Biomedical Engineering Reference
In-Depth Information
included phenatoine and lidocaine at the various dilutions starting from a
concentration of 200 μg/ml and 50 mM PhB, pH 7.2, containing 1% BSA
and 0.05% tween-20 was used in all cases.
13.2.2.2
Determination of Some Pharmaceutical Substances [5]
h e minimal biosensor's response time in the concentrations range of
20 ng-20 mg/ml was 50 and 75 sec for lidocaine and phenatoine, respec-
tively. Although the measured concentration is equal and the kinetic curves
similar to Langmuir's adsorption curves, there was a dif erence in kinetic
response of the above mentioned substances. Firstly, it is possible since the
detected substances with like dif usion factors have dif erent association
constants in the immunochemical reaction. Secondly, FITC and B-Phyco
have dif erent stocks width (30 and 85 nm, respectively) which is an impor-
tant index for calculating the signal/noise ratio. h e biosensor's maximum
response was achieved through 2 min at 100 ng/ml. h is is much less than
that required for a therapeutic ef ect.
To control the selectivity of the analysis, such substances as digoxin, fer-
ritin, human Ig, phenobarbital, methotrexate, digitoxin, gentamicin and
theophylline were used. h e response value of the biosensor to the above-
mentioned list of substances was no more than 6.7% of the specii c sig-
nal. When analyzing the same concentration of phenatoine or lidocaine,
a 3-8% variation was observed among i ve optrodes. At er 2 months of
storing optrodes in dry and sterile conditions at 4
0
C the response time was
increased by 15 s, while sensitivity decreased 2%.
Such a biosensor may i nd wide application in dif erent i elds, especially
medicine. It is highly selective and sensitive with the response time in sev-
eral minutes that allows fuli lling analysis of many pharmaceutical sub-
stances online or under
in situ
regimes.
13.2.3
Immune Biosensor Based on the Ef ect of the Enhanced
Chemiluminescence (ChL) [6]
h is approach may also be ef ective for medical diagnostics as recently
some variants of such analysis in form of the 'dot'-ELISA-method were
developed [7, 8].
13.2.3.1
Construction of Biosensor, Used Reagents and
Measurements
A scheme for such biosensor is presented in Figure 13.3. h e optrode
with the immobilized material was placed into a tel on cell of 8 μl capacity
