Electrodeposited conductive polymers for controlled drug release: polypyrrole

Abstract

Over the last 40 years, electrically conductive polymers have become well established as important electrode materials. Polyanilines, polythiophenes and polypyrroles have received particular attention due to their ease of synthesis, chemical stability, mechanical robustness and the ability to tailor their properties. Electrochemical synthesis of these materials as films have proved to be a robust and simple way to realise surface layers with controlled thickness, electrical conductivity and ion transport. In the last decade, the biomedical compatibility of electrodeposited polymers has become recognised; in particular, polypyrroles have been studied extensively and can provide an effective route to pharmaceutical drug release. The factors controlling the electrodeposition of this polymer from practical electrolytes are considered in this review including electrolyte composition and operating conditions such as the temperature and electrode potential. Voltammetry and current-time behaviour are seen to be effective techniques for film characterisation during and after their formation. The degree of take-up and the rate of drug release depend greatly on the structure, composition and oxidation state of the polymer film. Specialised aspects are considered, including galvanic cells with a Mg anode, use of catalytic nanomotors or implantable biofuel cells for a self-powered drug delivery system and nanoporous surfaces and nanostructures. Following a survey of polymer and drug types, progress in this field is summarised and aspects requiring further research are highlighted.

Polymer nanocomposites having a high filler content: synthesis, structures, properties, and applications

“…The electropolymerisation potential and efficiency are restrained through monomer concentration, the type of solvent, and pH of the solution 114 .…”

The incorporation and controlled release of dopamine from a sulfonated β–cyclodextrin–doped conducting polymer

“…Conducting polymers, and in particular polypyrrole, have been considered and investigated as membranes for the controlled delivery of drugs [1][2][3][4][5][6][7]. In addition to exhibiting biocompatible properties, polypyrrole films are responsive and they can be stimulated to uptake and release ions.…”

“…This uptake and release which maintains charge neutrality is associated with the redox switching between the oxidised and the reduced states, where the polymer backbone is positively charged when oxidised and neutral when reduced. A number of studies has been reported describing the uptake and release of anionic drug molecules [1][2][3][4][5]. During electrochemical polymerisation, the anionic drug molecules are incorporated into the polymer film as dopants to compensate the positive charge on the oxidised polypyrrole.…”

The importance of the film structure during self-powered ibuprofen salicylate drug release from polypyrrole electrodeposited on AZ31 Mg

“…Polypyrrole is one of the most common, biocompatible, and mechanically robust conductive polymers (CPs) which has been used for corrosion protection of metals [7,[12][13][14] and local drug delivery [4]. The size, steric effects, functional groups, charge, and chemical structure of the uploaded drug may affect the polymer nucleation and growth processes and its mechanical properties [13].…”