Two zinc-aminoclays' in-vitro cytotoxicity assessment in HeLa cells and in-vivo embryotoxicity assay in zebrafish

Two zinc-aminoclays [ZnACs] with functionalized primary amines [(-CH2)(3)NH2] were prepared by a simple solgel reaction using cationic metal precursors of ZnCl2 and Zn(NO3)(2) with 3-aminopropyl triethoxysilane [APTES] under ambient conditions. Due to the facile interaction of heavy metals with primary amine sites and Zn-related intrinsic antimicrobial activity, toxicity assays of ZnACs nanoparticles (NPs) prior to their environmental and human-health applications are essential. However, such reports remain rare. Thus, in the present study, a cell viability assay of in-vitro HeLa cells comparing ZnCl2, Zn(NO3)(2) salts, and ZnO (similar to 50 mn average diameter) NPs was performed. Interestingly, compared with the ZnCl2, and Zn(NO3)(2) salts, and ZnO NPs (18.73/18.12/ 51.49 mu g/mL and 18.12/15.19/46.10 mu g/mL of IC50 values for 24 and 48 h), the two ZnACs NPs exhibited the highest toxicity (1050 values of 21.18/18.36 mu g/mL and 18.37/17.09 mu g/mL for 24 and 48 h, respectively), whose concentrations were calculated on Zn elemental composition. This might be due to the enhanced bioavailability and uptake into cells of ZnAC NPs themselves and their positively charged hydrophilicity by reactive oxygen species (ROS) generation, particularly as ZnACs exist in cationic NP's form, not in released Zn2+ ionic form (i.e., dissolved nanometal). However, in an in-vivo embryotoxicity assay in zebrafish, ZnACs and ZnO NPs showed toxic effects at 50-100 mu g/mL (corresponding to 37.88-75.76 of Zn wt% mu g/mL). The hatching rate (%) of zebrafish was lowest for the ZnO NPs, particularly where ZnAC-[(NO3)(2)] is slightly more toxic than ZnAC-[Cl-2]. These results are all very pertinent to the issue of ZnACs' potential applications in the environmental and biomedical fields.