Electrochemically Controlled Drug-Mimicking Protein Release from Iron-Alginate Thin-Films Associated with an Electrode

Novel biocompatible hybrid-material composed of iron-ion-cross-linked alginate with embedded protein molecules has been designed for the signal-triggered drug release. Electrochemically controlled oxidation of Fe2+ ions in the presence of soluble natural alginate polymer and drug-mimicking protein (bovine serum albumin, BSA) results in the formation of an alginate-based thin-film cross-linked by Fe3+ ions at the electrode interface with the entrapped protein. The electrochemically generated composite thin-film was characterized by electrochemistry and atomic force microscopy (AFM). Preliminary experiments demonstrated that the electrochemically controlled deposition of the protein-containing thin-film can be performed at microscale using scanning electrochemical microscopy (SECM) as the deposition tool producing polymer-patterned spots potentially containing various entrapped drugs. Application of reductive potentials on the modified electrode produced Fe2+ cations which do not keep complexation with alginate, thus resulting in the electrochemically triggered thin-film dissolution and the protein release. Different experimental parameters, such as the film-deposition time, concentrations of compounds and applied potentials, were varied in order to demonstrate that the electrodepositon and electrodissolution of the alginate composite film can be tuned to the optimum performance. A statistical modeling technique was applied to find optimal conditions for the formation of the composite thin-film for the maximal encapsulation and release of the drug-mimicking protein at the lowest possible potential.