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Sigma-Aldrich

Gram′s safranin solution

for microscopy

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Synonym(s):
Safranin T solution
Empirical Formula (Hill Notation):
C20H19ClN4
CAS Number:
Molecular Weight:
350.84
Beilstein:
3924099
MDL number:
PubChem Substance ID:
NACRES:
MA.02

grade

for microscopy

Quality Level

form

liquid

shelf life

limited shelf life, expiry date on the label

composition

ethanol, 10%

technique(s)

microbe id | staining: suitable

color

red to very dark red

refractive index

n20/D 1.339

solubility

water: soluble at 20 °C

density

0.986 g/mL at 20 °C

εmax

4.0 at 532 nm in 50% ethanol

antibiotic activity spectrum

Gram-negative bacteria
Gram-positive bacteria

application(s)

diagnostic assay manufacturing
hematology
histology

storage temp.

room temp

SMILES string

[Cl-].Cc1cc2nc3cc(C)c(N)cc3[n+](-c4ccccc4)c2cc1N

InChI

1S/C20H18N4.ClH/c1-12-8-17-19(10-15(12)21)24(14-6-4-3-5-7-14)20-11-16(22)13(2)9-18(20)23-17;/h3-11H,1-2H3,(H3,21,22);1H

InChI key

OARRHUQTFTUEOS-UHFFFAOYSA-N

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General description

Gram’s safranin solution, also known as Safranin T or Basic Red 2, is a ready-to-use staining solution that comprises 10% safranin in ethanol. Safranin is a basic, cationic, azine dye containing a planar, diaminophenazine chromophore, with a phenyl substituent attached to a ring nitrogen. The trimethyl cationic form of safranine is lipophilic, whereas the dimethyl forms are weakly hydrophilic. It is most notably used in bacteriology as a counterstain in Gram staining to differentiate between Gram-positive and Gram-negative bacteria.

Application

Gram’s safranin solution has been used in the following applications:
  • as a non-toxic replacement for crystal violet for the quantification of biofilm formation
  • to develop a hyaluronic acid visualization method
  • to study improved β-lactam susceptibility against biofilm-embedded staphylococcus aureus by 2-aminothiazole

Features and Benefits

  • Ready-to-use solution.
  • Modified and designed in such a way that staining can be carried out in staining cells, on the staining rack, and in automated staining systems.

Principle

Gram staining enables the differentiation of bacteria into Gram-positive and Gram-negative. The mureine structure of the bacterial cell wall is the basis of the color affinity. Bacteria are first stained with crystal violet, and then with iodine solution, which forms a dye-iodine complex. This complex is retained in the multi-layer mureine structure of the cell wall of Gram-positive bacteria after decolorization, imparting a blue-violet color. The cell wall of Gram-negative bacteria comprises a single-layered murein structure that does not retain the dye-iodine complex, allowing the uptake of safranine counterstain, and imparting a pink-red color.

Pictograms

Flame

Signal Word

Warning

Hazard Statements

Hazard Classifications

Flam. Liq. 3

Storage Class Code

3 - Flammable liquids

WGK

WGK 2

Flash Point(F)

114.8 °F

Flash Point(C)

46 °C

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

Regulatory Information

危险化学品

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Conn's Biological Stains
Kiernan & Horobin
Conn?s Biological Stains (2002)
Quantification of biofilm biomass by staining: Non-toxic safranin can replace the popular crystal violet
Ommen, et al.
Journal of Microbiological Methods, 141, 87-89 (2017)
Visualization of a hyaluronan network on the surface of silicone-hydrogel materials
Katarzyna A Wygladacz, Daniel J Hook
Clinical Ophthalmology (Auckland, N.Z.) (2016)
Improved ?-Lactam Susceptibility Against ica-Dependent Biofilm-Embedded Staphylococcus aureus by 2-Aminothiazole
Sahra Kirmusaoglu
Clinical Laboratory (2020)
Alexandra Gonçalves et al.
Acta biomaterialia, 7(4), 1644-1652 (2010-12-07)
Cartilage tissue engineering (TE) typically involves the combination of a 3-D biodegradable polymeric support material, with primary chondrocytes or other cell types able to differentiate into chondrocytes. The culture environment in which cell-material constructs are created and stored is an

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