Biomedical Engineering Reference
In-Depth Information
Figure 1.6
(a) Helical complexes of AuNP with identical sizes. CD is
calculatedforsuchcomplexeswithdifferentnumbersofNPs.(b)Tetramers:
two structures with overall similar parameters can show inverted CD
signals. (c) In pyramidal structures, our study shows that the CD signal is
extremely sensitive to the size of particles and complexes with a symmetric
frame will show a very low CD signal in the dipole regime. Adapted with
permission from Ref. [18]. Copyright 2010, American Chemical Society.
structures investigated, the helical structure is found to be the most
e
cientstructuretocreateCDresponses(Fig.1.6).Onthecontrary,
a significant CD signal is not found for a tetrahedral tetramer that
has a symmetric frame but differing particles on its vertices. This
is similar to a pyramid with a symmetric frame that exhibits a very
small CD signal. In the dipole interaction regime, we conclude that a
chiral MNP complex with a symmetric frame only exhibits weak CD
signal. An interesting extension of the theory was made for another
type of metal NCs, nanorods, in Ref. [2]. As nanorods typically have
strongopticaldipoles,chiralassembliescomposedofnanorodsmay
produce strong plasmonic CD signals.
