I am using chitosan and alginate to make nanoparticles, they are in 170 nm size range. Before further study, I want to separate them from free polymer. I have tried centrifuge, but it's hard to disperse them afterwards. Also, there are still nanoparticles in the supernatant, which means centrifuge didn't really separate them. Chitosan and alginate form nanoparticles by electrostatic interaction, it easily aggregate if the speed is too high. I thought about dialysis,but chitosan and alginate are huge molecules, didn't find any membrane is big enough for them to go through. Does anyone have any idea how I could separate them? Thanks a lot!
precipitate free alginate with EtOH, or with Ca++. They will make non-nano particles that you can centrifuge. Or use the pH shift to precipitate chitosan. If you nano's dont respond to these methods, the free polymers will.
Perhaps try my favorite Anatop filters with 20nm pores? They may block if your sample is too concentrated.... Maybe also look at GE Healthcare Vivaspin products. Biggest molecular weight cutoff is 100,000. Smaller molecules pass through the membrane, leaving the nanoparticles pure in the top part of the centrifuge tube. Other companies make similar products - Google is your friend.
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