DNA repair enzymes (e.g., DNA glycosylases) play a critical role in the repair of DNA lesions, and their aberrant levels are associated with various diseases. Herein, we develop a sensitive method for simultaneous detection of multiple DNA repair enzymes based on the integration of single-molecule detection with rolling circle amplification (RCA)-driven encoding of different fluorescent molecules. We use human alkyladenine DNA glycosylase (hAAG) and uracil DNA glycosylase (UDG) as the target analytes. We design a bifunctional double-stranded DNA (dsDNA) substrate with a hypoxanthine base (I) in one strand for hAAG recognition and an uracil (U) base in the other strand for UDG recognition, whose cleavage by APE1 generates two corresponding primers. The resultant two primers can hybridize with their respective circular templates to initiate RCA, resulting in the incorporation of multiple Cy3-dCTP and Cy5-dGTP nucleotides into the amplified products. https://www.selleckchem.com/products/cd532.html After magnetic separation and exonuclease cleavage, the Cy3 and Cy5 fluorescent molecules in the amplified products are released into the solution and subsequently quantified by total internal reflection fluorescence (TIRF)-based single-molecule detection, with Cy3 indicating the presence of hAAG and Cy5 indicating the presence of UDG. This strategy greatly increases the number of fluorescent molecules per concatemer through the introduction of RCA-driven encoding of different fluorescent molecules, without the requirement of any specially labeled detection probes for simultaneous detection. Due to the high amplification efficiency of RCA and the high signal-to-ratio of single-molecule detection, this method can achieve a detection limit of 6.10 × 10-9 U mL-1 for hAAG and 1.54 × 10-9 U mL-1 for UDG. It can be further applied for simultaneous detection of multiple DNA glycosylases in cancer cells at the single-cell level and the screening of DNA glycosylase inhibitors, holding great potential in early clinical diagnosis and drug discovery.Many fundamental questions remain in the elucidation of energy migration mechanisms across the interface between semiconductor nanomaterials and molecular chromophores. The present transient absorption study focuses on PbS quantum dots (QDs) of variable size and band-edge exciton energy (ranging from 1.15 to 1.54 eV) post-synthetically modified with a carboxylic acid-functionalized TIPS-pentacene derivative (TPn) serving as the molecular triplet acceptor. In all instances, selective excitation of the PbS NCs at 743 nm leads to QD size-dependent formation of an intermediate with time constants ranging from 2-13 ps, uncorrelated to the PbS QD valence band potential. However, the rate constant for the delayed formation of the TPn triplet excited state markedly increases with increasing PbS conduction band energy, featuring a parabolic Marcus free energy dependence in the normal region. These observations provide evidence of an indirect triplet sensitization process being inconsistent with a concerted Dexter-like energy transfer process. The collective data are consistent with the generation of an intermediate resulting from hole trapping of the initial PbS excited state by midgap states, followed by formation of the TPn triplet excited state whose rate constant and yield increases with decreasing quantum dot size.Bifunctional AlIII porphyrins with quaternary ammonium halides, 2-Cl and 2-Br, worked as excellent catalysts for the copolymerization of cyclohexene oxide (CHO) and CO2 at 120 °C. Turnover frequency (TOF) and turnover number (TON) reached 10 000 h-1 and 55 000, respectively, and poly(cyclohexene carbonate) (PCHC) with molecular weight of up to 281 000 was obtained with a catalyst loading of 0.001 mol%. In contrast, bifunctional MgII and ZnII counterparts, 3-Cl and 4-Cl, as well as a binary catalyst system, 1-Cl with bis(triphenylphosphine)iminium chloride (PPNCl), showed poor catalytic performances. Kinetic studies revealed that the reaction rate was first-order in [CHO] and [2-Br] and zero-order in [CO2], and the activation parameters were determined ΔH‡ = 12.4 kcal mol-1, ΔS‡ = -26.1 cal mol-1 K-1, and ΔG‡ = 21.6 kcal mol-1 at 80 °C. Comparative DFT calculations on two model catalysts, AlIII complex 2' and MgII complex 3', allowed us to extract key factors in the catalytic behavior of the bifunctional AlIII catalyst. The high polymerization activity and carbonate-linkage selectivity originate from the cooperative actions of the metal center and the quaternary ammonium cation, both of which facilitate the epoxide-ring opening by the carbonate anion to form the carbonate linkage in the key transition state such as TS3b (ΔH‡ = 13.3 kcal mol-1, ΔS‡ = -3.1 cal mol-1 K-1, and ΔG‡ = 14.4 kcal mol-1 at 80 °C).Lateral forces in biological membranes affect a variety of dynamic cellular processes. Recent synthetic efforts have introduced fluorescent "flippers" as environment-sensitive planarizable push-pull probes that can detect lipid packing and membrane tension, and respond to lipid-induced mechanical forces by a shift in their spectroscopic properties. Herein, we investigate the molecular origin of the mechanosensitivity of the best known flipper, Flipper-TR, by an extended set of molecular dynamics (MD) simulations in membranes of increasing complexity and under different physicochemical conditions, revealing unprecedented details of the sensing process. Simulations enabled by accurate refinement of Flipper-TR force field using quantum mechanical calculations allowed us to unambiguously correlate the planarization of the two fluorescent flippers to spectroscopic response. In particular, Flipper-TR conformation exhibits bimodal distribution in disordered membranes and a unimodal distribution in highly ordered memon of Flipper-TR is elucidated, corroborating experimental evidence that the probe tilt angle is strongly dependent on lipid ordering. The obtained atomic-resolution description of Flipper-TR mechanosensitivity is key to the interpretation of experimental data and to the design of novel mechanosensors with improved spectroscopic properties.