Electronics, New Zealand
Electronics, New Zealand

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Uppalapati D.,University of Auckland | Boyd B.,Drug Delivery | Boyd B.,Monash Institute of Pharmaceutical Sciences | Travas-Sejdic J.,Polymer Electronics Research Center | And 2 more authors.
International Journal of Nanotechnology | Year: 2017

Unlike conventional controlled drug delivery systems where drug is released at a constant pre-programmed rate, drug release from conducting polymers (CPs) can be controlled through electrical stimuli and adjusted based on the patient's needs. However, owing to their low drug loading capacity and limited electrical responsiveness CP systems cannot currently be applied for systemic drug delivery or to treat chronic disease. To overcome that obstacle one approach is to fabricate porous CP structures. In this work, polypyrrole (PPy) was used owing to its electrical responsiveness and biocompatibility. Liquid crystals were used as a template through which PPy was grown. Dexamethasone phosphate was loaded as a dopant into PPy during polymerisation and its release was quantified by HPLC after the removal of liquid crystal; release could be modified by electrical stimulus. This system has potential applications in conditions where required drug dosing changes with time, such as in age-related macular degeneration. Copyright © 2017 Inderscience Enterprises Ltd.


Nand A.V.,Polymer Electronics Research Center | Nand A.V.,University of Auckland | Ray S.,Polymer Electronics Research Center | Ray S.,University of Auckland | And 11 more authors.
Synthetic Metals | Year: 2011

Polyaniline was chemically synthesized by oxidizing aniline with ammonium persulfate with and without hydrochloric acid (G-PANI and NR-PANI, respectively). NR-PANI and G-PANI were dedoped with ammonium hydroxide to yield NR-PANIdd and G-PANIdd. SEM images revealed a typical granular morphology for G-PANI and G-PANIdd, while NR-PANI, formed using a 'falling pH method', and NR-PANIdd, consisted of micro/nanorods and flakes. The samples were characterized using FTIR and the level of oxidation was determined by X-ray photoelectron spectroscopy (XPS). The surface area of the samples was measured by the BET method. The free radical scavenging activity, using the DPPH assay, showed the following ranking: NR-PANI > G-PANI ≈ NR-PANIdd > G-PANIdd. The radical scavenging activity of the polyanilines did not correlate with conductivity or surface area measurements, but was critically dependent upon the level of oxidation, and higher activity was obtained with the more reduced polyaniline samples. © 2011 Elsevier B.V. All rights reserved.

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