In-vitro assessment of cytotoxicity of halloysite nanotubes against HepG2, HCT116 and human peripheral blood lymphocytes.

Halloysite is a clay mineral with chemical similarity to kaolin, a pharmaceutical ingredient. It consists of mainly aluminosilicate nanotubular particles in the size range of ∼ 200-1000 nm. Many studies have tried to empirically explore this novel clay for its potential in drug delivery systems but no work has yet studied its cytotoxicity from the perspective of oral drug delivery system. In this study, the halloysite nanotubes (HNTs) were subjected to size distribution analyses, which reveal more than 50% of nanotubes in the size range of 500 nm and rest mainly in the sub micrometer range. HNTs were then evaluated for in-vitro cytotoxicity against HCT116 (colorectal carcinoma) and HepG2 (hepatocellular carcinoma) cells which represent the earliest entry point and the first accumulating organ, respectively, for nanoparticles en-route to systemic circulation after oral delivery. Moreover, HNTs were tested for their cytogenetic toxicity against human peripheral blood lymphocytes. Both these results collectively indicated that HNTs are generally safe at practical concentrations of excipients for oral dosage forms.