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International Journal of Polymer Science
Volume 2013, Article ID 925235, 9 pages
http://dx.doi.org/10.1155/2013/925235
Research Article

Biphasic Equilibrium Dialysis of Poly(N-Isopropyl Acrylamide) Nanogels Synthesized at Decreased Temperatures for Targeted Delivery of Thermosensitive Bioactives

1Department of Physical Chemistry, Wroclaw Medical University, Borowska 211, 50-556 Wroclaw, Poland
2Department of Polymer Gels, Institute of Macromolecular Chemistry of the Academy of Sciences of Czech Republic, Heyrovského Nám. 2, 162 06 Praha, Břevnov, Czech Republic
3Department of Pharmaceutical Technology, Wroclaw Medical University, Borowska 211, 50-556 Wroclaw, Poland
4Department of Lipids and Liposomes, Faculty of Biotechnology, University of Wroclaw, Przybyszewskiego 63/77, 51-148 Wroclaw, Poland
5Department of Organic Technology, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland

Received 8 July 2013; Accepted 7 September 2013

Academic Editor: Kattimuttathu I. Suresh

Copyright © 2013 Witold Musial et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Hydrogel nanoparticles, referred to also as nanogels, are of special interest for medical and pharmaceutical applications. Due to small size in the range below the diameter of the capillaries, they are proposed as drug delivery carriers. The aim of the study was to estimate the influence of composition and reaction conditions during synthesis of poly-N-isopropyl acrylamide cross-linked by polyethylene glycol diacrylate on the purification rates of the polymer. Six types of thermosensitive nanogels were prepared by surfactant-free dispersion polymerization and assessed in terms of process yield, composition, and size at temperatures below and over volume phase temperature. During the diffusion of impurities, in the course of dialysis, assessed by the conductometric method, the remarkable influence of temperature and initiator concentration on the process was revealed. The release rates varied in the range between 9.63 · 10−2 and 1.39 · 10−1 h−1 in the first stage of the process, whereas in the second stage they were between 2.09 · 10−2 and 6.28 · 10−2 h−1. The evaluated time to obtain acceptable purity of the preparation was estimated to be in the range of 18 days. More detailed research should be directed towards the influence of the structure of obtained material on the purification process.