Spontaneous catanionic vesicles formed by the interaction between an anionic b-cyclodextrins derivative and a cationic surfactant† O. Fernando Silva, * a Rita H. de Rossi, a N. Mariano Correa, b Juana J. Silber b and R. Dar ´ ıo Falcone b The present work shows the synthesis of a new type of catanionic surfactant, ModCD14–BHD, which involves an anionic amphiphilic cyclodextrin and the cationic benzyl-n-hexadecyldimethylammonium (BHD). It is obtained from the simple association of the cationic surfactant benzyl-n- hexadecyldimethylammonium chloride (BHDC) and b-cyclodextrin (b-CD) monosubstituted with an alkenyl succinate group (Mod-b-CD14). ModCD14–BHD form unilamellar vesicles spontaneously in water, while the individual components (BHDC and Mod-b-CD14) do not. The vesicles were character- ized by dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and 1 H NMR techniques. We suggest that the formation of an inclusion complex between some of the cyclodextrins units and the long hydrocarbon moiety of the cationic surfactant play a crucial role in the vesicles formation. Besides, some or the cavities are available to interact with an external guest. We think that the new surfactant molecule has properties that may lead to important applications in biomedical and pharmaceutical sciences. Introduction The construction of nanocarriers for drug delivery is an area of current scientic interest. The main reason for that is to explore new ways for deliver therapeutics agents directly into the desired zone and so decreasing the side effects of the drug in living organisms. Vesicles play an important role in this area because they can be constructed with bio-compatible materials and can be designed to have very interesting properties such as to respond to external stimuli. 1 Among the compounds that form vesicles, we can mention catanionic surfactants which form different kinds of aggregates and have been subject to extensive experimental investiga- tions. 2–5 It has been demonstrated that they form molecular bilayers 6,7 and that they are good candidates as drug delivery vehicles, 8 as well as in other areas such as detergents, foaming, etc. 9 During the screening of self-assemblies systems suitable for various applications, the combination of catanionic surfactants with macrocycles have been studied. In recent years several reports involving calixarenes appeared in the literature, 10 but to the best of our knowledge, there are no reports involving cyclodextrins. It is worth to mention that a zwitterionic cyclodextrin bearing positive groups on one rim and negative groups on the other has been reported. 11 This compound assembles in water forming elongated tape-like structures through the hydrogen bonding interaction of the ammonium group and the carboxylate group of adjacent molecules. 11 It is also important to remark that there are two studies using b- cyclodextrin (b-CD) to induce transition phase in non- stoichiometric mixed cationic and anionic surfactants. 12,13 In those reports, the transition micelle to vesicles is achieved by altering the composition of mixed surfactants due to the selective formation of inclusion complexes between b-CD and the major component in the mixed system. 12,13 In our lab, we have synthetized amphiphilic CD derivatives from the esterication of one of the OH groups with an alkenyl succinic acid. 14 These CDs resemble surfactants molecules and form micelles in water, monolayers at the air-aqueous interface 15 and can be solubilized in reverse micelles. 16,17 We considered that this type of molecules might be good candidates to form cata- nionic surfactants with a peculiar feature, they have an additional recognition site, namely the cavity of cyclodextrin, which might be important for the interaction of the organized structures with a desired guest. a Instituto de Investigaciones en F´ ısico-Qu´ ımica de C´ ordoba, INFIQC-CONICET, Facultad de Ciencias Qu´ ımicas, Departamento de Qu´ ımica Org´ anica, Universidad Nacional de C´ ordoba, Ciudad Universitaria, C´ ordoba, Argentina. E-mail: fersilva@ fcq.unc.edu.ar b Departamento de Qu´ ımica, Universidad Nacional de R´ ıo Cuarto, Agencia Postal # 3, C. P. X5804BYA, R´ ıo Cuarto, Argentina † Electronic supplementary informations (ESI) available: Size distribution at different time, scanning electron microscopy micrographs (SEM) of ModCD14–BHD vesicles and experimental details included materials and methods, are available free of charge. See DOI: 10.1039/c8ra01482e Cite this: RSC Adv. , 2018, 8, 12535 Received 16th February 2018 Accepted 21st March 2018 DOI: 10.1039/c8ra01482e rsc.li/rsc-advances This journal is © The Royal Society of Chemistry 2018 RSC Adv. , 2018, 8, 12535–12539 | 12535 RSC Advances PAPER Open Access Article. Published on 03 April 2018. Downloaded on 5/21/2019 3:42:16 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online View Journal | View Issue