Electrochemical Triggered Dissolution of Hydroxyapatite/Doxorubicin Nanocarriers.

The controlled release of drugs by an external stimulus is of pivotal interest and importance as a means of increasing administration efficacy. Accordingly, many responsive systems have been developed based on primarily pH, temperature, and light changes. Here, a novel electrochemical triggered release of a doxorubicin (Dox)-loaded hydroxyapatite (HAp) nanoparticle (NP) system is presented. Dox is loaded onto HAp NPs by producing a stable dispersion in DMSO. The Dox-HAp NPs are electrophoretically deposited on a stainless steel (S.S) surface. The adsorbed Dox-HAp NPs are released either by applying a moderate electrochemical potential pulse or upon scanning the potential. Two mechanisms were proposed. The first is that the positive potential induces the desorption of the Dox-HAp NPs. Alternatively, the positive potential could drive the oxidation of water and generation of protons, causing the dissolution of the Dox-HAp NPs. In situ characterization techniques, such as atomic force microscopy (AFM) and confocal microscopy, were used to gain insight on the release mechanism. All measurements allude to the electrochemically driven dissolution of the Dox-HAp NPs and release of the embedded drug. In vitro antitumor activity against both HT-29 and A2780 cancer cells revealed that the efficacy of the released Dox was not significantly affected by the electrochemical process. We believe that the electrochemically triggered release of NPs could be applied to many other responsive systems.