Synthesis Of Ligand Functionalization And Water-soluble CdTe Quantum Dots And Their Application In Sensors

In recent years,the CdTe quantum dots（QDs）have attracted much attention for biological imaging,sensors,metal ions detection and other fields applications from its excellent optical properties.The aqueous synthesis of QDs with high quality have been the focus of extensive research.This paper investigated the synthetic route of mercaptopropionic acid（MPA）and nucleic acid aptamer（ssDNA fragment）functionalized CdTe QDs,and made the discussion the influence of the reaction conditions on the structure and the optical properties of the quantum dots,and put forward the principle of the nucleation and growth of the quantum dots.The interaction between the synthesized CdTe QDs and metal ions were constructed the sensors to detect metal ions.Furthermore,we discussed the influence of the parameters on the sensitivity of the sensors and analyzed its quenching mechanisms,which promoted the applications of quantum dots in the analysis field.（1）A facile one-step synthesis of MPA functionalized Cd Te QDs in aqueous solution has been developed.The optimum synthetic conditions were determined by the studied the effect of reaction parameters,including pH,reaction temperature,molar ratio of Cd²⁺:TeO32-: MPA: SC,on the growth of CdTe QDs.The as-prepared CdTe exhibited narrow size distribution,high quantum yield and strong fluorescence intensity.（2）Th use of CdTe QDs to optically detect Cu²⁺ based on the fluorescence quenching of QDs was demonstrated.As high sensitive fluorescent sensor,CdTe QDs was applied to optically detect Cu²⁺ based on the fluorescence quenching of QDs resulting from the addition of Cu²⁺ with different concentration.The Stern–Volmer quenching curve showed a good linear relationship in the range of 1 μM to 10 μM with detection limit of 0.235 μM.（3）A facile one-step synthesis of DNA functionalized Cd Te QDs in aqueous solution has been developed using MPA and ssDNA（dna1）as co-ligand.According to our research,the optimum synthetic conditions were determined by discussed the effect such as reaction time,pH,ssDNA concentration and sequence length of the ss DNA ligand,on the growth of CdTe QDs.Furthermore,the as-prepared CdTe QDs exhibited size controllability,good biocompatibility and high quantum yield.（4）The Cd Te QDs was synthesized by the DNAzyme（dna3）as ligand,which was recognized by Mg²⁺.DNA sensors for detection of Mg²⁺ was constructed by the DNA capped CdTe QDs with ssDNA（dna4）which was labeled with fluorescent dyes（Cy5）by Watson-Crick base-pairing.The DNA sensor showed that the linear response in the range of 1²0 nM between the of fluorescence intensity ratio of the CdTe QDs to Cy5 and the concentration of Mg²⁺.The detection limit of was 0.3 nM.