Electrochemically controlled release of molecular guests from redox responsive polymeric multilayers and devices

A novel platform technology for a tunable molecular payload release, employing complex release profiles, from electrode surfaces is reported. Organometallic poly(ferrocenylsilanes) (PFSs), featuring redox responsive ferrocene units in their main chain, are used as a carrier medium to prepare thin films by the layer-by-layer (LbL) method for redox triggered delivery. These films form the active component of the device. The release of guest molecules from PFS multilayer templates was monitored by fluorescence spectroscopy by varying the supporting electrolyte, the ionic strength of electrolyte, redox inactive components, blocking layers and the molar mass of the polymer. Incorporation of Dextran–TRITC and Dextran–Alexa 488 dye molecules into PFS multilayers, at various depths of the film, enabled tuning of the release profiles with different release kinetics for the each component. Composite multilayers encompassing dual redox and pH responsive polyelectrolytes show double responsive control over the dye release. Finally a device was build featuring the combination of a microelectrode array (MEA) and PFS multilayers to demonstrate area addressable pulsed release for potential applications.