Methylene Blue BB with C.I. Basic Blue 9

Basic Blue 9 is a classic dye with a long history, more widely known as Methylene Blue BB. It belongs to the phenothiazine class of dyes and has been extensively applied in numerous fields since it was first manufactured by BASF in 1876.

Physical Appearance: Generally dark green powder or fine crystals with bronze luster.

Solubility: Soluble in water and ethanol, delivering sky-blue aqueous solution. Approximately 1 gram of the product dissolves in 25 mL water or 65 mL ethanol.

Chemical and Optical Properties:

1)Redox Property: It features unique redox performance. The oxidized form appears blue, while the reduced form is colorless.

2)PH Discoloration: It turns yellowish brown in concentrated sulfuric acid and shifts to reddish yellow after dilution; olive green in concentrated nitric acid. Its aqueous solution will turn reddish brown upon contact with alkalis such as sodium hydroxide.

Color Fastness: As a basic dye, it generally has unsatisfactory color fastness. For instance, its light fastness is only Grade 2–3. When dyed on acrylic fibers, its wash, perspiration and ironing fastness can reach around Grade 4, yet light fastness remains Grade 2.

Safety Profile: Low-toxic substance with an oral LD50 of 1180 mg/kg in rats. However, it is irritant to eyes, respiratory tract and skin.

Basic Blue 9 (Methylene Blue BB) boasts an extremely wide range of applications covering industrial, scientific research, medical and other fields.

1. Industrial Dye

Textile Dyeing: Applied to dye fibers including cotton, linen, silk and acrylic fiber. Despite poor color fastness, it delivers bright and vivid shades.

Paper & Stationery: Used for tinting paper, bamboo and wood products, as well as manufacturing ink, carbon paper and ballpoint pen paste.

Others: Its double salt formed with zinc chloride can be adopted for leather coloring.

2. Laboratory & Scientific Reagents

Biological Stain: One of the most commonly used stains in histology and microbiology. It stains microscopic structures such as bacteria, cell nuclei and blood smears to facilitate observation and identification.

Viability Test for Microbes: Its redox property enables differentiation between live and dead microbial cells such as yeast. Live cells reduce the dye to colorless, whereas dead cells are stained blue.

Chemical Indicator: Serves as a redox indicator in analytical chemistry, and can also be applied for the determination of mercury, tin, perchlorate and other substances.

3. Medical & Pharmaceutical Uses

Antidote: A classic drug for the treatment of methemoglobinemia and cyanide poisoning.

Medical Stain: Sprayed on gastrointestinal mucosa during chromoendoscopy to identify dysplasia or precancerous lesions.

Pharmacological Activity: Acts as an inhibitor of soluble guanylate cyclase (sGC), monoamine oxidase A (MAO-A) and nitric oxide synthase (NOS).

Neuroprotective Research: Studies prove it can cross the blood-brain barrier and exhibits promising potential in research on neurodegenerative diseases such as Alzheimer’s disease.

4. Cosmetics

In cosmetic formulations, Basic Brilliant Blue 4R is primarily utilized as a colorant in certain hair dyes, eyeliners and other cosmetic products.

Basic Methylene Blue BB (Basic Blue 9) is a highly versatile multi-purpose dye. It not only plays an important role in traditional industrial sectors such as textile and paper manufacturing, but also serves as an indispensable reagent and pharmaceutical agent in biomedical research and clinical diagnosis and treatment.