Xinggui Gu

Convenient and Continuous Fluorometric Assay Method for Acetylcholinesterase and Inhibitor Screening Based on the Aggregation-Induced Emission

A new convenient and continuous fluorometric assay method for acetylcholinesterase (AChE) and its inhibitor screening is successfully established with the ensemble of 1 [a TPE (tetraphenylethylene) compound with two sulfonate (-SO(3)(-)) units] and myristoylcholine (an amphiphilic compound as a good substrate of AChE). This new assay method is designed by making use of the aggregation-induced emission (AIE) feature of TPE compounds. Both dynamic light scattering (DLS) and fluorescence confocal microscopic measurements indicated the formation of aggregation complex for the ensemble of 1 and myristoylcholine and further disassembly of the aggregation complex after introducing AChE. The analysis for AChE can be carried out continuously, and AChE with concentration as low as 0.5 U/mL can be assayed. The results also clearly demonstrate the usefulness of this convenient assay method for kinetic study of AChE-catalyzed myristoylcholine hydrolysis and screening inhibitors of AChE. Given its simplicity and easy operation, this method may extend to high-throughput screening of AChE inhibitors and relevant Alzheimers disease (AD) drug discovery.

Continuous Colorimetric Assay for Acetylcholinesterase and Inhibitor Screening with Gold Nanoparticles

We report herein a new colorimetric assay method for acetylcholinesterase (AChE) activity and its inhibitor screening by making use of the following facts: (1) the aggregation of gold nanoparticles (Au-NPs) results in the red-shift of the plasmon absorption due to interparticle plasmon interactions and (2) AChE can catalyze the hydrolysis of acetylthiocholine into thiocholine which can induce the aggregation of Au-NPs. With this convenient method, the activity of AChE with a concentration as low as 0.6 mU/mL can be assayed. Moreover, this assay method is also useful for screening inhibitors of AChE. Given its simplicity and easy-operation, this method may extend to high-throughput screening of AChE inhibitors and relevant drug discovery.

New Electron-Donor/Acceptor-Substituted Tetraphenylethylenes: Aggregation-Induced Emission with Tunable Emission Color and Optical-Waveguide Behavior

Herein, we report the synthesis of new tetraphenylethylene derivatives 1-5 that feature electron-donating (methoxy) and -accepting (dicyanomethane) groups as AIE-active molecules with tunable emission colors. The crystal structures of compounds 3 and 4 are described and the intermolecular interactions within their crystals agree with the observation that they exhibit strong solid-state emission. Compounds 1-4 exhibit typical AIE behavior and their emission maxima are red-shifted in the order: 1<2<3<4. Such red-shifts are ascribed to the fact that intramolecular interactions between the electron donor and the electron acceptor become stronger with increasing number of methoxy groups. The solid-state emission colors of compounds 1-4 are successfully tuned from yellow-green to red. Compound 5 shows AIE behavior, but its emission is only slightly enhanced after aggregation and its solid shows a low quantum yield. Furthermore, microplates of compound 3 exhibit 2D optical-waveguide behavior.

A Mitochondrion-Specific Photoactivatable Fluorescence Turn-On AIE-Based Bioprobe for Localization Super-Resolution Microscope

A novel mitochondrion-specific photo-activatable fluorescence turn-on bioprobe, named as o-TPE-ON+, is designed and readily prepared, operating through a new photoactivatable mechanism of photocyclodehydrogenation. This bioprobe exhibits unique photoactivation behavior in cells, and is applied to super-resolution imaging of mitochondrion and its dynamic investigation in both fixed and live cells under physiological conditions without any external additives.

A New Fluorescence Turn-on Assay for Trypsin and Inhibitor Screening Based on Graphene Oxide

In this paper, we describe a new continuous fluorescence turn-on method for trypsin assay and inhibitor screening in situ. This assay is designed based on the following assumptions: (1) It is expected that the fluorescein-labeled peptide composed of six arginine residues (Arg(6)-FAM) with positive charges will interact with the negatively charged edge of water-soluble graphene oxide (GO) because of electrostatic interactions to form a GO/Arg(6)-FAM complex. As a result, the fluorescence of fluorescein will be quenched because of the energy transfer from fluorescein to GO. (2) Arg(6)-FAM can be hydrolyzed into small fragments in the presence of trypsin, and accordingly, the GO/Arg(6)-FAM complex will be dissociated, gradually leading to fluorescence recovery for the solution. In this way, the trypsin activity can be easily assayed with the ensemble of Arg(6)-FAM and GO. Additionally, the ensemble can be employed for screening of the inhibitors of trypsin.

