Intracellular dielectric tagging for improved optical manipulation of mammalian cells

Patience Mthunzi, Woei Ming Lee, Andrew Clive Riches, Christian Tom A. Brown, Frank J. Gunn-Moore, Kishan Dholakia

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Optical micromanipulation of transparent microparticles such as cellular materials relies upon the application of optical forces that are crucially dependent on the refractive index contrast between the particle and the surrounding medium. We briefly review the application of optical forces for cell manipulation and sorting, highlighting some of the key experiments over the last twenty years. We then introduce a new technique for enhancing the dielectric contrast of mammalian cells, which is a result of cells naturally taking up microspheres from their environment. We explore how these intracellular dielectric tags can influence the scattering and gradient forces upon these cells from an externally applied optical field. We show that intracellular polymer microspheres can serve as highly directional optical scatterers and that scattering forces can enable sorting through axial guiding onto laminin-coated glass coverslips upon which the selected cells adhere. Such internal dielectric tagging presents a simple, inexpensive, sterile technique to enhance optical manipulation procedures for cellular material and may enable new sorting techniques within microfluidic systems.

Original languageEnglish
Article number5361341
Pages (from-to)608-618
Number of pages11
JournalIEEE Journal on Selected Topics in Quantum Electronics
Issue number3
Publication statusPublished - 2010 May

Bibliographical note

Funding Information:
Manuscript received July 13, 2009; revised August 3, 2009 and August 24, 2009; accepted August 25, 2009. Date of publication December 28, 2009; date of current version June 4, 2010. This work was supported by the U.K. Engineering and Physical Sciences Research Council and the Council for Scientific and Industrial Research (CSIR), Pretoria, South Africa.

Funding Information:
P. Mthunzi is with the School of Physics and Astronomy, University of St. Andrews Scottish Universities Physics Alliance (SUPA), Fife, KY16 9SS, U.K., and also with the Council for Scientific and Industrial Research (CSIR), National Laser Centre, Pretoria 0001, South Africa (e-mail:

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering


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