Core-shell quantum dots are colloidal particles consisting of a semiconductor core and a shell material as an outer coating layer.It can be utilized to develop sensitive methods for the detection of specific biological entities,such as microbial species,their transcription products,and single genes etc.The goal of current research is to synthesize CdTe and core-shell CdTe/ZnS quantum dots (QDs) with an improved process,and to investigate their properties.Well-dispersed CdTe core was prepared in aqueous phase with using 3-mercaptopropionic acid (MPA) as stabilizer and core-shell CdTe/ZnS QDs were then synthesized to improve the optical properties and biocompatibility.Various conditions were researched to obtain the QDs with the highest quantum yields,fluorescence intensity,and the well dispersion in size etc.The results indicated that the qualified CdTe were synthesized at pH 9.1,temperature of 100 ℃,refluxing for 5h,and tool ratio of Cd2+/Te2-/MPA is 1∶0.5∶2.4; the core-shell CdTe/ZnS was prepared under conditions of pH 9.0,temperature of 45 ℃,refluxing for lh,and mol ratio of CdTe/S2-/Zn2+ is 4/1/1.About 5 nm of CdTe core and 8-10 nm of core-shell CdTe/ZnS in size were achieved and confnrmed via high resolution transmission electron microscopy (HRTEM).Moreover,red shift of a maximum emission wavelength from 547 um of CdTe to 587 of CdTe/ZnS was observed via fluorescence spectrum (FS),which inferred the growth of QDs and formation of ZnS shells.Furthermore,the compositions of CdTe core and core-shell CdTe/ZnS were investigated with powder X-ray diffraction analysis (XRD),the results simultaneously suggested that CdTe core was doped or coated by the ZnS shells.FS results showed that fluorescent intensity changed gradually with the refluxing time ranged from 0h to 5h.The achieved ZnS shell make CdTe core less toxic and more biocompatible,it will be useful in biological labeling,diagnostic process and biosensing system based on fluorescence resonance energy transition (FRET).