Searching for the needle in the haystack

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Why a doctoral student at Furtwangen University is working on making identical, tiny holes

"Measuring molecules by means of nanopores" - this exciting fundamental research topic is currently being researched at the Institute of Precision Medicine (IPM) at Furtwangen University. The principle works in a similar way to a sieve. Doctoral student Isabel Quint is working on minuscule membranes into which even more minuscule holes are inserted. The aim is to detect and count molecules with the help of these nanopores. The method will open up new possibilities, in particular for medical diagnostics.

"If we succeed in achieving reliably reproducible results with this technique, then this could replace the conventional – and much more expensive and complex – predominantly chromatographic-mass spectrometric measurement methods currently used in clinics, for example," reports IPM director, Prof. Dr. Hans-Peter Deigner. The idea of detecting and counting molecules by means of nanopores is not new. "Theoretically, it works, and you can find a lot about it in the technical literature," reports Isabel Quint. However, thus far, the principle has rarely been transferred into practice. Quint already has an idea of how the prototype will function – "simply introduce the sample via an inlet, a few sensors, surrounded by a small housing" – but the road there is long and hard. The nanopores in the five-by-five-millimetre silicon-based membranes are produced by placing the platelets under increasing voltage. "At about 10 volts, after seven to eight minutes, the whole thing breaks at the weakest point," says Quint. However, the exact placement of the small holes, which should be less than 5 nm in size, is difficult and unpredictable using conventional methods. Isabel Quint is therefore particularly pleased about the new electron microscope "FIB-SEM" (LINK to press release), which HFU is currently putting into operation on the Furtwangen campus – with it, surfaces can be observed and processed at the smallest level. 

The goal of doctoral student Quint and Prof. Deigner is to detect molecules quantitatively through nanopores – but the method should be generalisable and also applicable to bacteria or viruses on the nanoscale. "At the moment, clinics sometimes don't test that much because conventional methods are too expensive," explains Deigner. If the researchers at HFU succeed in transferring what is theoretically possible into practice, it is conceivable that it might even be used as the new determination method for self-tests, in doctors' practices or diagnostic laboratories. Bacteria or viruses, whose size is also in the nanometre range, could also be identifiable using the method. Isabel Quint estimates it will take another two years to complete her research and her doctoral thesis. Until then, she is happy with every small success. Quint compares the beginning with the search "for a needle in a haystack" – at the moment, she is mainly working on achieving reproducible results with the same material. 

The research on molecule determination through nanopores is so promising that the research work is being funded by the State of Baden-Württemberg as part of the Gesundheitsstandort BW Forum.

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