Numerous papers reporeted that centrifugation could be used to seperate free drug from drug-loaded nanoparticles. And newly prepared nanoparticles usually will be redispersed, centrifugated and washed several times to remove the free drug.
However, our data showed that centrifugation always leads to poor dispersion of nanoparticles and thus larger particle size and higher PDI. Is there any feasible method to solve the problem?
Thanks in advance.
Hi,
Try to dialysisf your NP's suspension against a counter dialysing solution (dextran for example), you will concentrate your suspension without agregation, and you will also remove some free drug and stabilizer.
have a look at this paper by C Vautier at al., How to concentrate nanoparticles and avoid agregation? Eur J Pharm Biopharm, 69, 2008: 466-475
Best regards,
Use dialysis in a solution that makes your drug loaded NPs stable.
It hugely depends. If your NPs are stable, i.e. do not dissolve, dialysis might be an option. You could use spin filters in the centrifuge. Size exclusion chromatography is a nice one. There are also machines which wash particle dispersion through osmosis (if I recall correctly).
Still the best way to wash most particles in gentrification due to the large dilution factor. Have you tried altering your procedure? You could centrifuge at lower speeds or for less time and only remove part of the supernatural. You could also reduce the number of wash cycles you do. You could also introduce a sonication step (if not there already) into your dispersion protocol.
Depending on size (and surface charge) of the nanoparticle prep SEC (i.e. a PD-10 column) may also be an answer.
Centrifugation and dialysis often cause aggregation. SEC with sephadex coloumn can be used for seperation of free drug and ultrafilteration can be used to concentrate the suspension.
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