Analysis of the structure of block copolymer films by atomic force microscopy

The structure of thin films of the polysterene-polymethylacrylate-polysterene triblock copolymer was studied. Universal algorithms to analyze atomic-force-microscopy images of thin block-copolymer films were developed.     

Use of biospecific reactions for the design of high-sensitivity biosensors based on nanomechanical cantilever systems

The study of nanomechanical cantilever systems is among the priority directions in the progression of nanotechnologies. Principally new ways of designing biosensors based on nanocantilever transducers are investigated, the effect of orientation of receptor immunoglobulin molecules in the sensor layer on the formation of lateral strain during complementary binding is examined for the first time, and unique techniques for creation of selective receptor transducers based on cantilevers are developed. The unique data of this study make it possible to state that, owing to the presence of 13-thiotridecane-1,1,2-triol molecules in the probe DNA layer, the lateral strain tends to increase during hybridization of complementary molecules. Theoretical predictions and experimental data are compared, and the effect of the formation of lateral strain in polymer layers on the bending of the cantilever transducer is revealed. The nature of lateral strain arising in films of biopolymers (proteins and DNA) during complementary binding (formation of the immune complex for protein molecules and hybridization for DNA) is ascertained.     

Release of ribonucleic acid from human common cold HRV 2 virus in acidic medium

The mechanism of the release of viral RNA from the capsid under the conditions that model this process in cell endosomes upon the virus infection is studied by atomic force microscopy using the human common cold virus (HRV 2 rhinovirus) as an example. Characteristic images of the RNA-protein complex resulted from the release of nucleic acid from virus at pH 4.8–6.0 are presented. It is revealed that, upon its release, RNA undergoes a number of conformational transformations in free form or in a complex with viral protein.     

Comparative study of structure and properties of nucleoproteides synthesized using plant virus coat protein

The self-assembly of virus-like artificial particles from the coat protein of a helical virus (potato virus X) and nucleic acids (RNA and DNA) is studied. The structure and properties of the particles are investigated by transmission electron microscopy, atomic force microscopy, and enzymatic analysis.     

Studying the structure of nanocomposites obtained via the chemical decomposition of metal siloxanes in polymer matrices

The structure of polymer nanocomposites containing CuS clusters is studied by atom force (AFM), scanning (SEM), and transmission (TEM) electron microscopy, and by narrow-angle X-ray scattering (SAXS). The results point to the existence of spherical nanoparticles of 3?C50 nm in diameter and larger agglomerates of sizes 1?C5 ??m in the studied nanocomposites (NCs). The morphology of NCs depends on the conditions of synthesis.     

Dependence of the step velocity on its length on the (010) face of the orthorhombic lysozyme crystal

The length of a two-dimensional critical nucleus has been measured, and the Gibbs-Thomson formula has been experimentally verified on orthorhombic lysozyme crystals. The step velocity was found to be independent of its length. The critical length initiating the step motion can be determined by a low density of kinks on a step, and not the critical-nucleus size. The invalidity of the Gibbs-Thomson formula in this case is discussed.     

Specific features of interaction of ionogenic surface-active substance with κ-carrageenan

Atomic force microscopy was used for the investigation of local lattices of κ-carrageenan adsorbed on a surface in the presence of an ionogenic surface-active substance. The effective binding of the surface-active substance by helical and native forms of carrageenan is demonstrated.     

Physicochemical properties of a new group of regulatory proteins isolated from various mammal tissues

Russian Chemical Bulletin - The found similarity of the set of physicochemical characteristics of regulatory proteins active in microdoses isolated from various mammal tissues allows them to be...     

Metal Nanoparticles on Polymer Surfaces: 1. A New Method of Determining Glass Transition Temperature of the Surface Layer

New experimental approach allowing to study the structure and properties of polymer surface layers at a nanolevel is proposed. According to this method, metal nanoparticles are first adsorbed on a polymer surface from colloidal solution, then resultant system is stepwise annealed, and the particle embedding in a polymer is examined with atomic force microscope. Potentialities of the method are demonstrated using the gold nanoparticles–polystyrene system (including polystyrene modified with the UV radiation) as an example. It was established that the glass transition temperature of polystyrene surface layer is noticeably lower compared with the bulk value and decreases even more after the UV modification of a polymer surface. Possible use of the results obtained for the solution of other, independent problem, namely for the creation of two-dimensional nanocomposites by embedding nanoparticle monolayer ensemble in the surface layer of a glassy polymer at a temperature lower than the glass transition temperature of its bulk is analyzed.     

Optical properties of excitons in CdS semiconductor-insulator quantum wires

The characteristic features of the luminescence spectra of CdS semiconductor nanocrystals, crystallized in hollow channels in a dielectric template, are explained in terms of excitonic transitions in semiconductor-insulator quantum wires. The excitonic transition energies agree with the values calculated taking into account the effects of size quantization and the “dielectric enhancement of excitons” — the large increase in the electron-hole attraction as a result of the difference between the permittivities of the semiconductor and insulator. The theoretically computed binding energies of excitons in CdS quantum wires with a diameter of 10 nm reach 170 meV. It is shown that the excitonic transition energy is constant for a wide range of wire diameters. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 3, 216–220 (10 August 1999)