A new “naked-eye” colorimetric and ratiometric fluorescent sensor for imaging Hg2+ in living cells

A new oligothiophene-based sensor 3 TH for monitoring Hg²⁺ has been designed and synthesized based on the intramolecular charge transfer (ICT) mechanism. The 3 TH shows the significant specificity toward Hg²⁺ through “naked-eye” colorimetric detection as well as via ratiometric fluorescence enhancement response with low detection limit of 62 nM. In addition, sensor 3 TH shows high selectivity and sensitivity for Hg²⁺ with fast response in a suitable pH range. Moreover, the 3 TH-based test strips was used to conveniently detect Hg²⁺ ions in water. Furthermore, considering its good ‘‘turn-on’’ fluorescent sensing behavior and low cell cytotoxicity, 3 TH was successfully applied to detect and image Hg²⁺ in real water samples and living cells, which shows great potentials for application in environmental and biological systems.     

Hyphenone A,the first 3,3-diisoprenylated bicyclic polyprenylated acylphloroglucinols as Cav3.1 T-type calcium channel inhibitor from Hypericum henryi

Hyphenone A (1), a new type of bicyclic polyprenylated acylphloroglucinols (BPAPs) featured with an unprecedented 3,3-diisoprenylated 1,3,5-trione core, were characterized from the roots of Hypericum henryi together with two new congeners (hyphenones B–C, 2–3) and five known biosynthetic related PPAPs. Biogenetically, 1 should be derived from a novel 3,3,5,5-tetraisoprenylated MPAPs precursor. Their structures were elucidated by comprehensive spectroscopic data and X-ray diffraction. Moreover, 1–3 were identified as the first PPAPs type Ca_v3.1 T-type calcium channel (TTCC) inhibitors, with IC₅₀ values of 7.07, 6.19, and 5.47 μM, respectively.     

AIEgens/Nucleic Acid Nanostructures for Bioanalytical Applications

DNA occupies significant roles in life processes, which include encoding the sequences of proteins and accurately transferring genetic information from generation to generation. Recent discoveries have demonstrated that a variety of biological functions are correlated with DNA′s conformational transitions. The non‐B form has attained great attention among the diverse forms of DNA over the past several years. The main reason for this is that a large number of studies have shown that the non‐B form of DNA is associated with gross deletions, inversions, duplications, translocations as well as simple repeating sequences, which therefore causes human diseases. Consequently, the conformational transition of DNA between the B‐form and the non‐B form is important for biology. Conventional fluorescence probes based on the conformational transitions of DNA usually need a fluorophore and a quencher group, which suffers from the complex design of the structure and tedious synthetic procedures. Moreover, conventional fluorescence probes are subject to the aggregation‐caused quenching (ACQ) effect, which limits their application toward imaging and analyte detection. Fluorogens exhibiting aggregation‐induced emission (AIE) have attracted tremendous attention over the past decade. By taking advantage of this unique behavior, plenty of fluorescent switch‐on probes without the incorporation of fluorescent quenchers/fluorophore pairs have been widely developed as biosensors for imaging a variety of analytes. Herein, the recent progress in bioanalytical applications on the basis of aggregation‐induced emission luminogens (AIEgens)/nucleic acid nanostructures are presented and discussed.     

Aqueous Electrochemical Reduction of Carbon Dioxide and Carbon Monoxide into Methanol with Cobalt Phthalocyanine

Conversion of CO₂ into valuable molecules is a field of intensive investigation with the aim of developing scalable technologies for making fuels using renewable energy sources. While electrochemical reduction into CO and formate are approaching industrial maturity, a current challenge is obtaining more reduced products like methanol. However, literature on the matter is scarce, and even more for the use of molecular catalysts. Here, we demonstrate that cobalt phthalocyanine, a well‐known catalyst for the electrochemical conversion of CO₂ to CO, can also catalyze the reaction from CO₂ or CO to methanol in aqueous electrolytes at ambient conditions of temperature and pressure. The studies identify formaldehyde as a key intermediate and an unexpected pH effect on selectivity. This paves the way for establishing a sequential process where CO₂ is first converted to CO which is subsequently used as a reactant to produce methanol. Under ideal conditions, the reaction shows a global Faradaic efficiency of 19.5 % and chemical selectivity of 7.5 %.     

