  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
goldcoated 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 to 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.

Biological Physics