Electrochemically induced release of a model dye from a pH-sensitive and electroactive microgel monolayer attached to an electrode surface

Abstract

We present a novel electrochemically-induced release system featuring a pH-responsive and electroactive microgel monolayer specifically designed to enhance drug delivery mechanisms. This microgel, synthesized from acrylic acid and a ferrocene derivative, was formed on a conductive electrode surface, providing a robust platform for controlled release applications. The physical and chemical properties of the microgel were meticulously characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), nuclear magnetic resonance (NMR), and electrochemical techniques. The microgel particles modified the electrode surface by forming a monolayer through interactions between the sulfur present in the crosslinking agent and the gold surface of the electrode. Cyclic voltammetry was used to analyze the properties of the modified electrode, and the morphology of the monolayer was confirmed by scanning electron microscopy (SEM). Notably, we demonstrated that the incorporation of positively charged crystal violet (CV) dye molecules was facilitated through electrostatic interactions with the negatively charged carboxylic groups of the microgel, resulting in effective dye retention. Our investigation revealed that the electrochemical oxidation of the ferrocene groups significantly weakens the interactions between the crystal violet (CV) dye and the polymer chains within the microgel network, facilitating controlled dye release. The release process was successfully monitored using quartz crystal microbalance with dissipation monitoring (QCM-D), confirming the system's potential for innovative drug delivery platforms and implant construction.