Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula (CH3)2SO. DMSO is used frequently in cell banking applications as a cryoprotectant because it prevents intracellular and extracellular crystals from forming in cells during the freezing process. For most cryopreservation applications, DMSO is used at a concentration of 10%, and is usually combined with saline or serum albumin.
Hydrophobic peptides can be dissolved easily in DMSO. However, peptides in DMSO might be cytotoxic to cells, even though DMSO increases cell permeability. High concentrations of DMSO should never be used for cell culture. 5% is very high and will dissolve the cell membranes. Most cell lines can tolerate 0.5% DMSO, and some cells can tolerate up to 1% without severe cytotoxicity. However, primary cell cultures are far more sensitive. Therefore, if you are using primary cells a dose-response curve (viability) should be performed using DMSO concentrations <0.1%.
Try to dissolve very hydrophobic peptides in a small amount of DMSO (30–50 μl, 100%), and then slowly add the solution dropwise to a stirring aqueous buffered solution such as PBS (or your desired buffer) to the required concentration. If the resulting peptide solution begins to show turbidity, you have reached the limit of solubility. Sonication will help dissolve the peptides.
Rule of thumb:
0.1% DMSO is considered to be safe for almost all cells.
A final concentration of 0.5% DMSO is used widely for cell culture without cytotoxicity.
1% DMSO does not cause any toxicity in some cells, but 0.5% DMSO is recommended.
5% DMSO was used successfully in some cells.
To maintain a final concentration of 0.5%, you can make 200x stock in 100% DMSO.