Toluidine Blue (Blutene chloride), a phenothiazine, is used as a biological stain, a hemostatic, and a dye for silk and wool. Blutene chloride is also used as a diagnostic aid for gastric neoplasms and oral, and used in the identification of the parathyroid gland in thyroid surgery.

I. Histological staining
1. Tissue section preparation: Cut tissue samples into thin slices and fix them.
2. Staining steps: Immerse the slices in Toluidine Blue solution, the common concentration is 0.05%-0.1%.
3. Staining time: Usually stain for 2-5 minutes and observe the staining effect.
4. Washing: After staining, wash the sample with water or PBS to remove excess dye.
5. Microscope observation: Use a microscope to examine the staining results. Toluidine Blue makes cell and tissue structures clearly visible, especially in acidic matrix components.
II. Special staining
1. Add Toluidine Blue solution to tissue samples at the required concentration and time.
2. Depending on the experimental design, it may be necessary to combine acid-base treatment to enhance the staining effect.
III. Staining of cells and organelles
1. Incubate cell samples or sections with Toluidine Blue solution.
2. Observe the staining pattern of cells and organelles under a fluorescence microscope.
IV. Cancer research and histological pathological diagnosis
1. After processing the tumor tissue sections, stain them with Toluidine Blue to analyze the histological characteristics of the tumor.