V. P. Kim

Pulsed electric field-induced remote decapsulation of nanocomposite liposomes with implanted conducting nanoparticles

The results obtained in creating the new nanocomposite hybrid systems sensitive to external nonthermal electric-field pulses, which are created for the encapsulation, addressed delivery, and the controlled decapsulation of various substances in aqueous media, are presented. Such systems are based on liposomes containing electrically neutral biogenic lipids that are functionalized by conducting nanoparticles and polymers. The fabricated systems have been investigated using transmission electron microscopy, atomic-force microscopy, electron magnetic resonance, laser light scattering, electrophoresis, and conductometry. The systems constructed under the action of short (on the order of 8 ns) electric pulses with high intensities (up to 100 kV/m) are found to exhibit the remote decapsulation effect. The model describing the mechanism of interaction between nanostructured liposomes with surface conducting nanoparticles and an external electric field leading to substantial changes in liposome structure is proposed. The critical values of the external electric field stimulating the decapsulation of nanocomposite liposomes are estimated with the help of the constructed model.

Planar nanosystems on the basis of complexes formed by amphiphilic polyamine, magnetite nanoparticles, and DNA molecules

In the present paper the results of a study of new planar composite nanosystems on the basis of complexes formed by amphiphilic polyamine, magnetite nanoparticles, and DNA molecules are presented. Amphiphilic polyamine stearylspermine is synthesized and characterized by the FTIR spectroscopy technique. It is found that a Langmuir monolayer on an aqueous subphase surface can be formed by synthesized stearylspermine molecules. The stearylspermine Langmuir monolayer compression isotherm changes caused by the interaction of a monolayer with colloid magnetite nanoparticles and DNA molecules from the aqueous phase have been studied. The monolayer nanostructures on the surface of mica substrate-Langmuir-Blodgett films of complexes formed by stearylspermine, magnetite nanoparticles, and DNA molecules are formed. The structure of the obtained monolayer films was investigated using the AFM scanning probe technique. Possibilities for the formation of polycomplexes which comprise stearylspermine molecules, functional inorganic nanoparticles, and polymers have been discussed.

Change in the magnetic moment of a ferromagnetic nanoparticle under polarized current

The magnetization reversal of a ferromagnetic Fe3O4 nanoparticle with a volume of the order of several thousands of cubic nanometers under the influence of spin-polarized current has been investigated on a high-vacuum scanning tunneling microscope, where one of the electrodes is a magnetized iron wire needle and the second electrode is a ferromagnetic nanoparticle on a graphite substrate. The measured threshold current of magnetization reversal, i.e., the lowest value of the current corresponding to the magnetization reversal, is found to be Ithresh ≈ 9 nA. A change in the magnetization of a nanoparticle is revealed using the giant magnetoresistance effect, i.e., the dependence of the weak polarized current (I < Ithresh) on the relative orientation of the magnetizations of the electrodes.

Effect of Gold Nanorods on the Remote Decapsulation of Liposomal Capsules Using Ultrashort Electric Pulses

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.

Remote decapsulation of nanocomposite liposomal capsules containing gold nanorods by ultrashort electric pulses

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.