Figure 1. Atomic force microscopy studies of shape-restricted DNA molecules (rectangular shape): a) on mica; b) covalently bonded to amino-terminated self-assembled monolayer on Si(111).

We have used C₆₀ Buckminster fullerenes as spectroscopic and microscopic probes to establish the covalent nature of their binding to appropriately terminated self-assembled monolayers on silicon. We have investigated this chemistry using multiple spectroscopic and microscopic techniques and have verified the formation of a covalent link using computational investigation of core level energy shifts in N 1s spectral region and vibrational signatures of covalently bonded fullerenes. Current studies, as illustrated in Figure 1, focus on shape-restricted DNA molecules covalently bonded to SAM-covered Si(111) single crystal surface. These DNA structures are designed in the research group of our collaborator, Professor Junghuei Chen (Department of Chemistry and Biochemistry, University of Delaware). We have successfully bonded triangular and rectangular DNA molecules to the self-assembled monolayers on silicon, confirmed that they are bonded covalently, and analyzed their apparent height. The plan for further development of this research direction in the future includes design of the 3D structures using DNA molecules for preferential binding to the semiconductor surface on one side of the structure, design of the covalently linked scaffolds with specific biochemical binding sites located within the Debye length from the interface, and testing the sensing capabilities of a device based on this approach.

Xiaochun Zhang     xczhang@udel.edu
Yianna Antonopoulos    antonopy@udel.edu

Relevant Publications:

1. Zhang, X., Kumar, S., Chen, J. and Teplyakov, A. V. Covalent attachment of DNA molecules on amine-functionalized Si(111) surface. Submitted to Langmuir.

2. Zhang, X. and Teplyakov, A. V. Adsorption of C₆₀ Buckminster fullerenes on an 11-amino-1-undecene covered Si(111) substrate. Langmuir, 2008, 24, 810-820. This work is featured on the cover of the issue.