Latest ArticlesA general process for the construction of azaaryl alkanes was achieved by employing the photoredox/palladium dual catalysis under mild visible light irradiation. The palladium catalyst ligated with a diphosphamide ligand exhibited high effectiveness in facilitating the modular three-components transformation. Furthermore, the cascade transformation was not restricted to constructing tertiary carbon centers; it also encompassed the synthesis of more challenging quaternary carbon centers with sixteen representative azaarene-derived substrates as reactants. In addition, alkyl 1,4-dihydropyridines (DHP), alkyl BF3K, and alkyl carboxylic acids were identified as precursors for alkyl radicals. Mechanistic investigations revealed the involvement of two different active benzylic nucleophiles in the cascade transformation. One is azabenzylic radical, which generate the terminal product through an “inner sphere” reductive elimination process. The other is azabenzylic anions, generated through visible light induced radical anion cross-over, leading to the formation of terminal products via an “outer sphere” reaction pathway. The efficiency of current modular transformation was also demonstarted by the concise of oliceridine, a prominent USFDA drug for pain management.
The widespread occurrence of antibiotics in wastewater aroused serious attention. UV-based advanced oxidation processes (UV-AOPs) are powerful technologies in removing antibiotics in wastewater, which include UV/catalyst, UV/H2O2, UV/Fenton, UV/persulfate, UV/chlorine, UV/ozone, and UV/peracetic acid. In this review, we collated recent advances in application of UV-AOPs for the abatement of fluoroquinolones (FQs) as widely used class of antibiotics. Representative FQs of ciprofloxacin, norfloxacin, ofloxacin, and enrofloxacin were most extensively studied in the state-of-art studies. The evolvement of gas-state and solid-state UV light sources was presented and batch and continuous flow UV reactors were compared towards practical applications in UV-AOPs. Generally, degradation of FQs followed the pseudo-first order kinetics in UV-AOPs and strongly affected by the operating factors and components of water matrix. Participation of reactive species and transformation mechanisms of FQs were compared among different UV-AOPs. Challenges and future prospects were pointed out for providing insights into the practical application of UV-AOPs for antibiotic remediation in wastewater.
Black phosphorus (BP), as a rising star of 2D nanomaterials has drawn considerable attention in cancer therapy. However, the poor stability under ambient conditions limits their practical applications. Herein, a multiple supramolecular assembly composed of adamantane-modified hyaluronic acid (HAADA), ferrocene-modified cinnamaldehyde (Fc-CA), guanidinium-functionalized β-cyclodextrin (Guano-CD), and black phosphorus (BP) nanosheets was successfully fabricated through cooperative host-guest and electrostatic interactions. Owing to the cooperative contribution of these building blocks, the obtained supramolecular assembly simultaneously possesses multiple functions including excellent stability, good biocompatibility and targeting property, and a high inhibition effect toward cancer cells. We believe that this work might provide new insights into designing a new generation of cancer theranostic protocols for potential clinical applications.
Although inductively coupled plasma mass spectrometry (ICP-MS) retains high sensitivity and has been intensively used for the measurement of 99Tc, it usually suffers from tedious, expensive, and time-consuming sample pretreatments due to the isobaric interferences from 99Ru and 98Mo1H. Herein, capillary electrophoresis (CE) was applied as sample introduction system for the sensitive, and interference-free determination of 99TcO4- from RuO4-, and MoO42- by ICP-MS with a simple sample treatment. Compared to the conventional methods, the hyphenated CE-ICP-MS avoids the use of expensive separation resins and reduces the consumption of mineral acid, representing a simpler, more efficient and environmentally benign approach. Moreover, the proposed method exhibits higher accuracy compared with the mathematical correction method using the natural isotope ratio of 99Ru and 101Ru, and significantly reduces sample consumption and the amount of waste, thus remarkably alleviating the radioactive exposure to operators and the pressure of radioactive waste treatment. Under the optimized conditions, the detection limits of 25 µg/L and 0.06 µg/L were obtained for RuO4- and ReO4- (Tc was replaced by Re), respectively, with relative standard deviation (RSD) lower than 5%. In addition, efficient recoveries of RuO4-, ReO4-, and 99TcO4- from simulated Hanford site groundwater were achieved. The method is expected to be a promising candidate for sensitive and accurate analysis of 99Tc from contaminated environmental samples.
The fabrication of bioreceptor-free method for accurate and sensitive detection of ochratoxin A (OTA) in cereal is critical, but still a significant challenge to mitigate risks to food industries and public health. In this study, a smartphone-ratiometric fluorescence sensor for the ultrasensitive detection of OTA is developed based on a porphyrinic metal-organic framework and silica nanoparticle composite (Zr-MOF/SiNPs) away from the use of antibodies and aptamers. Due to the excellent recognition ability of Zr-MOF and good storage stability of SiNPs, OTA is detected by Zr-MOF/SiNPs with a wide linear range of 0.05–1000 ng/mL and low detection limit of 0.016 ng/mL. Moreover, the red–blue ratio values of the fluorescence images are extracted through the smartphone color recognizer application with a limit of detection of 1.74 ng/mL, lower than the permissible content of OTA in cereal prescribed by World Health Organization. This sensing platform has been successfully applied in maize samples with superior repeatability and satisfactory recoveries, providing a novel way for simple and label-free analysis of OTA in cereal.
