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Small Photostable Photoswitchable Quantum Dots as Nanotools for Live Cell Imaging

S.A. Díaz, T.M. Jovin, E.A. Jares-Erijman
University of Buenos Aires, CIHIDECAR, CONICET, AR

Keywords: FRET, photochromism, quantum dots, EGF/EGF receptors

Abstract:

We have developed a novel surface architecture for the generation of biocompatible and stable photoswitchable quantum dots (psQDs). The system is based on Förster Resonance Energy Transfer (FRET) from a QD donor to diheteroarylethenes photochromic (PC) acceptors (pcFRET). The PC molecules are linked to an amphiphilic polymer that self-assembles, creating a lipophilic space in which the hydrophobic PCs are included and carboxyl groups facing the external aqueous environment. This produces small (~7 nm diameter) nanoparticles that are soluble in aqueous medium. psQDs retain the desirable properties of the original QDs, but their brightness can be tailored by light (UV-visible cycles). The modulation of emission monitored by bulk and single-particle steady-state and time-resolved fluorescence was 35-40%. The epidermal growth factor receptor (EGFR) is of far-reaching biomedical importance due to its overexpression and/or mutation in various types of cancer. The carboxyl groups of the psQDs provide the means for preparing EGF-QDs with a smaller radius, improving the determination of diffusion constants and transport rates. Another advantage is the possibility for modifying the psQDs at the single particle level, allowing FRAP experiments which will not require irreversible photobleaching but only a reversible transition to an off state, allowing for repeated measurements.
 
 
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