Crystal of Yb^3＋-doped Ba3Gd（BO3）3 has been grown by the Czochralski method. The spectroscopic characterizations have been investigated at room temperature. The Yb^3＋：Ba3Gd（BO3）3 crystal exhibits broad absorption at 976 nm with FWHM of 7 nm and large overall spitting of ^2F7/2 manifold （823 cm^-1）. The absorption and emission cross sections are 5.09×10^-21 cm^2 at 976 nm and 0.97×10^-21 cm^2 at 1040 nm, respectively. The fluorescence lifetime is 2.84 ms.
A DNA biosensor with [Ru（DA-bpy）3]Cl2（DA-bpy：4,4＇-diamino-2,2＇-bipyridine） （RuL） as the electrochemical probe was prepared on pyrolytic graphite electrode （PGE） through the supramolecular interaction between RuL complex and DNA template. Cyclic voltammetry of RuL-DNA film showed a pair of stable and reversible peaks corresponding to the Ru（Ⅲ）/Ru（Ⅲ） redox potential of-0.165 V versus AglAgCl in pa 7.4 0.1 mol·L^-1Tris-HCl. The electron transfer was expected across the double-strand DNA by an ＂electron tunneling＂ mechanism. When the DNA biosensor was immerged in gold （Ⅲ） buffer solution, the current peak signal （I） of the RuL-DNA supramolecular depressed and △I was linear in the concentration range of Au ion from 1×10^-7 to 2×10^-5 mol·L^-1 with a regression coefficient of 0.9879. The detection limit was 5×10^-8 mol·L^-1. The developed procedures were applied to the analysis of synthetic samples of real materials with good sensitivity and selectivity.
