I want to prepare microparticles by the water in oil emulsion solvent diffusion method, using vegetable oil instead of solvents. The problem is, the recovery of microparticles and elimination of oil. Can anyone suggest a recovery method?
I would first mix the product in oil with ethanol or IPA then using not to high centrifugal acceleration to separate the oil. If necessary repeat this for the separated oil phase.
Then it should be much easier to separate the microparticles from the alcohol compared to separation from the oil directly.
The product you would get should be microparticles in oil, if my understanding is correct. You can utilize centrifuge and aspirate most of the oil. Then, add acetone, Ethanol or IPA, sonicate to mix them, centrifuge the mixture and aspirate the waste. Repeating this process a few times would wash and separate the microparticles from oil.
Can you tell how big are your particles and wfom which material?
i used to prepare microparticles of whey and soy protein isolate by water in oil emulsion. In order to remove the oil, we centrifuged the sample at high speed, around 20000g. We recover the pellet (protein particles), and then we did 2 - 3 washes with a solution of sodium caseinate 3% by using an homogenizer and centrifuging.
To check if (most) of the oil has been removed, you can use then red nile (it stains lipids) and see the particles using CLSM.
If you need further information, don´t hesitate to ask me.
Good luck!
I would first mix the product in oil with ethanol or IPA then using not to high centrifugal acceleration to separate the oil. If necessary repeat this for the separated oil phase.
Then it should be much easier to separate the microparticles from the alcohol compared to separation from the oil directly.
I think first of all it would be helpfull, to know more about your material. Is it a metal... an oxide... or an organic material.
As far as I made my experience, the most efficient way is to induce a precipitation by changing the density or/and ionic strength of the solvent by adding some salts.
Anotherway could be to transfere the particles back to the water-phase by a phase-transfer-reaction. However, here you need a water-soluble strong to the nanoparticles binding surfactant.
Dear Darius, my material is a hydrophilic polysaccharide, the problem is how to eliminate oil without affect the structure of microparticles.
You may wash and settle several times with hexane. Then evaporate the residual hexane after the last washing step. This will not much change the polarity around the microparticles and should therefore have the least effect.
Okay, since I am not so experienced with this kind of particles, its hard to find the right anwser.
However, a fast look in the literature http://www.sciencedirect.com/science/article/pii/S1742706114001834
gives:
"The oil phase was then removed by phase separation and the resulting MPs were washed in PBS. The suspensions were filtered in aqueous medium (0.9% NaCl) through 5 μm nylon filters with a vibrating sieve machine then centrifuged for 10 min at 3,000g. The resulting pellets were suspended at 1.5% (w/v) in saline buffer and stored at 4 °C until use".
But I think you are already familiar with this article :-)
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