In the article, new colloidal systems are obtained and studied, which have prospects for use as carriers of medicinal compounds. The colloidal systems under consideration are polymer complexes based on polyacrylic acid of various molecular weights and biogenic polyamine with magnetic iron oxide nanoparticles. The magnetic properties of polycomplexes with included magnetic iron oxide nanoparticles have been studied.

In this study, we provide the first experimental evidence that colloidal hydrophilic magnetite nanoparticles can penetrate through bilayer lipid membrane in a non-uniform stationary magnetic field. Hydrophilic ligand-free cationic colloidal magnetite nanoparticles with an average diameter of 4 nm were added to the surrounding aqueous solution on one side of the azolectin membrane. An external non-uniform magnetic field ensured the attraction of superparamagnetic magnetite nanoparticles to the membrane, resulting in the formation of a near-membrane charged layer of cationic nanoparticles resulting in the initial polarization of the membrane. As a result of the passage of magnetite nanoparticles through the membrane, the polarization of the membrane decreases, and the membrane becomes depolarized. Independent methods were used to detect magnetite nanoparticles that passed through the lipid membrane including transmission electron microscopy and energy-dispersive x-ray spectroscopy. The discovered effect may be due to the following factors and interactions of nanoparticles. Interaction of magnetic nanoparticles with external inhomogeneous magnetic field provides localization of nanoparticles on the membrane surface. Collective interactions between nanoparticles, as well as their interactions with external electric and magnetic fields, lead to the formation of magnetite nanoparticle aggregates. Interaction of nanoparticles with the membrane lipid matrix leads to the formation of organic-inorganic complexes in which the polar surface of nanoparticles is enveloped by a lipid layer. The penetration of nanoparticles through the membrane is caused by the interaction of organic-inorganic complexes of nanoparticles and their aggregates with local intramembrane and near-membrane electric and magnetic fields.

This work is devoted to the study of the combined effects of applied magnetic field and MNPs on the electrical characteristics of bilayer lipid membranes. We present results of the study of electrical parameters of azolectin membranes in a static inhomogeneous magnetic field at the one-sided addition of positively charged quasi-spherical superparamagnetic magnetite nanoparticles with a diameter of about 4 nm. The magnet was located at different distances from the membrane, and the magnetic field attracted the nanoparticles to the membrane surface with different strengths. We observed three pronounced effects that depended on the external magnetic field. Firstly, after addition of nanoparticles in a magnetic field, the conductance of the membranes increased. A smooth increase in conductance was accompanied in some cases by the appearance of current jumps, which can be associated with the formation of through pores with a radius of no more than 1 nm. The conductance increased with increasing magnetic field gradient. Secondly, at zero command voltage, a negative current through the membrane was observed. Although our experiments did not allow us to unambiguously determine which particles create this current, we believe that this current is associated with the penetration of particles through the membrane. This effect intensified with increasing magnetic field gradient. Thirdly, we observed a sharp change in the nonlinear dependence of capacitance on voltage associated both with the change in the surface potential of the azolectin membrane and with the effect of MNP binding to the membrane surface on the apparent membrane capacitance.

The review presents an analysis of the current state of research related to the design, development, and practical application of methods for biomedical radioelectronics and nanomedicine, including the use of magnetic nanoparticles. The important role of rational scientific physical approaches and experimental methods in the design of efficient and safe magnetic nanoparticle-based agents for therapy, controlled targeted drug delivery, and diagnostics, including spatial imaging, is emphasized. Examples of successful practical application of magnetic nanoparticles in medicine based on these methods are given, and an analysis of the main problems and prospects of this area of science is conducted.

Nanocomposite liposomes with modified structure containing functional conducting nanoparticles bound to both inner and outer surface of the liposomal membrane are fabricated. Effect of ultrashort electric-field pulses with a duration of less than 10 ns and a field strength of about 10 kV/cm on an aqueous suspension of the liposomes containing encapsulated model substance (NaCl) leads to decapsulation and a corresponding increase in the conductivity of the aqueous medium. Selectivity of the effect is provided by the presence of functional nanoparticles on both surfaces of the liposomal membranes. A theoretical model of a nonthermal effect of ultrashort electric pulses on the nanocomposite liposomes with modified structure is proposed to account for destruction of the liposomal membrane.

