Investigation of pharmaceutically active ionic liquids as electrolyte for the electrosynthesis of polypyrrole and active component in controlled drug delivery

Abstract

Ionic liquids containing pharmaceutically active ingredients (API-ILs) have been used to electrosynthesize polypyrrole (PPy) films. Two different cations have been investigated, imidazolium and cholinium, respectively. These cations have been paired with saccharinate, acesulfamate and ibuprofenate anions. Growth of polypyrrole films in neat imidazolium API-ILs, which are liquid at room temperature, was shown to be difficult due to their high viscosities even at higher temperature. Moreover, the use of IL containing ibuprofenate anions led to the formation of crystalline ibuprofen deposited onto the PPy surface. This has been ascribed to the formation of local acidity during pyrrole oxidation. Using aqueous solutions of the biocompatible cholinium API-ILs, thick films have been obtained. Differences in term of morphology and roughness have been evidenced by SEM, depending on the anion used. GDOES analysis showed the incorporation of anions into the whole polypyrrole film thickness with small enrichment near the surface. Finally, we demonstrated that drug release kinetics can be controlled both by application of different negative stimulus and the nature of the anion. Upon application of more negative potential, drug release rates increased. The calculated kinetic parameters have evidenced a diffusion regime without stimulus and a change to anomalous regime upon applied potential.