Dynamic structure factor of a lipid bilayer in the presence of a high electric field

Abstract

The influence of a high average electric field (∼1 V/nm) in the hydrophobic interior of a bilayer lipid membrane on short-wavelength in-plane phononic motions of lipid chains is considered. The average electric field is assumed to be nearly constant on a picosecond time scale and a nanometer length scale. This field may be induced, for instance, by externally applied subnanosecond electric pulses or the membrane dipole potential. Using a generalized hydrodynamic approach, we derive a corresponding electrohydrodynamic model generalized to high wave numbers. In the considered approximation, all electric field effects are reduced only to a constant contribution to the generalized isothermal compressibility modulus. The corresponding dynamic structure factor for a lipid bilayer is derived. We show that due to polarization effects, the high field can critically impact the dynamics of longitudinal acousticlike modes at wave numbers near the major peak of the static structure factor. We estimate quantitatively that for typical lipid bilayers, transverse high electric fields can cause strong phonon energy softening, enhancement of phonon population, and formation of a gap in the dispersion of excitation frequency. The results obtained agree with simulations of the initiation of lipid bilayer electropores, suggesting that the proposed model reproduces the essential features of the field’s impact on atomic density fluctuations. The proposed mechanism may have significant implications for the understanding of electroporation, passive molecular transport, and spontaneous pore formation in lipid bilayers.

Disentangling Memristive and Memcapacitive Effects in Droplet Interface Bilayers Using Dynamic Impedance Spectroscopy

“…However, the lack of a clear pinched hysteresis, in both cases, is likely due to the time-domain current signal (Figure 4a) becoming saturated with perturbations from over 40 separate sinusoidal waveforms (see Figure 2). Similar behavior has been reported for several electrochemical systems, both in the time domain using I-E scans, [32][33][34] and in the frequency domain with EIS, [35] and have been attributed to capacitively and inductively coupled memristive models. We also note that we had previously reported zero-crossing pinched hysteresis in the I-E and the q-E planes for the same DPhPC DIBs system as studied here, as expected for voltage-controlled memristive and memcapacitive systems.…”

“…It has been suggested that stress, which can be induced electrostatically through surface charge storage, is a driver for ion channel induction. [34][35][36][37] The fact that τ increases with increases in bias voltage suggests that additional energy must be expended to initiate surface charging, implying that interfacial ions respond in a kinetically slow fashion to strong interfacial forces. Indeed, ion-pairing and related interfacial interactions are essential to the assembly of soft-matter systems.…”

“…A large change in τ is indicative of a physicochemical transition induced by increasing charge density to the point where intermolecular interactions at the lipid-water interface are changed significantly. It has been suggested that stress, which can be induced electrostatically through surface charge storage, is a driver for ion channel induction [34][35][36][37]. The…”

Molecular Picture of the Transient Nature of Lipid Rafts

“…It is accepted that the collective dynamics of phospholipid bilayers plays an important role in cellular membrane mechano-transduction (i.e., the conversion of a mechanical stimulus into electrochemical activity) and the transmembrane passive transport of protons, water, ionic solutes, and other small molecules. − ,− Currently, it is an open question as to how molecular stress is distributed in membranes and how it propagates to influence membrane-bound mechano-sensitive macromolecules, such as enzymes and ionic channels, to name a few. Moreover, the onset of stress-driven processes remains practically unexplored .…”

Large amplitude density fluctuations in a lipid bilayer, induced by picosecond electric pulses, and their possible biotechnological applications

“…We earlier described one possible electroporation mechanism that consists in the formation of large amplitude density fluctuations on subnanometer length scales in the hydrophobic region of a lipid bilayer due to the impact of electric pulses [13,14]. Here, we argue that the formation of large amplitude, subnanometer density fluctuations in lipid bilayers, induced by high-intensity pulsed electric fields with picosecond durations, may produce lipid nanopores and change transmembrane transport with subsequent cellular responses, which could be of interest for the development of electroporation biotechnologies.…”