10.1021/acs.biomac.6b00752.s001
Kai Tao
Kai
Tao
Guy Jacoby
Guy
Jacoby
Luba Burlaka
Luba
Burlaka
Roy Beck
Roy
Beck
Ehud Gazit
Ehud
Gazit
Design of Controllable Bio-Inspired Chiroptic Self-Assemblies
American Chemical Society
2016
myristic acid chain
chromophore
FFK
chiroptic
template
nanoribbon
Cotton effect
self-assemblie
chiral
FK
nanofiber
superstructure
Controllable Bio-Inspired Chiroptic Self-Assemblies Modulation
lipopeptide
2016-07-26 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Design_of_Controllable_Bio-Inspired_Chiroptic_Self-Assemblies/3519596
Modulation of chiroptics, chiral
phenomena of the optical properties,
is pivotal in a variety of advanced applications, including chirality-specific
biosensing and photonic switches. One of the most effective methods
for achieving this control is assembly of the optical moieties into
chiral nanostructures. Lipopeptide self-assemblies have been extensively
employed as soft templates to organize composites into low-dimensional
superstructures due to their rigidity and ease of functionalization.
Therefore, an appealing approach is to provide chiroptical control
by using lipopeptide self-assemblies as templates to assemble chromophores.
Herein, two lipopeptidic molecules, namely, C<sub>14</sub>–FFK
and C<sub>14</sub>–FK, composed of phenylalanine and lysine
residues conjugated to a myristic acid chain, were custom-designed.
Spectroscopic and microscopic characterizations indicated that C<sub>14</sub>–FFK self-assembled to wide, slightly left-handed
nanoribbons, while C<sub>14</sub>–FK formed narrow, intensely
right-handed nanofibers. The different chirality was derived from
the distinct self-assembly driving forces, especially the molecular
bending dimensions. These superstructures presented an ideal capability
to serve as soft templates to assemble porphyrin (ZnTPyP) through
noncovalent electrostatic attractive interactions, or assemble the
phenolic groups through covalent conjugation to peptide backbones.
The distinct exciton coupling of the chromophores allowed their achiral
optics to become chiral, showing negative Cotton effect when templated
by nanoribbons and positive Cotton effect with nanofibers as templates.
Following replacement of the lipopeptides with their d-type
enantiomers, the handedness of the superstructures and the associated
chiroptics were reversed and presented “mirror” symmetric
CD signals to their l-type counterparts. These findings may
pave the way to the formation of morphologically and chioptically
controllable nanomaterials.