Safety aspect of inorganic layered nanoparticles: size-dependency in vitro and in vivo.

In past decades, much attention has focused on the potential of inorganic nanoparticles as drug or gene delivery carriers due to their high cellular uptake capacity, non immunogenic response, and low toxicity. Layered double hydroxide (LDH), so-called anionic clay, is one of the most promising candidates for various biological purposes. Our previous report demonstrated that LDH had no significant cytotoxic effects at the concentration level of practical usage in human cell lines as well as in red blood cells. In this study, the optimum size of LDH nanoparticles was determined based on their toxicity in vitro and in vivo. Size-dependent toxicity of LDH was examined in cultured human lung cells; 50 nm particles were determined to be more toxic than larger particles, while LDHs within the size range of 100 to 200 nm exhibited very low cytotoxicity in terms of cell proliferation, membrane damage, and inflammation response. In animal model, all different-sized LDHs did not cause any mortality or body weight loss up to 600 mg/kg. Therefore, LDH is an attractive biocompatible delivery carrier for biological and medical applications.