Luminous nano-detectors for living healthier!
To begin with
Scientists fabricate silicon nanoparticles with photoluminescent properties that can trace cancerous cells.
About
Scientists at the Francis Perrin Laboratory (FPL) have manage to produced miniscule particles, or nanoparticles, made of silicon, which display important optical properties, like light emission in different colours. These properties are valuable for research in a broad range of fields, medical and pharmaceutical among others.
Silicon nanoparticles produced at FPL
Links with society
Medical and pharmaceutical research, among others, has developed an acute interest in the miniscule silicon nanoparticles –also known as quantum dots. (watch Dr. Herlin explaining why they are interested in silicon nanoparticles)
The photoluminescence of silicon nanoparticles is extremely important for many beneficial applications in biomedicine, pharmaceutical research etc. These particles offer a major advantage in the battle against cancer. Silicon nanoparticles emit light when irradiated with non visible light, i.e. ultraviolet radiation. The tissues of the body absorb the small amounts of light emitted by the silicon nanoparticles, and become sufficiently transparent, a quality necessary for medical detection processes.
The detection method could be described in a simple way as follows: a type of protein sensitive to cancerous cells is embedded into silicon nanoparticles. The protein, attracted by the cancerous cells, will drive directly to them the luminescent sources, thus allowing the detection of their position through the emitted light. Such an application may be a key to identifying cancer virulence and to developing individualized treatment.
Silicon nanoparticles may be also used in photovoltaic cells, which are used to convert solar energy into electricity. The use of silicon nanoparticles can even double the efficiency of the photovoltaic cells.
Dr. Herlin stands by scientific posters communicating their research results
Research innovation
Scientists at the Francis Perrin Laboratory fabricate nanoparticles made of silicon, a chemical element (with the symbol Si) essential in biology which also has many industrial uses. What makes silicon really special among other elements is the fact that when its size is reduced at the nanometric scale, it becomes luminous! Moreover, their luminescent colour changes in conjunction with their size: when the size of the particles decreases from about 8 nanometres to 3 nanometres, the colour they emit turns from infrared to red, respectively. This is due to the so called quantum confinement effect, which is responsible for a material’s different optical properties when nano-sized, in comparison with its bulk form. (watch Dr. Herlin talking about silicon photoluminescent properties)
Checking the final product
Description of the method
Scientists at the Francis Perrin Laboratory by use of sophisticated laser light techniques produce silicon nanoparticles of particular sizes suitable for various scientific research purposes. Their method, called laser pyrolysis, is based on the interaction between a laser light beam and a molecule containing silicon. (watch Dr. Herlin describing the research method)
The light beam is produced by high powered lasers called carbon dioxide lasers (CO2 lasers). These lasers emit in a continuous way high light energy, which means a large number of photons. The light beams interact with a molecule containing silicon. A very common source of silicon used by scientists is the silane gas. This gas is also widely used in electronics. A main property of the silane gas is that it may absorb electromagnetic radiation of specific wavelengths, which is produced by the carbon dioxide laser. Once the photons are emitted into the silane gas, they become absorbed by the silane molecule. As a result, the molecule becomes rapidly heated and it becomes dissociated in smaller fragments.
We can see a flame accompanying the whole procedure. This flame is created by the emission of hot particles (black body radiation) arising from excited chemical species (i.e. radicals), which have been produced by the molecule’s dissociation. Right after this, the small fragments of the molecule containing silicon collide with each other and form nanocrystals. These nanocrystals look like powder, which is then collected in filters and dispersed in an appropriate liquid.
It is therefore much easier to transfer the nanocrystals and work on their surface.
Achievements so far
Scientists at the Francis Perrin Laboratory have enhanced the versatility of the laser pyrolysis method in producing original nanoparticles with many potential applications. They have successfully synthesized new materials ranging from extremely small nanoparticles (photoluminescent silicon nanocrystals) to more complex structures (nanocomposites).
What’s next?
The newly fabricated silicon nanoparticles could be efficiently used as “bio-tracers” of cancerous cells. They need first to become stronger in order to endure in biological environments, and also more sensitive to interacting and binding with certain types of cells. (watch Dr. Herlin talking about challenges in research)
The first challenge calls for the production of biocompatible particles that resist dilution when inserted in a biochemical medium within the body. A possible solution to this problem would be the creation of a protective shell on the surface of the nanoparticles.
As far as becoming more sensitive to cancerous cells, siliconmagnetic fields. This is what happens with the Magnetic Resonance Imaging technique (known as MRI). nanoparticles could be enhanced so as to develop magnetic and optical properties. These new characteristics could drive the particles to their targets through specified
Part of the laser equipment where the nanocrystal powder is collected
Historical background
The idea of nanotechnology was introduced for the first time in 1959, when Richard Feynman, a physicist at Caltech, gave a lecture with the subject: "There's Plenty of Room at the Bottom". Though he never explicitly mentioned the term "nanotechnology," Feynman suggested that it would eventually be possible to precisely manipulate atoms and molecules. Fifteen years later professor Norio Taniguchi of Tokyo Science University invented the word “nanotechnology” in order to refer to “production technology to get the extra high accuracy and ultra fine dimensions, i.e. the preciseness and fineness on the order of 1 nm (nanometer)”. The term has since evolved to mean everything from “the science of manipulating atoms and molecules” to “the synthesis of novel life forms”.
The "face" of Science: Let's meet the scientists!
Scientists at the Francis Perrin Laboratory (FPL) located near Paris, have successfully produced silicon nanoparticles with photoluminescent properties, which can be effectively used in the early diagnosis of cancer. But who are these people working behind the scenes?
The “face” of science: Dr. Nathalie Herlin, Staff scientist at CNRS
Brief introduction: She studied Physical Chemistry at the University of Orsay in Paris. She worked at the National Aerospace Research Center on her thesis subject about the deposition mechanism of hard coating. She joined CEAlaser pyrolysis (French Atomic Energy Commission) in 1990 and she is currently in charge of the technique in the frame of the research conducted by the Nanometric Structures group.
Research interests: Dr. Nathalie Herlin is interested in discovering, studying and taking advantage of the new properties of matter when minimized to the nanoscale level, i.e. the nanoparticles.
Sources of inspiration:
• discussions with colleagues
• professional meetings and conferences
• scientific (or sometimes less scientific) literature
Important moments in her “scientific life”:
Dr. Nathalie Herlin remembers most some meetings with impressive people in the field of science that greatly affected her way of thinking. Especially Prof. Olivier Kahn was the academic teacher that introduced her and inspired her to further explore the amazing world of Physical Chemistry.
Research team behind the scenes:
Nanoparticles synthesis has been conducted at FPL since the 80s. The research group consists of three scientists: Yann Leconte, Olivier Sublemontier and Nathalie Herlin. There are also many other post doctoral researchers and PhD students who work with them. Especially the study on the application of “bio-tracers” is supported by collaborators in European countries such as Germany, Spain etc, which are mostly specialized in other functions and characteristics of nanoparticles (for example, their toxicity).
Dr. Herlin in her office discussing with a colleague
Editing team
Editing team of the Digital Exhibit "Luminus nano-detectors for living healthier!"
Scientific editors: Dr. Nathalie Herlin, Staff scientist at CNRS
Content Coordination: Glykeria Anyfandi
Science Communication Editors: Evlalia Amygdalaki, Glykeria Anyfandi
Content Administration: Christina Troumpetari, John Stoitsis
Technical Development: John Stoitsis
Photographs, videos & web material: Evlalia Amygdalaki
e-Knownet Live experiments: Interactive Science & Technology Exhibition, Eugenides Foundation