title: Large-scale synthesis of water-soluble luminescent hydroxyapatite nanorods for security printing.
abstract: Luminescent hydroxyapatite nanoparticles, which have excellent biocompatibility, excellent photostability, and strong fluorescence, have received increasing attention as bioprobes in cell imaging. However, they are also excellent candidates for use in ink-jet security printing. Successful products for related applications usually require highly crystalline, mono-dispersible hydroxyapatite nanorods with good colloidal stability and high fluorescence in aqueous media. These requirements are hard to simultaneously satisfy using most synthetic methods. In this paper, we report a simple and versatile hydrothermal method that incorporates the use of sodium citrate to prepare water-dispersible Eu(3+)-doped hydroxyapatite nanorods. The hydroxyapatite nanorods obtained using this method are highly crystalline rod-shaped particles with an average length of 50-80 nm and an average diameter of 15-30 nm. Dispersions of these hydroxyapatite nanorods, which are transparent with a slightly milky color under natural light and a bright red color when excited with 241 nm UV light, display zeta potentials of -35 mV and hydrodynamic diameters of 120 nm. These dispersions remain colloidally stable for a few months. Dispersions with these properties could be easily applied to security printing for confidential information storage and anti-counterfeiting technologies.
authors: School of Pulp and Paper Engineering, Hubei University of Technology, Wuhan 430068, Hubei, PR China.
authors: Xiaohu
authors: X
authors: Chen
authors: School of Chemistry and Chemical Engineering, Hubei University of Technology, Wuhan 430068, Hubei, PR China.
authors: Xiaoying
authors: X
authors: Jin
authors: School of Chemistry and Chemical Engineering, Hubei University of Technology, Wuhan 430068, Hubei, PR China. Electronic address: tanjunjun_martyr@126.com.
authors: Junjun
authors: J
authors: Tan
authors: School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, PR China.
authors: Wei
authors: W
authors: Li
authors: School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, PR China.
authors: Minfang
authors: M
authors: Chen
authors: School of Pulp and Paper Engineering, Hubei University of Technology, Wuhan 430068, Hubei, PR China.
authors: Lan
authors: L
authors: Yao
authors: School of Pulp and Paper Engineering, Hubei University of Technology, Wuhan 430068, Hubei, PR China.
authors: Haitao
authors: H
authors: Yang
keywords: Colloidal stability; Europium doping; Hydroxyapatite nanorods; Luminescence; Security printing