Commonly-used Dyes in Laboratory

1
Commonly-used Dyes in Laboratory
2
Introduction

• Dyes commonly used in laboratories can be
  classified into natural dyes and synthetic dyes.
  Natural dyes mainly include hematoxylin and
  magenta, and synthetic dyes mainly include acid
  magenta, congo red, methyl blue, solid green,
  sudan III, eosin, basic fuchsin, crystal violet,
  gentian violet, neutral red, safranin, methylene
  blue and methyl green.

3
Natural dyes

• 1.1 Hematoxylin
• 1.2 Magenta

4
1.1 Hematoxylin

• Hematoxylin is a pigment extracted from the dried
  branches of hematoxylon (tropical legumes) and is
  one of the most commonly used natural dyes.
  Hematoxylin can not be used directly for dyeing.
  It must be exposed to ventilated place to become
  oxidized hematoxylin, and this process is called
  mature. The mature process of hematoxylin
  takes a long time, and the longer the time, the
  stronger the dyeing power. The dyed material will
  have a coloring power only under the action of a
  mordant such as a metal salt, so a metal salt is
  required in the preparation of the hematoxylin.
  Commonly used mordants are aluminum sulfate,
  potassium alum and iron alum. Hematoxylin is a
  pale yellow to rust purple crystal, and it is
  easily soluble in alcohol, slightly soluble in
  water and glycerin. Hematoxylin is an excellent
  material for staining cell nuclei, which can
  differentiate different structures in cells into
  different colors.

5
1.2 Magenta

• Magenta is also called carmine or kermes. Magenta
  is produced by extracting a dried female tropical
  cochineal worm red, and then removing the
  impurities with alum. Separate magenta cannot be
  used for dyeing and can only be used for dyeing
  after it has been dissolved in an acidic or
  alkaline solution. Commonly used acidic solutions
  are glacial acetic acid and picric acid, commonly
  used alkaline solutions are ammonia, borax and
  the like. Magenta is an excellent dye for the
  nucleus, and stained specimens are not easily
  faded. Magenta is suitable for staining of
  sections or tissues, and is particularly suitable
  for overall dyeing of small materials. The color
  can be maintained for several years after dyeing
  with a solution prepared from magenta.

6
2 Synthetic dyes

• 2.1 Acid magenta
• 2.2 Congo red
• 2.3 Methyl blue
• 2.4 Solid green
• 2.5 Sudan III
• 2.6 Eosin
• 2.7 Basic fuchsin
• 2.8 Crystal violet
• 2.9 Gentian violet
• 2.10 Neutral red
• 2.11 Safranin
• 2.12 Methylene blue
• 2.13 Methyl green

7
Synthetic dyes-introduction

• Synthetic dyes, namely aniline dyes or coal tar
  dyes, come in many varieties and are widely used.
  Its shortcoming is that it is easy to fade after
  exposure to sunlight, and synthetic dyes such as
  aniline blue, bright green, and methyl green are
  more likely to fade. However, if you pay
  attention to the pH during dyeing and avoid
  direct sunlight, the color can remain for several
  years.

8
2.1 Acid magenta

• Acid magenta is an acid dye that is red powder,
  soluble in water and slightly soluble in alcohol
  (0.3). It is a good cell staining agent and is
  widely used in animal cell staining. It can also
  be used for the staining of parenchyma cells and
  cellulose walls in the cortex and pith of plants.
  Tissue sections are immersed in acidic water
  prior to staining to enhance staining power.

9
2.2 Congo red

• Congo red is an acid dye that is jujube red
  powder, soluble in water and alcohol, and blue in
  acid. It can be used as a dye and an indicator.
  It is often used as a liner for hematoxylin or
  other cellular dyes in plant staining. When Congo
  red is used to stain the cytoplasm, it can dye
  the gel or cellulose red. It is used to dye nerve
  shafts, elastic fibers, embryo materials, etc. in
  animal tissue preparation. Congo red can be
  double-stained with hematoxylin and can also be
  used for starch-like staining. Since congo red is
  soluble in water and alcohol, washing and
  dehydration must be rapid.

