Charge-driven Water Molecule Eversion And Signal Transfer In Nanotubes

Water is the material basis for human beings and all living things on the earth.In humans and other organisms,water is the reactant of many biochemical reactions,and the vast majority of activities take place with water as a carrier.Because of its unique structure and excellent physical and chemical properties,carbon nanotubes have a broad application prospect in the nano field.With proper parameter settings,water will form a stable one-dimensional water chain structure in carbon nanotubes,and its transport and turnover patterns in the tube have many interesting characteristics.Studying the transport laws of water and other biological molecules in protein channels is of great significance for understanding the microscopic processes in life activities and exploring the characteristics of signal transmission in organisms.Various organic molecules and charged ions use water as a solvent to pass through protein channels on cells,and various bioelectrical signals are also transmitted in the aqueous environment.However,protein channels contain complex structures and characteristics,and their effects on the transmission of microparticles and bioelectrical signals is not clear,so they are not suitable as an accurate model for molecular dynamics simulation of signal transmission using water as a carrier.But carbon nanotubes can also be used as a channel,and its structure is simple,and in some conditions it has similar characteristics to protein channels.Therefore,the carbon nanotube and water system is very suitable for simulating physical processes such as the transport behavior of water in biological channels and the transmission of bioelectric signals in channels.Several studies have shown that as a polar molecule,the orientation of the dipole of water molecules can be controlled by an electric field,so water molecules in carbon nanotubes should also be controlled by an applied electric charge or electric field.The results of some molecular dynamics simulations show that an external electric field can realize the adjustment of the orientation and flow direction of the water dipole in the tube.In this article,we use single-walled carbon nanotubes and SPCE model water molecules to study the one-dimensional water molecule chains confined in carbon nanotubes by means of molecular dynamics simulation.We explored the distribution probability of dipole orientation on the one-dimensional water chain in the equilibrium state.It is found that when the direction of the carbon nanotube tube axis is used as a reference,the dipole orientation is either the same or opposite to the tube axis direction,and the probability of distribution in the two directions is almost equal.We also investigated the regulation of dipole orientation in the case of external charge,and found that one elementary charge can change the dipole orientation of the water chain in the tube,and this change will move along the whole water chain,so that all the dipole orientations will become consistent.When a positive charge is added near the carbon nanotube,the angle between the orientation of the dipole and the tube axis will be small,and when a negative charge is added,the angle will be large.This suggests that the charge signal can be converted into the state signal of the orientation of the dipole,and this signal can be transmitted along the water chain.We also investigated the introduction of periodic vibrational charges near carbon nanotubes to simulate the regulation of one-dimensional water chain dipoles by periodic electrical signals.This is also to simulate the driving effect of bioelectrical signals on the particles in the channel.The simulation results show that,driven by the rectangular signal,the water molecules in the carbon nanotubes will have periodic flipping behavior,which means the orientation of the dipoles will change periodically.This suggests that a periodic electrical signal can also be converted into a state signal of orientation,and that the signal can be transmitted along a one-dimensional water chain in the tube.In the process of signal transformation and transmission,the response time of the signal will be controlled by the electric property of the driving charge,and the transmission distance and stability of the signal will also be affected by the period of charge vibration.