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The effect of CdSe–ZnS quantum dots on calcium currents and catecholamine secretion in mouse chromaffin cells

Paper ID Volume ID Publish Year Pages File Format Full-Text
7125 535 2011 11 PDF Available
Title
The effect of CdSe–ZnS quantum dots on calcium currents and catecholamine secretion in mouse chromaffin cells
Abstract

Semiconductor nanocrystal quantum dots (QDs) possess an enormous potential of applications in nanomedicine, drug delivery and bioimaging which derives from their unique photoemission and photostability characteristics. In spite of this, however, their interactions with biological systems and impact on human health are still largely unknown. Here we used neurosecretory mouse chromaffin cells of the adrenal gland for testing the effects of CdSe–ZnS core–shell quantum dots (5–36 nM) on Ca2+ channels functionality and Ca2+-dependent neurosecretion. Prolonged exposure (24 h) to commonly used concentrations of CdSe–ZnS QDs (≥16 nM) showed that the semiconductor nanocrystal is effectively internalized into the cells without affecting cell integrity (no changes of membrane resistance and cell capacitance). QDs reduced the size of Ca2+ currents by ∼28% in a voltage-independent manner without affecting channel gating. Correspondingly, depolarization-evoked exocytosis, measured at +10 mV, where Ca2+ currents are maximal, was reduced by 29%. CdSe–ZnS QDs reduced the size of the readily releasable pool (RRP) of secretory vesicles by 32%, the frequency of release by 33% and the overall quantity of released catecholamines by 61%, as measured by carbon fibers amperometry. In addition, the Ca2+-dependence of exocytosis was reduced, whereas the catecholamine content of single granules, as well as the kinetics of release, remained unaltered. These data suggest that exposure to CdSe–ZnS QDs impairs Ca2+ influx and severely interferes with the functionality of the exocytotic machinery, compromising the overall catecholamine supply from chromaffin cells.

Keywords
Semiconductor nanocrystals; Adrenal chromaffin cells; Voltage-gated Ca2+ channels; Membrane capacitance changes; Exocytosis; Amperometry
First Page Preview
The effect of CdSe–ZnS quantum dots on calcium currents and catecholamine secretion in mouse chromaffin cells
Publisher
Database: Elsevier - ScienceDirect
Journal: Biomaterials - Volume 32, Issue 34, December 2011, Pages 9040–9050
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering