Self-Organizing Self-Organizing Bio-structuresBio-structures

NB2-2008NB2-2008

L. DurouxL. Duroux

Lecture 7Lecture 7

Protein-based nanomaterialsProtein-based nanomaterials

1. Peptide-based 1. Peptide-based nanostructuresnanostructures

A first insight into SA A first insight into SA peptidespeptides

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

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

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

Ghadiri’s cyclic Ghadiri’s cyclic polypeptides (CPP)polypeptides (CPP)

Electronic microscopyElectronic microscopy

pH-dependance of CP SApH-dependance of CP SA

CPP forming pores in CPP forming pores in membranesmembranes

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)

Self-Assembling Peptide Nanotubes

SA based on SA based on native 2native 2ndaryndary

structural motifsstructural motifs

Protein structural motifs & SA Protein structural motifs & SA designs designs

Type II polyPro helixAmyloid fibrils

SA Fibers engineering based SA Fibers engineering based on coiled-coilson coiled-coils

Woolfson & Ryadnov, 2006

Amyloid peptidesAmyloid peptides

A generic, universal form of A generic, universal form of protein/peptide aggregationprotein/peptide aggregation

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

Extended Extended -sheet SA forming fibrils-sheet SA forming fibrils

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

Object formed

Amyloid fibrils (pancreas type II diabetes)

Amyloid fibrils

Nanotubes

Nanospheres

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

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

Forms nanotubes

Applications in nano-electronics

SA based on SA based on amphiphilicityamphiphilicity

Structures of peptides used Structures of peptides used in SAin SA

Reches and Gazit, 2006

Boloamphiphile

Amphiphile

Surfactant-like

Phenylalaninedipeptide

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 Peptide-Amphiphile and Tissue EngineeringTissue Engineering

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

Aromatic Aromatic dipeptidesdipeptides

Hydrophobic layers made with Hydrophobic layers made with dipeptidesdipeptides

Görbitz, 2006

Types of nanostructures Types of nanostructures from various dipeptidesfrom various dipeptides

SA of Val-Ala classSA of Val-Ala class

SA patterns of the Phe-SA patterns of the Phe-Phe classPhe class

Phe-Trp Phe-Gly

Phe-Leu Phe-Phe

Formation of nanotubes Formation of nanotubes with Phe-Phe dipeptideswith Phe-Phe dipeptides

2. Protein-based 2. Protein-based SA nanotoolsSA nanotools

S-layer proteinsS-layer proteins

What are S-Layer What are S-Layer proteins?proteins?

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

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

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

Applications of S-layersApplications of S-layers1. production of isoporous ultrafiltration membranes2. supporting structures for defined immobilization or

incorporation of functional molecules (e.g. antigens, antibodies, ligands, enzymes)

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

4. Support and stabilizing matrices for functional lipid membranes, liposomes, and emulsomes

5. adjuvants for weakly immunogenic antigens and haptens

6. 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 latticesS-Layer lattices

Gram+ bacterium

100nm

Self-Assembled Self-Assembled monomolecular layersmonomolecular layers

S-layer as template for PSA S-layer as template for PSA detectiondetection

Assembly of lipids on S-Assembly of lipids on S-layerslayers

Non-covalent bondingNon-covalent bonding

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

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

S-layers as support for lipid S-layers as support for lipid membranesmembranes

Self-Assembly of a ion-Self-Assembly of a ion-channel in channel in

S-layersS-layers

Expected applications of S-Expected applications of S-layer-driven SA of lipid layer-driven SA of lipid

membranesmembranes Life Sciences:Life Sciences:

Drug deliveryDrug delivery DiagnosticsDiagnostics BiosensorsBiosensors

Chemistry and material sciencesChemistry and material sciences Bio-mineralizationBio-mineralization Non-linear opticsNon-linear optics Molecular electronicsMolecular electronics CatalysisCatalysis