GFD3E peptide self-assembling and functionalization with silver nanoparticles. Experimental and theoretical approach
Author
Maldonado, Andreu Mor
Term
4. term
Education
Publication year
2021
Abstract
This master's thesis explores the design, self-assembly, and metal functionalization of a short amphiphilic peptide, Fmoc-GFD3E (Gly-Phe-Asp-Phe-Asp-Phe-Glu), as a scaffold for nanomaterials. The central question is whether GFD3E can form ordered amyloid fibers and how these structures interact with silver species. Self-assembly was probed by coarse-grained molecular dynamics simulations and verified experimentally. Simulations indicated peptide aggregation, while experiments revealed ribbon-like amyloid fibers with a height of about 15 nm. The fibers were characterized by circular dichroism, atomic force microscopy, and fluorescence spectroscopy. Silver functionalization was assessed through quantum chemical calculations and laboratory trials. Calculations support predominantly electrostatic interactions between silver cations and the carboxylate groups of aspartic and glutamic acid residues. Several coating strategies were tested; although no individual fiber was fully coated, abundant silver-containing aggregates were observed by AFM and SEM. The work outlines the potential of GFD3E as a self-assembling scaffold and clarifies key interaction modes with silver, while highlighting challenges in achieving continuous metallic coverage.
Denne kandidatafhandling undersøger design, selvorganisering og metal-funktionalisering af et kort amphifilt peptid, Fmoc-GFD3E (Gly-Phe-Asp-Phe-Asp-Phe-Glu), som skabelon for nanomaterialer. Det centrale spørgsmål er, om GFD3E kan danne ordnede amyloide fibre, og hvordan disse strukturer interagerer med sølv. Selvorganisering blev undersøgt med grovkornede molekylældynamiske simuleringer og bekræftet eksperimentelt. Simulationerne viste peptid-aggregation, mens eksperimenter afslørede båndlignende amyloide fibre med en højde omkring 15 nm. Fibrene blev karakteriseret med cirkulær dikroisme, atomkraftmikroskopi og fluorescensspektroskopi. Sølvfunktionalisering blev vurderet med kvantekemiske beregninger og laboratorieforsøg. Beregningerne peger på overvejende elektrostatiske interaktioner mellem sølvkationer og carboxylatgrupperne i asparaginsyre- og glutaminsyrerester. Flere belægningsstrategier blev afprøvet; ingen enkeltfiber blev fuldt belagt, men talrige sølvholdige aggregater blev observeret med AFM og SEM. Arbejdet viser GFD3E’s potentiale som selvorganiserende skabelon og tydeliggør vigtige interaktionsformer med sølv, samtidig med at det fremhæver udfordringer ved at opnå sammenhængende metallisk dækning.
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