N. A. Kasyanenko

Investigation of DNA complexes with iron ions in solution.

The optical anisotropy and intrinsic viscosity of DNA-Fe3+ complexes have been investigated. It was shown that the binding of iron ions to DNA causes the shrinkage of the macromolecule. The formation of such complexes is accompanied by increasing DNA optical anisotropy. We suggest that the binding of iron ions to widely spaced along the chain DNA groups creates the conditions for initiation of mutually oriented DNA fragments, thus, ensuring a higher molecular optical anisotropy.

Fluorescent Silver Nanoclusters in Condensed DNA

We study the formation and fluorescent properties of silver nanoclusters encapsulated in condensed DNA nanoparticles. Fluorescent globular DNA nanoparticles are formed using a dsDNA-cluster complex and polyallylamine as condensing agents. The fluorescence emission spectrum of single DNA nanoparticles is obtained using tip-enhanced fluorescence microscopy. Fluorescent clusters in condensed DNA nanoparticles appear to be more protected against destructive damage in solution compared to clusters synthesized on a linear polymer chain. The fluorescent clusters on both dsDNA and ssDNA exhibit the same emission bands (at 590 and 680 nm) and the same formation efficiency, which suggests the same binding sites. By using density functional theory, we show that the clusters may bind to the Watson-Crick guanine-cytosine base pairs and to single DNA bases with about the same affinity.

Interaction of protonated DNA with trans-dichlorodiammineplatinum(II)

Abstract The optical anisotropy and spectral properties of protonated double-stranded DNA during its interaction with trans -dichlorodiammineplatinum(II) ( trans -DDP) have been studied. No changes in the optical anisotropy of protonated DNA macromolecules were observed during the preparation of protonated DNA complexes with trans -DDP. It is known, however, that the binding of trans -DDP to native DNA in solution at neutral pH increases its optical anisotropy. The spectral properties of the complexes under study correspond to those of protonated DNA. The experimental data show that the site of native DNA protonation also plays an important role in its binding to trans -DDP. In contrast, a decrease in the pH of the solution containing trans -DDP–DNA complexes to the value at which DNA protonation takes place does not lead to changes in the optical anisotropy or absorption spectrum of the macromolecule. These facts indicate that the protonation sites on the macromolecule are blocked by trans -DDP.

Peptide Regulation of Gene Expression and Protein Synthesis in Bronchial Epithelium

IntroductionSome studies have shown that peptides have high treatment potential due to their biological activity, harmlessness, and tissue-specific action. Tetrapeptide Ala-Asp-Glu-Leu (ADEL) was effective on models of acute bacterial lung inflammation, fibrosis, and toxic lung damage in several studies.MethodsWe measured Ki67, Mcl-1, p53, CD79, and NOS-3 protein levels in the 1st, 7th, and 14th passages of bronchoepithelial human embryonic cell cultures. Gene expression of NKX2-1, SCGB1A1, SCGB3A2, FOXA1, FOXA2, MUC4, MUC5AC, and SFTPA1 was measured by real-time polymerase chain reaction. Using the methods of spectrophotometry, viscometry, and circular dichroism, we studied the ADEL–DNA interaction in vitro.ResultsPeptide ADEL regulates the levels of Ki67, Mcl-1, p53, CD79, and NOS-3 proteins in cell cultures of human bronchial epithelium in various passages. The strongest activating effect of peptide ADEL on bronchial epithelial cell proliferation through Ki67 and Mcl-1 was observed in “old” cell cultures. ADEL regulates the expression of genes involved in bronchial epithelium differentiation: NKX2-1, SCGB1A1, SCGB3A2, FOXA1, and FOXA2. ADEL also activates several genes, which reduced expression correlated with pathological lung development: MUC4, MUC5AC, and SFTPA1. Spectrophotometry, viscometry, and circular dichroism showed ADEL–DNA interaction, with a binding region in the major groove (N7 guanine).ConclusionsADEL can bind to specific DNA regions and regulate gene expression and synthesis of proteins involved in the differentiation and maintenance of functional activity of the bronchial epithelium. Through activation of some specific gene expression, peptide ADEL may protect the bronchial epithelium from pulmonary pathology. ADEL also may have a geroprotective effect on bronchial tissue.

