Nanocomposite hydrogel of poly(vinyl alcohol) and biocatalytically synthesized polypyrrole as potential system for controlled release of metoprolol

The inclusion of nanostructures into cross-linked polymer networks allows obtaining nanocomposite hydrogels with suitable multifuncionalities for drug delivery applications. In this work, polypyrrole (PPy) nanoparticles, synthesized by a biocatalytic route, were encapsulated into a hydrogel matrix of poly(vinyl alcohol) (PVA) during its reticulation with glutaraldehyde. The novel composite hydrogels were characterized by infrared spectroscopy, thermogravimetric analysis, swelling kinetic measurements, scanning electron microscopy and cyclic voltammetry. The loading capabilities of PVA/PPy hydrogels were tested for metoprolol, a beta blocker used to treat angina, hypertension and to prevent heart attack. In vitro drug release profiles were obtained without and under electrical stimulations. The kinetics of drug release exhibited a power-law time dependence, typical of hydrogel-based systems. The application of electrical potentials changed the release rate of the drug, increasing or decreasing the delivery rate depending on bias voltage. Composite system of PVA and PPy combines the electrochemical redox properties of the conductive polymer with the swelling capacity and molecular diffusivity associated with PVA network; therefore, it can be considered a potential stimuli-responsive platform for biomedical applications.