Hi all,
Recently I saw quite a number of articles using 1-5% BSA to prevent nanoparticles from aggregation during freeze dry. Yet, I didn't figure out how they get rid of the BSA after that. Especially when we weigh the particles to prepare a solution with desired doses, we will have to be sure whatever we weigh is definitely nanoparticles. But I doubt that BSA also will precipitate down during the freeze drying process. Does anyone have experience on this?
Many thanks in advance!
Kenny
What is your nanoparticle? What is the capping agent? The existing capping agent may be enough to prevent aggregation upon freeze drying? BSA likely absorbs onto the surface of your nanoparticles protecting them during freeze drying. It may be difficult to remove after, as it may be tightly boud to the surface. Excess BSA will freeze dry along with your nanoparticles as part of the mixture, though you could remove excess, non-surface bound BSA via centrifugtion / diafiltration of your BSA-particles.
You may want to try other materials that protect your nanoparticles but may not absorb, e.g. PEG and washing in water & centrifugation cycles to remove this material, after freeze drying.
Related Question:
https://www.researchgate.net/post/How_to_remove_the_capping_agent_from_the_nanoparticle_surface_after_the_synthesis1
Using any sort of stabilizers might result in surface adsorption of the stabilizer on the nanoparticles. So, before and after freeze drying, centrifuge the mixture and check the stabilizer (BSA, PEG, etc.) concentration in the supernatant e.g. by Uv/Vis spectrophotometer. Calculate the adsorbed amount of the stabilizer (q=(Cinitial-Cfinal)*(Solution volume)/(nanoparticles mass)). If there is not a considerable surface adsorption of the stabilizer, you may use the stabilizer and tolerate the tiny amount of the mass gain!
John Clarkson
Hi John, very much thanks for your input! Actually my np is just plain silica nanoparticles without further surface modification so according to your thought, it may aggregate during freeze drying. I am taking note of your suggestion that PEG seems one better option. But can I know what is the mechanism behind, if PEG protects nps from aggregation not by physical absorption?
Ali Nematollahzadeh
Hi Ali,
Your input is very much helpful! I think NOW i could do some preliminary trial to see if what is the acceptable amount of BSA/PEG can be used for protection.
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanostructured Materials
- Nanoparticles