title: Exploring the ultrashort pulse laser parameter space for membrane permeabilisation in mammalian cells.
abstract: The use of ultrashort femtosecond pulsed lasers to effect membrane permeabilisation and initiate both optoinjection and transfection of cells has recently seen immense interest. We investigate femtosecond laser-induced membrane permeabilisation in mammalian cells as a function of pulse duration, pulse energy and number of pulses, by quantifying the efficiency of optoinjection for these parameters. Depending on pulse duration and pulse energy we identify two distinct membrane permeabilisation regimes. In the first regime a nonlinear dependence of order 3.4-9.6 is exhibited below a threshold peak power of at least 6 kW. Above this threshold peak power, the nonlinear dependence is saturated resulting in linear behaviour. This indicates that the membrane permeabilisation mechanism requires efficient multiphoton absorption to produce free electrons but once this process saturates, linear absorption dominates. Our experimental findings support a previously proposed theoretical model and provide a step towards the optimisation of laser-mediated gene delivery into mammalian cells.
authors.affiliation: SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife, UK.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Rudhall
authors.forename: Maciej
authors.initials: M
authors.lastname: Antkowiak
authors.forename: Xanthi
authors.initials: X
authors.lastname: Tsampoula
authors.forename: Michael
authors.initials: M
authors.lastname: Mazilu
authors.forename: Nikolaus K
authors.initials: NK
authors.lastname: Metzger
authors.forename: Frank
authors.initials: F
authors.lastname: Gunn-Moore
authors.forename: Kishan
authors.initials: K
authors.lastname: Dholakia
mesh_terms: D000818:Animals; D016466:CHO Cells; D002463:Cell Membrane Permeability / Q000528:radiation effects*; D006224:Cricetinae; D007834:Lasers; D013997:Time Factors