CONTEXT

In the nanotechnology sector, examples of methodology enabling supramolecular scaffold manufacture have already been done. These methods are mainly based on the auto assembly of « building blocks ». More particularly, DNA based methods are advantageously used because of the its natural properties : programmability of Watson-Crick base-paired secondary interactions, useful both to design branched molecular motifs and to connect them through sticky-ended cohesion. However several drawbacks are associated with self assemblies involving classical Watson-Crick base-paired structures:

• thermodynamic equilibrium based assemblies involving reversible hybridization conditions at fairly high temperatures (DNA melting) are poorly compatible with functionalized structures involving protein or fragile components​
• kinetically controled assemblies at low temperature are fairly complex to design and require sophisticated strategies to avoid formation of misassemblies limiting their general use

Aternate DNA building blocks (“i-motifs”) involving hemiprotonated [Cytidine• (neutral) C+ (protonated)] pairs forming two parallel duplexes mutually intercalated in a head to tail orientation offers the advantage to allow controllable assemblies at room temperature by slight pH shifts modulating base protonation. “I-motifs” made of homopolymer of cytidine can easily self-assemble into large supramolecular structures by successive block addition. However such assemblies are hardly controlable due to the use of a unique molecular block lacking functional diversity.

TECHNICAL DESCRIPTION

The present technology is a methodology allowing self-assembly of “i-motifs” into solution or preferably on a surface, thus generating nanostructures of controllable forms and functionalities. The method involves novel semi-synthetic (proteo) nucleic molecular blocks able to self-organise into dynamic polymers on a pH dependant manner. Assembly can be driven by surface features giving rise to organized 2D-structures that can be dynamically rearranged. The supramolecular structure assembly is driven by specialy designed oligonucleotidic sequences including streches of cytidine originally interupted on a suitable manner by other nucleic bases.

BENEFITS

Advantages of this method are:

• Reversible (dynamic) assembly controled by pH and temperature
• elf-assembling can be controlled by physico-chemical properties of a surface
• Assembly of hybrid blocks [DNA – proteins – inorganic structures] of various size and form
• Variability of resulting polymers : from rigid nanowires to nanomembrane

INDUSTRIAL APPLICATIONS

These structures would be usefull for many nanotechnologic applications, including fuel cells, biosensors, living/electronic devices, controled nanoencapsulation.

DEVELOPMENT STAGE

Different types of building blocks have been developped leading to different self-organised structures. Self-organisation control by surface is curently further investigated in view of combining nanofabrication and self-organisation techniques.

For further information, please contact us (Ref 02616-01)