Biomedical Engineering Reference
In-Depth Information
three-dimensional electropolymerized assembly. The high selectivity of the
imprinted matrices, evident in Fig.
8B
, C and reflected by the lower reflectance
responses for the Ca
2+
,Sr
2+
, and Ba
2+
analyses on the Mg
2+
-imprinted matrix, was
further reconfirmed by the synthesis of imprinted composites for each of the earth-
metal ions. As expected, in all cases the specific ion-imprinted matrices revealed
the highest performance for the sensing of the respective metal ion analytes, and
sensitive detection was also demonstrated in the presence of solutions containing a
mixture of all relevant ions [
56
].
3 Conclusions and Perspectives
The chapter introduced the electrochemical assembly and the application of Au
electrodes modified with molecularly imprinted bis-aniline-cross-linked Au NPs
matrices for sensitive and selective detection of a broad range of analytes, including
explosives, herbicides, sugars, earth-metal ions, antibiotics, and amino acids. Three
main interactions between the analytes and the matrices, facilitating the imprinting
process, were discussed: (1) donor-acceptor association, (2) ionic/H-bonds, and
(3) ligand-analyte complexation. The development of sensors, based on those
interactions, involved the careful selection of the imprint molecule, a process
which proved to be of a primary importance to the performance of the resulting
sensors, as well as the nano-engineering of the matrix by the incorporation of
receptor elements, such as specific ligands for the target molecules or ions.
The imprinted bis-aniline-cross-linked Au NPs matrices exhibit remarkable and
often unprecedented detection capabilities. The Au NPs matrices offer a dynamic
analyte sensing range that is often in the fM-pM regime, high stereoselectivity
(and/or chiroselectivity) toward the analysis of chemical interferants, a good repro-
ducibility and stability, and a relatively easy and cost-effective preparation. Albeit
these advances, many challenging topics associated with the imprinted Au NPs
matrices still need to be addressed. Whereas in most of the studies presented in this
chapter, the SPR technique has been used as a readout method for the sensing
events, other analytical techniques, such as surface enhanced Raman spectroscopy
(SERS), might be successfully employed for following the recognition processes.
With the advantage of detecting the spectroscopic fingerprints of the analytes, such
technique may be well suited for both quantitative and qualitative multiplexed
analyses of the various substrates in different environments.
Further challenging topics may involve the investigation of the correlation
between the morphology of the NPs, including their size, shape, and composition,
and the sensing performance of the imprinted matrices. Also, gas phase detection of
volatile explosive analytes and nano-engineering of the matrices for the detection of
other important substrates, such as street drugs or toxins, may be envisaged.
Finally, the applications of imprinted bis-aniline-cross-linked Au NPs matrices
are not confined to sensing. In fact, the imprinted matrices have already been
implemented in several scientific fields, including the generation of electrically
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