Biomedical Engineering Reference
In-Depth Information
22.5
Conclusions
Electrochemical biosensors have emerged as a dynamic technique for qualitative and
quantitative determination of different analytes for environmental, clinical, agricultural,
food, or military applications. Despite the enormous potentials compared with labora-
tory-based analytical techniques, numerous problems still remained to be solved. Most
biosensors have shown excellent characteristics for synthetic samples, pristine labora-
tory samples; they are not sufficiently robust in real samples. Most of the existing limi-
tations could be directly related to operational and long-term stability of the biological
receptor and the physical transducer. Other limitations could be attributed to poor
reproducibility between sensors and selectivity in complex matrices. For practical appli-
cations, the most important obstacles are encountered once the sensor is used outside
pristine laboratory conditions and is applied for in situ real-sample monitoring [25].
Elimination of various problems associated with hemolysis of sample was the subject of this
study, in which a flow-through immunoassay system was developed on the basis of sandwich
scheme of immunoassay using naphthol formed as a result of enzymatic hydrolysis of
-
naphthyl phosphate in the presence of AP label, which has been quantified amperometrically.
The main problems faced while analyzing antibodies against Hanta virus in hemolyzed mice
blood samples were found to be due to various electroactive species present in the hemolyzed
blood have been eliminated. The nonspecific signal due to the interaction of hydrogen perox-
ide used in the substrate solution with the hemolyzed blood samples was eliminated using
AP-marked enzyme label. Our study showed improved results in minimizing the interfer-
ences by covering the Ag/AgCl electrode surface with a layer of Nafion. The analysis required
large dilution of analyte sample to the order of 1:1000, to avoid electrode fouling and mini-
mize the effect of interference, nonspecific binding due to the presence of electroactive species
at the working potential. The device exhibited high degree of sensitivity capable of working
up to an analyte dilution as high as 1:10,000. As a result extremely small blood samples can be
analyzed increasing the utility of this device for working in the field. The biosensor has high
selectivity and sensitivity for direct measurement of anti-Hanta virus antibodies in blood sam-
ples with minimum or no sample preparation. The total time of analysis is 25½ min.
It is evident also that our device can detect the PIV, IAV as well as Hanta virus. The
amperometric signal for different types of flu is different, for each of the two types we
tested. However, the signal is reliable and reproducible, even after 5-month immunosor-
bent was kept in refrigerator.
Each year influenza viruses are responsible for recurrent epidemics, frequently in asso-
ciation with genetic variation. There is a requirement for sensitive and rapid diagnostic
techniques to improve both the diagnosis of infections and medication dispensed by the
physician as soon as possible to enhance patient's recovery. The quality of surveillance
systems will be trusted if the signal does not degrade fast [29].
Electrochemistry has superior properties over the other existing measurement systems
because electrochemical biosensors can provide rapid, simple, and low-cost on-field detec-
tion. Electrochemical measurement protocols are also suitable for mass fabrication of
miniaturized devices [30].
References
1. CDC. (1998). Update of emerging infection from the centers for disease control and preven-
tion.
Annals of Emergency Medicine.
31:121.
