Abstract
CdSe/ZnS quantum dots (QDs) conjugated to biomolecules that quench their fluorescence, particularly dopamine, have particular spectral properties that allow determination of the number of conjugates per particle, namely, photoenhancement and photobleaching. In this work, we quantify these properties on a single-particle and ensemble basis in order to evaluate their usefulness as a tool for indicating QD uptake, breakdown, and processing in living cells. This creates a general framework for the use of fluorescence quenching and intermittency to better understand nanoparticle-cell interactions.
Highlights
The interactions of semiconductor quantum dots (QDs) with living cells remain poorly understood
QDs were conjugated to the neurotransmitter dopamine via the primary amine located on the opposite end of the molecule from the redox-active catechol
A strong dependence was observed of the number of EDCs per QD on the number of dopamine molecules that bound
Summary
The interactions of semiconductor quantum dots (QDs) with living cells remain poorly understood. No satisfactory explanation exists for differences in these properties among batches of particles there appear to be loose correlations with particle size, for nuclear entry [3]. Our previous work demonstrated that QD-dopamine conjugates (see Figure 1) can be used as static fluorescent labels, and as sensors for intracellular redox processes such as endocytosis, lysosomal processing, and mitochondrial depolarization [5]. This is due to the electron-donating properties of dopamine (DA), which permit this molecule to act as an electron shuttle between the nanoparticle and other molecules
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