Electrophoresis

Introduction to Electrophoresis

Electrophoresis is a technique used to separate charged particles, such as ions or molecules, under the influence of an electric field. This process is widely used in analytical and diagnostic laboratories to separate and analyze biomolecules, including proteins and nucleic acids.

• Principle: Charged particles migrate through a medium when subjected to an electric field, moving towards the electrode of opposite charge.

• Applications: Used for separation, identification, and analysis of biomolecules in research and clinical diagnostics.

Types of Electrophoresis

Electrophoresis can be classified based on the medium through which the particles migrate:

• a) Electrophoresis in free solution (capillary electrophoresis): Migration occurs in a liquid medium without any supporting matrix.

• b) Electrophoresis in porous bodies (such as filter paper, synthetic resins, gels): The medium acts as a support and can influence separation based on size and charge.

• c) Zone electrophoresis: Separation occurs in a defined zone, often used for analytical purposes.

Mobility of Particles

The mobility of a particle in an electric field is a measure of its velocity under the influence of the field, normalized by the field strength. It is defined as:

• Formula:

• Where: = mobility (m2 V-1 s-1) = velocity of the particle (m/s) = electric field strength (V/m)

• Interpretation: Mobility is a numerical value that expresses how fast a particle moves in a uniform electric field, under the influence of the field and at a constant current intensity.

Electric Current Intensity

The intensity of electric current represents the amount of electric charge passing through a cross-section of the conductor per unit time. It is given by:

• Where: = current intensity (Amperes, A) = electric charge (Coulombs, C) = time (seconds, s)

Electric Field Intensity

The intensity of the electric field is the force experienced by a unit charge placed at a point in the field. It is defined as:

• Where: = electric field intensity (V/m) = force (Newtons, N) = charge (Coulombs, C)

Force on a Charged Particle

The force acting on a charged particle in an electric field is given by:

• Where: = electric force (N) = elementary charge (C) = number of elementary charges on the particle = electric field intensity (V/m)

Components of Electrophoresis Apparatus

The main components of an electrophoresis setup include:

• 1 – Filter paper strip

• 2 – Sample application spot

• 3 – Buffer solution tank

• 4 – Metallic electrodes

• 5 – Power supply

Medical Importance of Electrophoresis

Electrophoresis is a crucial diagnostic tool in medicine, allowing for the separation and identification of various biomolecules, such as proteins and nucleic acids. It is especially important in the diagnosis of diseases that alter the composition of these molecules in biological fluids.

• Diagnostic Applications: Used to detect abnormal protein patterns in blood (e.g., in multiple myeloma, sickle cell anemia).

• Immunology: Helps in the identification of immunoglobulin classes and subclasses.

• Forensic Science: Used in DNA fingerprinting and analysis of biological samples.

Additional info: Electrophoresis is also used in research to purify and characterize nucleic acids and proteins, and in the development of new diagnostic assays.