Hydroxyl radical (•OH), a highly reactive oxygen species (ROS), is assumed as one of the most aggressive free radicals. This radical has a detrimental impact on cells as it can react with different biological substrates leading to pathophysiological disorders, including inflammation, mitochondrion dysfunction, and cancer. Quantification of this free radical in-situ plays critical roles in early diagnosis and treatment monitoring of various disorders, like macrophage polarization and tumor cell development. Luminescence analysis using responsive probes has been an emerging and reliable technique for in-situ detection of various cellular ROS, and some recently developed •OH responsive nanoprobes have confirmed the association with cancer development. This paper aims to summarize the recent advances in the characterization of •OH in living organisms using responsive nanoprobes, covering the production, the sources of •OH, and biological function, especially in the development of related diseases followed by the discussion of luminescence nanoprobes for •OH detection.
Monthly Archives: March 2024
[ASAP] Highly Accurate Determination of the Total Amount of Pb2+ and Pb(OH)+ in a Natural Water Environment Revealed by Dynamic Simulation and DFT Calculation: Benefit from the Electron Inverse Effect of Pt Nanoclusters over Defective g-C3N4
Analytical Chemistry
DOI: 10.1021/acs.analchem.3c05707
[ASAP] Application of Aptamer-SERS Nanotags for Unveiling the PD-L1 Immunomarker Progression Correlated to the Cell Metabolic Bioprocess
Analytical Chemistry
DOI: 10.1021/acs.analchem.3c05334
Ligand environment and light: two triggers for controlling cytotoxicity of ruthenium nitrosyl complexes
Photoinduced nitric oxide (NO) release for complexes [RuNO(L)2(NO2)2OH], where L = methyl isonicotinate (1), ethyl isonicotinate (2), methyl nicotinate (3) and ethyl nicotinate (4) was studied in DMSO, MeCN and water solutions (PBS, CTAB) using spectroscopic methods (UV-vis, IR, EPR) and spectrometric techniques (ESI-МS). Additionally, we present methodological evidence for improving the calculation of the quantum yield (QY) of NO release through the utilization of a combined IR-UV-vis-spectroscopy flow-through setup. According to DFT calculations, the production of nitric oxide occurs through the photoinduced cleavage of the Ru-NO bond, triggered by irradiation at 445 or 532 nm. This cleavage is a consequence of charge transfer from the orbitals of the Ru-OH group and the equatorial ligands (HOMO, HOMO-1) to the Ru-NO antibonding orbital (LUMO). The cytotoxicity and photoinduced cytotoxicity of the investigated compounds were assessed against the breast adenocarcinoma cell line MCF-7. Moreover, the investigation of the lipophilic properties of compounds 1-4 unveiled a significant influence of their lipophilicity on cytotoxic behavior, allowing for the modification of cytotoxicity through changes in the ligand L or by light irradiation.
Merging Photoredox with Nickel Catalysis for Decarboxylative Arylation of Indole‐3‐Acetic Acids with Aryl Halides
Photoredox-catalysis was synergistically merged with nickel-catalysis for the synthesis of biologically important 3-benzyl indoles with good functional group tolerance. The merit of this methodology is demonstrated by the synthesis of amino acid derived substrates.
Abstract
Late-stage functionalization of indoles can be a valuable strategy for modifying different existing indolyl-drugs and natural products to get their new analogues. In this study, we report the photoredox-metal catalyzed decarboxylative arylation strategy of indole-3-acetic acids with aryl halides. Here, photoredox-catalysis was synergistically merged with nickel-catalysis for the synthesis of biologically important 3-benzyl indoles with good functional group tolerance. The merit of this methodology is demonstrated by the synthesis of amino acid derived substrates 3 p, 3 v and 3 x.
Shape‐Editable Transparent Wood Based on In‐Situ Polymerization of Epoxy Vitrimers Embedded with Luminescent BODIPY Molecules for Smart Decoration Materials
A shape-editable transparent wood with luminescent BODIPY is applied to smart decoration materials.
Abstract
Transparent wood (TW) combining unique anisotropic structure has broad application prospects in the field of advanced building furniture materials. Many efforts have been made to add quantum dots or nanoparticles to TW to endow it with additional functionality, such as luminescent, electrochromic, and thermochromic TW. However, luminous TW with shape-editable functionality and its new applications have yet to be explored. Benefiting from the excellent luminescence performance in a diluted solution state, BODIPY (4,4-difluoro-4-bora-3a,4a-diazas-indacene) dyes have been widely used for bio-sensing and bioimaging. In addition, vitrimers exhibit excellent stimuli-responsive, shape-memory, and reprocessing properties thanks to exchangeable dynamic covalent crosslinking networks, which are suitable for fabricating smart TW. Herein, combing these advantages, a dual-functional transparent wood composite (P-SEFTW) with photoluminescent and shape editable function was developed by introducing BODIPY dyes and vitrimers into the delignified wood (DW) templates. P-SEFTW displays good UV luminescence, unique light guiding and directional scattering effects. Meanwhile, it shows excellent shape-recovery, shape-programming, shape-erasing, and re-programming capability under thermal-stimulus. These characteristics enable TW to exhibit great prospect as an advanced smart and functional building material.
