title: Cytotoxicity of ZnO Nanoparticles Can Be Tailored by Modifying Their Surface Structure: A Green Chemistry Approach for Safer Nanomaterials.
abstract: ZnO nanoparticles (NP) are extensively used in numerous nanotechnology applications; however, they also happen to be one of the most toxic nanomaterials. This raises significant environmental and health concerns and calls for the need to develop new synthetic approaches to produce safer ZnO NP, while preserving their attractive optical, electronic, and structural properties. In this work, we demonstrate that the cytotoxicity of ZnO NP can be tailored by modifying their surface-bound chemical groups, while maintaining the core ZnO structure and related properties. Two equally sized (9.26 ± 0.11 nm) ZnO NP samples were synthesized from the same zinc acetate precursor using a forced hydrolysis process, and their surface chemical structures were modified by using different reaction solvents. X-ray diffraction and optical studies showed that the lattice parameters, optical properties, and band gap (3.44 eV) of the two ZnO NP samples were similar. However, FTIR spectroscopy showed significant differences in the surface structures and surface-bound chemical groups. This led to major differences in the zeta potential, hydrodynamic size, photocatalytic rate constant, and more importantly, their cytotoxic effects on Hut-78 cancer cells. The ZnO NP sample with the higher zeta potential and catalytic activity displayed a 1.5-fold stronger cytotoxic effect on cancer cells. These results suggest that by modifying the synthesis parameters/conditions and the surface chemical structures of the nanocrystals, their surface charge density, catalytic activity, and cytotoxicity can be tailored. This provides a green chemistry approach to produce safer ZnO NP.
authors: Department of Physics, Boise State University , Boise, Idaho 83725, United States.
authors: Alex
authors: A
authors: Punnoose
authors: Department of Physics, Boise State University , Boise, Idaho 83725, United States.
authors: Kelsey
authors: K
authors: Dodge
authors: Department of Biological Science, Boise State University , Boise, Idaho 83725, United States.
authors: John W
authors: JW
authors: Rasmussen
authors: Department of Physics, Boise State University , Boise, Idaho 83725, United States.
authors: Jordan
authors: J
authors: Chess
authors: Department of Biological Science, Boise State University , Boise, Idaho 83725, United States.
authors: Denise
authors: D
authors: Wingett
authors: Department of Physics, Boise State University , Boise, Idaho 83725, United States.
authors: Catherine
authors: C
authors: Anders
keywords: Cancer; Cytotoxicity; Green chemistry; Nanoparticles; Oxides; Semiconductors; Sustainability