水溶性CdTe量子点的制备和表面修饰及表征

Synthesis,Surface-modification and Characterization of CdTe Quantum Dots

近年来,半导体纳米晶CdTe引起人们越来越多的关注。它具有吸收光谱宽,发射光谱窄而对称,发光颜色可调,荧光强度和光稳定性高等特点,已经广泛用于生物标记,生物传感及生物检测领域。尤其在基于荧光共振能量转移原理的生物传感领域,量子点有望取代有机荧光发色基团作为能量供体。在文章实验中,以巯基丙酸(MPA)作为稳定剂,在水相中合成了CdTe量子点,并考察了回流时间,反应温度,溶液pH对CdTe光学性质的影响。利用透射电子显微镜(TEM),荧光分光光度计(FS)等手段对产物进行分析和表征。结果表明:在pH为9.1,反应温度为30℃,回流5 h,可以实现CdTe的优化合成。在紫外灯(254 nm)照射下,回流时间从1 h到7 h所得到的CdTe量子点,颜色由绿色变到黄色,对应的荧光光谱图的吸收峰位从515 nm(回流1 h)红移到573 nm(回流7 h),证实了CdTe量子点的尺寸随着回流时间的增长而增加。由TEM结果,所合成的CdTe量子点分散性好,且粒径大约在5 nm左右。该本实验制备的CdTe量子点具有较高的荧光强度和量子效率,将在生物标记,生物传感,生物成像等领域有重要作用。

CdTe quantum dots （QDs）, also known as semiconductor nano crystals, gained much more concerns in recent years. CdTe QDs can be used as luminescent materials in biolebeling （bioimaging） and fluorescent energy donor in biosensing based on the theory of fluorescence resonance energy transfer （FRET） for its excellent properties, such as broad and continuous excitation spectrum, narrow size-tunable, symmetric emission spectrum and high fluorescence quantum yield and so on. CdTe QDs, as inorganic nano luminescent and fluorescent materials, was a potential candidate to replace the organic fluorophores in some researching fields. In the current research, CdTe QDs were synthesized in aqueous phase using thioglycollic acid （TGA） as stabilizer and linker, and some optimum impacting factors were investigated. Morphology of the prepared QDs was determined on a transmission electron microscopy （TEM）. The spectral properties were investigated via fluorescence spectrophotometer. We found that optical properties of CdTe QDs is dependant on refluxing time, reaction temperature, and pH values, and the optimum conditions were proposed to be pH 9.1 under 96 ℃, and 5h of refluxing. Image of excited QDs fluorescent light under UV254 nm was record and data showed that the colors of QDs in aqueous solution were ranged from light green to yellow when refluxed from lh to 7 h. Correspondingly, a 58 nm of red-shift from 515 nm （CdTe QDs with refluxing for 1 h） to 573 nm （CdTe QDs with refluxing for 7 h） was detected on a fluorescent spectrum （FS）, which indicated the growth of QDs. TEM image showed well dispersed CdTe QDs, and size of QDs under optimum conditions was estimated to be ca 5 nm. The qualified CdTe QDs with high fluorescence was achieved, and it was expected that the synthesized QDs would be useful in the bioimaging, biolabeling, and biosensing area.