Mechanochemical delivery and dynamic tracking of fluorescent quantum dots in the cytoplasm and nucleus of living cells.

Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, Illinois 61801, USA.
Nano Letters (Impact Factor: 13.03). 05/2009; 9(5):2193-8. DOI: 10.1021/nl901047u
Source: PubMed

ABSTRACT Studying molecular dynamics inside living cells is a major but highly rewarding challenge in cell biology. We present a nanoscale mechanochemical method to deliver fluorescent quantum dots (QDs) into living cells, using a membrane-penetrating nanoneedle. We demonstrate the selective delivery of monodispersed QDs into the cytoplasm and the nucleus of living cells and the tracking of the delivered QDs inside the cells. The ability to deliver and track QDs may invite unconventional strategies for studying biological processes and biophysical properties in living cells with spatial and temporal precision, potentially with molecular resolution.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The growing potential of quantum dots (QDs) in applications as diverse as biomedicine and energy has provoked much dialogue about their conceivable impact on human health and the environment at large. Consequently, there has been an urgent need to understand their interaction with biological systems. Parameters such as size, composition, surface charge, and functionalization can be modified in ways to either enhance biocompatibility or reduce their deleterious effects. In the current study, we simultaneously compared the impact of size, charge, and functionalization alone or in combination on biological responses using primary normal human bronchial epithelial cells. Using a suite of cellular end points and gene expression analysis, we determined the biological impact of each of these properties. Our results suggest that positively charged QDs are significantly more cytotoxic compared to negative QDs. Furthermore, while QDs functionalized with long ligands were found to be more cytotoxic than those functionalized with short ligands, negative QDs functionalized with long ligands also demonstrated size-dependent cytotoxicity. We conclude that QD-elicited cytotoxicity is not a function of a single property but a combination of factors. The mechanism of toxicity was found to be independent of reactive oxygen species formation, as cellular viability could not be rescued in the presence of the antioxidant n-acetyl cysteine. Further exploring these responses at the molecular level, we found that the relatively benign negative QDs increased gene expression of proinflammatory cytokines and those associated with DNA damage, while the highly toxic positive QDs induced changes in genes associated with mitochondrial function. In an attempt to tentatively "rank" the contribution of each property in the observed QD-induced responses, we concluded that QD charge and ligand length, and to a lesser extent, size, are key factors that should be considered when engineering nanomaterials with minimal bioimpact (charge > functionalization > size).
    ACS Nano 05/2012; 6(6):4748-62. · 12.03 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We present here an alternative, force-based measurement method for the detection of intracellular cytoskeletal proteins in the live cell. High aspect ratio nanoneedles of 200 nm in diameter were functionalized with anti-tubulin antibodies and inserted, using an atomic force microscope (AFM), into live NIH3T3 cells, without affecting cell viability. Force curves were recorded during insertion and evacuation of nanoneedles from the cells, and used to analyse intracellular interactions of the nanoneedles with the microtubule cytoskeleton during evacuation from the cell. Disruption of microtubules led to a correlated time-dependent decrease in the measured intracellular binding forces, pointing to the high-sensitivity and high-specificity of this detection method. This analytical technique allows for real-time evaluation of the microtubule network in the live cell, without the need to use potentially harmful molecular markers as do conventional detection methods, and may prove beneficial in the diagnosis and investigation of cytoskeleton-associated diseases.
    Journal of Bioscience and Bioengineering 07/2013; · 1.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A dense diamond nanoneedle array is capable of rapidly and conveniently delivering fluorescent probe and drug molecules to a large number of cells. This simple approach paves the way for potential high-throughput delivery of genes, drugs, and fluorescent probes into cells without endocytosis.
    Advanced Healthcare Materials. 02/2013;


1 Download
Available from