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Author: Subject: Question about Liposomes
Boba155
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[*] posted on 17-5-2011 at 16:46
Question about Liposomes


Could anyone help me with this?

I was trying to encapsulate insulin into liposomes.

Every study I see calls for a Branson Probe Sonicator to sonicate them. Could I simply use an ultrasonic jewelery cleaner from Brooks Brothers instead?

Adding in large (>5000 daltons) insoluble molecules to the liposomes btw.

Thanks!
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watson.fawkes
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[*] posted on 18-5-2011 at 04:17


Quote: Originally posted by Boba155  
I was trying to encapsulate insulin into liposomes. [...] Adding in large (>5000 daltons) insoluble molecules to the liposomes btw.
Physically, the difference between using a probe sonicator and a jewelry cleaner is going to be amplitude of the standing pressure waves inside the vessel. If you use the jewelry cleaner as a double-bath, i.e. vessel-in-vessel, you're going to lose a lot of the amplitude vibrating the inner vessel (presumably glass). If you use it directly, you may have contamination problems. In addition, many consumer-level ultrasonic cleaners just aren't as strong as commercial units to start with.

Strength of the vibration matters if there are threshold effects in getting molecules to cross the boundary. I'd guess there are, but it's worth an experiment.

There are special kinds of materials used to transfer ultrasonic vibration. Quartz windows are evidently quite good. I also imagine that various high-quality steels have lower vibration loss after appropriate heat treatment. Neither of these, I imagine is particularly viable for you.
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phlogiston
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[*] posted on 18-5-2011 at 12:05


I tried both ways, and the tip sonicator was a lot faster, and even that took quite some time. To fully convert all the lipid to liposomes took about an hour, using a 5 seconds on/4 seconds off cycle. With the bath sonicator, I never got more than a small fraction of lipid converted into liposomes.



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Boba155
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[*] posted on 18-5-2011 at 14:01


phlogiston, did you use a simple jewelry cleaner?

I have an Avantii Lipid Ultrasonic Cleaner that clean deliver over 200 watts. Perhaps that will work better?

I wish I could use a probe sonicator, but it simply is far too expensive. Even the cheapest ones run for over a thousand bucks.
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phlogiston
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[*] posted on 18-5-2011 at 14:29


No, I used one in a chemical laboratory, but I don't recall the brand or power level and I now work in a different lab so I can't look it up easily. It's common use in the lab is to speed up dissolving some compounds.

An advantage of the bath sonicator is that you can fill your flask with an inert gas, preventing oxidation of your lipids (which is a common problem). With a tip sonicator, it is more work to set up a continuous flow of inert gas.




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Boba155
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[*] posted on 18-5-2011 at 14:48


Ah well.

I'll give the more powerful sonication bath a try. Hopefully it will work out!
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chemoleo
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phlogiston
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[*] posted on 19-5-2011 at 01:56


How are you planning to monitor liposome formation?



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