Delivered by Publishing Technology to: McMaster University IP: 206.214.1.140 On: Tue, 29 Dec 2015 19:44:19 Copyright: American Scientific Publishers Copyright © 2007 American Scientific Publishers All rights reserved Printed in the United States of America Journal of Nanoscience and Nanotechnology Vol. 7, 4017–4020, 2007 Cellular Toxicity of Inorganic Hydroxide Nanoparticles Soo-Jin Choi 1 , Jae-Min Oh 12 , Taeun Park 2 , and Jin-Ho Choy 1∗ 1 Center for Intelligent Nano-Bio Materials, Division of Nanoscience and Department of Chemistry, Ewha Womans University, Seoul, 120-750, Korea 2 Nanohybrid Co., Ltd., Ewha Womans University, Seoul, 120-750, Korea Layered double hydroxides (LDHs), anionic clays, have attracted increasing interest as nanovehicles for delivering genes, drugs, and bio-active molecules into cells. However, no attempts have been made to evaluate the potential undesirable effects of LDH nanoparticles. The cytotoxicity of LDHs with different chemical compositions (ZnAl- and MgAl-LDH) was systematically evaluated in various cell types, such as human normal cells, carcinoma cells, and red blood cells, by measuring cell viability, cell proliferation, membrane damage, and hemolytic effect. No significant cytotoxic effects could be seen in both cases, but ZnAl-LDH was determined to be slightly more toxic than MgAl-LDH in terms of membrane damage and hemolysis induction. It is, therefore, expected that LDHs could be promising candidates for novel inorganic drug delivery carriers. Keywords: Cellular Toxicity, Hemolysis, Layered Double Hydroxides, Chemical Composition, Nanovehicles. 1. INTRODUCTION During past decades, many efforts have been made in exploiting desirable functions by manipulating the nano- particles for improving human life and health. 12 How- ever, few researches have been performed to evaluate the potential undesirable effects of nanoparticles, for example, when administered for medical purposes or after expo- sure during manufacture processing for industrial applica- tions. Research on the toxicity of nanoparticles will not only provide data for safety evaluation of engineered nano- structures and devices, but also help to advance the field of nanomedicine by providing exact information about their undesirable properties and means to avoid them. 3 Layered double hydroxides (LDHs) are layered inor- ganic materials that possess high anionic exchange capac- ity, pH dependent solubility, and anion release property. 45 As such, LDHs have attracted increasing attention as carri- ers for various biological molecules. 6–9 For example, they have been used in medicine and pharmacy as antacid and antipepsine agents. It was also reported that LDHs can act as non-viral vectors for the efficient delivery of genes and biomolecules. 710–13 Moreover, recent researches show that they have a great potential as drug delivery nanove- hicles for anti-cancer 69 and anti-inflammatory drugs. 1415 However, no information is currently available about the potential cellular toxicity of LDHs. Evaluation of the ∗ Author to whom correspondence should be addressed. possible adverse effects of LDHs on human cells or deter- mination of their tolerance dose is, therefore, urgently needed to establish minimal standards for their biological applications. In this study, we evaluated the toxicity of LDH nanopar- ticles with two different chemical compositions, MgAl- LDH and ZnAl-LDH, on cultured cell lines. 2. EXPERIMENTAL DETAILS LDHs with formulas of Mg 068 Al 032 (OH) 2 (CO 3 016 · 01H 2 O (MgAl-LDH) and Zn 068 Al 032 (OH) 2 (CO 3 016 · 01H 2 O (ZnAl-LDH) were prepared by coprecipitation method; for MgAl-LDH, a clear metal solution con- taining 0.088 M of Mg(NO 3 2 · 6H 2 O and 0.044 M of Al(NO 3 3 · 9H 2 O was prepared and the mixed metal solu- tion was titrated dropwisely with 0.5 M NaOH solu- tion containing 0.5 M of NaHCO 3 until pH reached to ∼9.5, resulting in white and turbid suspension. For ZnAl-LDH, a mixed metal solution of Zn(NO 3 2 · 6H 2 O (0.088 M) and Al(NO 3 3 · 9H 2 O (0.044 M) was titrated with the same 0.5 M NaOH/0.5 M NaHCO 3 solution until pH reached to ∼7.0. Each suspension was stirred at room temperature for 24 h, and then the resulting white precipitate was isolated by centrifugation, washed with deionized water, and freeze-dried to produce white powder. Thus prepared MgAl- and ZnAl-LDH nanoparticles were analyzed by powder X-ray diffraction (PXRD; Phillips PW3710 diffractometer with Ni-filtered CuKradiation J. Nanosci. Nanotechnol. 2007, Vol. 7, No. 11 1533-4880/2007/7/4017/004 doi:10.1166/jnn.2007.085 4017