A Versatile Naphthalimide–Sulfonamide‐Coated Tetraphenylethene: Aggregation‐Induced Emission Behavior,Mechanochromism, and Tracking Glutathione in Living Cells

A tetraphenylethene (TPE) derivative substituted with a sulfonyl‐based naphthalimide unit ( TPE‐Np ) was designed and synthesized. Its optical properties in solution and in the solid state were investigated. Photophysical properties indicated that the target molecule, TPE‐Np , possessed aggregation‐induced emission (AIE) behavior, although the linkage between TPE and the naphthalimide unit was nonconjugated. Additionally, it exhibited an unexpected, highly reversible mechanochromism in the solid state, which was attributed to the change in manner of aggregation between crystalline and amorphous states. On the other hand, a solution of TPE‐Np in a mixture of dimethyl sulfoxide/phosphate‐buffered saline was capable of efficiently distinguishing glutathione (GSH) from cysteine and homocysteine in the presence of cetyltrimethylammonium bromide. Furthermore, the strategy of using poly(ethylene glycol)–polyethylenimine (PEG‐PEI) nanogel as a carrier to cross‐link TPE‐Np to obtain a water‐soluble PEG‐PEI/ TPE‐Np nanoprobe greatly improved the biocompatibility, and this nanoprobe could be successfully applied in the visualization of GSH levels in living cells.     

Effectively controlled microfluidic trap for spatiotemporal analysis of the electrotaxis of Caenorhabditis elegans

C. elegans is a popular model organism with a well‐developed neural network. Approximately 60% of the genes in C. elegans have genomic counterparts in humans, including those involved in building neural circuits. Therefore, we can extend the study of human neural network mechanisms to C. elegans which is easy to genetically manipulate. C. elegans shows behavioural responses to various external physical and chemical stimuli. Electrotaxis is one of its distinct behavioural responses, which is defined as movement towards the cathode in an electric field. In this study, we developed an effective microfluidic trap system for analysing electrotaxis in C. elegans. In addition, two mutant strains (unc‐54(s74) and unc‐6(e78)) from wild‐type (N2) worms were screened using the system. Wild‐type (N2) worms and the two mutant strains clearly showed different behavioural responses to the applied electric field, thus enabling the effective screening of the mutant worms from the wild type (N2). This microfluidic system can be utilized as a platform for the study of behavioural responses, and for the sorting and mutant screening of C. elegans.     

Radical Monofluoroalkylative Alkynylation of Olefins by a Docking–Migration Strategy

A radical‐mediated monofluoroalkylative alkynylation of alkenes is disclosed for the first time. The reaction demonstrates a remarkably broad substrate scope in which both activated and unactivated alkenes are suitable starting materials. The concurrent addition of an alkynyl and a monofluoroalkyl group onto an alkene proceeds through a docking–migration sequence, affording a vast array of valuable fluoroalkyl‐substituted alkynes. Many complex natural products and drug derivatives are readily functionalized, demonstrating that this method can be used for late‐stage alkynylation.     

A Bifunctional Luminescent Metal–Organic Framework for the Sensing of Paraquat and Fe3+ Ions in Water

The hydrothermal reaction of Zn²⁺ ions with a mixture of two ligands, Hcptpy and H₃btc (Hcptpy=4‐(4‐carboxyphenyl)‐2,2′:4′,4′′‐terpyridine; H₃btc=1,3,5‐benzenetricarboxylic acid), led to the formation of a 3D metal–organic framework (MOF) with 1D channels, [Zn₂(cptpy)(btc)(H₂O)]_n ( 1 ), which was structurally characterized by using single‐crystal X‐ray diffraction (SXRD). In MOF 1 , two independent Zn²⁺ ions were interconnected by btc^3? ligands to form a 1D chain, whilst adjacent Zn²⁺ ions were alternately bridged by cptpy^? ligands to generate a 2D sheet, which was further linked by 1D chains to form a 3D framework with a new (3,3,4,4)‐connected topology. Furthermore, compound 1 also exhibited excellent stability towards air and water and, more importantly, luminescence experiments indicated that it could serve as a probe for the sensitive detection of paraquat (PAQ) and Fe³⁺ ions in aqueous solution.