Let's start by correcting one misunderstanding: nanoparticles are not extremely small. In fact, they vary in size - from a couple of atoms to millions of atoms or thousands of molecules - and make up an intermediate form between loose molecules and relatively large grains. Proteins are also a type of nanoparticle. “In light of this, chemists see nanoparticles as actually being quite large,” explains Professor Velders in his inaugural speech entitled 'Much ado about nano'. “Nanoparticles form a whole new world, complete with its own peculiarities. With this in mind, it is important that all nanoparticles which form spontaneously or are formed by human intervention are properly catalogued. This is why we are working on technology which will allow us to catalogue them effectively, adopting an optical approach via absorption and fluorescence and using magnetic resonance spectroscopy such as the technology used in MRI scans. We also do not have a periodic table of nanoparticles like the one we have for all chemical elements. We currently only know a few classes of particles, and we have very few predictive values. We also have very little understanding of how nanoparticles behave in biological systems - this despite the fact that the basis of life is found within the interaction of molecules and that nanoparticles could hold a range of useful applications.”
Aside from carrying out pure research, Velders is also active in creating therapeutic and diagnostic nanoparticles. “We can create nanoparticles which change colour when they are in the vicinity of other molecules. We are currently working on this project together with Leiden University Medical Center. Amongst other things, we aim to create applications for robot-assisted surgery. It is also possible to make hard and soft nanoparticles, as well as to insert extra molecules into the soft nanoparticles. We are currently researching how we can insert metal complexes into a large nanoparticle, or a 'micelle’, which can then be implemented as a sort of Trojan horse. This technique can be used in the first instance for diagnostic purposes; later, it could be used to administer medication into a cell. To give you an idea of the scale of this: if an atom were a large as a football, the micelle would be as large as the Main Auditorium of the university, and the cell would be a city as large as Wageningen. Alongside this, we are studying the coming together and break up of nanoparticles under the influence of biomarkers in blood samples and other areas. Changes in light absorption or fluorescence indicate that somebody has a certain disease.”
A lab on a chip
Velders is also involved in researching how nanotechnology can be applied. This mostly involves the development of diagnostic sensors, as he explains. “By developing miniature instruments, we can produce cheaper and portable devices that can be used everywhere. We can create a lab on a chip. This is useful for analyses of ditchwater on the campus, for instance, or for monitoring malaria infections in the field in Sub-Saharan Africa.” A significant development in this respect is that Velders and his group are now able to create microchannels in small blocks that are made of polydimethylsiloxane (PDMS), a type of rubber. They use the same plastic as Lego bricks to do this. By creating a flow of substances - in some cases cooled, heated, and/or illuminated - through the small channels, you can trigger reactions in the PDMS blocks or carry out measurements without the need for large and expensive apparatus.
“We are also in the process of developing very small NMR antennae. Using NMR, we can observe energy in the form of radio frequencies. These are specific to an element or atom, so this can also tell us how atoms will look later in the same molecule or nanoparticle. Every element has its own specific frequency. Our nanospools can listen to all frequencies simultaneously instead of just one, which is usually the case. Our nanospools are also a lot cheaper. A normal spool can easily cost ten thousand euros, whereas our most recently development antennae cost less than one euro.”
Finally, Velders will soon become involved with the catching and removing of antibiotic-resistant bacteria from the waste water of hospitals in order to prevent these bacteria from spreading. “We are developing technology that will allow us to attach these cells to nanoplates. We can convert expensive hospital technology to purify waste water; so from nanotechnology used in refined medicines to nanotechnology used in mud.”