Développement d'une imagerie vidéo de nanosystèmes biologiques et bioinspirés

The project PIA VIBBnano is an Interdisciplinary consortium gathering teams working in the fields of physics, nano & micro technology, bio chemistry and chemistry. Starting with 7 teams coming from three areas Lille, Bordeaux and Toulouse, the PIA ends with 8. Below, a chart summarizes the VIBBnano’ knowledge and know how.

Synergies Between Teams at the State of Art

(i) Near Field Instrumentation

- MEMS AFM Head a technological Breakthrough 

- AFM & Near field optics know how in Biosystems

- AFM & Near field optics know how in Dynamics

- Colocalisation of Near field optics & MEMS AFM images

- Micro & Nano fluidic Cells properties

MEMS: Micro Electro Mechanical System; AFM: Atomic Force Microscopy

(ii) DNA_RNA BioNanotech

- Imaging Brain disease with Aptamers

- Unusual nucleic acids

- Algorithmic materials.

- DNA Origamis & DNA Computing

- Patterning from nano to tens of micrometers

- Modeling: theory & simulations.

The PIA belongs the Nanobiotechnology Initiative through the development of a new Near Field instrumentation based on a MEMS head vibrating at several tens of MHz and of the merging field DNA_RNA BioNanotech. Focusing on the MEMS AFM Head, we set a list that gives a technical description and the scientific goals on which were based the project VIBBnano. When the items are star marked, it indicates that the results are direct products of the VIBBnano’ activity.

- AFM Head vibrating @tens of MHz: makes available a large bandwidth improving the rate of recorded images.

- AFM head with integrated forcing and detection.

- Tip orientation perpendicular to the scanned surface. A much powerful AFM head to access quantitative information.

- AFM Head vibrating @tens of MHz: a new tool to investigate viscoelastic materials, proteins & polymers, giving robust images of soft materials at the nanometer scale. *

- Tiny forcing and perturbation within the picometer range. A key achievement to investigate material properties and biodynamic at the nanometer scale. *

 - The MEMS AFM head reopens the area with foreseen evolution. Other alternatives: Cantilevers, Diapason, Kolibri are limited and technological dead ends.*

The first three items were the bottom line of the MEMS AFM VIBBnano proposal, thanks to the remarkable work accumulated over years by the IEMN team. The last three items come from the numerous experiments we performed on soft polymers, copolymers and in liquids. In spite of the high MEMS stiffness of about 10⁵ N/m, the very sensitive electrical detection allows recording images with a gradient force sensitivity down to 10^-2 N/m. Moreover, because we use oscillation amplitudes of only a few tens of picometer, experiments performed on copolymers showed that a contrast below a tenth of k_BT is readily achieved. In addition, both the experiments in liquids and soft polymers have shown that the picometer range provides us with the appropriate experimental condition to investigate the mechanical properties of nano-objects. As a consequence new experiments can be envisioned, so are a quantitative measurement of the ligand protein interaction and of allosteric mechanisms, experiments that can only be done by combining near field optics with the MEMS AFM, another key result obtained during the VIBBnano period. This combination of results supports the claim that the development of the MEMS Head provides the route to reopen the area in the near field domain.

DNA_RNA Bionanotech aims at delineating a merging field where the teams, over the world, involved in often use common concepts such as Universal Language, DNA computing, Algorithmic materials, Aptamers, and even more Origamis in place of self assembled, self organised, structures. The whole field has been triggered by the Seeman’ vision in the early eighties, which we can shortly summarise as follow: the use of DNA molecules must not be restricted to its primary genetic code function but used as any kind of nanomaterial. Within this frame, VIBBnano gathers complementary skills with in depth understanding of Aptamers, Unusual Nucleotides, fabrication of Origamis and more recently DNA computing on origamis.

The DNA computation on origamis corresponds to engineering a sequence of chemical hybridisation reactions in a confined environment. The many experiments done during the VIBBnano period show that there is a recurrent leakage effect in confined environment. To partly overcome this problem, we have shown that the use of G quadruplex provides an interesting alternative to the strand displacement method to trigger a cascade of chemical reactions. Another key result is the patterning of origamis with a photo imprint technique from which the structuration of surfaces from the nanometer up to tens of micrometers is achieved.

While the discovery of new Aptamers has obvious applications in the field of biosensing and medicine imagery, also they are at the heart of what is named a Universal Language based on the use of nucleic acids. When properly selected, Aptamers can translate any kind of nanoobjects, proteins, large enough molecules etc… as a sequence of nucleic acids that can further be processed. However, a key problem of combinatorial approaches, phage and cell display, SELEX, is the difficulty to select a few molecules among a huge amount of candidates, typically 10¹² 10¹⁵. There are many reasons that make the task truly difficult. Thanks to the complementary skills gathered in the VIBBnano’ project, we propose an instrumental evolution to improve the selection process. The technical improvement aims at reducing significantly the time spent and number of cycles, which may become a redhibitory problem, and to increase the reliability of the selection. A patent has been written and is under evaluation.

Overall, the works done during the VIBBnano period have shown significant progresses, both in the understanding and know how, supporting the claim that the MEMS is the appropriate tool to set a completely new and efficient generation of AFM Head combined to Near field optics. The work did in the field of DNA_RNA Bionanotech has shown hints that confirm a general evolution showing that DNA based devices will contribute and boost the domain of nanotechnology and nanomedecine.