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Open Access Nano Express

AFM-assisted fabrication of thiol SAM pattern with alternating quantified surface potential

Bradley Moores1, Janet Simons2, Song Xu3 and Zoya Leonenko12*

Author Affiliations

1 Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada

2 Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada

3 Agilent Technologies, 4330 W. Chandler Blvd. Chandler, AZ 85226, USA

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Nanoscale Research Letters 2011, 6:185  doi:10.1186/1556-276X-6-185

Published: 1 March 2011

Abstract

Thiol self-assembled monolayers (SAMs) are widely used in many nano- and bio-technology applications. We report a new approach to create and characterize a thiol SAMs micropattern with alternating charges on a flat gold-coated substrate using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We produced SAMs-patterns made of alternating positively charged, negatively charged, and hydrophobic-terminated thiols by an automated AFM-assisted manipulation, or nanografting. We show that these thiol patterns possess only small topographical differences as revealed by AFM, and distinguished differences in surface potential (20-50 mV), revealed by KPFM. The pattern can be helpful in the development of biosensor technologies, specifically for selective binding of biomolecules based on charge and hydrophobicity, and serve as a model for creating surfaces with quantified alternating surface potential distribution.