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Date of Award
Master of Science (MS)
Department of Biology
The decline in the development of novel antimicrobials, combined with the misusage and over prescription of antibiotics, has contributed to the increasing prevalence of antimicrobial-resistant infections. Thus development of effective novel disinfectants could reduce the transmission of pathogens and decrease the risk of infection by antibiotic resistant organisms. The antimicrobial activity of amphiphiles, compounds with hydrophobic and hydrophilic regions, was first reported in 1935, and has influenced the synthesis of amphiphiles with variations in structure. In this study, three series of amphiphiles were synthesized by two subsequent Menshutkin reactions. Each amphiphile contains one or two hydrocarbon tails ranging from 8 to 22 carbons in their hydrophobic region and three cationic headgroups in their hydrophilic region. Using isothermal titration calorimetry (ITC) the critical micelle concentration (CMC) and thermodynamic parameters of micelle formation were measured. As tail length increases the CMC decreases where micelle formation is favorable (negative ∆G) for all three series of amphiphiles. Micelle formation is both enthalpically and entropically favorable for short chained amphiphiles whereas micelle formation is enthalpically favorable and entropically disfavored for long chained derivatives. The minimum inhibitory concentration (MIC) of each compound was measured against 6 different strains of bacteria. As tail length increases the MIC decreases until an optimal tail length where antibacterial activity is lowest. The water solubility of an amphiphile decreases with increasing tail length; amphiphiles that have intermediate solubility, within a series, were found to have with lower MIC values.
Marafino, John N., "Colloidal and biological properties of triscationic amphiphiles with one or two tails" (2014). Masters Theses. 7.