Development of biomechanical models of electroporation

In an electroporation system, a biomechanical function is proposed, based on Newton's Second Law, for a small patch with proteins and lipids, in a cell membrane and on the positive or the negative side. Two biomechanical models of the critical potential deference /spl Delta//spl psi//sub 0/ of electroporation are developed from the function. One is expressed in terms of the Law of the Conservation of Energy and another one is presented in terms of the Impulse-Momentum principle. The two models elucidate that: /spl Delta//spl psi//sub 0/ is proportional to the mass m, the thickness L and the departure velocity v/sub L/ of the patch and the electric attraction force f between the patch and the cell membrane; /spl Delta//spl psi//sub 0/ is inversely proportional to the net charge q carried by the patch and the absolute temperature T of the system. A concept of work function /spl phi//sub w/ of electroporation is proposed and /spl phi//sub w/ is described as /spl phi//sub w/=q /spl Delta//spl psi//sub 0//2 in the first model. The second model particularly indicates that /spl Delta//spl psi//sub 0/ and the critical width /spl tau//sub 0/ of the externally imposed electric pulse can compensate each other. Many previous experimental results can be qualitatively explained with the two models. The essential and sufficient conditions of electroporation occurrence at the patch are proposed too. The essential condition is -qd/spl psi//dx>f and the sufficient condition is /spl tau/>/spl tau//sub 0/, where -d/spl psi//dx and /spl tau/ are the electric field at the patch and the pulse width respectively.