Malachite green (Solid Green Crystals O) is an N-methylated diaminotriphenylmethane dye used for coloring.

Instructions
I. Solution preparation:
1. Preparation of storage solution: Dissolve Safranin O in deionized water to prepare a 0.1%-1% (w/v) stock solution. If a higher solubility is required, a small amount of ethanol can be added to help dissolve.
Note: The stock solution should be stored in a dark place and refrigerated to avoid dye degradation.
2. Preparation of working solution: Dilute the storage solution to the required working solution according to experimental requirements.
II. Biological tissue staining
1. Sample fixation: Fix the tissue sample in formalin solution, dehydrate and embed. After slicing, prepare the tissue slices for staining.
2. Staining steps:
1) Place the tissue slices in Safranin O staining solution. The staining time is adjusted according to the sample type, generally 2-5 minutes.
2) If contrast staining is required, Fast Green or other suitable dyes can be used.
3) Use 70%-95% ethanol for graded decolorization until the dye in non-target areas is removed.
4) Sealing:
Seal the slide with neutral gum or other suitable sealing agent to prevent the sample from drying or dye loss.
5) Microscopic observation: Use an optical microscope to observe the staining results:
Cell nuclei and cartilage matrix will appear red.
Collagen fibers, extracellular matrix, etc. will appear green (if Fast Green is used as a contrast dye).
Precautions:
1) Operation safety: Wear gloves and goggles when using to avoid contact of dye with skin or eyes.
2) Dye storage: Safranin O is light-sensitive and should be stored in a dark place and refrigerated. Ensure that there is no precipitation in the dye before use.
3) Contrast staining: Select a suitable contrast stain (such as Fast Green) according to the purpose of the experiment.