Biomedical Engineering Reference
In-Depth Information
of the disease when specii c Ab titre is low. However, a complication of
this process is not appropriate for practice, because the main advantage
of biosensor analysis belongs to its expressivity. h us, it was analysed the
ef ectiveness of selective immobilization of biological material on the sur-
face previously covered with thiols, PAA, PSS, separately. It was stated that
the use of PAA for the modii cation of the transducer surface is the most
appropriate, af ordable and simple. It was found [32, 33] too that the most
acceptable is the algorithm of analysis, namely when insulin immobilized
on the surface of the optical transducer directly interacts with specii c Ab.
To i nd the optimal concentrations of the components for the biosensor
application it was prepared samples of insulin and Ab from dif erent sources
(from two dif erent i rms) and recombinant insulin in 0.01 M PhBS (pH 7.4).
It was stated that the optimal concentration of recombinant insulin should
be considered about 20 μg/ml and for pig insulin there is necessary dilution
in 10 times. With the used insulin samples it was constructed the needed
calibration curves. To avoid the non-specii c interaction of biomoleculs the
dilution of serum should be not less than 1:100. h e samples from ill persons
were divided by the standard ELISA-method according to levels of antibod-
ies against insulin (the maximum and minimum). As it can see from the
data presented in Figure 13.6 there was a very high correlation biosensor
response with predei ned initial levels of Ab against insulin in samples.
So, if all procedures needed for the analysis, including pre-processing
transducer surface and insulin immobilization will perform simultane-
ously with the sample analysis it is necessary to spend more than 30-40
min. But this time is much less that needed to perform the traditional
ELISA-method (4-5 h). Moreover, in case of biosensor method there is a
possibility to fuli l preliminary procedures as the previous surface trans-
ducer treatment and immobilization of insulin and then pure time of anal-
ysis will take only 5-10 min.
100
50
0
1
2
3
Figure 13.6
Response of the immune biosensor at the analysis of antiserums (dissolved in
1:100) from the immunized pig (1), patients with maximal (2) and minimal (3) content of
antibodies. Abscissa - changes of rel ectance angle, min.