10
2.3 Methyl blue

• Methyl blue is a weak acid dye that is soluble in
  water and alcohol. Methyl blue is widely used in
  the cell staining of animals and plants. It can
  be used in combination with eosin to stain nerve
  cells and is an indispensable dye in bacterial
  preparation. Its aqueous solution is coloring
  agent for protozoa. Methyl blue is extremely
  oxidizable, so the color cannot be preserved for
  a long time after being dyed with methyl blue.

11
2.4 Solid green

• Solid green is an acid dye with a solubility of
  4 in water and a solubility of 9 in alcohol.
  Solid green is a dye for the staining of
  cellulose cell tissue containing pulp. It is
  listed as the three most commonly used dyes in
  plant histology along with hematoxylin and
  fragrant red.

12
2.5 Sudan III

• Sudan III is a weakly acidic dye in the form of a
  red powder that is readily soluble in fats and
  alcohols. Sudan III is a coloring agent for fat.

13
2.6 Eosin

• There are many types of eosin dyes. The commonly
  used Eosin Y is an acid dye, a small crystalline
  with a reddish blue color or brown powder,
  soluble in water (solubility is 44 at 15 C) and
  alcohol (solubility in anhydrous alcohol is 2).
  Eosin is widely used in animal cell staining and
  is a good cytoplasmic dye. It is often used as a
  lining agent for hematoxylin.

14
2.7 Basic fuchsin

• Basic fuchsin is a basic dye that is dark red
  powder or crystalline, and it is soluble in water
  and alcohol. Basic fuchsin is widely used in
  biological preparation and can be used to dye
  collagen fibers, elastin fibers,
  redness-reinforcing particles and nuclear
  material of central nervous tissues. Basic
  fuchsin is commonly used to identify
  mycobacterium tuberculosis.

15
2.8 Crystal violet

• Crystal violet is a basic dye with a solubility
  in water of 9 and a solubility in alcohol of
  8.75. Crystal violet is an excellent stain for
  cell, tissue and bacterial staining. It is
  commonly used for the staining of the nucleus. It
  can be used to highlight the centrosome of the
  chromosome and can be used for staining starch,
  fibrin, glial and the like. When safranin,
  hematoxylin can not successfully stain the
  nucleus, it may be possible to use crystal
  violet. Safranin and crystal violet can be used
  for the double staining of chromosomes, the
  chromosomes will be dyed red, and the spindle
  will be dyed purple, so crystal violet is also an
  excellent stain that can show the cell division
  process.

16
2.9 Gentian violet

• Gentian violet is a basic dye and is a mixture of
  crystal violet and methyl violet. When necessary,
  gentian violet and crystal violet can be used
  interchangeably. The main ingredient of the
  purple syrup used in medicine is methyl violet,
  which can be replaced with gentian violet and
  crystal violet when needed.

17
2.10 Neutral red

• Neutral red is a weakly basic dye in the form of
  red powder with a solubility of 4 in water and a
  solubility of 1.8 in alcohol. It appears yellow
  in alkaline solution, blue in strongly alkaline
  solution, and red in weakly acidic solution, so
  it can be used as an indicator. Neutral red is
  non-toxic and is often used for the dyeing of
  living body. It can be used to dye protozoa and
  show the contents of living cells in animal and
  plant tissues.

18
2.11 Safranin

• Safranin is a basic dye that is soluble in water
  and alcohol. Safranin is commonly used to stain
  cells and animal and plant tissues. It can stain
  the nucleus, chromosomes, plant proteins, corked
  tissue, keratinized tissue, and sporangia.

19
2.12 Methylene blue

• Methylene blue is a basic dye in the form of blue
  powder with a solubility in water of 9.5 and a
  solubility in alcohol of 6. Methylene blue is an
  important dye for the nucleus, which has the
  advantage that the color is not too deep.

20
2.13 Methyl green

• Methyl green is a basic dye. It is green powder
  with a solubility of 8 in water and a solubility
  of 3 in alcohol. Methyl green is the most
  valuable dye for cells. It is commonly used for
  the staining of chromatin, and can be used
  together with acid magenta for the staining of
  xylem in plants.