I am treating cells with water-soluble cholesterol. (https://www.sigmaaldrich.com/SG/en/product/sigma/c4951) Most papers recommend 1-10mM. Upon treatment of cells in medium, even within 10 minutes, I can see crystallization of the cholesterol.
How should I treat my cells with the cholesterol?
Thank you.
The product consists of cholesterol mixed with a cyclodextrin for solubility. The cholesterol accounts for about 4% by weight. The solubility is said to be 300 mg/ml in water (but it's probably lower in medium because of the higher ionic strength). In terms of cholesterol, that is 12 mg/ml solubility. (Free cholesterol is practically insoluble in water). The molecular weight of cholesterol is 386.6, so 12 mg/ml = 31 mM.
If you dissolve the cholesterol/cyclodextrin directly in the medium at the desired concentrations you wish to test, then let it stand for a while at the incubation temperature, you should be able to establish the maximum soluble concentration in your medium.
ago
The product consists of cholesterol mixed with a cyclodextrin for solubility. The cholesterol accounts for about 4% by weight. The solubility is said to be 300 mg/ml in water
Dear Alice Chan this seems to be a common problem when working with so-called "water-soluble cholesterol". Unfortunately I'm not a specialist enough to give you a qualified answer. However, as a chemist I might add that "water-soluble cholesterol" is in reality the inclusion complex cholesterol-methyl-β-cyclodextrin. As such it is not just a mixture of the two components, but the cholesterol is encapsulated in the cavity of the cyclodextrin. I'm pretty sure that the formation of this inclusion complex is reversible depending on factors like solvents and temperature. Thus I assume that it is advisable to always use freshly prepared solutions.
It might also be worth having a look at the answers given to the following closely related RG questions:
How to store water-soluble cholesterol?
https://www.researchgate.net/post/How_to_store_water-soluble_cholesterol
(3 answers)
and
How to complex cholesterol in B-cyclodextrin for better solubility and stability?
https://www.researchgate.net/post/How_to_complex_cholesterol_in_B-cyclodextrin_for_better_solubility_and_stability
(9 answers)
Good luck with your work and best wishes!
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