Biomedical Engineering Reference
In-Depth Information
SWCNTs presented Ni and Fe particles entrapped in their structures to
selectively “move” cells. 75 Neuroblastoma cells were seeded with a CNT-
modiied medium under a permanent magnetic ield, obtaining cell
displacements, with a higher concentration of cells where the magnetic ield
was stronger. Although the mechanism is not yet understood, it seems to take
place during cell duplication and to be driven by the presence of magnetic
CNTs, either uptaken by cells or attached to their membranes.
3.7 BIOSENSORS BASED ON CARBON NANOTUBES
As already mentioned, the detection of speciic proteins (the so-called
biomarkers, indicators of a pathological state) in blood or other biological
luids is really important for the early diagnosis of cancer, and nanotechnology
can help the development in this direction.
A biosensor is a device able to detect the presence of speciic molecules
and to transform the recognition events into analytical outputs, transducing
chemical responses into physical, measurable signals, usually current signals .
The ideal biosensor should be simple, sensitive, cheap and real-time, and the
recent achievements in proteomics are paving the way in this direction. 76
A speciic branch of biosensors is constituted by immunobiosensors:
the traditional techniques for protein detections are enzyme-linked
immunosorbent assay (ELISA), radioimmunoassay (RIA) and electrophoretic
immunoassay. They are rather time-consuming and need sophisticated
instrumentation, and moreover, the labelling exigency could affect the
detection eficiency. An immunosensor is an analytical device constituted
by an antibody or an antigen or a fragment of them combined with a
physicochemical transducer responsible for speciic properties, such as
optical or electrochemical ones or changes in mass or heat (Fig. 3.13). The
best sensitivity for this class of devices is, so far, in the picomolar range.
Figure 3.13 Schematic immuno-biosensoring set-up.
 
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