Model system for multifunctional delivery nanoplatforms based on DNA-Polymer complexes containing silver nanoparticles and fluorescent dye

Creation of multifunctional nanoplatforms is one of the new approaches to complex treatment and diagnosis with the monitoring of the curative process. Inclusion of various components into the drug delivery system may reduce toxicity and enhance or modify the therapeutic effects of medicines. In particular, some properties of metal nanoparticles and nanoclusters provide the ability to create new systems for treatment and diagnosis of diseases, biocatalysis and imaging of objects. For example, the ability of metal nanoparticles to enhance the quantum yield of luminescence can be used in bioimaging and therapy. The aim of the research was to construct and examine a multicomponent system based on DNA-polycation compact structure with the inclusion of silver nanoparticles and luminescent dye as a model system for delivery of genes and drugs with the possibility of modification and enhancement of their action.

DNA modified with metal nanoparticles: preparation and characterization of ordered metal-DNA nanostructures in a solution and on a substrate

DNA interaction with silver and aluminum nanoparticles in a solution has been investigated with the AFM, SEM, dynamic light scattering, viscometry, and spectral methods. The comparison of DNA interaction with nanoparticles synthesized by the reduction of Ag+ ions and with nanoparticles obtained by the electric discharge plasma method was done. DNA metallization in a solution and on n-silicon surface with metal nanoparticles or by the reduction of silver ions after their binding to DNA was executed and studied. It was shown that DNA strands with regular location of silver or aluminum nanoparticles can be prepared. The conditions for the formation of silver nanoparticles and silver nanoclusters on DNA were analyzed.

Conformational and phase transitions in DNA—photosensitive surfactant solutions: Experiment and modeling

DNA binding to trans‐ and cis‐isomers of azobenzene containing cationic surfactant in 5 mM NaCl solution was investigated by the methods of dynamic light scattering (DLS), low‐gradient viscometry (LGV), atomic force microscopy (AFM), circular dichroism (CD), gel electrophoresis (GE), flow birefringence (FB), UV–Vis spectrophotometry. Light‐responsive conformational transitions of DNA in complex with photosensitive surfactant, changes in DNA optical anisotropy and persistent length, phase transition of DNA into nanoparticles induced by high surfactant concentration, as well as transformation of surfactant conformation under its binding to macromolecule were studied. Computer simulations of micelles formation for cis‐ and trans‐isomers of azobenzene containing surfactant, as well as DNA‐surfactant interaction, were carried out. Phase diagram for DNA‐surfactant solutions was designed. The possibility to reverse the DNA packaging induced by surfactant binding with the dilution and light irradiation was shown.

DNA-polymer complexes for gene therapy

The condensation of DNA induced by vinyl saccharide graft copolymers of N-methacryloy-lamino-D-glucose with N,N-dimethylaminoethyl methacrylate and N-vinylpyrrolidone with N-vinylamine and induced by the linear polycation poly(L-lysine) in solution, as well as the conformational changes of a DNA molecule during its interaction with polycations in solution, is studied by atomic-force microscopy, low-gradient viscometry, dynamic birefringence, spectrophotometry, circular dichroism, and electrophoresis. The differences in the conformational changes of DNA related to the effect of polycations and other agents inducing its condensation are discussed.

Conformational Changes of a DNA Molecule Induced by Metal Complexes Formed in Solution

Changes in the tertiary structure of a high-molecular-mass DNA in solution that result from the addition of trivalent lanthanum ions, including intramolecular structuring of the macromolecule, are studied by atomic-force microscopy. The effect of bivalent magnesium and manganese ions on the structure of DNA in an aqueous-alcohol solution is analyzed. The data are compared with the results of viscometry, dynamic light scattering, flow birefringence, circular dichroism, and UV spectrophotometry.

DNA Self-Assembling Nanostructures Induced by Trivalent Ions and Polycations

The purpose of this work is to compare DNA condensation induced by small multivalent ions and polycations. DNA complexes with trivalent ions Fe3+, La3+, [Co(NH3)6]3+, spermidine and cationic polymers in a solution were investigated. The influence of cations on the volume, persistent length, and secondary structure of DNA was studied. A comparison of DNA packaging induced by trivalent ions and polycations was made. DNA complexes with trivalent metal ions and polycations were characterized by means of low gradient viscometry, dynamic light scattering, circular dichroism, UV spectrometry, flow birefringence, and atomic force microscopy.