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Teaser, summary, work performed and final results

Periodic Reporting for period 1 - HiPhore (High-temperature Thermophoresis using advanced optical microscopies)


What is the problem/issue being addressed?Thermophoresis denotes the motion of dissolved species in fluids created by temperature gradients. In water, the origin of thermophoresis is multiple, complex and still a matter of active research activities for solutes such as...


What is the problem/issue being addressed?

Thermophoresis denotes the motion of dissolved species in fluids created by temperature gradients. In water, the origin of thermophoresis is multiple, complex and still a matter of active research activities for solutes such as proteins, DNA or colloids.
Thermophoresis at small scales (sub-100 µm) aroused a strong interest this last decade because it makes the diffusion process faster and because of the development of breakthrough applications, e.g. in life sciences (PCR [1], bioanalytics [2], ...). However, reducing the spatial scale makes quantitative and non-invasive measurements of temperature and molecular concentration more challenging. Today the techniques developped for the study of thermophoresis at small scales are slow and invasive.
In the HiPhore project, I wish to provide the research community working on thermophoresis at small scale with innovative tools that enable a faster collection of data and that are label-free.

Why is it important for society?

The most important benefit for sociecty is related to the development of a technique capable of observing living hyperthermophilic bacteria. These organisms live at temperature as high as 113°C, maike it impossible to observe them alive under an optical microscope. The project is aimed to make them alive under the field of view of a microscope by microscale optical heating using a laser and gold nanoparticles as light absorbers. Thus, it will be possible to observe hyperthermophilic organisms living and interacting, and the amount of knowledge that the society could gather from this kind of observation is limitless. Hyperthermophilic organisms are already at the basis of the technique called PCR (polymerase chain reaction) to replicate DNA, a gold standard in molecular biology to make several copies of a specific DNA segment.

What are the overall objectives?
Using gold nanoparticles under illumination as nanosources of heat and advanced microscopy tools, I wish to achieve major breakthroughs in the field of microscale thermophoresis in liquids (MTL): - (i) developing new instrumentations for MTL
(ii) make the basics of MTL richer (clarify the enigmatic mechanism of protein thermophoresis and introducing a new concept: superthermophoresis)
(iii) introduce new applications of MTL in life sciences.

Work performed

From the beginning of the project, focus has been put of Workpackage 1, related to the implementation of the setup and the basic components of the project.
- The setup has been mounted and is fully operational.
- Task 1.1 We reproduced the chemical synthesis technique for the production of gold nanoparticle samples
- Task 1.2 We achieved microscale temperature shaping using gold nanoparticles and patterned laser illumination (publication in Sci. Rep. 2019)
- Task 1.3 We achieved the development of the optical microscopy technique aimed at label-free concentration mapping in liquids at the microscale
- Task 3.2 As a prelinary experiment, we observed the activation of bacteria under an optical microscope by microscale laser heating

Final results

Progress beyond the state of the art

- We developed a new label-free optical microscopy technique to image concentration of molecules at the microscale

- We developed a procedure to shape any tempeture profile at the microscale using a spatially contrasted laser beam and a layer of gold nanoparticles

- We introduce a new concept : activating micro-organisms under the field of view of an optical microscope by laser heating of gold nanoparticles

Expected results until the end of the project

- Introduce the concept of superthermphoresis, i.e., thermphoresis is superheated liquid water (above 100°C)

- Clarify the mechanisms of thermophoresis of proteins in water

- Achieve the activation of hyperthermophilic archaea

- illustrate the benefit of these new developments for practical cases in bioanalytics