Hierarchical Self-Assembly of Bile-Acid-Derived Dicationic Amphiphiles and Their Toxicity Assessment on Microbial and Mammalian Systems

A thiol-yne click chemistry approach was adopted for the first time to prepare highly water-soluble bile acid derived dicationic amphiphiles. The synthesized amphiphiles dicationic cysteamine conjugated cholic acid (DCaC), dicationic cysteamine conjugated deoxycholic acid (DCaDC), and dicationic cysteamine conjugated lithocholic acid (DCaLC) exhibited hierarchically self-assembled microstructures at various concentrations in an aqueous medium. Interestingly at below critical micellar concentration (CMC) the amphiphiles showed distinct fractal patterns such as fractal grass, microdendrites and fern leaf like fractals for DCaC, DCaDC and DCaLC respectively. The fractal dimension (Df) analysis indicated that the formation of fractal like aggregates is a diffusion limited aggregation (DLA) process. The preliminary aggregation studies such as determination of CMC, fluorescence quenching, wettability and contact angle measurements were elaborately investigated. The morphology of the aggregates were analyzed by SEM and OPM techniques. Further, we demonstrated the antimicrobial and hemolytic activity for the cationic amphiphiles. DCaC had potent antimicrobial activity and showed no toxicity on human RBCs indicating that DCaC could be used in biomedical applications, in addition to their industrial and laboratory applications such as detergency, surface cleaning, and disinfection agent.