The Incorporation and Controlled Release of Anionic Drugs from a Polypyrrole Membrane Film
type: CreativeWork
description: In this thesis, results are presented and discussed on the synthesis and characterisation of polypyrrole (PPy) doped with various anionic drugs. The drugs, which were small to medium‐large in size, included the aqueous soluble dexamethasone 21‐phosphate disodium (NaDex) and valproic acid sodium (NaVPA) salts, and the less soluble diclofenac sodium (NaDF) salt. Two other drugs, indomethacin sodium (NaIndo) and sulindac sodium (NaSul) with very imited solubility in aqueous solution, were chosen. r l The incorporation of dexamethasone (Dex2‐) and diclofenac anions (DF‐) within the PPy membrane was achieved by a potentiostatic mode of growth from an aqueous solution of pyrrole and the drug under investigation. For the PPy doped with Dex2‐, characterisation and release studies found the doping level of the polymer to be about 0.30, and approximately 31 μmol cm‐2 of Dex2‐ was incorporated into the polymer upon polymerisation. Furthermore, it was observed that the rate of release could be controlled by the potential applied with approximately 89 % of the Dex2‐ released within 60 min at an applied potential of – 0.900 V vs SCE. For the PPy doped with DF‐, unusual patterns in growth and morphology were observed. During the deposition of the polymer, the rate of polymerisation decreased with increasing time and higher applied potentials. The polymer had features of an insulating film, as evident from electrochemical impedance measurements, while SEM confirmed the presence of crystal‐like shards on the surface of the polymer. These findings suggest that insoluble drug crystals are formed during polymerisation. DF‐ displays a limited solubility in aqueous solutions and during the oxidation of the monomer and drop of pH at the surface, the equilibrium is shifted from the soluble DF‐ towards the insoluble HDF causing insoluble crystals of the drug to deposit on the surface of the polymer, which hinders further polymerisation. The incorporation of two insoluble medium sized drugs,…
abstract: In this thesis, results are presented and discussed on the synthesis and characterisation of polypyrrole (PPy) doped with various anionic drugs. The drugs, which were small to medium‐large in size, included the aqueous soluble dexamethasone 21‐phosphate disodium (NaDex) and valproic acid sodium (NaVPA) salts, and the less soluble diclofenac sodium (NaDF) salt. Two other drugs, indomethacin sodium (NaIndo) and sulindac sodium (NaSul) with very imited solubility in aqueous solution, were chosen. r l The incorporation of dexamethasone (Dex2‐) and diclofenac anions (DF‐) within the PPy membrane was achieved by a potentiostatic mode of growth from an aqueous solution of pyrrole and the drug under investigation. For the PPy doped with Dex2‐, characterisation and release studies found the doping level of the polymer to be about 0.30, and approximately 31 μmol cm‐2 of Dex2‐ was incorporated into the polymer upon polymerisation. Furthermore, it was observed that the rate of release could be controlled by the potential applied with approximately 89 % of the Dex2‐ released within 60 min at an applied potential of – 0.900 V vs SCE. For the PPy doped with DF‐, unusual patterns in growth and morphology were observed. During the deposition of the polymer, the rate of polymerisation decreased with increasing time and higher applied potentials. The polymer had features of an insulating film, as evident from electrochemical impedance measurements, while SEM confirmed the presence of crystal‐like shards on the surface of the polymer. These findings suggest that insoluble drug crystals are formed during polymerisation. DF‐ displays a limited solubility in aqueous solutions and during the oxidation of the monomer and drop of pH at the surface, the equilibrium is shifted from the soluble DF‐ towards the insoluble HDF causing insoluble crystals of the drug to deposit on the surface of the polymer, which hinders further polymerisation. The incorporation of two insoluble medium sized drugs,…
author: Ryan, Eimear M.
language: en
keywords: Chemistry
date published: 2010-11
date modified: 2026-07-24T03:02:36Z
provider: National University of Ireland - Maynooth
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: National University of Ireland Maynooth