A one-step synthesis of glutathione-capped ZnxHg1-xSe quantum dots (QDs) has been accomplished by reacting a mixture of Zn(ClO4)(2) and Hg(ClO4)(2) With NaHSe and using glutathione as surface-stabilizing agent. The fluorescent color of the alloyed QDs could be tuned by varying the Zn2+:Hg2+ molar ratio, reaction pH, intrinsic Zn2+ and Hg2+ reactivity toward NaHSe, and the concentration of NaHSe. The size, composition, and inner structures of these QDs are characterized using dynamic light scattering, inductively coupled plasma-mass spectrometry, and X-ray powder diffraction. By varying the molar ratio of Zn2+ to Hg2+ in the precursor solution, the ZnxHg1-xSe QDs exhibited a tunable PL wavelength in the range of 548-621 nm. These QDs offered advantages of short reaction time (1 h), low reaction temperature (95 degrees C), high quantum yield, water solubility and biocompatibility. Additionally, glutathione-capped Zn0.96Hg0.04Se QDs (quantum yield = 78%) have been applied for sensing Cu2+. (C) 2009 Elsevier Inc. All rights reserved.