1 research outputs found
Chiral Plasmonic Nanochains <i>via</i> the Self-Assembly of Gold Nanorods and Helical Glutathione Oligomers Facilitated by Cetyltrimethylammonium Bromide Micelles
Gold
nanorods are excellent anisotropic building blocks for plasmonic
chiral nanostructures. The near-infrared plasmonic band of nanorods
makes them highly desirable for biomedical applications such as chiral
bioimaging and sensing, in which a strong circular dichroism (CD)
signal is required. Chiral assemblies of gold nanorods induced by
self-associating peptides are especially attractive for this purpose
as they exhibit plasmonic-enhanced chiroptical activity. Here, we
showed that the presence of cetyltrimethylammonium bromide (CTAB)
micelles in a gold nanorod solution promoted the self-association
of l-/d-glutathione (GSH) and significantly enhanced
the chirality of the resulting plasmonic nanochains. Chiroptical signals
for the ensemble in the presence of CTAB micelles were 20 times greater
than those obtained below the critical micelle concentration of CTAB.
The strong optical activity was attributed to the formation of helical
GSH oligomers in the hydrophobic core of the CTAB micelles. The helical
GSH oligomers led the nanorods to assemble in a chiral, end-to-end
crossed fashion. The CD signal intensities were also proportional
to the fraction of nanorods in the nanochains. In addition, finite-difference
time-domain simulations agreed well with the experimental extinction
and CD spectra. Our work demonstrated a substantial effect from the
CTAB micelles on gold nanoparticle assemblies induced by biomolecules
and showed the importance of size matching between the inorganic nanobuilding
blocks and the chiral molecular templates (<i>i.e.</i>,
the GSH oligomers in the present case) in order to attain strong chiroptical
activities