For the first time, new nanocomposite liposomes and vesicles with a modified structure containing functional inorganic electrically conductive nanoparticles associated with both the inner and the outer surface of the liposomal membrane were prepared. The effect of ultrashort electric field pulses with a duration of less than 10 ns and an intensity in a dielectric aqueous medium of the order of 10 kV/cm on the aqueous suspension of such nanocomposite liposomes containing an encapsulated model low molecular weight compound (NaCl) has been studied. It was found that as a result of exposure to such impulses, decapsulation and destruction of nanocomposite liposomes present in the suspension occurs, accompanied by a corresponding increase in the conductivity of the suspension. It is shown that the sensitivity of nanocomposite liposomal capsules to external electrical effects is due to the inclusion of electrically conductive nanoparticles in their structure. It was found that the effect of decapsulation of liposomal capsules is significantly higher in the case of the impact of electric field pulses on liposomal capsules with bound magnetite nanoparticles compared with the case of a similar effect on the same capsules that do not contain conducting nanoparticles. This fact determines the selectivity of the effect of electric pulses on nanocomposite membrane vesicles containing electrically conductive nanoparticles. A theoretical analysis of non-thermal interaction of nanostructured liposomal capsules containing conducting nanoparticles on the outer and inner surfaces of the membrane with ultrashort electrical pulses was carried out. A theoretical model of non-thermal interaction of nanostructured liposomal capsules with ultrashort electrical pulses is constructed. In the model under consideration, electrically conductive nanoparticles are associated with the outer and inner surfaces of membranes of nanocomposite liposomal capsules. Within the framework of the constructed model, the mechanisms of destruction of the liposomal capsule membrane are described, due to the interaction of conducting spherical nanoparticles located on opposite surfaces of the liposomal membrane resulting from the ultrashort electrical effect on aqueous suspensions of nanostructured liposomal capsules.

This paper presents the results of experimental studies of effects of remote pulsed microwave exposure on polyelectrolyte nanocomposite microcapsules (PNMC). The microwave radiation of a pulsed with a pulse duration of about 5 ns with eight-millimeter wavelength range with a power of about 1 MW was used. The microcapsules contained 3 layers of inorganic iron oxide (Fe3O4) nanoparticles. The effect of remote pulsed microwave exposure on PNMC was discovered. This effect consist in substantial changes of the structure of PNMC including their destruction.

Decapsulation of nanocomposite liposomal capsules due to the effect of ultrashort electric pulses is obtained when the liposomal sheaths of the capsules are bound to significantly anisotropic gold nanoparticles (nanorods). Destruction of the liposomal sheath is interpreted using the rotational displacement of gold nanorods in the presence of the pulsed electric field. Such an interpretation is used to derive an expression for the critical electric field that determines the threshold level of the effect. The calculated critical field is in agreement with the experimental results. It is shown that the decapsulation is related to the presence of the gold nanorods in the sheath of liposomal capsules and is not obtained in the absence of the nanorods.

In this paper, we describe three series of polyampholytes synthesized via quaternization of poly(4-vinylpyridin) by ω-bromocarboxylic acids and alkyl bromides: (1) with cationic and anionic groups in each unit (polybetaines), (2) with betaine and cationic groups, and (3) with betaine and pendant alkyl groups. The polymers were complexed with anionic mixed lipid membranes, liposomes, and Langmuir monolayers. By varying a length of –(CH2)n– spacer in the betaine group, different behaviors of polybetaines in a suspension of anionic liposomes can be realized: from no interaction to complexation followed by significant structural reorganization in the liposomal membrane. Cytotoxicities of polyampholytes are one to two orders of magnitude less than the cytotoxicity of a pure polycationic polymer with the same degree of polymerization. These results are of importance in designing polyelectrolytes with a higher affinity to the biolodical (cell) membrane and minimum cytotoxicity and demonstrate the potential of polyampholytes in developing biocompatible polymeric structures.

