NANOSTRUCTURES FROM AN AMPHIPHILIC CARBOXYCALIX[ 4]ARENE DERIVATIVE

Amphiphilic molecules have been proven to be promising building blocks for self-assembled structures with a variegated level of structural complexity and exciting potential applications in different fields. Calix[4]arene is very attractive platform for developing self-assembling amphiphiles [1]. The calixarene cone shape and relatively rigid framework ensure highcurvature and enhanced stability, favorable for the formation of well-defined and discrete aggregates. Among the amphiphilic calixarenes, the carboxylate derivatives have shown interesting complexing and self-assembling properties, which are making them useful for application in fields ranging from material science to biological chemistry [2]. Here we describe the synthesis of a new amphiphilic carboxy-calix[4]arene and its aggregation in aqueous medium (figure 1). Dynamic Light Scattering (DLS) measurements, Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) images provided information about size, size distribution and morphology of the nanostructured assemblies. The amphiphilic carboxy-calix[4]arene represents the first example of calix[4]arene derivative assembling in discrete and stable multilamellar vesicles in aqueous medium. Suitable nanometer-size, very size narrow distribution, well-defined spherical shape, negatively charged hydrophilic surface, and guest encapsulation ability make the vesicles of the carboxy-calix[4]arene derivative appealing in the research of more effective drug delivery systems. Moreover, the multilamellar structure of these vesicular assemblies can offer additional advantages including effect of a reservoir and co-delivery of hydrophobic and hydrophilic drugs useful for synergistic effects in the treatment of a wide range of diseases. Figure 1. Structure of the carboxy-calix[4]arene derivative, FE-SEM and TEM images. References 1. Vicens, J., Harrowfield, J. (eds.) Calixarenes in the Nanoworld. Springer, Dordrecht The Netherland (2007). 2. Perret, F.; Coleman, A.W. Biochemistry Chem. Commun. 47, (2011) 7303-7319 and reference therein.