Synthesis And Property Studies Of Water-Soluble ZnO Quantum Dots

Zinc oxide is a kind of Ⅱ-Ⅵ semiconductor oxide with a wide bandgap.Because of its excellent physical and chemical properities, ZnO is the promisingoptical nanomaterial, and have been the focus of intensive research in recent years. Inthis paper, two kinds of ZnO quantum dots with different colour emission have beenprepared by simple chemical methods. Many analysis techniques, including X-raypower diffraction (XRD), transmission electron microscope (TEM), FT-IR spectrum,UV-vis specra, Photoluminescence spetra (PL), were used to characterize the products,respectively. The detailed contents can be summarized as follows:1. A sol-gel method was developed to prepare the water-soluble APTES-cappedZnO quantum dots with yellow emission. Compared with pure ZnO, the solubility ofAPTES-capped ZnO quantum dots has been improved. Hemolytic results indicate thatAPTES-capped ZnO nanocrystals have good biocompatibility.2. ZnO:MgO quantum dots have been synthesized by a sequential preparativeprocedure and capped with γ-Aminopropyl triethoxysilane (APTES), therebyrendering the surface of the quantum dots hydrophilic and the particles water-soluble.Orthogonal experiment was employed to optimize the correlated parameters of thereaction of capping ZnO:MgO quantum dots with APTES. The effects of the quantityof APTES, reaction time, and reaction temperature on the aqueous stability ofAPTES-capped ZnO:MgO quantum dots were investigated by orthogonal experimentand their optimal values were determined to be:0.25mmol,60min, and25C,respectively. The water-soluble APTES-capped ZnO:MgO quantum dots emitstrongly in the visible region on excitation by UV radiation and are stable overextended periods. The aqueous-stability of the quantum dots is attributed to theexposed hydrophilic groups (-NH2,-OH). Furthermore, hemolysis was performed toevaluate the biocompatibility of the quantum dots. Hemolytic results indicate thatAPTES-capped ZnO:MgO quantum dots have good biocompatibility, which isespecially important for ensuring their potential in biomedical applications.