A wandlike probe quickly gathers
chemical information; © Purdue News
Service photo/David Umberger
A new ultra-fast chemical-analysis tool has numerous promising uses for detecting everything from cancer in the liver to explosives residues on luggage and biomarkers in urine that provide an early warning for diseases.
The researchers have demonstrated how the technology, called desorption electrospray ionisation, or DESI, rapidly detects the boundaries of cancerous tumours, information that could help ensure that surgeons remove the entire tumour. "I wouldn't be surprised if pathologists are using this in operating rooms within two years," said R. Graham Cooks, Professor of Analytical Chemistry.
The technology has made it possible to speed up and simplify the use of a mass spectrometer. While ordinary mass spectrometry is both time- and labour-intensive, the group has modified the technology to make it faster, more versatile and more portable.
Mass spectrometry works by first turning molecules into ions, which can be detected and analysed. The key DESI innovation is performing the ionisation step in the air or directly on surfaces outside of the mass spectrometer's vacuum chamber.
The procedure involves spraying water in the presence of an electric field, causing water molecules to become positively charged hydronium ions. When the positively charged droplets hit the surface of the sample being tested, the hydronium ions transfer their extra proton to molecules in the sample, turning them into ions. The ionised molecules are then vacuumed through a tube and into the mass spectrometer, where the masses of the ions are measured and the material analysed.
DESI promises to be an important high-throughput tool to collect large amounts of data used in metabolomics, a field in which researchers search for chemical compounds called biomarkers. These biomarkers are early warnings of disease, but they can be difficult to spot among the hundreds of distinct chemicals normally present in the urine, blood or serum of healthy people. The DESI experiment allows testing to be done without separating the compounds of interest from biological fluids.
COMPAMED.de; Source: Purdue University