Biomedical Engineering Reference
In-Depth Information
20 μg/ml in 10 mM PhB, pH 7.3. For the quantitative analysis the changes
of the I-V parameters were investigated (ΔIі/I) as a function of voltage and
thickness of Ni and PS-layer (where:
I
is current through structure with-
out drawing substrate and Δ
I
і is the dif erence between currents through
structure before and at er drawing appropriate substrate. h e index
i
meets
following: bulk structure (0) and at er the deposition of Mb (1), its specii c
monoclonal Ab (2), consequent deposition of Mb and it's Ab (3), mixture
of Mb and Ab (4) on the surface).
At er the deposition of Mb or its specii c monoclonal Ab on the super-
thin Ni i lm the changes in the I-V characteristics of the SBS are observed.
h e response of these structures varies more essentially when the specii c
immune complex was on the surface (at er the consecutive deposition of
Ag and then Ab). For all investigated types of biological molecules and
their specii c complexes the characteristic optimum thicknesses of Ni i lm
and PS-layer that give the largest changes of the I-V characteristics are
equal to 200 - 300 A
0
and about 200 A
0
respectively. h e morphology of
Ni or PS surface inl uences on the structure of active centers of biological
molecules that leads to the changes in electrometric characteristics of the
SBS. Also it is possible to assume that at er the deposition of protein com-
pounds conductivity through pores or some deepening's of Ni i lm, i lled
with a biological substance, dominates.
h e current research demonstrates a possibility of immediate detection
of a specii c immune complex in electrometric way. h e data obtained in
this research open a perspective to use the electrometric approach as a
basis for the creation of new types of immune sensors.
13.2.6
Immune Biosensor Based on the Surface Plasmon
Resonance (SPR)
Direct control of biospecii c interactions is very important for solving of a
number of tasks in the i eld practical medicine in the respect of application
of the new methods for diagnostics. h e optical technique, in particular
based on the SPR phenomenon, is the most promising. Kretschmann in
1973 has proposed[26] the attenuated-total-rel ectance method which is
widely used now. In 1983 it was demonstrated for biosensing [27]. From
that time, the SPR method gives possibility to monitor the association and
dissociation of a wide range of biomolecular complexes in real time with-
out the use of labeled molecules. In this technique light is totally rel ected
at a glass-metal i lm interface and the rel ectance is monitored as a function
of incidence angle (resonance curve). At a certain angle, a minimum in the
intensity of rel ected light is observed. h is indicates that the coupling of
