Abstract:
Nanostructure morphology originating from the self-assembly of molecules has attracted substantial
attention due to its role in toxic amyloid fibril formation and immense potential in the design and
fabrication of novel biomaterials. This study presents the role of intermolecular electrostatic interaction
on the self-assembly process of L-phenylalanine (L-Phe) amino acid. We have employed attenuated total
reflection Fourier transform infrared spectroscopy to probe the existence of different ionization states of
the amino acid in various pH aqueous solutions. The self-assembly process of L-Phe in the aqueous
phase is explored by using circular dichroism absorption and nuclear magnetic resonance spectroscopic
tools. The observed spectral features have shown the signature of higher order structures and possible
perturbation in the p–p stacking aromatic interactions for the cationic and anionic states of the amino
acid. Scanning electron microscopy is used to probe the self-assembled morphology of the L-Phe
amino acid dried samples prepared from the same pH aqueous solutions. We find that for the case of
zwitterionic states the self-assembly nanostructures are dominated by the presence of fibrillar
morphology, however interestingly for cationic and anionic states the morphology is dominated by the
presence of flakes. Our finding demonstrates the potential influence of intermolecular electrostatic
interaction over the aromatic p–p stacking interaction in hindering the fibril formation.
