Highly fluorescent CdTe nanocrystals: Synthesis, characterization, property, mechanism, and application as a sensor for
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Highly luminescent CdTe quantum dots (QDs) were prepared through a fast, facile, and straightforward method. The crystal structure, particle size, optical properties as well as molecular interactions between the CdTe QDs and their capping agents have been investigated by high resolution transmission electron microscopy, selected area electron diffraction, scanning transmission electron microscope–energy dispersive x-ray spectroscopy, UV-vis absorption, photoluminescence, and Fourier transform infrared, respectively. The results illustrate that the CdTe nanoparticles exhibit cubic structure and the average crystallite size is 2.3 nm. Meanwhile, fluorescence and UV-vis spectroscopic techniques were used to study the interaction between hemin and the well-defined CdTe QDs. In weak basic media, the fluorescence of CdTe QDs was quenched notably by hemin, and the quenching values were proportional to the concentration of the quencher in a certain range. The quenching mechanism was discussed to be a dynamic quenching procedure, collisional process, and hemin as a fluorescence quencher donated its electron to CdTe QDs to occupy the hole and accordingly disrupted the electron–hole recombination.
I. INTRODUCTION
Recent experimental and industrial advances in the field of nanotechnology have boosted the development of interdisciplinary research, one of the most constructive and inspiring human pursuits.1,2 Semiconductor quantum dots (QDs), as a kind of increasingly important nanosized materials, have attracted great interests in many fields across the physical, chemical, and biological sciences and become well-established photoluminescent platforms for scientific and industrial applications.3–11 Compared with typical organic dyes and fluorescent proteins, semiconductor QDs offer several unique advantages, such as high absorption cross sections and narrow/symmetric emission spectra, which make them highly suitable for using as reporters for multiplexing assays.12–16 In addition, QDs exhibit high fluorescence quantum yields, high stability against photobleaching, and a pronounced resistance to photo- and chemical-degradation, endowing them the possibility of continuous or long-term monitoring slow biological processes.17,18 These unique properties of QDs make them appealing as in vivo and in vitro fluorophores in a variety of biological investigations.19–21 The controlled fluorescence quenching of QDs, such as CdTe, CdSe, ZnSe, CdS, and ZnS, has led to the development of a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2014.25 J. Mater. Res., Vol. 29, No. 5, Mar 14, 2014
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probes for sensing a variety of molecules such as enzyme, DNA, nitric oxide, anions, and cations.22–26 Hemin, the oxidized form of iron protoporphyrin IX, is an iron-containing complex and often can be regarded as an essential regulator of gene expression and growth promoter of hematopoietic progenitor cells. It is usually selected as an oxidant in several systems involving th
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