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Luminescent Conjugated Polymers for Staining and Characterization of Amyloid Deposits 333
1.2
1.0
Absorbance (a.u.) 0.6
0.8
0.4
0.2
0.0
350 400 450 500 550 600 650 700
Wavelength (nm)
(a)
2500
2000
Absorbance (a.u.) 1500
1000
500
0
450 500 550 600 650 700
Wavelength (nm)
(b)
pH
O
H C –
N H O Absorption: red shifted
H Emission: red shifted/decreased
O
Isoelectric H C O – Absorption: blue shifted
point H N + H Emission: blue shifted/increased
(pl = 5.9) H
O
H H
H N + C O Absorption: red shifted
H H Emission: red shifted/increased
(c)
FIGURE 9.2 (a) Absorption and (b) emission spectra of POWT in different buffer
solutions: pH 2 (◊), pH 5 ( ), pH 8 (Δ), and pH 11 (×). (c) The charge of the zwitter-
ionic side chain, schematic drawing of the proposed backbone conformations, and
optical properties of POWT at different pH values. (From Ref. 36. Represented with
permission from the Institute of physics. Copyright 2002.)
