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Proceedings Paper

Imaging heterostructured quantum dots in cultured cells with epifluorescence and transmission electron microscopy
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Paper Abstract

Quantum dots (QDs) are semiconductor nanocrystals with extensive imaging and diagnostic capabilities, including the potential for single molecule tracking. Commercially available QDs offer distinct advantages over organic fluorophores, such as increased photostability and tunable emission spectra, but their cadmium selenide (CdSe) core raises toxicity concerns. For this reason, replacements for CdSe-based QDs have been sought that can offer equivalent optical properties. The spectral range, brightness and stability of InP QDs may comprise such a solution. To this end, LANL/CINT personnel fabricated moderately thick-shell novel InP QDs that retain brightness and emission over time in an aqueous environment. We are interested in evaluating how the composition and surface properties of these novel QDs affect their entry and sequestration within the cell. Here we use epifluorescence and transmission electron microscopy (TEM) to evaluate the structural properties of cultured Xenopus kidney cells (A6; ATCC) that were exposed either to commercially available CdSe QDs (Qtracker® 565, Invitrogen) or to heterostructured InP QDs (LANL). Epifluorescence imaging permitted assessment of the general morphology of cells labeled with fluorescent molecular probes (Alexa Fluor® ® phalloidin; Hoechst 33342), and the prevalence of QD association with cells. In contrast, TEM offered unique advantages for viewing electron dense QDs at higher resolution with regard to subcellular sequestration and compartmentalization. Preliminary results show that in the absence of targeting moieties, InP QDs (200 nM) can passively enter cells and sequester nonspecifically in cytosolic regions whereas commercially available targeted QDs principally associate with membranous structures within the cell. Supported by: NIH 5R01GM084702.

Paper Details

Date Published: 11 February 2011
PDF: 12 pages
Proc. SPIE 7909, Colloidal Quantum Dots/Nanocrystals for Biomedical Applications VI, 79090N (11 February 2011); doi: 10.1117/12.875737
Show Author Affiliations
Erin M. Rivera, New Mexico State Univ. (United States)
Casilda Trujillo Provencio, New Mexico State Univ. (United States)
Andrea Steinbrueck, Los Alamos National Lab. (United States)
Ctr. for Integrated Nanotechnologies (United States)
Pawan Rastogi, Los Alamos National Lab. (United States)
Ctr. for Integrated Nanotechnologies (United States)
Allison Dennis, Los Alamos National Lab. (United States)
Ctr. for Integrated Nanotechnologies (United States)
Jennifer Hollingsworth, Los Alamos National Lab. (United States)
Ctr. for Integrated Nanotechnologies (United States)
Elba Serrano, New Mexico State Univ. (United States)
Ctr. for Integrated Nanotechnologies (United States)


Published in SPIE Proceedings Vol. 7909:
Colloidal Quantum Dots/Nanocrystals for Biomedical Applications VI
Wolfgang J. Parak; Kenji Yamamoto; Marek Osinski, Editor(s)

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