Activity of CdTe Quantum-Dot-Tagged Superoxide Dismutase and Its Analysis in Capillary Electrophoresis.

Natalia Zaręba,Dominika Kunachowicz,Rene Kizek,Marta Kepinska,Łukasz Lewandowski

doi:10.3390/ijms22116156

Natalia Zaręba, Dominika Kunachowicz + Show 3 more

Open Access

https://doi.org/10.3390/ijms22116156

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Abstract

Quantum dots (QDs) have a broad range of applications in cell biolabeling, cancer treatment, metastasis imaging, and therapeutic drug monitoring. Despite their wide use, relatively little is known about their influence on other molecules. Interactions between QDs and proteins can influence the properties of both nanoparticles and proteins. The effect of mercaptosuccinic acid-capped CdTe QDs on intercellular copper–zinc superoxide dismutase (SOD1)—one of the main enzymatic antioxidants—was investigated. Incubation of SOD1 with QDs caused an increase in SOD1 activity, unlike in the case of CdCl2, which inhibited SOD1. Moreover, this effect on SOD1 increased with the size and potential of QDs, although the effect became clearly visible in higher concentrations of QDs. The intensity of QD-SOD1 fluorescence, analyzed with the use of capillary electrophoresis with laser-induced fluorescence detection, was dependent on SOD1 concentration. In the case of green QDs, the fluorescence signal decreased with increasing SOD1 concentration. In contrast, the signal strength for Y-QD complexes was not dependent on SOD1 dilutions. The migration time of QDs and their complexes with SOD1 varied depending on the type of QD used. The migration time of G-QD complexes with SOD1 differed slightly. However, in the case of Y-QD complexes with SOD1, the differences in the migration time were not dependent on SOD concentration. This research shows that QDs interact with SOD1 and the influence of QDs on SOD activity is size-dependent. With this knowledge, one might be able to control the activation/inhibition of specific enzymes, such as SOD1.

Highlights

Quantum dots (QDs) are semiconductor nanocrystals, often composed of atoms of elements from groups II–VI, or III–V [1]
Tials were: −40.8 mV, −42.8 mV, and −24.4 mV, respectively. These data are shown in FigWith the increasing sizea shift of QDs, a shift in their fluorescence spectra, from green (550 nm) to ure 1
QDs may activate Cu,Zn-SOD, which would mean that QDs could have an indirect antioxidant effect in vivo

Summary

Introduction

Quantum dots (QDs) are semiconductor nanocrystals, often composed of atoms of elements from groups II–VI, or III–V [1]. They are characterized by physical dimensions smaller than the exciton Bohr radius [2,3], the values of their confinement energy of the hole and the excited electron are related to their size [3,4]. As the size of QDs increases, their absorption onset and fluorescence spectrum shift from blue to red [5]. Due to the ability to influence the duration and temperature of the synthesis and the type of ligands used for the synthesis, the size and shape of QDs can be controlled [6]. QDs can be modified (e.g., by adding layers to their surface or by bioconjugation of ligands), which affects their physicochemical properties, such as water solubility and biocompatibility [9]

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