Quantum dots can enter cells in vitro via different routes: non-specific internalisation by endocytosis, specific uptake mediated by biomolecules attached to the quantum dots surface, microinjection, electroporation, and possibly by inducing plasma membrane damage. The different uptake mechanisms largely depend on the surface modifications made to quantum dots [1-5].

 

Non-functionalised quantum dots are only equipped with a basic coating that does not serve any additional biological function. Further details on this topic can be found in the article "Exposure - Studies Outside of Organisms - in vitro". Such non-functionalised quantum dots usually enter cells via endocytosis and most often end up in the cytoplasm. Certain types of quantum dots could also be detected in the cell nucleus. Furthermore, different coatings of non-functionalised quantum dots seem to influence their uptake behaviour. The more biocompatible (thus non-toxic) the coating renders the quantum dots, the less cellular uptake occurs [2,6-8].

 

Quantum dots can also be functionalised by attaching specific biomolecules like peptides or antibodies to the surface of the nanoparticles. Such (bio)molecules are known as functional groups or moieties (parts or portions). The mode of entry into the cells as well as the intracellular localisation of certain groups of quantum dots strongly depends on the respective choice of functional moieties attached to the quantum dots surface

Various imaging techniques make use of this behaviour. Specific staining of the plasma membrane or various intracellular organelles can be realised using quantum dots labelled with antibodies. Furthermore, selected protein markers such as immunoglobulin G can specifically identify and visualize breast cancer cells [2,9].

 

In summary, varying the coating of quantum dots can be used to selectively control the uptake behaviour of the nanoparticles into the cell. In addition, quantum dots equipped with specific biomolecules can be used to label and visualise specific cell types or intracellular structures.

 

Literature arrow down

  1. Jaiswal, JK et al. (2003), Nat Biotechnol, 21(1): 47-51.
  2. Maysinger, D et al. (2007), Eur J Pharm Biopharm, 65(3): 270-281.
  3. Chan, WC et al. (1998), Science, 281(5385): 2016-2018.
  4. Chen, F et al. (2004), Nano Letters, 4(10): 1827-1832.
  5. Voura, EB et al. (2004), Nat Med, 10(9): 993-998.
  6. Lovric, J et al. (2005), J Mol Med (Berl), 83(5): 377-385.
  7. Bottrill, M et al. (2011), Chem Commun (Camb), 47(25): 7039-7050.
  8. Chang, E et al. (2006), Small, 2(12): 1412-1417.
  9. Wu, X et al. (2003), Nat Biotechnol, 21(1): 41-46.

 

 

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