Controllable Self-Assembly of Di(p-methoxylphenyl)Dibenzofulvene into Three Different Emission Forms

Self-assembly of di(p-methoxylphenyl)dibenzofulvene in the absence and presence of CTAB (cetyl trimethylammonium bromide) leads to three emission forms: strongly yellow-green- and blue-emissive crystalline forms (as microrods), and weakly orange-emissive amorphous form. Each of these three emission forms can be prepared by adjusting the concentration of CTAB.

Mitochondrion-Specific Live-Cell Bioprobe Operated in a Fluorescence Turn-On Manner and a Well-Designed Photoactivatable Mechanism

A novel mitochondrion-specific live-cell fluorescence turn-on photoactivatable bioprobe, named o-TPP3M, is designed and readily prepared, operating in a new photoactivatable mechanism based on a twisted intramolecular charge-transfer effect, the restriction of intramolecular rotations, and photocyclodehydrogenation. This bioprobe exhibits unique photoactivation behavior, a large signal-to-background ratio, and no cytotoxicity to living cells, providing a promising candidate for varied bioresearch.

Pressure effect on the structural relaxation and glass transition in metallic glasses

Two different enthalpy recovery methods were applied to investigate the effects of pressure on structural relaxation and glass transition temperature (T-g) in two metallic glasses (Pd40Ni10Cu30P20 and Zr65Al7.5Cu27.5). The pressure-induced enhancement of T-g (dT(g)/dP) was derived to be 6 K/GPa in Pd40Ni10Cu30P20 glass, while an increment of 50 K/5 GPa was observed in Zr65Al7.5Cu27.5 glass. Activation (formation and migration) volumes of the flow defect were used to interpret the pressure dependence of the structural relaxation and T-g in terms of the free volume model. According to the measured results, the activation volume of relaxation was derived to be 16.7 Angstrom(3) for Pd40Ni10Cu30P20, which is much smaller than that of the polymers

Pressure effect on crystallization of mechanically alloyed amorphous Al85Fe15 alloy

The pressure effect on the crystallization of amorphous Al85Fe15 alloy prepared by means of ball-milling was investigated in a pressure range up to 1.4 GPa. It was found that the applied pressure enhances the nanoscale fee Al precipitation from amorphous matrix which does not occur at ambient pressure. The precipitation temperature of nanoscale fee Al from amorphous matrix decreases from about 380 to 200 degrees C when the applied pressure increases from 0.4 to 1.0 GPa. The high-pressure annealing of mechanically alloyed Al-based amorphous powders provides an effective approach to optimize the synthesis procedure for nanocrystalline/amorphous composite materials

The synthesis of novel AIE emitters with the triphenylethene-carbazole skeleton and para-/meta-substituted arylboron groups and their application in efficient non-doped OLEDs

Four novel aggregation-induced emission (AIE)-active luminogens (p-DPDECZ, p-DBPDECZ, m-DPDECZ and m-DBPDECZ) with triphenylethene-carbazole skeleton and para-/meta-substituted arylboron groups have been synthesized. Their structures are fully characterized using elemental analysis, mass spectrometry and proton nuclear magnetic resonance spectroscopy. The thermal stabilities, photophysical properties, electronic structures, and electrochemical properties of these molecules are investigated systematically using thermal analysis, UV-vis absorption spectroscopy, fluorescence spectroscopy, theoretical calculation and electrochemical methods. The effects of donor–acceptor interaction and conjugation degree on the photoluminescent and electroluminescent properties of these compounds are investigated. The results show that these donor–AIE–acceptor type compounds exhibit good thermal stability and electrochemical stability as well as AIE properties. Non-doped fluorescent OLEDs fabricated by using para-linked p-DPDECZ as an emitting layer emits a green light with a turn-on voltage of 4.8 V, a maximum brightness of 30 210 cd m−2 and a maximum current efficiency of 9.96 cd A−1. While the OLED prepared with meta-linked m-DBPDECZ exhibits efficient blue light emission with a maximum current efficiency of 4.49 cd A−1 and a maximum luminance of 16 410 cd m−2. The electroluminescence properties of these compounds demonstrate their potential application in OLEDs.