Membrane potential function as a battery, providing power to operate a variety of "molecular devices" embedded in the membrane. Second, in electrically excitable cells such as neurons and muscle cells, it is used for transmitting signals between different parts of a cell. Signals are generated by opening or closing of ion channels at one point in the membrane, producing a local change in the membrane potential. This change in the electric field can be quickly affected by either adjacent or more distant ion channels in the membrane. Those ion channels can then open or close as a result of the potential change,
Nanoparticles for drug delivery to the brain that it can bind and undergo endocytosis. Another mechanism is "adsorption mediated transcytosis", where electrostatic interactions are involved in mediating nanoparticle crossing of the BBB. Cationic nanoparticles (including cationic liposomes) are of interest for this mechanism, because their positive charges assist binding on the brain's endothelial cells. Using TAT-peptides, a cell-penetrating peptide, to functionalize the surface of cationic nanoparticles can further improve drug transport into the brain. In contrast to the above mechanisms, a delivery with magnetic fields doesn't strongly depend on the biochemistry of the brain. In this case, nanoparticles are literally pulled across the BBB via application of