What is the Difference Between Zeta Potential and Nernst Potential

The main difference between zeta potential and Nernst potential is that zeta potential is the potential on the cell’s surface, whereas Nernst potential is the potential difference between the cell membrane.

Zeta potential and Nernst potential are two types of potentials that occur in nerve cells.

Key Areas Covered

1. What is Zeta Potential
– Definition, Features, Importance
2. What is Nernst Potential
– Definition, Features, Importance
3. Similarities Between Zeta Potential and Nernst Potential
– Outline of Common Features
4. Difference Between Zeta Potential and Nernst Potential
– Comparison of Key Differences

Key Terms

Nernst Potential, Zeta Potential

What is Zeta Potential

Zeta potential is the potential at the slipping plane. Here, the slipping plane is the interface that separates the mobile fluid from the fluid attached to the surface. Electrophoresis is the method of measuring zeta potential. The electric field causes the movement of the water. Therefore, the measurements must be made at the point where it is motionless. A microscope can be used to view the particles and determine their velocity. On the other hand, the velocity (V) of migration of a molecule is proportional to the electric field. However, the species’ charge (Z) is indirectly proportional to the frictional coefficient, f. The velocity can be related to zeta potential.

Figure 1: Zeta Potential

Furthermore, the zeta potential of the membrane can be determined by the measurement of streaming potential, which is an electrical potential originating when an electrolyte solution is driven through a porous material or a channel with charged walls. An electrolyte solution of known pH is forced through a channel formed between two membranes whose active layers are facing the solution to measure this potential. Then, two electrodes are placed at both ends of the channel, and the potential is measured at different pressures. Zeta potential is an important tool to measure the electrical charge of the membrane surface.

What is Nernst Potential

Nernst potential is the potential difference across the cell membrane that is exactly opposite to the net diffusion of a particular ion through the cell membrane. An essential characteristic of a functional cell membrane is the electrical potential difference across the membrane. The electrical potential across the cell membrane is necessary for signal transduction in nerve cells. Therefore, cell membrane act as batteries maintaining the electric potential differences across the cell membrane. However, concentration differences of ions between cell membrane results in the separation of charge across the cell membrane.

Figure 2: Membrane Potential

Moreover, each side of the cell membrane contains equal concentrations of ions. But when the concentrations are different on each side of the membrane, there will be more positive ions than negative ions on one side. Then, more positive ions move to the other side of the cell membrane through ion channels that allow to pass only positive ions. This type of diffusion is also called passive diffusion. The concentration difference of positive charge on one side of the membrane while a negative charge on the other side of the membrane. Nernst potential is the potential difference across the membrane.

Similarities Between Zeta Potential and Nernst Potential

• Zeta potential and Nernst potential are two types of potential differences occurring in the cell.
• They are essential for the determination of the ionic behavior of the cell.

Difference Between Zeta Potential and Nernst Potential

Definition

Zeta potential refers to the potential difference between the surface of a solid particle immersed in a conducting liquid (e.g., water) and the bulk of the liquid. Meanwhile, Nernst potential refers to the potential across the cell membrane that exactly opposes the net diffusion of a particular ion through the membrane.

Type

The zeta potential is the electrokinetic potential in colloidal dispersions, while the Nernst potential is the reduction potential of a reaction.

In the Cell

The zeta potential is the potential on the cell’s surface, while the Nernst potential is the potential difference between the cell membrane.

Conclusion

In brief, the zeta potential and Nernst potential are two types of potentials occurring in the cell. The zeta potential is the potential difference on an existing surface of solid particles when immersed in a conducting liquid. Also, it is the electrokinetic potential in colloidal dispersions. In the cell, zeta potential occurs on the surface of the cell. In comparison, Nernst potential is the potential across the cell membrane opposite to the net diffusion of a particular ion through the membrane. Also, it is a reduction potential. In the cell, it is a potential difference between the cell membrane. Therefore, the main difference between zeta potential and Nernst potential is their type of potential.   

References:

1. Zeta potential. Zeta Potential – an overview | ScienceDirect Topics. (n.d.). 
2. The Nernst potential. The Nernst potential – Nexus Wiki. (n.d.). 

Image Courtesy:

1. “Diagram of zeta potential and slipping planeV2” By Larryisgood – Own work (CC-BY SA 3.0) via Commons Wikimedia
2. “Membrane Potential” By smonsays – Own Work (CC-BY SA 4.0) via Commons Wikimedia