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

Moores B, Simons J, Xu S, Leonenko Z - Nanoscale Res Lett (2011)

Bottom Line: 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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada. zleonenk@uwaterloo.ca.

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.

No MeSH data available.


Related in: MedlinePlus

AFM topography of CH3 thiol SAM and pattern. AFM topography of (a) a uniformly covered CH3 thiol surface, and (b) a nanopattern shaved into a thiol surface exposing gold surface.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211238&req=5

Figure 1: AFM topography of CH3 thiol SAM and pattern. AFM topography of (a) a uniformly covered CH3 thiol surface, and (b) a nanopattern shaved into a thiol surface exposing gold surface.

Mentions: We first incubated a solution of CH3-terminated thiol molecules on gold-coated glass for 24 h. Figure 1a shows an AFM topography image of this thiol SAM in air. We applied a three-step nanografting method [11] to produce a pattern. First, AFM was used to image a previously formed monolayer (matrix SAM) in a solution with another thiol (COOH-terminated thiol). Second, the tip was positioned into a selected spot to start a programmed scratching of defined areas. The scratching was performed with a higher load than the threshold for thiol 1 (CH3-terminated) displacement [12]. During the scratching, the AFM probe removed matrix thiol 1 and produced bare gold squares exposed to thiol 2 (COOH-terminated) solution (nanoshaving) [13].


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

Moores B, Simons J, Xu S, Leonenko Z - Nanoscale Res Lett (2011)

AFM topography of CH3 thiol SAM and pattern. AFM topography of (a) a uniformly covered CH3 thiol surface, and (b) a nanopattern shaved into a thiol surface exposing gold surface.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211238&req=5

Figure 1: AFM topography of CH3 thiol SAM and pattern. AFM topography of (a) a uniformly covered CH3 thiol surface, and (b) a nanopattern shaved into a thiol surface exposing gold surface.
Mentions: We first incubated a solution of CH3-terminated thiol molecules on gold-coated glass for 24 h. Figure 1a shows an AFM topography image of this thiol SAM in air. We applied a three-step nanografting method [11] to produce a pattern. First, AFM was used to image a previously formed monolayer (matrix SAM) in a solution with another thiol (COOH-terminated thiol). Second, the tip was positioned into a selected spot to start a programmed scratching of defined areas. The scratching was performed with a higher load than the threshold for thiol 1 (CH3-terminated) displacement [12]. During the scratching, the AFM probe removed matrix thiol 1 and produced bare gold squares exposed to thiol 2 (COOH-terminated) solution (nanoshaving) [13].

Bottom Line: 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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada. zleonenk@uwaterloo.ca.

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.

No MeSH data available.


Related in: MedlinePlus