Changes in the Optical and Electronic Properties of CdTe Quantum Dots By the Effect of Interaction with Free Radicals in Aqueous Solution

Tuesday, 3 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)


Quantum Dots (QDs) are semiconductor nanomaterials with interesting optical properties, which are dependent on the nanoparticle size, i.e., the quantization of the energy levels that lead to a confinement of the loaders. These nanoparticles exhibited a wide excitation spectrum along with a narrow emission (size-adjustable), high photostability and photobleaching resistance [1]. Generally, QDs consist of group II atoms (alkyls, metallic oxides or organic salts) and group VI (Se, S and Te). The luminescent properties present in this type of nanomaterials, in addition to an elevated area-volume relation, allow their application in the field of biological species sensors [2,3]. The physicochemical interaction QDs-molecule causes changes in the fluorescence emission intensity of the nanoparticle (quenching of the fluorescence), where such change is measurable. In the present work we studied the interaction of different sizes of CdTe QDs with 3 free radicals: 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 4-Amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), and hydroxyl radical (OH). Emission intensity spectra and lifetime decay curve were obtained by UV-Vis spectroscopy and fluorescence spectroscopy. On the other hand, transmission electron microscopy (TEM), dynamic light scattering (DLS) and X-ray diffraction (XRD), are used for the morphological and structural characterization of the CdTe nanoparticle. Finally, voltammetric profiles and impedance plots of QDs supported on electrodes were obtained before and after exposure to free radicals. The previous results have obtained important information about the interaction between QDs and free radicals, for which they constitute the fundamental bases for an eventual development of the sensors for these reactive species.