Model polypeptides and molecular recognition at a monolayer interface
Abstract (Summary)The enormous interest in organic thin films during the last fifteen years has been driven by the prospect of utilizing these films in applications, particularly in the areas of nonlinear optics, pyroelectric materials, sensors and protective layers. The ease of formation and monolayer stability of self-assembled films, has been responsible, in part, for this renaissance. In fact, these self-assembled monolayers are now widely used to study more complex systems. Presented herein, is an example of a self-assembling process, wherein a relatively weak hydrogen bonding interaction (molecular recognition) leads to the formation of bilayers. The molecular recognition at a 2,4-diaminopyrimidine terminated monolayer (host) by a succinimide derivative (guest) has resulted in the formation of bilayers. The bilayer structures and the hydrogen bonding interactions were analyzed by external-reflection Fourier transform infrared spectroscopy, ellipsometry, and X-ray photoelectron spectroscopy. The lateral stability of self-assembled monolayers is limited by the strength of the van der Waal interaction, although, the stability is improved over Langmuir-Blodgett systems. We propose to improve these systems further. We have been exploring the self-assembly of artificial proteins on metals. The hydrogen bonding capacity of protein monolayers would be expected to provide enhanced stability for these films due to the multiplicity of hydrogen bonds. Polymers of sequence [-(AlaGly)3 CysGly(AlaGly)3 GluGly-] n have been designed to adopt b-sheet structures on metallic and oxide surfaces. To better understand and control polypeptide adsorption, we have focused on the self-assembly of model compounds which capture the substrate and lateral interactions. Results are reported for the synthesis of layered arrays of C17 H35 COCysOCH3 and CH3 CO(AlaGly) 3 CysOCH3 on gold and the characterization of these arrays via ellipsometry, vibrational spectroscopy and X-ray photoelectron spectroscopy.
School Location:USA - Massachusetts
Source Type:Master's Thesis
Date of Publication:01/01/2000