Towards Synthetic Molecular Motors Interfaced by AFM
type: CreativeWork
description: Molecular machines are at the ultimate limit of miniaturization. Living organisms provide a variety of examples for such molecular machines, but in order to utilize and to control them, they need to be interfaced with the macroscopic world. On the other h and, there are synthetic molecular machines. Some have been interfaced already but usually in high vacuum at very low temperatures, which is clearly not desirable for technical applications. In this thesis, AFM-based single molecule force spectroscopy (S M FS) was utilized to investigate the mechanical change in single synthetic molecules upon environmental changes (external stimuli) in liquid environment at room temperature. The molecules are either from theory or from bulk experiments supposed to be ab le to convert such an external stimulus into mechanical work, which is a prerequisite for molecular motors. Three different types of molecules and various external energy inputs were investigated which led to the realization of a light driven synthetic mo le cular machine: - Polyelectrolytes should, by OSF-theory, change their persistence length (and therefore the overall length at a constant force) with the Debye screening length of the solvent (which is manipulated by the salt concentration). Therefore, t he elasticity of the polyelectrolyte polyvinylamine, which could be covalently attached to the substrate and the AFM tip, was investigated in dependence on the salt concentration. It was found that the dependence of persistence length on salt concentr atio n is much smaller than expected from OSF-theory, which made this system less attractive for a molecular machine, but led to new theoretical insights. - The adhesive properties of polyelectrolytes onto charged solid supports in aqueous solution are a subj ect of current research in industry and academia. A manipulation of polymer – substrate adhesion, e. g. at an AFM tip, could lead to a molecular 'grab and release' device. Therefore, the desorption force of si…
abstract: Molecular machines are at the ultimate limit of miniaturization. Living organisms provide a variety of examples for such molecular machines, but in order to utilize and to control them, they need to be interfaced with the macroscopic world. On the other h and, there are synthetic molecular machines. Some have been interfaced already but usually in high vacuum at very low temperatures, which is clearly not desirable for technical applications. In this thesis, AFM-based single molecule force spectroscopy (S M FS) was utilized to investigate the mechanical change in single synthetic molecules upon environmental changes (external stimuli) in liquid environment at room temperature. The molecules are either from theory or from bulk experiments supposed to be ab le to convert such an external stimulus into mechanical work, which is a prerequisite for molecular motors. Three different types of molecules and various external energy inputs were investigated which led to the realization of a light driven synthetic mo le cular machine: - Polyelectrolytes should, by OSF-theory, change their persistence length (and therefore the overall length at a constant force) with the Debye screening length of the solvent (which is manipulated by the salt concentration). Therefore, t he elasticity of the polyelectrolyte polyvinylamine, which could be covalently attached to the substrate and the AFM tip, was investigated in dependence on the salt concentration. It was found that the dependence of persistence length on salt concentr atio n is much smaller than expected from OSF-theory, which made this system less attractive for a molecular machine, but led to new theoretical insights. - The adhesive properties of polyelectrolytes onto charged solid supports in aqueous solution are a subj ect of current research in industry and academia. A manipulation of polymer – substrate adhesion, e. g. at an AFM tip, could lead to a molecular 'grab and release' device. Therefore, the desorption force of si…
author: Hugel, Thorsten
date published: 2003-02-03
date modified: 2026-07-24T02:51:36Z
provider: Ludwig Maxmilians Universität München
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Ludwig-Maximilians-Universität