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Message | User | Date(yyyy-mm-dd) |
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Which membrane i should select? | qianxm | 2001-09-22 | Click here to register. |
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Dear Dave,
Thanks for your answer, which is helpful for me. To check if the Con A can diffuse through the liposome,I firstly should separate the un-encapsulated CON A and liposome.
As your suggestion, I think it is better for me to use some MWCO membrane (the sample I have only 2 ml/each preparation). According to your reply, I think, you may very an expert in this field. So would you please tell me in detail what is the difference of MWCO centrifuge filter and an regular ultrafiltration system(larger samples) in your reply?
On the other hand please tell me wich membrane i should book in Spectrum Company? The Con A molecular weight is 27,000-104,000. And the liposome now i prepared is 400nm. Now the sample I prepared is the mixture of free ConA and liposomes with ConA inside. If I select MWCO 300,000 as your suggestion, Can I get the liposomes without free Con A?
Thank you very much! I am loooking forward to your reply! I am sorry for giving you so much trouble!
Sincerely yours,
Xinming Qian
My mail address: S71, Apt6, University place, Stillwater, OK 74075
(Department of Chemistry,
Oklahoma State University,
Stillwater, OK 74078)
Tel: 405-3320815(H); 405-744-7307(O) | | |
| dave | 2001-09-24 | Click here to register. |
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 | Centrifuge filters are small ultrafiltration cups that hold small samples (less than 5 mL) and use a centrifuge to drive the liquid through the filter. I'm not sure if the force of the centrifuge would damage your liposomes. Spectrum does not manufacture centrifuge filters so I cannot select one for you.
Regular ultrafiltration involves a larger membrane and larger samples (usually at least 100 mL or so) and uses either gas pressure or a pump to drive liquid through the filter. Let it dialyze overnight.
I'm assuming the con A cannot leak out of your liposomes. If con A can get through the liposome membrane then, of course, there will always be some free in solution.
For your small samples, dialysis is probably an easier method. Use something like the part 131447 or 131450. Using 131447 (12 mm flat width, 300k MWCO) your dialysis sack would be 7.5 mm in diameter and about 4 cm long for your 2 mL samples. Using 131450 (16 mm flat width, 300k MWCO) the sack would be about 10 mm diameter and 2.5 cm long.
When you dialyze, the liquid outside the dialysis bag should have nearly the same composition as the material inside the bag (dialysizing concentrated buffers against pure water is not something to try the first time). |
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| qianxm | 2001-09-24 | Click here to register. |
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| Dear Dave,
Thank you very much!
But I want to know the number you told me, such as 131447 or 131450,come from which company. I can not find them in Spectrum Lab Products,Inc.. Please tell me that information, then i will book the memebrane today.
Thanks again!
Xinming Qian |
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| dave | 2001-09-24 | Click here to register. |
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| Sorry, there are several companies in the US named Spectrum Labs. The dialysis one used to be called Spectrum Medical. They can be reached by phone at (800) 634-3300. Their web site is at http://www.spectrapor.com and the page with the membranes I listed is at http://www.spectrapor.com/dialysis/CE.html
You can usually also get their products through Fisher Scientific and VWR Scientific as well as many other dealers. Many times the dealers will sell the products for less than the list price.
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