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Journal of Biomedicine and Biotechnology
Volume 2007 (2007), Article ID 26796, 9 pages
Research Article

Gel Electrophoresis of Gold-DNA Nanoconjugates

1Center for Nanoscience, Ludwig Maximilians University Munich, M√ľnchen 80799, Germany
2Department of Chemistry and Lawrence Berkeley National Lab, University of California, Berkeley, CA 94720, USA
3National Nanotechnology Laboratory, INFM, Lecce 73100, Italy
4Fachbereich Physik, Philipps Universität Marburg, Marburg 35037, Germany

Received 20 July 2007; Accepted 13 December 2007

Academic Editor: Marek Osinski

Copyright © 2007 T. Pellegrino 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.


Gold-DNA conjugates were investigated in detail by a comprehensive gel electrophoresis study based on 1200 gels. A controlled number of single-stranded DNA of different length was attached specifically via thiol-Au bonds to phosphine-stabilized colloidal gold nanoparticles. Alternatively, the surface of the gold particles was saturated with single stranded DNA of different length either specifically via thiol-Au bonds or by nonspecific adsorption. From the experimentally determined electrophoretic mobilities, estimates for the effective diameters of the gold-DNA conjugates were derived by applying two different data treatment approaches. The first method is based on making a calibration curve for the relation between effective diameters and mobilities with gold nanoparticles of known diameter. The second method is based on Ferguson analysis which uses gold nanoparticles of known diameter as reference database. Our study shows that effective diameters derived from gel electrophoresis measurements are affected with a high error bar as the determined values strongly depend on the method of evaluation, though relative changes in size upon binding of molecules can be detected with high precision. Furthermore, in this study, the specific attachment of DNA via gold-thiol bonds to Au nanoparticles is compared to nonspecific adsorption of DNA. Also, the maximum number of DNA molecules that can be bound per particle was determined.