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Journal of Biomedicine and Biotechnology
Volume 2010 (2010), Article ID 168306, 9 pages
http://dx.doi.org/10.1155/2010/168306
Research Article

Bioimaging of Nucleolin Aptamer-Containing 5-(N-benzylcarboxyamide)-2′-deoxyuridine More Capable of Specific Binding to Targets in Cancer Cells

1Laboratory of Molecular Imaging, Department of Applied BioScience, CHA Stem Cell Institute, CHA University, Seoul 135-081, South Korea
2Aptamer Initiative, POSTECH Biotech Center, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, South Korea
3Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-744, South Korea

Received 11 June 2009; Revised 8 September 2009; Accepted 19 November 2009

Academic Editor: Daehee Kang

Copyright © 2010 Kyue Yim Lee 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

Chemically modified nucleotides have been developed and applied into SELEX procedure to find a novel type of aptamers to fit with targets of interest. In this study, we directly performed chemical modification of 5-( -benzylcarboxyamide)- -deoxyuridine (called 5-BzdU) in the AS1411 aptamer, which binds to the nucleolin protein expressed in cancer cells. Forty-seven compounds of AS1411-containing Cy3-labeled 5-BzdU (called Cy3-(5-BzdU)-modified-AS1411) were synthesized by randomly substituting thymidines one to twelve in AS1411 with Cy3-labeled 5-BzdU. Both statistically quantified fluorescence measurements and confocal imaging analysis demonstrated at least three potential compounds of interest: number 12, 29 and 41 that significantly increased the targeting affinity to cancer cells but no significant activity from normal healthy cells. These results suggest that the position and number of substituents in AS1411 are critical parameters to improve the aptamer function. In this study, we demonstrated that chemical modification of the existing aptamers enhanced the binding and targeting affinity to targets of interest without additional SELEX procedures.