Self-assembly versatility of fatty acid-amino acid conjugates

Fatty acids, as amphiphilic molecules, are widely recognized for their self-assembly behaviors, which are influenced by the hydrophilic and hydrophobic components of their structure. In biological systems, the conjugates of fatty acids with various biomolecules play important biological roles. In addition, synthetic conjugates of fatty acids with other molecules such as peptides can modulate their self-assembly properties, enabling the design of functional materials for diverse applications in drug delivery, biomedicine, and materials science. In this study, we explored the self-assembly behavior of a series of fatty acid-amino acid conjugates which were synthesized through N-acylation of glycine (Gly), threonine (Thr) and phenylalanine (Phe) respectively with Octanoic acid (OA). We at first determined the critical aggregation concentration (CAC) of the conjugates by using pyrene as the fluorescent probe. The CAC of the three conjugates varies which strongly depends on the amino acid residue. Transmission electron microscopy (TEM) further demonstrates that the conjugates self-assemble to both particle-like structures and fibrous structures. This study showcases the potential of fatty acid-amino acid conjugates as tunable amphiphiles and their potential applications in drug delivery, biomedicine, and material design.