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Lasers in medicine and biophotonics: Tom Brown

Cellular Nano-Surgery:
Enhanced techniques for optical transfection by the control of femtosecond lasers

 

C.T.A. Brown¹*, X. Tsampoula¹, D. Stevenson¹, T. Cizmar¹, C. McDougall¹, F.J. Gunn-Moore² and K. Dholakia<sup>1

1</sup> Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, U.K.
² School of Biology, Bute Building, University of St Andrews, St Andrews, Fife, KY16 9TS, U.K.
* Tom Brown's email: ctab@st-and.ac.uk

The transfection of cellular materials, in which a membrane impermeable DNA plasmid is injected into a cell and a protein subsequently expressed, is an important technique for Life Science applications and is an active area of research.  Currently several different methods exist for implementing this functionality including electroporation, gene guns, viral vectors, ultrasound (sonoporation) and chemical based techniques.

In this presentation, we will outline the techniques that we have developed for the use of femtosecond (fs) lasers to target and transfect individual cells with high efficiency. The use of lasers to transfect cells offers several advantages including selected targeting, sterility, and the ability to combine with other optical techniques including micromanipulation and spectroscopic analysis. This technique was first described by Tirlapur et al in 2002 [1] and makes use of a fs-Ti:Sapphire laser source operating around 800nm.  In our work, we have demonstrated that average transfection efficiencies >50% may be obtained using this technique for large numbers of cells (n=4000) under optimised operating conditions.  By moving from a Gaussian beam to a pseudo-Bessel beam, we have shown that the critical alignment condition of the beam focus and the cell membrane can be greatly reduced allowing the development of a near alignment free optical transfection system, which when implemented using a spatial light modulator allows a point-and-click transfection system to be developed.  The use of fibre delivery of the laser radiation to the cell under study has also been investigated and we will show that optical transfection can be achieved using such methodology.  We will also show that when the temporal behaviour of the laser is controlled, we can obtain multiple functionality from the same laser and microscope system, using the laser operating in a CW mode to optically tweeze a cell to a particular reagent of interest followed by obtaining photoporation when the laser is operated in fs mode before switching the laser back to CW to optically tweeze the cell to another area of interest.

In conclusion, we have shown that high efficiency transfection can be obtained using fs-lasers and that careful control of the laser output in both spatial and temporal domains can lead to further enhancements of this technique.

[1] U.K. Tirlapur and K. Konig, Nature, 418, pp.290-291 (2002)

 

Back to Programme

 

AILU one-day technology workshop as part of the Industry and Technology Programme at Photon08.

Photonics is an enabling technology for many products in different sectors. Increasingly important in all areas this seminar is designed to highlight developments in laser technology as applied to medical and biophotonics areas. The burgeoning specialism of photonics in the medical sector is addressed in this one-day meeting as part of Photon 08.

Duncan Hand of Heriot-Watt University will be chairing the event.

This is a Medical Group event - for more information about the Medical Special Interest Group or to join contact the AILU Office.