Development and study of novel biomimetic and biocompatible functional nanofilm structures, surfaces and colloid membranous vesicles are currently important from fundamental and applied viewpoints. They can serve as model systems for insight into the basic structural-functional interconnections and physicochemical mechanisms at the nano-scale in biomembranous systems, and are useful for development of engineering solutions efficient for bio-medical applications including controlled drug delivery. We present here the results of a study of novel nanofilm composite structures (Langmuir monolayers, Langmuir-Blodgett films and liposomes) based on the interfacial complexes formed by biogenic lipid phosphatidylcholine, synthetic amphiphilic water-insoluble polyamine stearoylspermine (a derivative of biogenic polyamine spermine and stearic acid), colloid cationic ligand-free magnetite nanoparticles and polyanions (DNA, Poly(styrenesulfonate)). It was found that stearoylspermine molecules formed stable Langmuir monolayer on an aqueous subphase surface and that monolayer compression isotherm changed as a result of interactions of the stearoylspermine monolayer with aqueous subphase components (colloid cationic magnetite nanoparticles and polyanions). Monolayer Langmuir-Blodgett films of interfacial polycomplexes formed by stearoylspermine and magnetite nanoparticles or DNA molecules were deposited onto the mica substrate surface and the structure of polycomplex films was investigated using AFM. The data obtained using Langmuir monolayer technique were further used in formation of new composite nanofilm magnetic colloidal membranous vesicles based on the interfacial polycomplexes of phosphatidylcholine, stearoylspermine, magnetite nanoparticles and polyanions. The nanocomposite membranous vesicles were prepared successfully by sequential adsorption of colloid cationic ligand-free magnetite nanoparticles and polyanions onto the cationic surface of mixed phosphatidylcholine/stearoylspermine liposomes preliminarily formed using conventional ultrasound method. The formed vesicles were characterized by transmission electron microscopy, AFM, electron magnetic resonance technique, laser light scattering and electrophoresis techniques. The synthesized stable biocompatible nanocomposite magnetic liposomal vesicles can be useful in development of novel efficient systems for capsulation, targeted transport, controlled spatial localization and physical stimuli-addressed drug and DNA delivery.

Colloidal membranous vesicles based on the functionalized liposomes are promising for development of novel efficient systems of controlled and stimuli-triggered drug delivery. In particular, the specific metabolism of cancer cells results in significant acidification in tumors, and thus the corresponding pH value changes can be used as a stimulus for drug release specifically in the tumor areas. pH-sensitive liposomes can be formed via incorporation of special pH-sensitive amphiphilic compounds into the liposomal membrane. Molecules of such compounds undergo a conformational transition caused by certain changes in the pH value of aqueous environment and resulting in corresponding membrane perturbations with rapid leakage of drug content from those liposomes into the areas with corresponding acidity. In the present work the pH-induced changes of Langmuir monolayer compression isotherm and of the structure of corresponding Langmuir-Blodgett films of pH-sensitive synthetic lipid trans-4,5, didodecyloxycarbonyl-trans-2-morpholinocyclohexanol have been observed and studied. The substantial expansion of Langmuir monolayer of that lipid caused by change of the aqueous subphase pH value from 7 to 5 was observed. Corresponding monolayer Langmuir-Blodgett films were deposited on mica substrate surface and studied using AFM technique. The substantial differences in the structure of Langmuir-Blodgett films deposited at pH values 7 and 5 were found. The observed effects directly demonstrate the pH-induced structural transformations in organized condensed planar molecular systems formed by pH-sensitive lipid molecules which underlie the pH-sensitivity of corresponding liposomal bilayer membranes containing such lipids.

The decapsulation effect of nanocomposite liposomal capsules containing anisotropic gold nanoparticles (nanorods), which is caused by the action of ultrashort electric pulses on these capsules, is discovered. The mechanism of destruction of liposomal shells of the capsules near poles of conducting gold nanorods under the pulse electric action is described. An expression for the critical intensity of the pulse electric field, which determines the threshold of initiation of this effect, is obtained. Its numerical value is in agreement with the obtained experimental data. It is shown experimentally that the discovered decapsulation effect is caused by the presence of gold nanorods connected to the liposomal shell of the capsules and does not arise in the absence of nanorods.

The remagnetization of ferromagnetic Fe3O4 nanoparticles of several thousand cubic nanometers by spin-polarized current is investigated. For this purpose, magnetite nanoparticles are synthesized and deposited on a conductive nonmagnetic substrate. The remagnetization is conducted in high-vacuum scanning tunneling microscope (STM). The STM tip from magnetized iron wire constitutes one electrode while the ferromagnetic nanoparticle on the graphite surface represents the second electrode. The measured threshold value of remagnetization current (I-thresh=9 nA) is the lowest value of current at which remagnetization occurs. The change in nanoparticle magnetization is detected by the effect of giant magnetic resistance, specifically, the dependence of the weak polarized current (I < I-thresh) on the mutual directions of magnetization of the electrodes. The results indicate essential difference with available literature data on the influence of polarized current on magnetic moment of small ferromagnetic nanoclusters. The peculiarities of size dependence of the observed effects are explained. (C) 2016 Elsevier B.V. All rights reserved.