Biomedical Engineering Reference
In-Depth Information
connection to cancer, impedimetric genosensors constructed using verti-
cally aligned diamond nanowires and the superior electrochemical sensing
properties of diamond as transducer material were employed to detect the
CK20 marker [107]. In another work, specii c DNA probe immobilized
onto interdigitated gold nanoelectrodes was succesfully employed to detect
the breast cancer gene BRCA1 through the associated change in capaci-
tance [128].
4.7
Conclusions (Past, Present and Future Perspectives)
h is chapter has presented current technology typically employed with
genosensors which makes use of electrochemical impedance spectroscopy
(EIS) as the detection technique. Its operational principles and the essential
protocols employed for impedimetric genosensing have been introduced.
Although impedance is commonly used to investigate a variety of elec-
trochemical systems, it has only recently been applied in the i eld of bio-
sensors. Given its ability to monitor the charge transfer resistance and the
double-layer capacitance, it is possible to derive applications for dif erent
types of sensing schemes with numerous recognition agents, by direct sig-
nal acquisition, or with the use of simple and inexpensive redox markers.
One main advantage of impedimetric genosensing is that it can provide
potentially label-free assays, as hybridization with the DNA probe immo-
bilized on a surface can be directly monitored. In general, impedimetric
genosensors are extremely simple in operation, and capable of achieving
low detection limits even when used without any amplii cation. If com-
bined with additional signal amplii cation strategies, their absolute detec-
tion limits may be comparable to other genosensing strategies.
h e contribution of nanostructured materials in the development of
genosensors is an active area of research activity, and the use of nanopar-
ticles, nanotubes, graphene or other nanostructured materials have
been signaled out in some of the signii cant research with impedimetric
nanosensors. Sensitivity of a biosensor depends on the dimensions and
morphological shape of the nanobiomaterials involved. h erefore, some
morphological (nanotube, nanowires)-based biosensing transducers could
function as ef ective mediators and facilitate the electron transfer between
the active site of probe DNA and surface of the electrodes. Other nanocom-
ponents can be used as aids to help in improving detection limits or detec-
tion capability. h e topic of the use of nanobiomaterials as impedimetric
genosensors is common in the biosensing literature, where many formats
and designs are proposed to improve the performance of biosensors, espe-
cially if devised for medical applications. h e resulting nanostructures
