Oil Solubilization Capacity, Liquid Crystalline Properties, and Antibacterial Activity of Alkanolamine‐Based Novel Cationic Surfactants

Abstract

A series of monomeric and dimeric cationic surfactants with tuned polarity was synthesized. Oil solubilization capacity, thermotropic liquid crystalline properties, and minimum inhibitory concentration (MIC) of novel hydroxylated cationic surfactants using selected gram positive and gram negative bacteria were examined. Antibacterial activity and the propensity of gemini surfactants for oil solubilization were observed to be better than those of corresponding monomeric surfactants. Pseudo ternary phase diagrams for these surfactants, methyl methacrylate (MMA), and water clearly showed, that microemulsions can be easily formulated with all these surfactants. Solubilization and foam studies of mixed surfactant systems were also examined. Molecular architecture like the tail length, head group area, and presence of ethanolic goups in the surfactant affect the performance properties. Unlike conventional gemini surfactants the synthesized gemini surfactants also show thermotropic liquid crystalline properties (smectic-A, L a phase).

Surface‐Active Properties and Antimicrobial Study of Conventional Cationic and Synthesized Symmetrical Gemini Surfactants

“…Indeed, when the spacer becomes too long and flexible (s C 10), it becomes too hydrophobic to remain in contact with water and moves to the air side of the interface, adopting a folded, wicket-like conformation. It partly penetrates into the hydrophobic core of the micelles, restricting the hydration of the alkyl chains in the micelles and as a result the head groups approach closer to each other and thus area of the surfactant molecule decreases upon increasing spacer length [13,14,17,20]. Our results follow the similar trend as reported in the literature for oligomeric surfactants and indicate that all synthesized symmetrical cationic dimeric compounds satisfy the primary requirement of being good surfactants [23,29,31].…”

“…While for s = 4-6, the spacer chain tends to remain in an extended conformation where the spacer comes in contact with bulk water leading to increase the hydrophobic hydration and delays the micellization thereby increasing CMC. Thus due to such enhanced hydrophobic interaction the gemini surfactants with s = 2 facilitate better germicidal activity and proton-binding ability of QAS [11,17]. Similar enhanced micellar aggregation and growth was observed in 12-2-12 and 16-2-16 due to shorter spacer unit, which most likely increases the geometrical constraints in the formation of aggregates with decreasing length of the spacer unit.…”

“…After incubation, the diameter of the clear zone of inhibition surrounding the sample is taken as a measure of the inhibitory power of the sample against the particular test organism [17,23,24,28].…”

“…Such quaternary ammonium salts kill microorganisms by damaging cytoplasmic membrane of cell and affect the permeability properties of cells, different from antibiotics that inhibit certain reproductive enzymes. Thus, the antimicrobial action of cationic surfactants is based on their ability to disrupt the integral bacterial membrane by a combined hydrophobic and electrostatic adsorption phenomenon at the membrane-water interface to create disorganization [16][17][18][19][20].…”

Structural, biocomplexation and gene delivery properties of hydroxyethylated gemini surfactants with varied spacer length

“…[35][36][37][38][39] while gemini G12 is described herein. Synthetic details and quantification of properties by NMR, IR spectroscopy and elemental analysis are given in Supplementary data section.…”