title: Ultraviolet radiation synthesis of water dispersed CdTe/CdS/ZnS core-shell-shell quantum dots with high fluorescence strength and biocompatibility.
abstract: This study explored a simple and fast method utilizing ultraviolet (UV) irradiation to synthesize CdTe/CdS/ZnS QDs in aqueous solution. Based on the reaction of photolysis and chemical deposition, the CdS and ZnS shell can be successively deposited around the thiol-capped CdTe cores through the interaction of Cd²⁺/Zn²⁺ and S²⁻ produced by UV irradiation. The effect of the UV irradiation time, the ratios of thioglycolic acid (TGA)/Cd and TGA/Zn on the shell formation, shell stability, and the photoluminescence (PL) intensity of the QDs, was systematically investigated. Keeping the ratio of TGA/Cd, increasing UV irradiation time from 30 to 120 s, the blue-shift of the fluorescence emission peak position of CdTe/CdS QDs was observed. As the irradiation time increased continuously from 120 to 300 s, the red-shift of the emission peak position was observed. In the total irradiation time, the PL intensity of all the samples was enhanced. By applying 300 s irradiation on the samples, the emission peak was blue-shifted at a fixed TGA/Cd ratio of 1:1 and red-shifted at the ratios of 2:1, 4:1, 8:1, and 13:1. The PL intensity reached its highest value at the ratio of 2:1. The effect of TGA/Zn ratio on ZnS shell formation showed a similar progress. Under an optimum synthesized reaction condition, the particle sizes of CdTe core, CdTe/CdS core-shell and CdTe/CdS/ZnS core-shell-shell QDs were 2.6 nm, 3.4 nm, and 4.6 nm respectively. This study confirmed that with the core-shell-shell structure, CdTe/CdS/ZnS QDs had high anti-oxidability, photostability, and low toxicity. Therefore they can be further used in cell imaging efficiently.
authors.affiliation: National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
authors.forename: Bing
authors.initials: B
authors.lastname: Cai
authors.forename: Ming
authors.initials: M
authors.lastname: Liu
authors.forename: Hongsong
authors.initials: H
authors.lastname: Fan
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D019187:Cadmium Compounds / Q000737:chemistry*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D006801:Humans; D018613:Microscopy, Confocal; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence; D013440:Sulfides / Q000737:chemistry*; D013691:Tellurium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014867:Water; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D019187:Cadmium Compounds; D005456:Fluorescent Dyes; D013440:Sulfides; D017967:Zinc Compounds; C034939:cadmium sulfide; D014867:Water; C031238:zinc sulfide; D013691:Tellurium; C028337:cadmium telluride