Abstract:
To accurately explore the molecular dynamics behavior of cell membranes and the formation process of nanochannels at the molecular level, avoiding the limitations of traditional experimental methods. These limitations include the challenges of directly observing dynamic changes at the molecular level and the restricted precision in controlling experimental conditions. In this paper, we introduce an innovative computer simulation scheme based on molecular dynamics, aimed at uncovering the intricacies of cell membrane molecular dynamics and nanochannel formation through meticulous simulation. Our new computer simulation approach encompasses two distinct steps: the initial construction of a 3D structural model and subsequent dynamic simulation. During the construction of the 3D model, we meticulously considered the real structure and composition of the cell membrane, ensuring that the model closely resembled actual conditions. By analyzing the impedance parameters of samples under various processing conditions, we selected impedance amplitude and phase angle as the electrical impedance indicators, as they sensitively reflect changes in the cell membrane's structure and function. Furthermore, we identified 15 measurement frequency points within the range of 0.05 to 300 kHz, spanning a broad spectrum from low to high frequencies. Based on these measurements, we assessed the impedance amplitude and phase angle of meat samples under different conditions, both before and after treatment. Comparative analysis revealed that varying processing conditions significantly impacted the integrity of the cell membrane, evident through changes in impedance amplitude and phase angle. To further validate and explore these findings, we constructed a 10 nm × 10 nm × 10 nm lipid bilayer structure model, inspired by the actual structure of the cell membrane, and performed molecular dynamics simulation calculations. During the simulation, we scrutinized not only the overall structural changes of the lipid bilayer but also evaluated its density distribution, mean square displacement, and radial distribution function. The results indicated that, within experimental conditions, the impedance amplitude of the sample decreased while the phase angle gradually increased with increasing electric field strength. During the molecular dynamics simulation, the lipopolysaccharide and phospholipid layers in the cell membrane structure maintained a stable configuration in the absence of an electric field and high salt conditions, without any loosening or dissociation, and no nanochannel structure was observed. However, upon applying an electric field of 4 kV/cm, nanochannel formation was evident. This phenomenon underscores the significant effect of an electric field on cell membrane structure, inducing nanochannel formation. In high-salt systems, NaCl tended to preferentially traverse these nanochannels, playing a crucial role in stabilizing the channel structure and enhancing its stability. Our findings suggest that 8% NaCl does not disrupt the order and structural dimension of the cell membrane at physiological levels. However, the introduction of pulsed electric field treatment accelerates the migration of lipid bilayer molecules, ultimately leading to the formation of nanochannels and disrupting the cell membrane's integrity. This degree of disruption is closely tied to the electric field's strength. Additionally, NaCl plays a positive role in stabilizing the porous structure and enhancing its stability in the high-salt system. These findings not only provide an important basis for us to better understand the molecular dynamics of cell membranes and the formation of nanochannels, but also provide new ideas and methods for research in related fields. The research findings provide references for optimizing brining processes and designing nanopores.