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Self-Organizing Bio-structures. NB2-2008 L. Duroux. Lecture 7. Protein-based nanomaterials. 1. Peptide-based nanostructures. A first insight into SA peptides. Concept of peptide SA introduced by Ghadiri et al. (1993)

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Self organizing bio structures

Self-Organizing Bio-structures

NB2-2008

L. Duroux


Lecture 7

Lecture 7

Protein-based nanomaterials



A first insight into sa peptides
A first insight into SA peptides

  • Concept of peptide SA introduced by Ghadiri et al. (1993)

  • Synthetic cyclic polypeptides (alternate L- & D-) self-assemble into Ø8-9nm nanotubes

  • Function as novel antimicrobial agents, drug delivery systems & nanomaterials






Self-Assembling Peptide Nanotubes

  • cyclic-peptides self-assembled into open tubes

  • consist of an even number of alternated D / L amino acids

  • formation of anti-parallel hydrogen bonded network

  • assembly could be controlled by electrostatic interactions

  • assembly could be directed toward particular environments (hydrophobic) by selection of amino acids

  • are functional material (ion channel & antibiotic)


Sa based on native 2 ndary structural motifs

SA based on native 2ndary structural motifs


Protein structural motifs sa designs
Protein structural motifs & SA designs

Amyloid fibrils

Type II polyPro helix



Amyloid peptides
Amyloid peptides

  • A generic, universal form of protein/peptide aggregation

  • Cause of many diseases: Altzheimer’s, Type II diabetes, Prions...

  • Extended b-sheet SA forming fibrils


Nano object formed by amyloid peptides
Nano-object formed by amyloid peptides

Object formed

Amyloid fibrils (pancreas type II diabetes)

Amyloid fibrils

Nanotubes

Nanospheres


The role of aromatics in amyloid fibrils formation
The role of aromatics in amyloid fibrils formation

  • Phe dipeptide: the recognition core of Altzheimer’s amyloid fibril

  • Forms nanotubes

  • Applications in nano-electronics



Structures of peptides used in sa
Structures of peptides used in SA

Boloamphiphile

Amphiphile

Surfactant-like

Phenylalanine

dipeptide

Reches and Gazit, 2006


Peptide nanotubes
Peptide nanotubes

Applications

Nanotubes with Ca-binding and cell-adhesion  bone-like material

Idem, non-conjugated

Nanofibers forming hydrogel  matrix for tissue regeneration & engineering


Peptide amphiphile and tissue engineering
Peptide-Amphiphile and Tissue Engineering

SA fibers with CCCCGGGS(PO4)PGD: without Ca2+ (a) and Ca2+ (b)






Sa patterns of the phe phe class
SA patterns of the Phe-Phe class

Phe-Trp

Phe-Gly

Phe-Leu

Phe-Phe





What are s layer proteins
What are S-Layer proteins?

  • S stands for surface: glycoprotein subunits forming outer envelope of Bacteria and Archea

  • Periodic structures with defined physico-chemical properties (pore size)

  • Self_assemble into 2D layers to form monomolecular lattices: potential in nanobiotechnologies (scaffolds, patterning matrices)


Applications of s layers
Applications of S-layers

  • production of isoporous ultrafiltration membranes

  • supporting structures for defined immobilization or incorporation of functional molecules (e.g. antigens, antibodies, ligands, enzymes)

  • matrix for the development of biosensors including solid-phase immunoassays and label-free detection systems

  • Support and stabilizing matrices for functional lipid membranes, liposomes, and emulsomes

  • adjuvants for weakly immunogenic antigens and haptens

  • Matrix for controlled biomineralization and structure for formation of ordered arrays of metal clusters or nanoparticles (molecular electronics and nonlinear optics or catalysts)


S layer lattices
S-Layer lattices

100nm

Gram+ bacterium




Assembly of lipids on s layers
Assembly of lipids on S-layers

  • Non-covalent bonding

  • Electrostatic interactions between corrugated (inner) side of S-layer (carboxy groups) and charges on lipid head groups (zwitterions)

  • 2-3 contact points between protein and lipid: most lipids free to diffuse laterally: semi-rigid membrane




Expected applications of s layer driven sa of lipid membranes
Expected applications of S-layer-driven SA of lipid membranes

  • Life Sciences:

    • Drug delivery

    • Diagnostics

    • Biosensors

  • Chemistry and material sciences

    • Bio-mineralization

    • Non-linear optics

    • Molecular electronics

    • Catalysis


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