Study on the Effects of Humic and Fulvic Acids on Quantum Dot Nanoparticles Using Capillary Electrophoresis with Laser-Induced Fluorescence Detection

Abstract

The increasing production and use of quantum dot (QD) nanoparticles have caused concerns on the possibility of contaminating the aquatic and terrestrial ecosystems with wastes that may contain QDs. Therefore, studies on the behavior of QDs upon interaction with components of the natural environment have become of interest. This study investigated the fluorescence and electrophoretic mobility of carboxylic or amine polyethylene glycol (PEG)-functionalized CdSe/ZnS QDs in the presence of two aquatic humic substances (HS), Suwannee River humic and fulvic acids, using capillary electrophoresis with laser-induced fluorescence detection. Results showed initial enhancement in fluorescence of QDs at the onset of the interaction with HS, followed by fluorescence quenching at longer exposure with HS (>30 min). It was also observed that the electrophoretic mobility of QDs increases with increasing concentration of HS, suggesting an increase in the ratio in charge to hydrodynamic size of the nanoparticles. To determine if the QDs degraded upon interaction with HS, the QD-HS mixtures were dialyzed to separate free Cd2+ from intact QDs, followed by analysis of the solutions using inductively coupled plasma-mass spectrometry. Results suggested that degradation of QDs in the presence of HS did not occur within the period of incubation.

Suitability of analytical methods to measure solubility for the purpose of nanoregulation

“…In relation to nanomaterial characterisation, electrophoresis has been shown to be able to separate nanomaterial of different, size, shape and compositions (Keeney et al, 2009;Lin et al, 2007;Muralidharan et al, 2007). In particular, CE has been used to separate (for example): carbon nanotubes (Pauwels & Van Schepdael, 2012), gold (Liu et al, 2011), iron oxide (Baharifar et al, 2014), silica (Vanifatova et al, 2011), quantum dots (Celiz et al, 2011;Oszwaldowski et al, 2012), polystyrene (Liu et al, 2012b), core shell particles (Vanifatova et al, 2010) and others (Abdel-Haq & Bossù, 2012).…”

Capillary electrophoresis of quantum dots: Minireview

“…To follow quantitative information of free zinc or cadmium ICP‐MS in combination with CE‐LIF was used. Data obtained from research showed that there is no degradation of QDs in the environment, but they do not exclude influence of sunlight and other environment parameters which have not been considered here .…”

Current limitations and challenges in nanowaste detection, characterisation and monitoring

“…CE has proven to be an excellent approach for the separation of a range of ENMs as long as they are in a charged state in solution (e.g. Liu et al, 2005;Schnabel et al, 1997) and is a promising technique for environmental studies (Celiz et al, 2011;Zanker and Schierz, 2012). Despite the limited development of CE for the analysis of ENMs in nanowaste, the use of this technique for routine analysis of waste samples has been demonstrated.…”