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: 13.59). 05/2009; 9(5):2193-8. DOI: 10.1021/nl901047u
Source: PubMed


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.

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    • "Tat peptide mediated delivery system QDs conjugated to cell penetrating peptide delivery from human immunodeficiency virus-1 transactivator protein Matan and Haya (2009), Chen et al. (2008) Peptide delivery system Arginine peptide is used to enhance delivery of sterptavidin –conjugated QDs into mammalian cells Ballou et al. (2004) Nanoscale mechanochemical method Using membrane penetrating nanoneedle Yum et al. (2009) Chitosan tumor targeted drug delivery QDs encapsulated with chitosan Yuan et al. (2010) Viral vector QDs encapsulated in viral capsule Dixit et al. (2006) Polymeric delivery system QDs were encapsulated by PEI-g –PEG Duan and Nie (2007) QDs: Quantum dots; MWCNT: Multiwalled carbon nanotube. "
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    ABSTRACT: Quantum dots (QDs) have captured the fascination and attention of scientists due to their simultaneous targeting and imaging potential in drug delivery, in pharmaceutical and biomedical applications. In the present study, we have exhaustively reviewed various aspects of QDs, highlighting their pharmaceutical and biomedical applications, pharmacology, interactions, and toxicological manifestations. The eventual use of QDs is to dramatically improve clinical diagnostic tests for early detection of cancer. In recent years, QDs were introduced to cell biology as an alternative fluorescent probe.
    Artificial Cells 06/2015; DOI:10.3109/21691401.2015.1052468 · 1.02 Impact Factor
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    • "Additionally, it is known that cytosol viscosity varies as function of sub-cellular environment and cell cycle [7], [8]. Our measurement of 9–12 cP is similar to that obtained for gold nanoparticles (<5 nm diameter) and quantum dots (26 nm diameter), which reported cytosolic viscosities of 20 cP (average) and 4–200 cP, respectively [30], [31]. Most similar to our system are measurements of the intracellular motion of endosomes containing cholera toxin, which showed a viscosity of 5 cP based on the diffusion coefficient, measured with fluorescence correlation spectroscopy, and an estimate of endosome diameter [32]. "
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    ABSTRACT: Lysosomes are membrane-bound organelles responsible for the transport and degradation of intracellular and extracellular cargo. The intracellular motion of lysosomes is both diffusive and active, mediated by motor proteins moving lysosomes along microtubules. We sought to determine how lysosome diameter influences lysosome transport. We used osmotic swelling to double the diameter of lysosomes, creating a population of enlarged lysosomes. This allowed us to directly examine the intracellular transport of the same organelle as a function of diameter. Lysosome transport was measured using live cell fluorescence microscopy and single particle tracking. We find, as expected, the diffusive component of intracellular transport is decreased proportional to the increased lysosome diameter. Active transport of the enlarged lysosomes is not affected by the increased lysosome diameter.
    PLoS ONE 01/2014; 9(1):e86847. DOI:10.1371/journal.pone.0086847 · 3.23 Impact Factor
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    • "The physical properties of culture substrates are found to widely affect the phenotypes and gene expression of a number of normal and cancerous cells [1], [17], [18], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55]. To respond to substrate stimuli, cells adhere to and spread on the substrate followed by sensing and processing both mechanical and chemical signals [26], [37], [44], [46], [49], [53], [55], [56], [57], [58], [59], [60], [61]. As we have previously shown [1], after 7-day culture on soft substrates, HCT-8 cells undergo an E to R transition characterized by R cells dissociating from the parent epithelial cell layer or cell islands. "
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    ABSTRACT: Human colon carcinoma (HCT-8) cells show a stable transition from low to high metastatic state when cultured on appropriately soft substrates (21 kPa). Initially epithelial (E) in nature, the HCT-8 cells become rounded (R) after seven days of culture on soft substrate. R cells show a number of metastatic hallmarks [1]. Here, we use gradient stiffness substrates, a bio-MEMS force sensor, and Coulter counter assays to study mechanosensitivity and adhesion of E and R cells. We find that HCT-8 cells lose mechanosensitivity as they undergo E-to-R transition. HCT-8 R cells' stiffness, spread area, proliferation and migration become insensitive to substrate stiffness in contrast to their epithelial counterpart. They are softer, proliferative and migratory on all substrates. R cells show negligible cell-cell homotypic adhesion, as well as non-specific cell-substrate adhesion. Consequently they show the same spread area on all substrates in contrast to E cells. Taken together, these results indicate that R cells acquire autonomy and anchorage independence, and are thus potentially more invasive than E cells. To the best of our knowledge, this is the first report of quantitative data relating changes in cancer cell adhesion and stiffness during the expression of an in vitro metastasis-like phenotype.
    PLoS ONE 11/2012; 7(11):e50443. DOI:10.1371/journal.pone.0050443 · 3.23 Impact Factor
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