Non-Covalent Functionalization of Carbon Nanotubes with Surfactants for Pharmaceutical Applications - A Critical Mini-Review

Due to their unique physicochemical properties, carbon nanotubes (CNTs) have great potential as a novel drug delivery platform in pharmaceutical applications. Unfortunately, their lack of solubility in aqueous media limits their suitability in biological applications. This review summarizes the use of pharmaceutically applicable surfactants for the dispersion of single-walled and multi-walled CNTs, examines the quantitative data available on dispersing ability and critically evaluates the factors limiting the establishment of a set of cross-comparable dispersibility parameters and development of non-covalent functionalization technologies using surfactants. Additionally, a novel class of dimeric surfactants, also called gemini surfactants, are discussed as potentially superior non-covalent functionalization agents for CNT-based formulations. In order for CNTs to become a useful pharmaceutical excipient, the development of standardized dispersion methodologies, analytical protocols and stability assays will be required.