Biomedical Engineering Reference
In-Depth Information
Figrue 13.3
Scheme of the sensor (A) and sensitive element (B): I - capillary, 2 - optrode,
3 - shutter, 4 - light diode, 5 - photon counter, 6 - recorder, 7 - light i ber, 8 - biological
material or special membrane, 9 - capacitor, 10 - casing.
containing specii c Ab of known dilution and Ab labeled by the HRP. h e
inoculated and washed optrode was placed in the cell with containing the
substrate for enhanced ChL. h e signal resulting from the agitated luminol
passed to the photon meter and recorder.
Optrodes were pretreated with a mixture which contained con-
centrated hydrochloric acid and dichloroethane in equal doses. One
approach was achieved by the direct immobilization of the biological
material on the surface of the optrode and on the inside wall of the spe-
cial capillary. In the latter case, a special membrane with a tightly bound
optical i bre was used.
Direct immobilization of the biological material was fuli lled in two
ways. In one case before, the immobilization the optrode surface was acti-
vated with cyanogen bromide at -150
0
C in the presence of triethylamine.
h en the optrodes were immersed in Ag or Ab solution for about 30 min
and in 0.1 M glycine solution for 40 min to block the remaining free func-
tional groups. In the other case, the optrodes were previously silanized and
then activated with GA. h e process of silanization was accomplished as
follows:
• aminopropyltriethoxysilane (APTES) was frozen and situ-
ated in a vacuum, where the optrodes were placed;
• the vacuum container was i lled with APTES vapor in which
the optrodes were held for no less than 12 h;
• the container was then placed for 3 h in vapors of GA
obtained by the method mentioned previously. Interaction
of the optrode surface with the biological materials, and
