Composition-Tunable Optical Properties of ZnxCd1 − xS Quantum Dot–Carboxymethylcellulose Conjugates: Towards One-Pot Green Synthesis of Multifunctional Nanoplatforms for Biomedical and Environmental ApplicationsReportar como inadecuado




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Nanoscale Research Letters

, 12:443

First Online: 05 July 2017Received: 04 May 2017Accepted: 25 June 2017

Abstract

Quantum dots QDs are colloidal semiconductor nanocrystals with unique properties that can be engineered by controlling the nanoparticle size and chemical composition by doping and alloying strategies. However, due to their potential toxicity, augmenting their biocompatibility is yet a challenge for expanding to several biomedical and environmentally friendly applications. Thus, the main goal of this study was to develop composition-tunable and biocompatible ZnxCd1 − xS QDs using carboxymethylcellulose polysaccharide as direct capping ligand via green colloidal aqueous route at neutral pH and at room temperature for potential biomedical and environmental applications. The ternary alloyed QDs were extensively characterized using UV–vis spectroscopy, photoluminescence spectroscopy PL, transmission electron microscopy TEM, X-ray diffraction XRD, electron energy loss spectroscopy EELS, and X-ray photoelectrons spectroscopy XPS. The results indicated that ZnxCd1 − xS QDs were surface stabilized by carboxymethylcellulose biopolymer with spherical morphology for all composition of alloys and narrow sizes distributions ranging from 4 to 5 nm. The XRD results indicated that monophasic ternary alloyed ZnxCd1 − xS nanocrystals were produced with homogenous composition of the core as evidenced by EELS and XPS analyses. In addition, the absorption and emission optical properties of ZnxCd1 − xS QDs were red shifted with increasing the amount of Cd in the alloyed nanocrystals, which have also increased the quantum yield compared to pure CdS and ZnS nanoparticles. These properties of alloyed nanomaterials were interpreted based on empirical model of Vegard’s law and chemical bond model CBM. As a proof of concept, these alloyed-QD conjugates were tested for biomedical and environmental applications. The results demonstrated that they were non-toxic and effective fluorophores for bioimaging live HEK293T cells human embryonic kidney cells using confocal laser scanning fluorescence microscopy. Moreover, these conjugates presented photocatalytic activity for photodegradation of methylene blue used as model organic industrial pollutant in water. Hence, composition-tunable optical properties of ternary ZnxCd1 − xS x = 0–1 fluorescent alloyed QDs was achieved using a facile eco-friendly aqueous processing route, which can offer promising alternatives for developing innovative nanomaterials for applications in nanomedicine and environmental science and technology.

KeywordsSemiconductor quantum dot nanoparticles Nanomaterials Semiconductor-biopolymer interfaces Nanophotocatalyst Core-shell nanostructures  Download fulltext PDF



Autor: Alexandra A. P. Mansur - Herman S. Mansur - Anderson J. Caires - Rafael L. Mansur - Luiz C. Oliveira

Fuente: https://link.springer.com/



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