Cationic Imidazolium Amphiphiles Bearing a Methoxyphenyl Fragment: Synthesis, Self-Assembly Behavior, and Antimicrobial Activity

Novel cationic amphiphiles of the 3-alkyl-1-(4-methoxyphenyl)-1H-imidazol-3-ium bromide series bearing methoxyphenyl fragments (MPI-n) have been synthesized. Their aggregation properties in aqueous solutions, solubilization capacity, and hemolytic and antimicrobial activities have been investigated by a number of physicochemical methods. Using tensiometry, conductometry, and fluorescence spectroscopy, it was shown that the MPI-n have lower CMCs than their nonfunctionalized counterparts. The unusual alkyl-chain-length-dependent morphology of aggregates is testified for this homological series. Amphiphiles with 12, 14, and 16 alkyl tails are characterized by the formation of micellar aggregates, while a surfactant with a decyl tail is characterized by the formation of larger aggregates with lower surface curvature. The MPI-10 aggregate morphology was rationalized in terms of the packing parameter consideration and was supported by size measurements and the fluorescence probe techniques, which showed that vesicle-like aggregates in close-packing mode probably occur. MPI-n aggregates have exhibited a high solubilization capacity toward hydrophobic azo dye Orange OT. Importantly, amphiphiles studied showed (i) high bacteriostatic activity at the level of ciprofloxacin; (ii) high bactericidal action against all Gram-positive bacteria, including methicillin-resistant strains; (iii) bactericidal properties against Gram-negative bacteria; and (iv) low hemolytic activity.

Self-Assembling Metallocomplexes of the Amphiphilic 1,4-Diazabicyclo[2.2.2]octane Derivative as a Platform for the Development of Nonplatinum Anticancer Drugs

New 1-cetyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide complexes with copper(II) bromide and lanthanum(III) nitrate were characterized using dynamic light scattering and transmission electron microscopy, with self-assembly and the morphological behavior elucidated. For the lanthanum(III) nitrate complex, the 3D crystal structure was characterized using X-ray diffractometry. These metallosurfactants were tested as antitumor agents, and a high cytotoxic effect comparable with doxorubicin was revealed against the M-HeLa and A-549 cell lines. Both complexes were 2 times more active toward the MCF-7 cell line than the breast cancer drug tamoxifen. The cytotoxic mechanism of complexes is assumed to be related to the induction of apoptosis through the mitochondrial pathway.

Supraamphiphilic Systems Based on Metallosurfactant and Calix[4]resorcinol: Self-Assembly and Drug Delivery Potential

Metallic amphiphiles are used as building blocks in the construction of nanoscale superstructures, where the hydrophobic effects induce the self-assembly of the nanoparticles of interest. However, the influence of synergizing multiple chemical interactions on an effective design of these structures mostly remains an open question. In this regard, supraamphiphilic systems based on flexible surfactant molecules and rigid macrocycles are being actively developed, but there are few works on the interaction between metallosurfactants and macrocycles. In the present work, the self-assembly and biological properties of a metallosurfactant with calixarene were studied for the first time. The metallosurfactant, a complex between lanthanum nitrate and two 4-aza-1-hexadecylazoniabicyclo[2.2.2]octane bromide units, and calix[4]resorcinol containing sulfonate groups on the upper rim were used to form a novel supraamphiphilic composition. The system formed was studied using a variety of physicochemical methods, including spectrophotometry, NMR, XRF, and dynamic and electrophoretic light scattering. It was found that the most optimal tetraanionic calix[4]resorcinol to dicationic metallosurfactant molar ratio, leading to mixed aggregation upon ion pair complexation, is 2:3. The mixed aggregates formed in the pentamolar concentration range were able to encapsulate hydrophilic substrates, including the anticancer drug cisplatin, the pure form of which is more cytotoxic toward healthy cells than toward diseased cells. Interestingly, the drug loaded into the macrocycle-metallosurfactant particles was less cytotoxic to a healthy Chang liver cell line and more cytotoxic to tumor M-HeLa cells. This selectivity depends on the amount of cisplatin added. The more drug is added to the macrocycle-metallosurfactant composition, the greater the biological activity against cancer cells. Taking into account that the appearance of resistance of cancer cells to drugs, especially to cisplatin, is one of the most important problems in treatment, the results of this work envisage the potential application of a mixed macrocycle-metallosurfactant system for the design of therapeutic cisplatin compositions.