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Advances in Materials Science and Engineering
Volume 2013 (2013), Article ID 853289, 5 pages
http://dx.doi.org/10.1155/2013/853289
Research Article

The Effect of Negative Poisson’s Ratio Polyurethane Scaffolds for Articular Cartilage Tissue Engineering Applications

Department of Biomedical Engineering, Graduate School, Inje University, Gimhae 621-749, Republic of Korea

Received 16 May 2013; Accepted 21 August 2013

Academic Editor: Hamdy Doweidar

Copyright © 2013 Yeong Jun Park and Jeong Koo Kim. 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

An auxetic polyurethane (PU) scaffold was prepared to investigate chondrocyte proliferation under compressive stimulation for cartilage regeneration. To give a negative Poisson’s ratio to the PU scaffold, volumetric compression with a 3 : 1 ratio was applied during heat treatment. For the control PU scaffold, the Poisson’s ratio was 0.9 ± 0.25 with elongation at 20% of the strain range. Poisson’s ratio for experimental specimens was approximately −0.4 ± 0.12 under the same conditions. In cell proliferation tests, cells were cultivated within the prepared scaffold under compression with a 20% strain range. With a 20% strain range elongation, the compressive load was approximately 0.3 N. The experimental group showed a 1.3 times higher cellular proliferation rate than that of the control group after 3 days in culture. At day 5 of culture, however, the rate of proliferation of the control group increased so that there was no significant difference between groups. However, collagen content (produced by the cells) in the cell-proliferated medium was 1.5 times higher in the experimental group after 5 days in culture. This may have been due to the effectiveness of the auxetic structure of the scaffold. An isotropic compressive load was transmitted to the cells due to the negative Poisson ratio of the scaffold.