Inspired by the light-dependent signal transduction in nature, we herein report a fully synthetic receptor AZO with the capacity of transmembrane signaling, working by photo-induced change of molecular conformation. Our receptor has an anchoring group, a rigid and photoresponsive transmembrane unit and a precatalyst tailgroup. After doping in lipid membranes, AZO is membrane anchored and the extended trans-isomer enables the tailgroup to bind with intravesicular Zn2+, thereby achieving enzyme activation and triggering downstream events (ester hydrolysis). However, the shortened cis-isomer pulls the tailgroup into lipids, thereby preventing the complexation and all transduction processes. Upon alternative irradiation of ultraviolet (UV) and visible light, the transduction process can be reversible switch between "ON" and "OFF", achieving light signal transduction. This study provides a new strategy for future design of artificial signal transduction receptors.
Herein, a simple and effective outer-surface interactions assisted supramolecular hierarchical assembly has been first exploited to uniformly distribute tungstosilicic acid (TSA) inside the porous structure of cucurbit[10]uril-based single-layer 2D supramolecular-organic-frameworks (Q[10]-SOFs) in water. Importantly, the 2D Q[10]-SOFs can further serve as light harvesting antenna, achieving fast energy transfer to the embedded redox-active TSA upon photoexcitation, resulting in efficient visible light-driven selective oxidation of benzyl alcohols into the corresponding aldehydes in high yield at room temperature. Further studies revealed that the integrated of 2D Q[10]-SOFs and TSA played a key role in the catalytic process, due to the presence of a novel stepwise electron transfer route in the single-layer hybrid 2D structures.
Researchers have shown significant interest in modulating the peroxidase-like activity of nanozymes. Among these, bimetallic nanozymes have shown superior peroxidase-like activity over monometallic counterparts, offering enhanced performance and cost-efficiency in nanozyme designs. Herein, bimetallic nanozymes comprising nickel (Ni) and osmium (Os) incorporated into hyaluronate (HA) have been developed, resulting in HA-Nin/Os nanoclusters. Subsequently, comprehensive characterizations have been conducted. Further investigation has revealed that HA-Nin/Os efficiently catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation with hydrogen peroxide (H2O2), confirming its peroxidase-like behavior and role as a nanozyme. Impressively, HA-Ni2/Os (Ni/Os = 2:1) displays heightened substrate affinity, accelerated reaction rates, enhanced hydroxyl radical production in acidic conditions, and exhibits activity unit of 1224 U/mg, representing more than two-fold increase compared to non-Ni-supported Os nanozyme. Theoretical calculations indicate that Ni support enhances the peroxidase-like process of Os nanozyme by improving H2O2 adsorption and TMB oxidation. Crucially, the support of Ni does not significantly alter the other enzyme-like activities of Os nanozymes, thereby enabling Ni to selectively enhance their peroxidase-like activity. In terms of application, the peroxidase-like ability of HA-Ni2/Os, facilitated by HA's carboxyl groups enabling crosslinking, proves effective in a squamous carcinoma antigen immunoassay. Moreover, HA-Ni2/Os exhibit reliable stability, promising as a peroxidase substitute. This work underscores the advantages of incorporating Ni into Os, specifically enhancing peroxidase-like activity, highlighting the potential of Os bimetallic nanozymes for peroxidase-based applications.
Compared with natural enzymes, nanozymes have the advantages of high stability and low cost; however, selectivity and sensitivity are key issues that prevent their further development. In this study, we report a cascade nanozymatic system with significantly improved selectivity and sensitivity that combines more substrate-specific reactions and sensitive fluorescence detection. Taking detection of ascorbic acid (AA) as an example, a cascade catalytic reaction system consisting of oxidase-like N-doped carbon nanocages (NC) and peroxidase-like copper oxide (CuO) improved the reaction selectivity in transforming the substrate into the target product by more than 1200 times against the interference of uric acid. The cascade catalytic reaction system was also applicable for transfer from open reactors into a spatially confined microfluidic device, increasing the slope of the calibration curves by approximately 1000-fold with a linear detection range of 2.5 nmol/L to 100 nmol/L and a low limit of detection of 0.77 nmol/L. This work offers a new strategy that achieves significant improvements in selectivity and sensitivity.
A cobalt pincer complex bearing both P and C-stereogenic centers has been designed and synthesized, allowing for the development of the first cobalt-catalyzed asymmetric hydrogenation of quinoxalines under relatively mild conditions. Valuable chiral 1,2,3,4-tetrahydroquinoxalines could be obtained with high yields and excellent enantioselectivities (35 examples, up to > 99% ee).
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