CAP films are known to undergo hydrolysis/dissolution at pH 8 or above and therefore the fact that the pH can be manipulated within the film offers an alternative approach to controlling the release. The electrolytic approach therefore offers two modes of action: rapid release as a consequence of the mechanical force exerted by the formation of the bubbles. The ability of the approach to release an actual drug was assessed through replacing the ferrocyanide with methotrexate, a common chemotherapeutic agent [20] and [21]. The electrochemical properties of the drug are not as pronounced as those of ferrocyanide – exhibiting irreversible oxidation as a consequence of the tertiary amino group. As such, the decision was made to monitor the transport of the drug through the fibre to the delivery side through UV–vis spectroscopy. The drug was dissolved in pH 7 buffer to yield a 0.2 mM solution and placed on the CAP side. The delivery side contained only KCl. A spectrum of the delivery side was taken before the imposition of the electrolysis potential and then at 5 min intervals after the CAP film had been ruptured. The resulting spectra are shown in Fig. 3 along with the spectrum of methotrexate before any manipulation (Inset) had taken place. The spectra show the sustained transport of the methotrexate through the carbon fibre gate by diffusion transport.