Zhong-Wei Zhang

Synthesis, DNA binding and cleavage activities of the copper (II) complexes of estrogen-macrocyclic polyamine conjugates

A series of the copper (II) complexes 5a-d of estrogen-macrocyclic polyamine conjugates were synthesized and characterized. The interactions of complexes 5a-d with DNA were studied by fluorescence spectroscopy and gel electrophoresis under physiological conditions. The results indicate that the conjugated estrogens have increased the cleavage efficiency of Cu[cyclen](2+) while the conjugates display poor binding affinities. The functional groups of D-ring of estrogens may play a key role in deciding binding and cleavage extent of the complexes to DNA.

Self-activating chemical nuclease: ferrocenyl cyclen Cu(II) complexes act as efficient DNA cleavage reagents in the absence of reductant.

The interactions of cyclen Cu(II) complexes functionalized by ferrocenyl group with plasmid DNA indicated that these complexes have high cleavage efficiency via an oxidative mechanism in the absence of any reductant or oxidant.

A new Schiff base copper (II) complex derived from estrone and d-glucosamine: Synthesis, characterization and its interaction with DNA

A novel copper (II) complex of Schiff base prepared through condensation between 2-formyl-17-deoxyestrone and d-glucosamine was synthesized and characterized. Fluorescence spectroscopy was conducted to assess their binding ability with CT-DNA. The results showed that the copper (II) complex could bind to DNA with a weak intercalative mode. The interaction between the copper (II) complex and DNA was also investigated by gel electrophoresis. Interestingly, we found that the complex could cleave plasmid DNA (pUC19) to nicked and linear forms through an oxidative mechanism without the use of exogenous agents.

Synthesis and DNA-cleavage activities of dinuclear copper(II) complexes of urea-bridged macrocyclic polyamines.

Two dinuclear macrocyclic polyamine copper(II) (CuII) complexes, which have two cyclen units linked by urea, were synthesized as DNA‐cleavage agents. The structures of these new dinuclear complexes were identified by HR‐ESI‐MS and IR analyses. The catalytic activities of DNA cleavage of these dinuclear CuII complexes were subsequently studied. The results show that 6a was the better catalyst in the DNA‐cleavage process than 6b. The effects of reaction time and concentration of complexes were also investigated. The results indicate, that the CuII complexes could catalyze the cleavage of supercoiled DNA (pUC 19 plasmid DNA; Formu2005I) under physiological conditions to produce selectively nicked DNA (Formu2005II; no Formu2005III was produced) with high yields (nearly 100%) in short time in the absence of reductant or oxidant.

Cyclen‐Based Side‐Chain Homopolymer Self‐Assembly with Plasmid DNA: Protection of DNA from Enzymatic Degradation

In this study, a 1,4,7,10-tetraazacyclododecane (cyclen)-based side-chain homopolymer was developed for the first time; this polymer can self-assembly with plasmid DNA to form polyelectrolyte complexes (polyplex), which can protect DNA from enzymatic degradation. Moreover, the polyplex can disassembly and release free DNA when NaCl solution is added to this system. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) are used for imaging of the surface structure of the polyplex, and results indicated that the polyplex structures respond to the polymer concentration. Circular dichroism (CD) spectrum suggested that the DNA configuration in the polyplex was retained.

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.