What is the use of gentian violet solution in biological experiments (I am currently in high school

In biological experiments, gentian violet solution stains chromatin (body).

To stain the chromatin (body) in the experiment, you must use alkaline stains such as gentian violet solution (also known as methyl violet solution) or acetic acid magenta solution. These stains are based on gentian violet or It is prepared by dissolving magenta acetate in an acetic acid solution. The prepared gentian violet solution has a pH value of less than 7 and is acidic.

Extended information:

As a stain, it must meet two conditions:

First, it must have color; second, it must have affinity with the stained tissue.

The color of the dye and its affinity with the tissue are determined by the molecular structure of the dye itself. The chromophoric group that produces the color and the auxiliary chromophore group that produces the affinity with the tissue are determined simultaneously. The dyeing properties of the dye. As a dye substance, in addition to a chromophoric group, it also needs an auxiliary chromophore group that ionizes the compound.

For example, dye compounds often form chromophoric groups from nitro, azo, vinyl, etc., while acidic groups such as -OH and -COOH and basic groups such as -NHCH? The group constitutes the auxiliary group. They ionize the dye substance, promote the interaction between the dye and the tissue, and produce the dyeing effect. We refer to dyes with acidic or basic groups in the auxiliary group as acidic or basic dyes respectively.

For example, nitro is a chromophore group. When three hydrogen atoms in the benzene ring are replaced by three nitro groups, it becomes a yellow compound of trinitrobenzene. Trinitrobenzene is not a dye, it has only one chromophore group. It is insoluble in water, cannot be ionized, is neither acidic nor alkali, and cannot form salts with acids or bases.

If a hydrogen atom is replaced with a hydroxyl group in the trinitrobenzene molecule, it becomes trinitrophenol, which is picric acid. It is a yellow dye that has ionization effect and can react with strong alkali. To form a salt, the hydroxyl group here is the auxiliary group.

It can be seen that the color of picric acid is caused by the chromophore group, and its dyeing performance is formed by the auxiliary group (hydroxyl group). If the amino group is used instead of the nitro group, it will Forms a colorless compound, not a dye. It can be seen that as a dye, there must be a chromogenic group and an auxiliary group that cooperate with each other, and both are indispensable.

Therefore, the definition of acidic dye is not determined by the pH value of the dye solution, but by the charge of the auxiliary group in the dye substance after ionization. Generally speaking, dyes with positively charged auxiliary groups are called basic dyes, and vice versa are acidic dyes.

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