Electron Energization by Parallel Electric Fields in Poloidal Standing Waves

A hybrid gyrofluid‐kinetic electron model is adapted and used to simulate poloidal standing modes for different electron temperatures and azimuthal mode numbers. As in previous studies of toroidal standing modes, mirror force effects lead to increased parallel potential drops, monoenergetic electron energization, and wave energy dissipation as the ambient electron temperature is increased. A similar trend is also observed when the electron temperature is held fixed and the azimuthal mode number increased—owing to the narrowing of the azimuthal flux tube width, which necessitates more electron energization to carry the increased parallel current density. In both cases, the increase in electron energization eventually leads to more rapid decreases in the parallel current with time because of the dissipation of wave energy

Systematic studies on the formation of DNA-LDH-nanocomplexes and their application as gene carriers

Over the last decade nanometre-sized layered double hydroxides (LDH) have been successfully explored as cellular delivery agents for various drugs [1, 2] and bio-active molecules such as peptides or DNA [3-5]. Despite its intrinsic promising properties such as good biocompatibility, low cytotoxicity [6, 7], high loading of anionic/polar molecules, pH controllable release, protection of guest molecules in the interlayer [6] and controllable particle size [3, 6, 8], initial transfection experiments showed disappointing performance of LDH compared to commercially available carriers. Therefore synthesis of DNA-LDH-nanocomplexes (LDH) and transfection protocols for mammalian cell lines were optimized, resulting in high transfection efficiencies of up to 60-70 % positive cells. We found that working at fairly high temperatures for DNA-intercalation with much diluted DNA solutions respective LDH suspensions at slightly acidic pH provides the best environment for high DNA uptake. Incubation time and DNA shape (plasmid/linearized) hardly affect the amount of intercalated DNA, whereas the size of DNA fragments seems to have major impact, with smaller plasmids being intercalated at five-fold higher rates than larger ones. Transfection and expression of various GFP plasmids in mammalian cell lines (HEK 293T, NIH 3T3, COS7) gave positive cells with DNA levels as low as 0.5 μg/well (Ø 35 mm). Production of LDH nanoparticles is less costly than for liposome based commercial competitors while showing similar efficiency, providing an alternative transfection agent with superior cost-performance-ratio

Subcellular compartment targeting of layered double hydroxide nanoparticles

Current investigations show that layered double hydroxide (LDH) nanoparticles have high potential as effective non-viral agents for cellular drug delivery due to their low cytotoxicity. good biocompatibility, high drug loading, control of particle size and shape, targeted delivery and drug release control. Two types of Mg2Al-LDH nanoparticles with fluorescein isothiocyanate (FITC) were controllably prepared. One is morphologically featured as typical hexagonal sheets (50-150 nm laterally wide and 10-20 nm thick), while the other as typical rods (30-60 nm wide and 100-200 nm long). These LDHFTIC nanoparticles are observed to immediately transfect into different mammalian cell lines. We found that internalized LDHFITC nanorods are quickly translocated into the nucleus while internalized LDHFITC nanosheets are retained in the cytoplasm. Inhibition experiments show that the cellular uptake is a clathrin-mediated time- and concentration-dependent endocytosis. Endosomal escape of LDHFITC nanoparticles is suggested to occur through the deacidification of LDH nanoparticles. Since quick nuclear targeting of LDHFITC nanorods requires an active process, and although the exact mechanism is yet to be fully understood, it probably involves an active transport via microtubule-mediated trafficking processes. Targeted addressing of two major subcellular compartments by simply controlling the particle morphology/size could find a number of applications in cellular biomedicine