Page 377 - Organic Electronics in Sensors and Biotechnology

354 Chapter Nine

necessary. Such molecules will be excellent for monitoring AD pathol-
ogy and disease progress upon treatment, especially in transgenic
mouse models. On the other hand, multiphoton imaging might not
be suitable as a clinical diagnostic tool for protein aggregation dis-
eases. In this regard, radiolabeled or fluorinated versions of the oligo-
meric thiophenes usable for positron emission tomography (PET) or
single-photon emission computerized tomography (SPECT) will be
advantageous.
Future chemical design of novel well-defined oligomeric thio-
phenes will certainly utilize combinatorial approaches for optimizing
the thiophene core structure, which may provide more effective bind-
ers for different classes of protein aggregates. As mentioned in earlier
sections, there is a great need for techniques identifying different
molecular species that are present on the pathway to the formation of
amyloid fibrils, and it may even be possible to develop LCPs that
selectively stain oligomeric or fibrillar species. Recently, a successful
approach for the synthesis of more well-defined oligomeric thio-
phenes was reported, and these molecules showed a higher selectiv-
ity for amyloid fibrils than their polymeric polydispersed counter-
14
parts. LCPs having different and well-defined chain lengths would
also be of interest to establish and optimize the maximum effective
conjugation length necessary for selective fluorescence from LCPs
being bound to a wide range of heterogenic protein aggregates. A
focus must also be turned to the fundamental underlying photophys-
ical processes of LCPs and the molecular details regarding the selec-
tive binding site of LCPs to specific protein aggregates. Therefore, a
general understanding of photophysical processes of LCPs and
design rules in the synthesis of LCPs will be important for continued
progress in understanding protein aggregation disease.
As described in this chapter, LCPs have been implemented into a
new area of science, and scientists have just begun to explore the use of
this material within the field of biology and pathology. So the question
remains, can the sensory performance of LCPs be utilized to gain novel
insight into the mysterious pathogenic events of protein aggregation
diseases? Hopefully, a multidisciplinary scientific approach will give
the answer to this question and also lead to development of LCP-based
sensors for studying other diseases.

References
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Polythiophene with a free amino acid side chain. Polymer Commun. 32:546–548
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2. McCullough, R. D.; Ewbank, P. C.; and Loewe, R. S. Self-assembly and disas-
sembly of regioregular, water soluble polythiophenes: Chemoselective ion-
chromatic sensing in water. J. Am. Chem. Soc. 119:633–634 (1997).
3. Kim, B.; Chen, L.; Gong, J.; and Osada, Y. Titration behavior and spectral
transitions of water-soluble polythiophene carboxylic acid. Macromolecules
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