In vitro evaluation of the physicochemical effects of drug loaded carbon nanotubes on toxicity

Abstract

Carbon nanotubes have attracted significant attentions as novel one-dimensional nanomaterials due to their unique structures and properties. Aggregate properties of Carbon Nanotubes (CNTs) such as high surface area, length or surface chemistry are further tailored to enhance their potential application in nanomedicine through post synthesis chemical modifications. These modifications simultaneously alter their aggregate physicochemical properties and this may have a direct impact on cytotoxity of CNTs in cells. Herein, as prepared Multiwalled Carbon Nanotubes (MWCNTs), were initially acid oxidized using strong acids at different temperature to remove impurities whilst introducing carboxylic groups on to the surface. The drug riluzole was then conjugated to the oxidized MWCNTs via carbodiimide activated amidation. Characterized physicochemical properties i.e. length, surface area, degree of functionalization and amount of chemical impurities were key determinants of the drug loaded MWCNTs' cytotoxicity. Covalently linking riluzole to MWCNTs and the consequent changes in the physicochemical properties did not lead to the generation of toxic effects in cells. Furthermore chemically binding riluzole to the MWCNTs did not deactivate the drug and reduce its ability to be antiglutamate. The identification of specific physicochemical properties governing CNT toxicity presents the opportunity for CNT based drug delivery system designs or applications that reduce human and environmental impacts. © 2012 Chigumbu N, et al.