Fluorescence is a major tool in life and material sciences. In biology/medicine, the coupling of fluorescent dyes, to proteins or nucleic acids (RNA, DNA) allows one to investigate their fate and interactions in cultured cells or in the body. Similarly, fluorescence is used in material sciences to detect electromagnetic fields, for optic storage or tracking (notably to detect fake products). However, most of fluorescent dyes are made of molecules with a limited life time due to chemical reactivity.
In this context fluorescent diamond nanoparticles present a valuable alternative thanks to their outstanding photophysical properties. They are very bright and possess long-term non-bleaching, non-blinking fluorescence in the red/NIR region. Based on these unique properties, multiple applications are foreseen in physics, material science, biochemistry and biology. However, until recently, the production of such nanoparticles was limited to the laboratory.
A single route is nowadays taken to fabricate such fluorescent nanoparticles. It consists of irradiating substitutional nitrogen-containing diamond nanocrystals, produced by the diamond industry, with electron or ion beams to create vacancies in the crystal lattice. Isolated substitutional nitrogen atoms then trap a moving vacancy during annealing to form a fluorescent NV centre. Unfortunately, the efficiency and yield of this route are low due to amorphization and the loss of moving vacancies to the surface during irradiation and annealing.
A top-down processing of diamond microcrystals, which are less prone to amorphization and vacancy loss, would provide a more industrially scalable route. However, in this case two barriers have to be surmounted – the difficulties of irradiating large amounts of material and converting microdiamonds into nanocrystals while keeping both fluorescence properties and crystal structure intact.
In a recent study, which is published in Nanotechnology, researchers in France and Germany have explored with success this alternative route to producing homogeneous samples of pure and very small fluorescent diamond nanoparticles with high yield. The fabrication procedure starts with the irradiation of finely controlled micron-size diamonds and requires subsequent milling and purification steps. In this novel process, substitutional nitrogen-containing microdiamonds with defined atomic composition were irradiated using a high-energy electron beam and then annealed at high temperature (800 °C) to create the desired photoluminescent centres in an intact diamond lattice. An original two-step milling protocol was designed to convert the fluorescent microdiamond into very small (down to 4 nm) round-shape nanoparticles of highly pure sp3 diamond with very bright and stable photoluminescent centres.
Such a fine fabrication process can now be used for the large-scale production of fluorescent diamond nanoparticles. One can vary and tailor their properties via the composition of the starting material to answer the needs of future applications. These fluorescent diamond nanoparticles open realistic perspectives to very long term labeling, to quantitative biology and innovative nanotechnology applications in composites, optoelectronics or analytical chemistry.
Reference : « High yield fabrication of fluorescent nanodiamonds », Jean-Paul Boudou, Patrick A. Curmi, Fedor Jelezko, Joerg Wrachtrup, Pascal Aubert, Mohamed Sennour, Gopalakrischnan Balasubramanian, Rolf Reuter, Alain Thorel and Eric Gaffet, 2009, Nanotechnology 20 235602
Patrick Curmi | EurekAlert!
Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie
Seeing the quantum future... literally
16.01.2017 | University of Sydney
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Machine Engineering
17.01.2017 | Physics and Astronomy