Evaluating the feasibility of using Polyvinyl Alcohol (PVA) as a scaffold for the structural and functional study of the purified curli fibers from E. coli W3110 biofilm

Abstract

Curli amyloid fibers, abundant in the Escherichia coli (E. coli) biofilm matrix, are highly stable protein nanofibers with potential as sustainable building blocks. Yet, their brittleness and the challenges of handling them in isolation limit systematic studies of their structure and function. This thesis explores Polyvinyl Alcohol (PVA) as a scaffold to overcome these limitations. Curli fibers were purified and confirmed to preserve their amyloid nature, then embedded in PVA films prepared by solvent casting. Spectroscopic analyses (FTIR, Raman, fluorescence) demonstrated that PVA does not disrupt the β-sheet–rich structure of curli, while the detection of their intrinsic blue autoflorescence enabled the analysis of fiber morphology and organization within the scaffold, providing a valuable label-free tool. By enabling both the handling and structural analysis of purified curli fibers within a polymer scaffold, this work contributes to overcome practical limitations in curli research and supports further investigation of curli-based bio-inspired materials.