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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.

Polypyrrole (PPy) was chemically prepared from aqueous solutions individually containing l-serine or l-glutamic acid, with the addition of ammonium persulfate as the oxidant. The electrical, XPS and FTIR characterizations indicated that the amino acids co-doped the PPy backbone. TEM revealed that PPy presented a quasi-spherical morphology with diameters in nanometric scale. The nanostructures of PPy-glutamic acid efficiently adsorbed therapeutic doses of amoxicillin. Composite hydrogels were obtained by the entrapment of amoxicillin-loaded PPy in polyacrylamide network. The antibiotic molecules can be subsequently released (or sustained) from composite hydrogel in response to application (or removal) of electrical stimulation. This tuning release profile can lead to promising drug delivery applications such as implantable devices and iontophoretic systems. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41804.