity. Further the detection of 2-MB and L-lysine in the lake water real samples with the reasonable recovery rate. Finally, the detection mechanisms for L-lysine and 2-MB were also investigated and discussed in detail.
Efficient and modular synthesis of structurally diverse 1,4-diketones from readily available building blocks represents an essential but challenging task in organic chemistry. Herein, we report a multi-component, regioselective bis-acylation of olefins by merging NHC organocatalysis and photoredox catalysis. With this protocol, a broad range of 1,4-diketones could be rapidly assembled using bench-stable feedstock materials. The robustness of this method was further evaluated by sensitivity screening, and good reproductivity was observed. Moreover, the diketone products could be readily converted into functionalized heterocycles, such as multi-substituted furan, pyrrole, and pyridazine. Mechanistic investigations shed light on the NHC and photoredox dual catalytic radical reaction mechanism.
Palladium-catalyzed cycloaddition reactions via Pd-π-allyl zwitterions have been established as significant synthetic transformations to enable numerous carbon- or heterocycles compounds that are key constituents of various biologically active natural products and pharmaceuticals. In addition to the well-known Pd-π-allyl zwitterions,including palladium-trimethylenemethane and Pd-1,3/1,4-zwitterions,chemists have recently discovered new applications of several long ago reported but less-studied Pd-π-allyl zwitterions,which can straightforwardly and efficiently construct novel cyclic architectures. Meanwhile,some impressive newly designed zwitterions have been also developed. Those zwitterions are diverse and can serve as transient and highly reactive intermediates for the subsequent cyclization with various acceptors. In this review,we highlight recent advances in applications of these two types of zwitterions in the synthesis of complex polycyclics and medium-sized cyclic compounds.
Glutathione depletion provides a promising strategy for the design of non-platinum anticancer drugs. Here we report a series of electrophilic (salen)osmium(Ⅵ) nitrides that react with glutathione to generate (salen)osmium(Ⅲ) ammine compounds. In vitro studies indicate that these osmium(Ⅵ) nitrides show comparable cytotoxicity to cisplatin against various carcinoma. Mechanistic studies with the representative compound [OsⅥ(N)(LH)(OH2)](PF6) (1, LH = N,N′-bis(salicylidene)-o-cyclohexyldiamine dianion) suggest that 1 induces glutathione depletion, reactive oxygen species generation, endoplasmic reticulum stress, and in turn triggers death receptor-mediated apoptosis and autophagy in lung cancer cells. In vivo evaluations show that 1 can inhibit tumor xenograft growth effectively with no body weight drop.
Mitochondria are essential for eukaryotic life as powerhouses for energy metabolism. Excessive mitochondrial hyperthermia and reactive oxygen species (ROS) production have been associated with aging, cancer, neurodegenerative diseases, and other disorders. Uncoupling protein 2 (UCP2) is the effector responsible for regulating cellular thermogenesis and ROS production via dissipating protons in an electrochemical gradient. A UCP2 inhibitor named genipin (GNP) is being researched for its effect on mitochondrial temperature, but little is known about its mechanisms. This study developed several molecular probes to explore the interactions between GNP and UCP2. The result indicated that the hemiacetal structure in GNP could selectively react with the ɛ-amine of lysine on the UCP2 proton leakage channel through ring-opening condensation at the mitochondrial, cellular, and animal levels. A notable feature of the reaction is its temperature sensitivity and ability to conjugate with UCP2 at high fever as lysine-specific covalent inhibitors that prevent mitochondrial thermogenesis. The result not only clarifies the existence of an antipyretic properties of GNP via its irreversible coupling to UCP2, but also reveals a bioorthogonal reaction of hemiacetal iridoid aglycone for selectively binding with the ɛ-amine of lysine on proteins.
Base pair mismatch has been regarded as the main source of DNA point mutations, where minor short-lived tautomers were usually involved. However, the detection and characterization of these unnatural species pose challenges to existing techniques. Here, by using systematic structural and ultrafast resonance Raman (RR) spectral analysis for the four possible conformers of guanine-cytosine base pairs, the prominent marker Raman bands were identified. We found that the hydrogen bonding vibrational region from 2300 cm−1 to 3700 cm−1 is ideal for the identification of these short live species. The marker bands provide direct evidence for the existence of the tautomer species, thus offering an effective strategy to detect the short-lived minor species. Ultrafast resonance Raman spectroscopy would be a powerful tool to provide direct evidence of critical dynamical details of complex systems involving protonation or tautomerization.
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