Conclusions - Nanomaterials for Medical Applications - page 413

single excitation source which is a unique characteristics that allows multiple
analyte sensing capability in one sample and in one sensor strip or chip. 124,261 In
contrast, organic dyes with different emission wavelengths must be excited by
different excitation sources, which do not allow multiple analyte sensing capa-
bility. 47,139,258,262,263 The need for simultaneous detection of multiple targets in
single assay drives the development of inorganic nanocrystal-based fluorescent
probes to replace organic fluorophores especially for diagnosing diseases with
symptoms that are similar to many different kinds of diseases and health condi-
tions. With QDs-based nanobiosensors, it is less of a challenge to integrate the
transducers with the molecular recognition probes that recognize the binding
events and actively transduce sensing signals simultaneously.
By far, most of the publications in the literature to date research on nano-
structured biosensors are proof-of-concept work that demonstrated the advan-
tages of NMs and nanostructures. Only a few nanobiosensors have entered the
market for specific medical applications to date ( Table 9.1 ). However, to achieve
a status that is similar to the nano-enabled drugs that are already in the market,
more efforts need to be made to move the proof-of-concept studies to the appli-
cations of biosensors to real-world samples. Since the signature of nanobiosen-
sors is small, integration with microfluidics to form lab-on-chip devices is not
an issue. Studies to integrate the nanostructured sensors with signal-processing
instruments to build portable devices for on-site measurement of analytes or for
on-time (real-time) monitoring targets of interest and rapid assessment of risks
are currently on-going. Among these are point-of-care devices that are easy to
use and now has an increasing commercial demand.
Various analytes such as proteins, DNA, and whole cell are presen-
ted. 42,117,122,127,175,194,253,262,264-281 Protein analyte may be found in a cell, in
which case, the whole cell will be captured on the solid surface. The concept of
using NMs in biosensors is similar to an ordinary ELISA except that the signal is
not attributed to an enzyme but the NM which may be a QD that emits bright flu-
orescent light or AuNP that can be detected due to their Raman signals. Because

TABLE 9.1 Commercially Available Nanomaterial Bases Biosensors
for Medical Applications

Nanoparticle Application Brand Manufacturer

Gold Pregnancy test Clear Blue Easy Unipath

Diagnostics

Gold Pregnancy test First Response First Response

Gold Pregnancy test Clear View Cytodiagnostics

Gold HIV test Oraquick Ora Sure

Technologies