NOVELTY - Hydrothermal synthesis of copper (Cu)-doped cadmium tellurium quantum dot of comprises preparing sodium hydrogen telluride (NaHTe) solution by reacting sodium boron hydride and tellurium (Te) powder in water in the presence of nitrogen at 80-100 degrees C, stirring for 1-8 hours, mixing cadmium (Cd) salts, water-soluble Cu salts, and modifying agent N-acetyl-L-cysteine solution in a three-necked flask at, adjusting pH to 7.0-9.0, adding oxygen and nitrogen, impregnating in 50 psi L-80 ml NaHTe solution for 40 minutes, transferring to hydrothermal reaction vessel, heating to 170-200 degrees C for 5-90 minutes.    USE - Hydrothermal synthesis of copper-doped cadmium tellurium quantum dot used as fluorescent nano-probe for biochemical analysis and in biomedical field.    ADVANTAGE - The hydrothermal synthesis is low cost, simple and environment-friendly, and produces high yield. The quantum dot has high stability, good compatibility and low toxicity.    DETAILED DESCRIPTION - Hydrothermal synthesis of copper (Cu)-doped cadmium tellurium quantum dot of formula CdxCu1-xTe comprises preparing sodium hydrogen telluride (NaHTe) solution by reacting sodium boron hydride (NaBH4) and tellurium (Te) powder at a molar ratio of 2:1-5:1 in water in the presence of nitrogen at 80-100 degrees C, stirring for 1-8 hours, mixing cadmium (Cd) salts, water-soluble Cu salts, and modifying agent N-acetyl-L-cysteine solution in a three-necked flask at a Cd2+ concentration of 0.0005-0.02 mol/L and Cd2+:Cu2+ molar ratio of 1:1 to 1:4, adjusting pH to 7.0-9.0, adding oxygen and nitrogen, impregnating in 50 psi L-80 ml NaHTe solution for 40 minutes, transferring to a hydrothermal reaction vessel, heating to 170-200 degrees C for 5-90 minutes. The molar ratio of Cd2+, Cu2+, and N-acetyl-L-cysteine, NaHTe is 1:1-4:1-3:0.1-0.8. The cadmium salt is cadmium chloride, cadmium bromide, or cadmium iodide. The Te powder has a particle size of 200 mesh and 99.8% tellurium content.    x=not defined.