Stanislav N. Zelinskiy

Novel fluorescent dyes based on oligopropylamines for the in vivo staining of eukaryotic unicellular algae

Weakly basic fluorescent dyes are used to visualize organelles within live cells due to their affinity to acidic subcellular organelles. In particular, they are used to stain the silica deposited in the silica deposition vesicles (SDVs) of diatoms during the course of their frustule synthesis. This study involved the synthesis of fluorescent dyes derived from oligopropylamines, compounds similar to those found in diatoms. The dyes were obtained by reacting oligopropylamines with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole. The reaction was realized using methylated oligopropylamines with two or three nitrogen atoms and yielded two novel fluorescent dyes: NBD-N2 and NBD-N3. The dyes appeared to be highly efficient in the in vivo staining of growing siliceous frustules of diatoms at concentrations at least 10 times lower than those required for staining with HCK-123. NBD-N3 also efficiently stained other subcellular vesicles of eukaryotic unicellular algae. NBD-N2 stained only growing diatom frustules, whereas NBD-N3 also stained various subcellular organelles of different eukaryotic unicellular algae. NBD-N2 and NBD-N3 were not removed from stained diatom frustules by drastic treatments with H(2)SO(4) and H(2)O(2). Fluorescent silica can also be obtained by its chemical precipitation in the presence of NBD-N2 and NBD-N3.

Bioinspired thermo- and pH-responsive polymeric amines: multimolecular aggregates in aqueous media and matrices for silica/polymer nanocomposites.

Polymeric amines have been intensively studied for application in smart systems and as matrices for the design of composite materials, including bioinspired substances. A new thermo- and pH-responsive polymer was obtained by radical polymerization of N-(3-(diethylamino)propyl)-N-methylacrylamide. Upon heating, the polymer precipitated from aqueous solutions above pH 9; the observed cloud point was dependent on the polymer concentration and decreased from 95°C at pH 9 to 40°C at pH 11. The basicity of the polymer decreased at elevated temperatures owing to an increase in the hydrophobicity-driven compaction of the macromolecules. Dynamic light scattering analysis demonstrated that the formation of large multimolecular associates with radius 1000-2000 nm was initiated from 1 to 2°C below the cloud point. The new polymer is demonstrated to be an effective matrix for various siliceous composite structures, including 200-300 nm solid spherical raspberry-like particles and hollow hemispherical particles of more than 1000 nm diameter. Condensation of silicic acid in the presence of polymeric amines is a model reaction in biosilicification studies, and the obtained data are also discussed from the perspective of the matrix hypothesis for biosilica formation.

Silicic acid condensation under the influence of water-soluble polymers: from biology to new materials

Silicon is among the most abundant elements on the Earth. It occurs in many minerals and plays an important role in several biochemical processes. Some living organisms use silicon dioxide as a substrate for building elements of their bodies. Unicellular diatom algae build frustules from silicon dioxide. The skeleton of siliceous sponges is a silica–protein composite. Similarly, rice hulls which protect seeds, contain silica as an important component. The living organisms assimilate silicon from the environment in the form of silicic acid. However, the biochemical mechanisms involved in the transformation of silicic acid to solid siliceous materials are still poorly understood. Evidently, condensation of silicic acid in the living organisms proceeds under control of biopolymers and it is important to know how various types of polymers influence the condensation. Bio-inspired chemistry involving the interaction between polymeric silicic acid and functional polymers results in interesting composite materials, including nanoparticles and bulk materials. This review contains a brief description of the mechanism of silicic acid condensation in aqueous medium and also includes a discussion on various precursors of silicic acid. The main focus of the review is on the influence of polymers bearing nitrogen and oxygen-containing functional groups on silicic acid condensation starting from monomer to three-dimensional polymer. Influence of molecular weight of the organic polymer on the condensation and structure of the resulting product is also elaborated. The biological importance of the obtained data and strategies for novel applications of the synthesized composite materials are described in the concluding section of the review. The biomimetic condensation processes open up new vistas for development of novel materials and applications in the biomedical and process industries.

Poly(vinyl amine) as a matrix for a new class of polymers

Abstract Poly(vinyl amine) was utilized as a matrix for the synthesis of polymers bearing short polyamine chains (1–3 amine groups) grafted to the main macromolecular chain with long (eight atoms) spacers. The new polymers were characterized with nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectra, size exclusion chromatography and potentiometry. Poly(vinyl amine) was applied in the form of narrow molecular mass fractions and the modification proceeded without destruction of the main chain. Condensation of silicic acid in the presence of the polymeric amines gives rise to composite nanoparticles which are stable in aqueous medium. New polymers and composite nanoparticles effectively complex with DNA and RNA oligonucleotides and were found to display good internalization in cancer cells which indicates their promise towards gene delivery applications.

Bioinspired Water-soluble Polymers with Grafted Polyamine Chains: Synthesis and Complexation with Oligonucleotides

The siliceous frustules of diatom algae contain complex proteins known as silaffins, which consist of a peptide chain with grafted polyamine chains. These polyamines contain twenty or more nitrogen atoms with trimethylene groups between the nitrogens. We synthesized a set of polymers containing grafted long-chain polyamine fragments by using acryloyl chloride (ACh) polymers and activated acrylic acid copolymers as the starting materials. The new polymers contained 0.05 mol%−3.2 mol% of polyamine chains, which corresponded to 0.06−3.56 mmol·g−1 amine groups. The new amine-containing polymers formed complexes with short (19-21-mer) deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) strands, and these complexes penetrated into model yeast cells and A549 lung cancer cell. This study demonstrates the potential of these species based on long-chain polyamines to serve as novel gene delivery systems.