Qiao-Sen Lu

Imidazolium-Functionalized BINOL as a Multifunctional Receptor for Chromogenic and Chiral Anion Recognition

A novel imidazolium-functionalized BINOL fluorescent receptor R-1 was developed as a multifunctional receptor for both chromogenic and chiral anion recognition. The different fluorescent responses and color changes of R-1 could be applied to the detection of fluoride and acetate ions by the naked eye. Furthermore, the chiral recognition of the two enantiomers of alpha-amino carboxylates was also studied, and R-1 displayed a remarkable binding ability for the t-Boc alanine anion with an interesting enantioselectivity (K(L)/K(D) = 4.5).

Synthesis, DNA binding and cleavage activity of macrocyclic polyamines bearing mono- or bis-acridine moieties

Two acridine-pendant cyclen (1,4,7,10-tetraazacyclododecane) derivatives 1 and 2 were synthesized, and their DNA interactions have been systematically investigated by UV absorption, fluorescence titration, viscosity measurement, DNA melting and gel electrophoresis experiments. The results showed that acridine-cyclen derivatives could bind to DNA in intercalative mode, and bis-acridine 2 has higher DNA binding ability than that of mono-acridine 1. Moreover, both compounds exhibited preferential interactions with G-rich DNA sequences. Their copper(II) complexes could cleave DNA without the existence of other additives under physiological conditions through an oxidative pathway.

Hydrolytic cleavage of DNA by urea-bridged macrocyclic polyamines

Novel bis-cyclen derivative A with urea, mono-cyclen derivative B with urea and amino acid urea C were synthesized as DNA cleavage agents. The structures of these new compounds were identified by MS and (1)H NMR spectroscopy. The catalytic activities on DNA cleavage of these compounds were subsequently studied, and results show that A is a much better catalyst in DNA cleavage process than that of B and C. The effects of reaction time and catalyst concentration were also investigated. The results indicate that A can catalyze the cleavage of supercoiled DNA (pUC 19 plasmid DNA) to nicked DNA under physiological conditions with high yields (nearly 100%) via a hydrolytic mechanism.

Linear disulfide-containing low polymer as efficient DNA cleavage reagent

A novel linear poly[1,7-bis(mercaptoacetyl)-1,4,7,10-tetraazacyclododecane] (PBMAC) containing macrocyclic polyamine was synthesized through oxidation of 1,7-bis(mercaptoacetyl)-1,4,7,10-tetraazacyclododecane (BMAC) and characterized. Gel electrophoresis experiments showed that PBMAC can promote the DNA cleavage more efficiently than its monomer under physiological conditions without any thiol additives. Fluorescence quenching and DNA melting experiments demonstrated that PBMAC has stronger binding ability with DNA than that of monomer.

The Effect of an Amino-Acid Bridge on Binding Affinity and Cleavage Efficiency of Pyrenyl-Macrocyclic Polyamine Conjugates toward DNA

A series of pyrenyl‐macrocyclic polyamines 5a–5c have been prepared and characterized. Their DNA‐cleavage properties were examined under physiological conditions. Without the presence of other additives, the DNA cleavage ability of 5a–5c showed the order of 5c>5a>5b. Absorption and fluorescence experiments showed the binding affinity of 5a–5c to DNA. The interactions of 5a–5c with CT‐DNA indicated that the DNA binding ability followed an order according to their cleavage efficiency. All the results indicated that the structures of amino‐acid bridge in the ligands may affect the DNA binding and cleavage ability. The cleavage‐mechanism studies indicated that singlet oxygen and superoxide free radicals were involved in the catalytic DNA cleavage process.