Where does gel collide?

In physical chemistry, a gel is a two-component system in which a dilute cross-linked network of molecules traps a liquid, giving a material that is mostly fluid by mass yet behaves as a soft solid; the instant the growing polymer first forms a network spanning the whole sample is the gel point. Flory’s Principles of Polymer Chemistry gives the theory of gelation and the critical conditions for network formation. The referent is a state of matter, a swollen cross-linked network, distinct from a lighting filter even though both were once called by the same word.[1]

Unit

The degree of cross-linking and the fraction of liquid held in the network

Recovery means

Not applicable

Measured by

Characterised by the gel point, elastic modulus, swelling ratio, and cross-link density

In biochemistry, a gel is the porous slab (typically polyacrylamide or agarose) through which an electric field drives charged molecules, so that proteins or nucleic acids separate by size as they migrate at different rates through the mesh. Laemmli’s 1970 method of sodium dodecyl sulfate polyacrylamide gel electrophoresis made such size-based separation routine and became one of the most cited techniques in biology. The referent is a separation matrix used as laboratory apparatus; it is physically a chemical gel put to a specific analytical use, and shares only the word with a stage-lighting gel.[2]

Unit

The pore size of the matrix (set by gel concentration) governing separation

Recovery means

Not applicable

Measured by

Read from band positions and migration distance versus molecular size after staining