Agarose: Properties and Research Applications

What is Agarose?

Agarose is a polysaccharide that is isolated and purified from agar or agar-bearing marine algae (sea kelp). It is a natural polymer, made up of alternating β-D-galactose and 3,6-anhydro-L-galactose units of agarobiose in its chemical structure. The linear agarose polymer forms chains which create fibers that are flexible and form a web of channels with diameters from 50 nm to 200 nm, depending on the amount of agarose used.

How is Agarose Used?

Agarose is non-toxic and has several properties and specifications that make it useful as a gelling agent in many applications, such as nucleic acid electrophoresis, immunodiffusion techniques, gel plates or overlays for cells in tissue culture, cell culture media, gel chromatography, affinity chromatography, and ion exchange chromatography. Gel electrophoresis is a common life science laboratory technique used to extract biological molecules based on their size, such as in DNA separation and DNA detection.

Key Agarose Properties

• Sulfate content - Sulfate is the major ionic group present and is therefore used as an indicator of purity.
• Gel strength - The force that must be applied to the gel to fracture it.
• Gel point - The temperature at which an aqueous solution of agarose forms a gel upon cooling. Agarose solutions exhibit hysteresis when transitioning from liquid to gel. In other words, the gel point is not the same as the melting temperature.
• Electroendosmosis (EEO) – Refers to the transfer of liquid through a gel. The anionic groups of the agarose gel are attached to the matrix and cannot migrate, while the dissociable countercations migrate to the cathode within the matrix to generate EEO. Since electrophoresis of biopolymers is usually toward the anode, EEO can interfere with separation by internal convection.