Researchers:
Christina Inman
Jenny Dahl

Funding By:

Keywords:Biomaterials, ultrathin films, self-assembled monolayers, peptide assemblies.

Goal #1: Tune monolayer structure and stability through interchain hydrogen bonding interactions

On this project we are investigating the effect of molecular structure on the properties of peptide-containing monolayer assemblies on solid substrates. Assembly of the molecules occurs through the adsorption of a headgroup onto a solid substrate (e.g. a thiol onto gold). The structure, degree of order, stability and other properties also depend upon the strength of the interactions between the neighboring chains. In our systems interchain hydrogen bonding occurs between the peptide groups.

By varying the amino acid composition of the adsorbate molecules we can assemble different monolayer structures. We use reflective FTIR spectroscopy, x-ray photoelectron spectroscopy, electrochemical methods and scanning probe microscopies to determine how the composition affects the overall structure and degree of order within the monolayer. The thermal and chemical stability of the films are also being explored to determine whether these hydrogen bond cross-linked films could be useful as protective coatings or platforms for applications such as (bio)sensing, catalysis, biocompatibility nano- /molecular-electronic devices. We are also exploring how amide-containing monolayers can be formed on other substrates

Goal #2: Investigate nanoscale clustering of surface functionality in peptide-containing monolayers and develop molecular strategies to form stable, phase-separated monolayers.

In collaboration with Paul Weiss’ lab at Penn State, we first demonstrated the first spontaneous phase separation in monolayers of methyl-terminated n-alkanethiols (n-decanethiol and an amide-containing alkanethiol of similar length) on gold. Because phase separation in these systems results from a buried, internal hydrogen bonding network, peptide monolayers present a unique opportunity to drive phase separation of terminal functionalities that would otherwise mix. Using ferrocene-terminated monolayer precursors, we have shown that amide functionality can be used to drive phase separation of molecules with terminal functionality that would otherwise mix. We are currently exploring the parameters that control phase separation in this system as well as how these systems can be used for a variety of applications, including nanoscale contact fabrication, attachment and physical isolation of (bio)polymers, and cell adhesion.

Recent publications associated with this project:

Clegg, R. S.; Hutchison, J. E. "Hydrogen-Bonding, Self-Assembled Monolayers: Ordered Molecular Films for Study of Through-Peptide Electron Transfer," Langmuir 1996, 12, 5239.

Clegg, R. S.; Reed, S. M.; Hutchison, J. E. "Self-Assembled Monolayers Stabilized by Three-Dimensional Networks of Hydrogen Bonds," J. Am. Chem. Soc. 1998, 120, 2486-2487.

Clegg, R. S.; Hutchison, J. E. "Self-Assembled Monolayers with Internal Amides: Control of Assembly Structures by Hydrogen Bonding Instead of Monolayer–Substrate Epitaxy." J. Am. Chem. Soc. 1999, 121, 5319-5327.

Clegg, R. S.; Reed, S. M.; Smith, R. K.; Barron, B. L.; Rear, J. A.; Hutchison, J. E. “The Interplay of Lateral and Tiered Interactions in Stratified Self-Organized Molecular Assemblies,” Langmuir 1999, 15, 8876-8883.

Lewis, P. A.; Smith, R. K.; Kelly, K. F.; Bumm, L. A.; Reed, S. M.; Clegg, R. S.; Hutchison, J. E.; and Weiss, P. S. “Phase Separation within a Binary Self-Assembled Monolayer on Au{111} Driven by an Amide-Containing Alkanethiol,” J. Phys. Chem. B., 2001, 105, 1119-1122 (Cover).

Clegg, R. S.; Hutchison, J. E. “Fundamental Aspects of Electron Transfer in Substrate Supported Organized Molecular Assemblies,” Electron Transfer in Chemistry 2001, (a) Wiley-VCH (Weinheim) Balzani, V. Ed. (b) Volume 4, 541-577.