PEC thrombin aptasensor based on Ag-Ag2S decorated hematite photoanode with signal-down effect of precipitation catalyzed by G-quadruplexes/hemin.

A photoelectrochemical (PEC) aptasensor for thrombin detection was rationally designed based on the photoanode of one-dimensional hematite nanorods (α-Fe2O3 NRs) with several steps of modifications. Uniform α-Fe2O3 NRs were grown vertically on the surface of fluorine-doped tin oxide (FTO) conductive glass through a one-step hydrothermal method; then Ag was grown on the surface of α-Fe2O3 NRs through a photoreduction method followed by a partial in-situ transformation into Ag2S, conferring an improvement on the initial photocurrent. Two main critical factors, namely, the steric hindrance of thrombin, benzoquinone (BQ) precipitation oxidized by H2O2 under the catalysis of G-quadruplexes/hemin, contributed to the sensitive signal-down response toward the target. Photocurrent signals related with thrombin concentration was established for thrombin analysis due to the non-conductive complex as well as their competitive consumption of electron donors and irradiation light. The excellent initial photocurrent was combined with the signal-down amplification in the design of the biosensor, conferring a limit of detection (LOD) as low as 40.2 fM and a wide linear range from 0.0001 nM to 50 nM for the detection of thrombin. The proposed biosensor was also assessed in terms of selectivity, stability, and applicability in human serum analyses, which provided an appealing maneuver for the specific analysis of thrombin in trace amount.

Hierarchically supramolecular polymerization of anthraquinone dye to chiral aggregates via 2D-monolayered nanosheets: the unanticipated role of pathway complexity.

An anthraquinone dye underwent supramolecular polymerization, affording 2D-monolayered nanosheets in a kinetically controlled state. The nanosheets then transformed into hierarchically chiral aggregates in a thermodynamically controlled step. The unanticipated role played by pathway complexity was clearly unravelled in this work, highlighting the diversified pathways in the supramolecular polymerization of various building blocks.

Blue emissive dimethylmethylene-bridged triphenylamine derivatives appending cross-linkable groups.

Five new dimethylmethylene-bridged triphenylamine (DTPA) derivatives 4a-e bearing peripheral cross-linkable vinyl and trifluorovinyl groups were synthesized. The chemical structure of these compounds was characterized by 1H NMR, 13C NMR and HRMS. Their optical properties were studied by UV/Vis spectroscopy and fluorescence spectroscopy. Based on these studies, blue-coloured fluorescence and high fluorescence quantum yields were obtained for 4a-e. The electrochemical properties of these compounds were studied by cyclic voltammetry and the results were further elucidated by DFT calculations. Furthermore, the thermotropic properties of the new DTPAs were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Compounds 4a-d exhibit high thermal stability and thermal cross-linkable properties. These results provide an effective strategy for the design and synthesis of thermally stable and cross-linkable DTPA derivatives with tunable optical and electrochemical properties.

Living Supramolecular Polymerization of an Aza-BODIPY Dye Controlled by a Hydrogen-Bond-Accepting Triazole Unit Introduced by Click Chemistry.

An aza-BODIPY dye 1 bearing two hydrophobic fan-shaped tridodecyloxybenzamide pendants through 1,2,3-triazole linkages was synthesized by a click reaction and characterized. 1 H NMR studies indicated that dye 1 exhibited variable conformations through intramolecular H-bonding interaction, which is beneficial for the polymorphism of aggregation. The thermodynamic, structural, and kinetic aspect of the supramolecular polymerization of dye 1 was investigated by UV/Vis absorption spectroscopy, IR spectroscopy, AFM, TEM, and SEM. Biphasic aggregation pathways of dye 1, leads to the formation of off-pathway, metastable Agg. I and thermodynamically stable Agg. II with distinct H-aggregation spectra and nanoscale morphology. The living manner of the supramolecular polymerization of dye 1 was demonstrated in seeded polymerization experiments with temperature-modulated successive cooling-heating cycles.