Qing Dai

Highly selective and sensitive heparin probing from supramolecular assembly of pyrene derivatives.

A new quinine derivative PQ, bearing pyrenyl as a fluorophore, was prepared to recognize heparin in aqueous solution. PQ exhibits good selectivity and sensitivity for heparin over other biological molecules. Upon binding with heparin, PQ shows a typical excimer emission peaked at 489 nm along with a weak monomer emission at 376 nm. Moreover, PQ also shows good performance to detect the heparin in serum.

Sensing of bacterial endotoxin in aqueous solution by supramolecular assembly of pyrene derivative.

N,N-dimethyl-N-(pyrenyl-1-methyl) dodecan-1-ammonium has been designed and applied as a fluorescent probe for sensing bacterial endotoxin. Upon assembly with bacterial endotoxin (lipopolysaccharide) in aqueous solution, the probe exhibits a ratiometric and sensitive fluorescence response with a low detection limit (100 nM). Moreover, the probe shows high selectivity for bacterial endotoxin over other related biological species.

Aggregation-induced emission enhancement materials with large red shifts and their self-assembled crystal microstructures

Two simple intramolecular charge transfer compounds (BzBMN and BzFAN), derived from 2-benzyloxy-4-diethylaminobenzaldehyde, have been synthesized. Unlike typical AIEE molecules, the enhanced emission of these compounds in the solid state is accompanied by large red shifts in emission wavelength. Absorption and photoluminescence (PL) spectra of the compounds in solution, film and the X-ray single crystal structures were investigated to understand the mechanism of enhanced emission in the solid state. The results indicate that the bathochromic shift excimer-like emissions originated from dimers induced by the dipole–dipole interaction and long-range ordered arrangement (e.g. J-aggregation), and the enhanced emission is attributed to the restriction of intramolecular rotations caused by multiple intermolecular hydrogen bonding interactions. In addition, it was also observed that BzBMN and BzFAN can facilely form single crystal microbelts and microtubes by a simple reprecipitation method.

Keto-benzo[h]-Coumarin-Based Near-Infrared Dyes with Large Stokes Shifts for Bioimaging Applications.

Fluorescence imaging is a promising tool for the visualization of biomolecules in living systems and there is great demand for new fluorescent dyes that absorb and emit in the near-infrared (NIR) region. Herein, we constructed three new fluorescent dyes (NBC dyes) based on keto-benzo[h]coumarin (k-BC) and benzopyrilium salts. These dyes showed large Stokes shifts (>100 nm) and NIR emission (>800 nm). The relationship between the structures and optical properties of these dyes was further investigated by using density functional theory calculations at the B3LYP/6-3G level of theory. Fluorescence images indicated that the fabricated dyes exhibited good photostability and low cytotoxicity and, thus, have potential applications as imaging agents in living cells and animals.

Application of the laser scanning confocal microscope in fluorescent film sensor research

Confocal microscopy offers several advantages over conventional optical microscopy; we show an experimental investigation laser scanning confocal microscope as a tool to be used in cubic boron nitride (cBN) film-based fluorescent sensor research. Cubic boron nitride cBN film sensors are modified with dansyl chloride and rhodamine B isothiocyanate respectively. Fluorescent modification quality on the cubic boron nitride film is clearly express and the sensor ability to Hg2+ cations and pH are investigated in detail. We evidence the rhodamine B isothiocyanate modified quality on cBN surface is much better than that of dansyl chloride. And laser scanning confocal microscope has potential application lighttight fundus film fluorescent sensor research.