17 - Calixarenes containing supramolecular vehicles for drug delivery

Abstract

Calixarenes are macrocyclic host molecules obtained after hydroxyl alkylation of phenols and aldehydes. Due to their high degree of steric flexibility, stability, and presence of a large number of well-defined hydrophobic cavities, calixarene-based systems have attracted a lot of attention in the design of controlled drug-delivery carriers. The poor water solubility limits their applications in the realm of drug delivery or biomedical science and engineering. Consequently, the upper or lower rims of calixarenes have been modified with highly hydrophilic moieties. Among water-soluble calixarenes, p-sulfonato-calixarenes have been investigated as complexing agents for poorly soluble drugs due to their low cytotoxicity and ability to form inclusion complexes with drug molecules. Calixarenes have hydrophobic cavities that can hold smaller molecules and act as controlled release carriers and, therefore, has emerged as one the most important host receptors in supramolecular chemistry. Further, the attachment of hydrophobic alkyl chains to calixarene imparts the macrocyclic host molecules' amphiphilic character. In this chapter, we summarize the recent developments made on the synthesis of calixarene-based vehicles and their application as drug-delivery carriers, including hybrid liposomes, lipid nanoparticles, and nanoconjugates.