05/15/2018

Accelerating analysis for designer drugs



Designer drugs - drugs that are similar in effect, but slightly different in structure, to existing drugs - are an increasing problem for regulators and lawmakers, and a real threat to society. They are synthesised by modifying existing drugs, but because they have a deliberately ever-so-slightly different molecular structure from drugs we know about, they elude classification as illicit substances. In other words, despite closely resembling illegal drugs, they aren't technically illegal. They are therefore used as a way of getting around current regulations, and their numbers are on the rise. In 2014-2017, 265 new psychoactive substances were reported to the EU's early warning system.

Scientists have developed analytical methods that can test for the presence of known drugs. For example, a chemosensor is a molecule that can recognise and interact with a specific drug molecule. It then signals its presence in some way, for example by emitting fluorescence. So if you know what drug you are looking for, you can often use a chemosensor. However, with brand-new, 'designer' drugs, their structure isn't known, and so identifying them has to be done from scratch, via a lengthy, involved process that can take weeks. In addition each chemosensor can only detect one drug - or at least one very narrow class of substances.

Fabrizio Mancin and his team of researchers from the University of Padova, in Italy, are hoping to change all that. "Our work tries to make the chemical analysis of psychoactive drugs as we see it in television. One finds a powder, or a tablet, goes in the lab, puts the powder into a test tube, the tube into an instrument and in a few hours know which substance it is."

Their method makes use of nanoparticles with a coating that binds to most types of psychoactive drugs. When added to water that contains psychoactive substances, a new compound is formed - part drug, part nanoparticle. The compound is then put into an NMR machine - an analytical tool that works in a very similar way to the MRI machines used in hospitals. The NMR scan produces a pattern that gives information about the molecular structure of the compound, and because the NMR scan produced by the nanoparticle itself is already known, this can be subtracted from the overall scan to give information about the structure of any drugs attached to it.

Using this system, "cocktails" of different drugs can be detected all at once, and the different drugs present can all be analysed. The method is highly sensitive, meaning that the drug can be detected even if it is only present in extremely low concentrations of 30µM. No other chemosensing-based system has achieve a similar performance. "In principle", says Dr Mancin in the paper, "by using this protocol it should be possible to propose a tentative chemical structure of a new 'designer' drug a few hours after the seizure of a single tablet."

» Original publication (open access)

Source: Royal Society of Chemistry




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