Electronically-responsive delivery from a calcified mesoporous silicon structure

The controlled release of substances from a semiconducting calcium phosphate/porous Si structure is reported. This is demonstrated principally for the case of the reversible adsorption and release of dyes (such as an anionic salt of fluorescein) upon the switching of the direction of bias to the underlying porous Si/Si substrate. The effect of bias on the diffusion of the cationic dyes ethidium bromide and acridine orange has also been investigated. For these species, their delivery can be mediated in part by the use of a surface layer of the biodegradable polymer poly-caprolactone (PCL).