Dayong Lin

Spectra, stability and labeling of 1-(5-carboxypentyl)-4-(2-(N-ethyl-carbazole-3-yl) vinyl) pyridinium bromide with a large Stokes shift

Carbazole and its derivatives have been widely utilized as a functional building block in the fabrication of the organic medicine, pesticides, materials, etc., because of their excellent solubility, stability and biological activity. In this paper, 1-(5-carboxypentyl)-4-(2-(N-ethyl-carbazole-3-yl) vinyl) pyridinium bromide with a large Stokes shift was synthesized and characterized by (1)H NMR and MS. The UV/vis absorption and fluorescence spectra in different solvents and at different pH values were investigated preliminarily. The photostability and thermostability were also studied and the results showed that the compound was stable. The compound was also used to label bovine serum albumin (BSA) and calf thymus (ct)DNA. The results showed that the fluorescence intensity is enhanced when labeling with BSA and the binding ability is stronger than ctDNA, making it may be used as a biological probe.

Design Mechanism and Property of the Novel Fluorescent Probes for the Identification of Microthrix Parvicella In Situ

In this study, two novel fluorescent probes, probe A and probe B were designed, synthesized and characterized, based on Microthrix parvicella (M. parvicella) preferring to utilize long-chain fatty acid (LCFA), for the labeling of M. parvicella in activated sludge. The molecular structure of probe A and probe B include long-chain alkane and LCFA, respectively. The results indicated that probe A and probe B had a large stokes shift of 118 nm and 120 nm and high quantum yield of 0.1043 and 0.1058, respectively, which were significantly helpful for the fluorescent labeling. As probe A was more stable than probe B in activated sludge, and the fluorescence intensity keep stable during 24 h, probe A was more suitable for labeling M. parvicella in situ. In addition, through the Image Pro Plus 6 (IPP 6) analysis, a quantitative relationship was established between sludge volume index (SVI) and integral optical density (IOD) of the labeled M. parvicella in activated sludge samples. The relationship between IOD and SVI conforms to Logistic curve (R2 = 0.94).

A light-up probe targeting for Bcl-2 2345 G-quadruplex DNA with carbazole TO

As its significant role, the selective recognition of G-quadruplex with specific structures and functions is important in biological and medicinal chemistry. Carbazole derivatives have been reported as a kind of fluorescent probe with many excellent optical properties. In the present study, the fluorescence of the dye (carbazole TO) increased almost 70 fold in the presence of bcl-2 2345 G4 compared to that alone in aqueous buffer condition with almost no fluorescence and 10-30 fold than those in the presence of other DNAs. The binding study results by activity inhibition of G4/Hemin peroxidase experiment, NMR titration and molecular docking simulation showed the high affinity and selectivity to bcl-2 2345 G4 arises from its end-stacking interaction with G-quartet. It is said that a facile approach with excellent sensitive, good selectivity and quick response for bcl-2 2345 G-quadruplex was developed and may be used for antitumor recognition or antitumor agents.

A novel fluorescent long-chain fatty acid-substituted dye: labeling and biodegrading of Microthrix parvicella

Microthrix parvicella (M. parvicella) is a filamentous bacterium that induces bulking in activated sludge. Here, we used the affinity of long-chain fatty acids (LCFA) for M. parvicella to create a novel fluorescent probe of carbazole modified by LCFA. The structure was characterized by 1H NMR spectroscopy and mass spectrometry. The spectral properties, photostability, and hydrophobic properties of the probe were also characterized. Fluorescent-labeling results showed that it can label M. parvicella in situ and could be biodegraded via metabolism. The stable docking mode of carbazole probes with different fatty acid chains and lipases was also docked by the density functional tight-binding (DFTB) method.