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Energetic constraints on the creation of cell membrane pores by magnetic particles
Vaughan TE, Weaver JC
Biophysical Journal 71: (2) 616-622 AUG 1996

Naturally occurring and contaminant ferromagnetic and ferrimagnetic particles have been found within or near cells, and might allow pulsed magnetic fields to create transient cell membrane openings (''pores''). We show that this possibility is significantly constrained by the maximum rotational energy that can be transferred to the cell membrane. For single biologically synthesized magnetosomes (radius r(mag) approximate to 10(-7) m, magnetic moment mu approximate to 2 x 10(-15) A m(2)) and typical cell membranes, the estimated pulse magnitude must exceed B-0 approximate to 6 x 10(-3) to 7 x 10(-2) T, and the optimal pulse durations are in the range 10(-5) s < t(pulse) < 10(-1) s. For larger contaminant particles with larger net magnetic moments, the pulse magnitudes could be only somewhat smaller, and the optimal durations are about the same. Very large pulses that exceed the coercive force of a particle are predicted to have a smaller effective magnitude and shorter effective duration.