By David Warmflash
The ability to deliver pharmaceutical agents at precise body locations improves treatment efficacy by allowing larger drug doses in tissues where they are needed, while minimizing systemic effects. Novel, emerging methods of targeted drug delivery systems include passive and active nanoparticles. Made of lipoproteins, synthetic DNA, or other macromolecules, nanoparticle drug carriers are inserted into the body remotely from the target organ but are designed to unload the drug where it is needed. Various micro-pumps are also available and can be implanted to deliver drugs either into blood vessels for systemic treatment, into cerebrospinal fluid (intrathecal delivery) for central nervous system effects, or very locally to specific organs and tissues. Whether for systemic, regional, or local treatment, drug delivery must be extremely reliable and accurate, and now a new method meeting these requirements beckons: electrically-controlled drug release.
The emerging system is not a mechanical pump, but a way to translate electrical signals directly into drug release. Described by Chinese investigators in a recent study, the approach uses graphene oxide (Fe3O4). This is the same compound that forms magnetite crystals, but, similar to graphite, it also can occur in sheets just one atom in thickness. These can be made into nanocomposite films that can bind and release drugs in response to electrical current, and then those films can be implanted into biological tissue.
For eventual implantation into laboratory animals and humans, the nanocomposite film material has been treated with dexamethasone to prevent inflammatory responses. For the time being, however, experiments use in vitro models in which the films are implanted into cell cultures. Using this model, the investigators have shown that the nanocomposite film releases the drug into the environment in response to voltage stimulation. The drug release is linear with respect to voltage and turns off when the electrical current is stopped, with no leakage when the electricity is turned off. Furthermore, the drug load, rate of release, and other dosing properties can be adjusted by modifying the size and thickness of the graphene oxide nanosheets in which the drug is embedded.
The research team expects that the new approach can be fine tuned, leading ultimately to entirely new, programmable systems for drug delivery. As the research proceeds through the cell culture stage and to in vivo studies, we can imagine it will open the door to electronic delivery, not only for targeted tissue/organ applications, but also for drug therapy requiring regional and systemic application.