1. Abstract
Amyloid fibrils are significant constituents of the pathologic plaques in the extracellular space
of the body tissue. Fibril formation and their deposition is a primer indicator of several types of organ
dysfunctions and various diseases, and also responsible for inducing defective protein structure
development, which consequently casuing peccant protein-aggregates in tissues thorughout the body.
Amyloid fibril assembly plays essential role in the pathogenesis of Alzheimer’s disease (AD) by making
deposits, called neuritic plaques, in the white matter of the brain. Typically the 39- to 43-residue-long
amyloid β-peptide (Aβ-peptide) forms filamentous structures found in the neuropil. A more profound
understanding of self-associative, self-organizing polymerization and supramolecular structuring
mechanisms of β-amyloid fibrils placing the basic motivation behind the investigation of amyloid-
systems and biopolymers into a new context. By more thorough understanding of fine structure of Aβ
filaments and fibrisls, which typically possessing cross-beta conformation and left-handed β-helical
geometry, reveled very interesting properties of these biopolymer-systems. Solid-phase synthesis of Aβ-
peptide subunits in a laboratory has now became a routine. Filbrils growing from these synthetic peptide-
fragment monomers are remain stable under harsh physical and chemical conditions. The suggestion
arises, whereby device components could be made from pre-designed, synthetically prepared Aβ-
peptide (or similar) building blocks, used for nano-biotechnological applications, by a manufacturing
technology following ’bottom-up’ instead of ’top-down’ paradigm. Our research group investigating
these Aβ-biopolymer systems with great interest in the recent years. Primarily, we are employing various
atomic force microscopy (AFM) techniques, such as single-molecule nanomechanical-, and in situ
molecular-force spectroscopy methods, respectively, in addition to scanning nanostructure topology in
situ and also applying a so-called ’AC Mode Imaging’ procedure for Non-contact mode AFM. Because
of the ponderous functional accessibility, a nanoscaled size-range of the structure and the uncertain
orientation of biopolymers, the controllability, thus the technological usability of these systems is not
so simple and trivial. According to our previous findings, trigonally oriented nano-mesh growing
epitaxially on freshly cleaved mica (muscovite) surface by self-assembling and self-organizing
polymerization of synthesized Aβ-peptide-fragment monomers, namely, the Aβ25-35wt (wild-type),
which comprising a stretch of residues from position 25 to 35 of the full-length peptide, and also from
it’s functionalizable mutant variant (Aβ25-35_N27C). Creating Aβ-foldamer conjugates (Aβ25-29-
ACPC), a special kind of chimeras, representing a conscious design of synthetic biopolymers at a higher
level. The N-terminal segment of these conjugates is the 25-29 pentapeptide-fragment (GSNKG) of the
beta-amyloid peptide, mentioned before, the C-terminal part consist of different configuration isomers
of 2-aminocyclopentane carboxylic acid (ACPC) hexamer, called the foldamer part. By using the
appropriate stereochemical patterns of the four ACPC enantiomers, we could grow filaments possessing
different intrinsic properties which appeares at a macroscopic-level as well. The pentapeptide part of the
chimera is thought to be responsible for binding to potassium-binding pocket on mica surface, therefore

2. determining the fibril orientation and the foldamer region is most likely playing an important role in the
polymerization process, while providing and enhancing the macromolecular stability. In the present
work the morphology and fine-tuning property of nano-networks, building up from either Aβ25-35wt
or Aβ25-29-ACPC monomers, have been examined. The topological characterization of the oriented
beta-fibrillar network was implemented under varying conditions, like using different physiological
phosphate-puffer solutions (NaPBSA, KPBSA), changing peptide or chimera concentration and K+
-ion
concentration or even the incubation time. The conductance measurement of the network was carried
out by using atomic-force microscopiy method combining with AFM-conductometry. Thanks to the
functionalization and easy-to-access properties of the mutant Aβ25-35 and Aβ-foldamer nano-networks,
they could be turned to conductive nano-wires and highly-ordered nanocircuits by conjugating gold and
silver nanoparticles (NPs) to the functional group of the cysteine side-schain in the Aβ fragment.