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BioMed Research International
Volume 2014, Article ID 702821, 7 pages
http://dx.doi.org/10.1155/2014/702821
Research Article

Characterization of Genipin-Modified Dentin Collagen

1Department of Operative Dentistry, School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
2NC Oral Health Institute, School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
3Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
4Department of Periodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA

Received 24 January 2014; Accepted 16 February 2014; Published 25 March 2014

Academic Editor: Yoshihiko Hayashi

Copyright © 2014 Hiroko Nagaoka 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

Application of biomodification techniques to dentin can improve its biochemical and biomechanical properties. Several collagen cross-linking agents have been reported to strengthen the mechanical properties of dentin. However, the characteristics of collagen that has undergone agent-induced biomodification are not well understood. The objective of this study was to analyze the effects of a natural cross-linking agent, genipin (GE), on dentin discoloration, collagen stability, and changes in amino acid composition and lysyl oxidase mediated natural collagen cross-links. Dentin collagen obtained from extracted bovine teeth was treated with three different concentrations of GE (0.01%, 0.1%, and 0.5%) for several treatment times (0–24 h). Changes in biochemical properties of NaB3H4-reduced collagen were characterized by amino acid and cross-link analyses. The treatment of dentin collagen with GE resulted in a concentration- and time-dependent pigmentation and stability against bacterial collagenase. The lysyl oxidase-mediated trivalent mature cross-link, pyridinoline, showed no difference among all groups while the major divalent immature cross-link, dehydro-dihydroxylysinonorleucine/its ketoamine in collagen treated with 0.5% GE for 24 h, significantly decreased compared to control ( ). The newly formed GE-induced cross-links most likely involve lysine and hydroxylysine residues of collagen in a concentration-dependent manner. Some of these cross-links appear to be reducible and stabilized with NaB3H4.