Reusable sensor

Scientists from ITEB RAS have created a multiple-use diagnostic system for clinical diagnostics

Alsu Dyukina, ITEB RAS Press Service

The use of diagnostic microcapsules was proposed in the mid-2000s by the head of the Laboratory of Physical and Radiation Chemistry of Biopolymers of the ITEB RAS, Professor, Doctor of Chemical Sciences Sukhorukov Boris Ivanovich together with a leading researcher, Doctor of Biological Sciences Saburova Ekaterina Andreevna. Fundamental studies of the physicochemical properties of microcapsules and polyelectrolyte-protein interactions led to the emergence of a cycle of work on the creation of several diagnostic systems. The results of one study from a series of works by a team of scientists are published in the 11th issue of the journal Analytical Methods (Kim et al., Determination of urea concentration using urease-containing polyelectrolyte microcapsules).

"The presented work is devoted not to the development, but to the modification of the existing method of clinical diagnostic analysis, the essence of which is that the enzyme sensor is enclosed in a polyelectrolyte microcapsule. This capsule is semi-permeable, i.e. the enzyme does not come out from there, and the substrate and the reaction product freely circulate from the medium, and due to this an enzyme microreactor is obtained. Our modification leads to an increase in the accuracy of the study: if standard methods have about 10% error, then in our case 3-5%," Sergei Tikhonenko, a leading researcher at the Institute, Candidate of Biological Sciences, told the press service of ITEB RAS.

The proposed modification makes it possible to reuse the encapsulated enzyme sensor. This made it possible for the first time to create a multiple-use diagnostic system capable of analyzing the analyte content in the medium at least 50 times. But this is not the limit, because the experiment was simply suspended. After that, the task appeared to find different ways to remove the enzyme from the medium with its repeated use (encapsulation of the enzyme allows us to offer different ways to remove it from the analyzed medium with its repeated use) and thus simplify the automation of the system for further application of the method in clinical and biochemical analysis.

"The first part of the article talks about diagnostic systems where we repeatedly use a capsule with an enzyme enclosed in it, removing it using filters; in the second part of the work we attached the capsules to a quartz plate. The diagnostic plate developed in this way is lowered into the test solution, the reaction takes place and then the plate is removed and it can continue to be used further, while maintaining high accuracy and repeatability (so far it has been brought to 12 repetitions)," Sergey Tikhonenko said.

The technology of fixing microcapsules on the plate.

Another interesting feature of the new diagnostic plate was discovered quite by chance – "This plate had been lying in the closet for two years under normal room conditions, it was discovered, and it was found out that the enzyme attached to it retained its activity, which indicates the unpretentiousness of this system during storage," added Sergey Tikhonenko.

This work was the fourth of a series of works devoted to the development of diagnostic systems based on encapsulated enzymes.

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