Development of powerful fluorescence imaging probes and techniques sets the basis for the spatiotemporal tracking of cells at different physiological and pathological stages. While current imaging approaches rely on passive probe–analyte interactions, here we develop photochromic fluorescent glycoprobes capable of remote light-controlled intracellular target recognition. Conjugation between a fluorophore and spiropyran produces the photochromic probe, which is subsequently equipped with a glycoligand “antenna” to actively localize a target cell expressing a selective receptor. We demonstrate that the amphiphilic glycoprobes that form micelles in water can selectively enter the target cell to operate photochromic cycling as controlled by alternate UV/Vis irradiations. We further show that remote light conversion of the photochromic probe from one isomeric state to the other activates its reactivity toward a target intracellular analyte, producing locked fluorescence that is no longer photoisomerizable. We envision that this research may spur the use of photochromism for the development of bioimaging probes.

Despite the rapid development of imaging techniques, precise probe localization and modulation in living cells is still a challenging task. Here we show that the simple hybridization between a photochromic fluorescent glycoprobe and human serum albumin (HSA) enables a unique fluorescence "double-check" mechanism for precisely localizing and manipulating probe molecules in living cells. Docking of a carbohydrate-modified naphthalimide (Naph)-spiropyran (SP) dyad to a hydrophobic pocket of HSA produces the glycoprobe-protein hybrid, causing the protein conformation to fold as determined by small-angle X-ray scattering. We show that the Naph and merocyanine (the photoisomer of SP) fluorescence of the resulting hybrid can be reversibly switched by light in buffer solution and in target cells overexpressing the carbohydrate receptor.

Natural systems transfer chiral information across multiple length scales through dynamic supramolecular interaction to accomplish various functions. Inspired by nature, many exquisite artificial supramolecular systems have been developed, in which controlling the supramolecular chirality holds the key to completing specific tasks. However, to achieve precise and non-invasive control and modulation of chirality in these systems remains challenging. As a non-invasive stimulus, light can be used to remotely control the chirality with high spatiotemporal precision. In contrast to common molecular switches, a synthetic molecular motor can act as a multistate chiroptical switch with unidirectional rotation, offering major potential to regulate more complex functions. Here, we present a light-driven molecular motor-based supramolecular polymer, in which the intrinsic chirality is transferred to the nanofibers, and the rotation of molecular motors governs the chirality and morphology of the supramolecular polymer. The resulting supramolecular polymer also exhibits light-controlled multistate aggregation-induced emission. These findings present a photochemically tunable multistate dynamic supramolecular system in water and pave the way for developing molecular motor-driven chiroptical materials.

Vous avez des questions?Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. highlights HMS-SnO 2 /GDE was developed for electrocatalytic reduction of CO 2 to formate fuel.The influence of ethanol/H 2 O ratio on selectivity and activity was studied by electrochemical characterization.A faradaic efficiency of 62.0% in a divided H-type two-compartment cell was observed at À1.7 V.The HMS-SnO 2 /GDE electrode was stable over 12 h of continuous electrolysis operation. graphical abstract article info abstractThe conversion of carbon dioxide to value-added fuel using electrical energy generated intermittently from renewable energy sources is very promising in terms of energy usage reconciliation. The process converts greenhouse carbon dioxide gas to produce diverse attractive chemicals and fuels like methanol, formate, and other hydrocarbons. In this paper, the electroreduction of CO 2 to formate in aqueous solution is performed by using novel hierarchical tin oxide microsphere (HMS-SnO 2 ) particles deposited over gas diffusion layer electrode (HMS-SnO 2 /GDE). The experiment is carried out in a divided H-type twocompartment cell with a Nafion Ò membrane as the diaphragm separating the cathodic and anodic compartments. The HMS-SnO 2 catalysts are synthesized by a facile hydrothermal self-assembled process using different ratios of ethanol to distilled water in the synthetic solution. Due to the outstanding catalytic activity and selectivity toward CO 2 electroreduction, SnO 2 -86/GDE exhibits a high Faradaic efficiency of 62% toward formate formation at À1.7 V vs. SHE (Standard Hydrogen Electrode). The electrode durability is also observed with a stable current density over 12 h of continuous electrolysis operation. The superior performance is credited to the morphology-and size-controlled hierarchical structure, which may provide more active sites to accelerate the slow kinetics of CO 2 reduction, leading to the improved energy efficiency. During electrolysis process, KHCO 3 electrolyte is found to have some contribution to formate formation on the micro-structured tin oxide catalysts coated GDE electrode.Please cite this article in press as: Fu Y et al. Novel hierarchical SnO 2 microsphere catalyst coated on gas diffusion electrode for enhancing energy efficiency of CO 2 reduction to formate fuel. Appl Energy (2016), http://dx.

The development of very fast, clean, and selective methods for indirect labeling in PET tracer synthesis is an ongoing challenge. Here we present the development of an ultrafast photoclick method for the synthesis of short-lived 18 F-PET tracers based on the photocycloaddition reaction of 9,10-phenanthrenequinones with electron-rich alkenes. The respective precursors are synthetically easily accessible and can be functionalized with various target groups. Using a flow photo-microreactor, the photoclick reaction can be performed in 60 s, and clinically relevant tracers for prostate cancer and bacterial infection imaging were prepared to demonstrate practicality of the method.

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The synthesis of a bis-glycosyl diarylethene derivative by click chemistry for the water-compatible photochromism and operation of molecular logic gates is reported.

Light-induced 9,10-phenanthrenequinoneelectron-rich alkene (PQ-ERA) photocycloadditions are an attractive new type of photoclick reaction, featuring fast conversions and high biocompatibility. However, the tunability of the reaction was hardly investigated up to now. To this end, we explored the influence of substituents on both reaction partners and the reaction rate between the PQs and ERAs. We identified new handles for functionalization and discovered that using enamines as ERAs leads to drastically enhanced rates (> 5400 times faster), high photoreaction quantum yields (Φ P , up to 65 %), and multicolor emission output as well as a high fluorescence quantum yield of the adducts (Φ F , up to 97 %). Further investigation of the photophysical and photochemical properties provided insights to design orthogonal reaction systems both in solution and on nanoparticle surfaces for ultrafast chemoselective functionalization by photoclick reactions.