Voltage Gated Carbon Nanotube Membranes for Programmed Transdermal Drug Delivery

Carbon nanotubes membranes have been successfully used as the active element in a programmed transdermal delivery system of clonidine. Membranes composed of aligned CNTs passing across a polymer film are chemically modified through diazonium electrochemical grafting for a high anionic surface charge density at CNT tips and along CNT cores. Electro-phoresis/osmosis is observed by measured cationic and neutral fluxes through the CNT membrane as a function of applied bias. High electro-osmotic flows of 0.05 cm/s at -300mV bias are seen. In-vitro studies using diffusion cells with human skin samples show modulated transdermal delivery. An initial flux (0V applied) was 2.1 nm/hr-cm2 while the ‘on' state (-300 mV bias) the flux increases to 12 nm/hr-cm2, a 5.7 fold increase. Therapeutically useful fluxes are between 1.7 and 5.4 nmol/hr-cm2. Low power programmable transdermal delivery devices can have important application in pain management and addiction treatment.