Biomedical Engineering Reference
In-Depth Information
ionic strength of the sample, NaCl should be added to the diluent up to
150 mM concentration (this procedure may be optional when using 5
mM as a diluent, since its ionic strength is sui cient to stabilize the sensor
response within the 10% relative accuracy usually required); (4) the almost
invariable sensor response in the pH range 7.0-8.0 makes it unnecessary
to adjust the sample pH to a certain value or to calibrate the sensor at a
predei ned pH value in this range.
h e biosensor was examined according to the next protocol at the blood
analysis: (a) the drawing baseline of biosensor immersed in diluting buf er
(2 mM of PBS, pH 7.4) then the registration of its response for 1 mM glu-
cose concentration, further at er rinsing, 0.1 volume of undiluted rat blood
was added and at erwards the sensor response for 1 mM glucose should be
examined again; (b) in another test at er adding 0.1 volume of rat blood, a
solution with native GOD was added which eliminated the glucose from
the reaction volume and the base level signal of the sensor was restored;
(c) the last test included addition of 0.1 volume of rat blood already treated
with GOD, no signal was obtained in this case. Subsequent addition of 1
mM glucose results in a correct response value.
h e biosensors did not exhibit any essential loss of activity at er 100
assays. It showed less than 10% loss of activity at er two month storage (in
0.5 mM PhB, pH 6.5, at +4
0
C). h e lifetime of the sensors can be signii -
cantly increased at the storage in a dry state and at +4
0
C.
In general, it is possible to conclude that the presented system is suf-
i ciently versatile to meet any requirement concerning accuracy, response
time, stability, calibration and reproducibility of biosensor. h ere is possi-
bility of applying the developed biosensor to blood glucose assay as incor-
porated in a l ow-through system or as a disposable probe. h e very small
volume of blood (up to 10 μl) and short time (less than a few seconds)
needed for one glucose test make such biosensor very attractive for bio-
medical applications.
13.4
Multi-parametrical Biosensors [49-51]
To provide creation of the analytical devices which will correspond to
full complex of practice demands including selectivity, sensitivity, stabil-
ity in general, repetition of results, needed time of functioning and oth-
ers 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