Catalyst‐Green Solvent System for Highly Efficient Production of Carboxylic Acids from Light Oxygenates, CO2 and H2
Catalytic hydrogenation of carbon dioxide (CO2) for the preparation of higher carboxylic acids is attractive and promising. Herein, we demonstrate a general strategy for producing higher carboxylic acids via reaction of CO2 and H2 with light (C2~C4) oxygenates such as ketones, alcohols, polyols, ethers and epoxides. In a green solvent consisting of ionic liquid (1-ethyl-3-methylimidazolium iodide) and water, the reaction can be efficiently accelerated by RhI3 catalyst and I2 promoter at 170 °C. Very high or remarkable yields of higher carboxylic acids were synthesized via C-C bond formation between the intermediates generated from the oxygenates and CO2. Detailed study indicated that the catalyst and the solvent had excellent synergistic effect for promoting the reaction. The strategy can effectively convert the bulk and inexpensive feedstocks to value-added carboxylic acids, and therefore is promising for commercial application.
Transition Metal and Photocatalyst Free Arylation via Photoexcitable Electron Donor Acceptor Complexes:Mediation and Catalysis
Electron donor acceptor (EDA) complexes formed between arylating agents and nucleophilic substrates or additives, undergo photoexcitation to produce aryl radicals. Two main modes of reactivity for such complexes exist: mediation, where EDA complex is formed between two reagents, or catalysis, in which the electron donor additive is used as an organocatalyst.
Abstract
Visible-light-activated organic reactions unlock novel avenues for complex molecular transformations, impossible under standard “thermal” conditions, which makes them powerful tools in the arsenal of synthetic chemistry. However, transition metal-based or organic photoredox catalysts are often used to ensure productive absorption of visible light, which might be not desirable to medicinal chemistry and industry due to toxicity, low sustainability, and high cost of most photocatalysts. A more environmentally and economically benign approach is based on the formation of transient electron donor-acceptor (EDA) complexes between two reagents or a reagent and an additive, that readily absorb visible light, acting as internal photosensitizers. Within the EDA complex-based arylation strategies, chemical transformations are mediated by noncovalent interaction between two molecules, namely between electron-poor aryl halides or their synthetic equivalents and electron-rich nucleophilic reagents or additives. Moreover, besides stoichiometric EDA complexes between two molecules, EDA complex based organocatalysis can be achieved in certain cases through regeneration of the donor molecules in the course of the reaction. Photoexcitation of the EDA complexes induces a single electron transfer (SET) process to generate aryl radical species for the arylation step. This Review will focus on the state-of-the-art EDA complex-based arylation strategies utilizing aryl halides, aryldiazonium, diaryliodonium, arylsulfonium and arylphosphonium salts as reactants, published mainly in the last five years.
Functional and Mechanistic Characterization of the 4,5‐diepi‐Isoishwarane Synthase from the Liverwort Radula lindenbergiana
The microbial type and multiproduct sesquiterpene synthase RlMTPSL4 from the liverwort Radula lindenbergiana produces the new sesquiterpene hydrocarbon 4,5-diepi-isoishwarane as the main product, besides the known compounds germacrene A, α-selinene, eremophilene and 4,5-diepi-aristolochene. The enzyme mechanism for the formation of the main product and its absolute configuration were determined through isotopic labeling experiments.
Abstract
The microbial type sesquiterpene synthase RlMTPSL4 from the liverwort Radula lindenbergiana was investigated for its products, showing the formation of several sesquiterpene hydrocarbons. The main product was structurally characterized as the new compound 4,5-diepi-isoishwarane, while the side products included the known hydrocarbons germacrene A, α-selinene, eremophilene and 4,5-diepi-aristolochene. The cyclization mechanism towards 4,5-diepi-isoishwarane catalyzed by RlMTPSL4 was investigated through isotopic labeling experiments, revealing the stereochemical course for the deprotonation step to the neutral intermediate germacrene A, a reprotonation for its further cyclization, and a 1,2-hydride shift along the cascade. The absolute configuration of 4,5-diepi-isoishwarane was determined using a stereoselective deuteration approach, revealing an absolute configuration typically observed for a microbial type sesquiterpene.
Oxygen Activation in Aromatic Ring Cleaving Salicylate Dioxygenase: Detection of Reaction Intermediates with a Nitro‐substituted Substrate Analog
Salicylate dioxygenase performs aromatic C−C bond scission of its substrates, salicylate and gentisate, with the aid of iron cofactor tethered to a 3-His binding motif. By utilizing a nitro substituted substrate analog, which attenuates the enzymatic k cat by 500-fold, detection and kinetics characterization two reaction intermediates was performed with stopped-flow optical absorption spectroscopy.
Abstract
Cupin dioxygenases such as salicylate 1,2-dioxygense (SDO) perform aromatic C−C bond scission via a 3-His motif tethered iron cofactor. Here, transient kinetics measurements are used to monitor the catalytic cycle of SDO by using a nitro-substituted substrate analog, 3-nitrogentisate. Compared to the natural substrate, the nitro group reduces the enzymatic k cat by 500-fold, thereby facilitating the detection and kinetic characterization of reaction intermediates. Sums and products of reciprocal relaxation times derived from kinetic measurements were found to be linearly dependent on O2 concentration, suggesting reversible formation of two distinct intermediates. Dioxygen binding to the metal cofactor takes place with a forward rate of 5.9×103 M−1 s−1: two orders of magnitude slower than other comparable ring-cleaving dioxygenses. Optical chromophore of the first intermediate is distinct from the in situ generated SDO Fe(III)−O2⋅− complex but closer to the enzyme-substrate precursor.