Voltammetric determination of size and particle concentration of Cd-based quantum dots

• Published in: Electrochimica acta 2015-06, Vol.166, p.100-106
• Main Authors: Martín-Yerga, Daniel, Bouzas-Ramos, Diego, Menéndez-Miranda, Mario, Bustos, Antonio R. Montoro, Encinar, Jorge Ruiz, Costa-Fernández, José M., Sanz-Medel, Alfredo, Costa-García, Agustín
• Format: Article
• Language: English
• Subjects: Electrochemical characterization; Nanoparticles; Quantum dots; Screen-printed electrodes; Voltammetry
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2015.03.051

In this article, we present two novel methodologies, using a simple electrochemical approach, for the determination of the size and particle concentration of Cd-based Quantum Dots (QDs), nanoparticles widely used as photoluminescent labels in many bioanalytical applications. Such QDs were analyzed directly in organic medium and in water after derivatization with an amphiphilic polymer. Screen-printed carbon electrodes modified with a bismuth film were employed as the electrochemical platform. The herein proposed methodologies allow the reliable determination of very low nanoparticle concentrations. Detection limits achieved with the selected experimental conditions were of 3.0×1012 nanoparticles mL−1 for CdSe QDs dispersed in organic medium and of 6.0×1012 nanoparticles mL−1 for water-solubilized CdSe/ZnS QDs (both with a core size of 3.26nm). However, detection limits could be improved increasing the QDs sample volume or the voltammetric deposition time. Furthermore, the proposed methodologies allowed the determination of the CdSe QDs diameters. Results obtained were validated after comparison with standard spectroscopic approaches. The electrochemical characterization of QDs, disclosed in this work, allows to perform a synthesis control with a simple, inexpensive and fast approach.