1 research outputs found
Self-Assembly of Peptide-Amphiphile Forming Helical Nanofibers and in Situ Template Synthesis of Uniform Mesoporous Single Wall Silica Nanotubes
A lysine based peptide amphiphile
(PA) is designed and synthesized
for efficient water immobilization. The PA with a minimum gelation
concentration (MGC) of 1% w/v in water shows prolonged stability and
can also efficiently immobilize aqueous mixtures of some other organic
solvents. The presence of a free amine induced pH dependency of the
gelation as the PA could form hydrogel at a pH range of 1–8
but failed to do so above that pH. Various spectroscopic and microscopic
experiments such as steady state fluorescence, NMR, IR, CD, and FESEM
reveal the presence of hydrophobic interaction, hydrogen bond, and
π–π stacking interaction in the self-assembly process.
The self-aggregation has been correlated with the design of the molecule
to show the involvement of supramolecular forces and the hierarchical
pathway. While the L analogue formed left-handed helical nanofibers,
the other enantiomer showed opposite helicity. Interestingly the equimolar
mixture of the isomers failed to form any fibrous aggregate. Although
fibers formed at a subgel concentration, no helical nature was observed
at this stage. The length and thickness of the fibers increased with
increase in the gelator concentration. The nanofibers formed by the
gelator are used as a template to prepare mesoporous single wall silica
nanotubes (SWSNTs) in situ in plain water without the requirement
of any organic solvent as well as any external hydrolyzing agent.
The SWSNTs formed are open at both ends, are few micrometers in length,
and have an average diameter of ∼10 nm. The BET isotherm showed
a type IV hysteresis loop suggesting mesoporous nature of the nanotubes