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.

The above information is based on published literature. Experimental procedures should be appropriately modified to meet specific research demands.

DMSO: 30 mg/mL (82.21 mM), Sonication is recommended.