Self-Assembling Peptide Fibres as Candidates for Bio-Inspired Nanowires: A study of GFDFDFD and GFKFKFK, and the Effect of N-terminus Modification with Biphenyl-Carboxylic Acid and Ferrocene-Carboxylic Acid
Authors
Christensen, Allan Aagaard ; Larsen, Jacob Aunstrup
Term
4. term
Education
Publication year
2019
Abstract
Molekylær elektronik har længe været inspireret af biologiske byggesten, men modsatrettede fund om DNA-ledningsevne motiverer søgningen efter alternative, selvassemblerende ledere. Dette projekt undersøger, om korte aromatiske peptider kan danne fibre egnede som bio-inspirerede nanowires, med fokus på GFDFDFD og GFKFKFK samt effekten af N-terminus-modificering med biphenyl- og ferrocen-carboxylsyre. Peptiderne blev designet og karakteriseret for fibrildannelse og ryggrads-konformation ved hjælp af cirkulær dikroisme (CD), fluorescensspektroskopi og atomkraftmikroskopi (AFM), og fibrene blev yderligere afbildet med elektrostatisk kraftmikroskopi (ESFM) og testet elektrisk via spændings-sweeps over platintråde efter adsorption. Arbejdet omfattede også blandinger af peptider og deres modificerede varianter, og der indgår molekylære dynamik-simulationer i metodikken. Resultaterne viste dannelse af fire distinkte fibertyper, hvoraf to dannede hydrogel ved millimolære koncentrationer (<3 mM). Én fibertype var polariserbar under ESFM, men ingen fibre udviste målbar ledningsevne i de udførte spændingsmålinger. Derudover dannede et enkelt peptid ringformede superstrukturer. Samlet set peger studiet på, at selvassemblerende peptidfibre kan opnå kontrolleret struktur og polariserbarhed, men yderligere designoptimering er nødvendig for at opnå elektrisk ledningsevne.
Molecular electronics has long looked to biological building blocks, yet conflicting reports on DNA conductivity motivate the search for alternative self-assembling conductors. This project examines whether short aromatic peptides can form fibers suitable as bio-inspired nanowires, focusing on GFDFDFD and GFKFKFK and on N-terminal modification with biphenyl- and ferrocene-carboxylic acids. Peptides were designed and characterized for fibril formation and backbone conformation using circular dichroism (CD), fluorescence spectroscopy, and atomic force microscopy (AFM); fibers were further imaged by electrostatic force microscopy (ESFM) and electrically tested via voltage sweeps across platinum wires after adsorption. The study also included mixtures of peptides and their modified variants, and molecular dynamics simulations were part of the methodology. The results show four distinct fiber types, two of which formed hydrogels at millimolar concentrations (<3 mM). One fiber type was polarizable under ESFM, but none exhibited measurable conductivity in the voltage measurements. Additionally, one peptide formed ring-like superstructures. Overall, the findings indicate that self-assembling peptide fibers can achieve ordered structures and polarizability, but further design optimization is needed to realize electrical conductivity.
[This summary has been generated with the help of AI directly from the project (PDF)]
Documents