Physicochemical properties of surface charge-modified ZnO nanoparticles with different particle sizes

Abstract

Kyoung-Min Kim,1 Mun-Hyoung Choi,2 Jong-Kwon Lee,3 Jayoung Jeong,3 Yu-Ri Kim,4 Meyoung-Kon Kim,4 Seung-Min Paek,2 Jae-Min Oh1 1Department of Chemistry and Medical Chemistry, College of Science and Technology, Yonsei University, Gangwon-do, 2Department of Chemistry, Kyungpook National University, Taegu, 3Toxicological Research Division, National Institute of Food and Drug Safety Evaluation, Chungchungbuk-do, 4Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seoul, South Korea Abstract: In this study, four types of standardized ZnO nanoparticles were prepared for assessment of their potential biological risk. Powder-phased ZnO nanoparticles with different particle sizes (20 nm and 100 nm) were coated with citrate or L-serine to induce a negative or positive surface charge, respectively. The four types of coated ZnO nanoparticles were subjected to physicochemical evaluation according to the guidelines published by the Organisation for Economic Cooperation and Development. All four samples had a well crystallized Wurtzite phase, with particle sizes of ~30 nm and ~70 nm after coating with organic molecules. The coating agents were determined to have attached to the ZnO surfaces through either electrostatic interaction or partial coordination bonding. Electrokinetic measurements showed that the surface charges of the ZnO nanoparticles were successfully modified to be negative (about −40 mV) or positive (about +25 mV). Although all the four types of ZnO nanoparticles showed some agglomeration when suspended in water according to dynamic light scattering analysis, they had clearly distinguishable particle size and surface charge parameters and well defined physicochemical properties. Keywords: ZnO nanoparticles, surface coating, surface charge, particle size, physicochemical properties