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N.F. Starodub,
National University of Life and Environmental Science, Kiev, Ukraine,
O.M. Shmireva,
National Technical University „KPI”, av. Peremoga, 37, Kiev, 03056, Ukraine
L.M. Shuliak

Institute of Laboratory Diagnostics of Alpha Medical Ukraine

Introduction: To provide creation of the analytical devices which will correspond to full complex of practice demands including selectivity, sensitivity, stability in general and to contaminated substances, repetition of results, needed time of functioning and others it was developed microelectronic enzymatic biosensor which gives possibility to simultaneously register a number of parameters, namely, the determination of glucose, sucrose and lactose in case of control of technological process at the sucrose production or the estimation of glucose, insulin (I) and anti-insulin antibodies (anti-I Ab) level at the control of the diabetic and autoimmune state development.
Methods: The integral biosensor contents simultaneously two separate channels: amperometrical and thermo metrical. Amperometrical channel includes whole line of planar microelectrodes with help of which current was registered. As a rule the average value of three microelectrodes was preceded. Thermo metrical channel is presented by thin layer sensors which work in differential regime. Output signals of the integral biosensor are processed by the special electronic block. Thin layer temperature sensors were prepared by two ways: on the basis of platinum or oxide cerium. These sensors together with the platinum working electrodes and reference electrode (AgCl) for the amperometrical measuring were situated on the common solid phase. Three working electrodes were taken for the increasing of accuracy of measurements. Thermo metrical channel contents also working and reference thermistors which have weaving form (Fig. 1, 2, 3). Enzymes as well as I were immobilized on the transducer surface after its preliminary treatment by polyelectrolytes (polyalylamine hydrochloride or poly/sterenesulphonate/ sodium salt).
Results: It was demonstrated that thermometry allows providing control of concentrations in frame of 0.002-25; 0.005-100; 0.1-10 mM and sensitivity about 2.35; 0.45 and 0.85 rel. units/mM for glucose, sucrose and lactate correspondingly. From other side amperometry was characterized by values of controlled concentrations in frame of 0.5-50; 0.1-80; 0.1-200 mM and sensitivity on the level of 4.3; 3.3; 3.3 nA/mM for above mentioned substances correspondingly (Fig. 4). In general it is necessary to mention that these values correspond to the practice demand in respect the sensitivity from one side and from other one the obtained values have been conformed by special biochemical experiments. It is very important to underline that total time of analysis is very short and in additional to there is possibility to obtain irrespective data about level of some parameter by different approaches. The sensitivity of the determination of I and anti-I Ab in serum blood of patients with diabetics is highest at the application of the thermo metrical channel of the multi-parametrical biosensor among other ones. It was chosen the optimal insulin concentration for the immobilization (Fig. 5). Then the calibration curves were constructed for both channels (Fig. 6, 7) and at last, it was examined the efficiencies of work both channels at the analysis real samples preliminary tested by the ELISA-method (Fig. 8 and Table).