11 January 2017

With nanomole accuracy

Scientists have created a universal sensor on aptamers

Anna Manshina, N+1

Structure of the biotin-bound aptamer (Fdardel / Wikimedia Commons)

American scientists have created a miniature universal sensor that measures the concentration of target molecules in the blood of awake laboratory animals in real time. Such a device opens up new opportunities for research into the pharmacology, physiology and toxicology of drugs. An article about the development was published in the journal Proceedings of the National Academy of Sciences (Real-time measurement of small molecules directly in awake, ambulatory animals).

The inability to continuously measure the concentration of important substances directly in living organisms is one of the key limitations of bioanalytical chemistry. The design of a sensor capable of measuring the level of molecules directly in the blood should bypass two technical obstacles: the measurement should not be divided into stages and the sensor should be stable in the blood. There are sensors that bypass technical limitations and continuously determine the level of individual compounds – glucose, lactate, serotonin and some other molecules in the blood, but they work on the basis of specific reactions of target molecules and are not universal: for each type of molecule, you need to invent and optimize your own reaction.

One of the promising technologies, the electrochemical aptamer sensor, has a versatility that reactive sensors lack. Its basis is aptamers, molecules of nucleic acids with a length of several tens of nucleotides that specifically bind to various target molecules. Due to the astronomical number of base combinations in an oligonucleid molecule, it is possible to find an aptamer for almost any arbitrary target. Due to the specific binding to the target, such sensors are also very resistant to clogging when working in the blood.

Scientists from the University of California have taken an aptamer sensor as the basis of their new development. They created a microfluidic chip that allowed only small molecules to pass to the sensor, preventing large and slow-moving blood cells. In order to further protect the sensor from clogging, they covered it with a biocompatible membrane. Scientists used a protected biosensor to measure the concentration of doxorubicin, a well–known anti-cancer drug, in the blood of rats. During the five-hour monitoring, the sensor demonstrated nanomolar measurement accuracy.

To show the versatility of the sensor, the scientists used a replaceable aptamer element to recognize another type of substance – aminoglycoside antibiotics. The biosensor also quickly showed a change in the concentration of the drug during a series of injections. A sensor inserted through a catheter into the jugular vein allowed the animals to move almost unhindered and gave continuous access to data on the concentration of the antibiotic in the blood of a waking animal.

This biosensor was able to quickly and continuously read information about the level of target molecules in real time, for several hours, even on a waking animal. With this functionality, pharmacologists will be able to see how quickly the drug is absorbed, physiologists will be able to track the spread of hormones and metabolites in the blood with a new level of accuracy.

Only scientists and doctors will be able to use the new biosensor in the near future, but already there are skin microfluidic chips that may be of interest to athletes.

Portal "Eternal youth" http://vechnayamolodost.ru  11.01.2017

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