Once the drug loaded nanoparticles are prepared the nanoparticles needed to be separated from unloaded drug. we usually use dialysis or centrifugation.
1) during dialysis even the entrapped drug get released
2) when we use centrifugation method, the pellet formed cannot be re-dispersed completely.
I tried with chitosan, PLGA, PLA and PCL nanoparticles, the problem is same with all.
Can anyone suggest me the better method to separate the nanoparticles or please tell me the methods to reduce the aggregation of nanoparticles.
Centrifuging at lower RPM may form the loose pellet but in case of smaller nanoparticles the speed had to be increased.
Use of probe sonication to break pellet is also a bad idea as it may alter the morphology of the nanoparticles.
Hi Maruthi,
I would recommend tangential flow filtration (TFF) AKA cross-flow filtration to purify/concentrate the particles. Other concerns would be related to how you are producing the particles (e.g., emulsification / solvent evaporation).
Dear Dr. Joseph,
I am using solvent evaporation for PLGA, PLA and PCL where as Ionic gelation for chitosan nanoparticles.
Dear Nooshin,
Thanks for your suggestion, I will definitely try it this time.
Known aggregation issues for solvent evaporation include incomplete evaporation of the volatile organic solvent. You need to ensure that you stir the final emulsion long enough to remove volatile solvent from the hardening particles, otherwise they tend to aggregate after centrifugation because the polymer becomes tacky after when partially solvated by the remaining organic solvent. The time required to remove the volatile solvent can be determined by monitoring the mass of the final emulsion over time and determining the time point when (assuming your volume of continuous phase can dissolve the entire volume of aqueous dispersed phase) the rate of mass loss changes from first-order (due to volatile solvent evaporating from the dispersed phase) to zero-order (due to water evaporating from the aqueous dispersed phase). If the volume of dispersed phase saturates the volume of continuous phase (i.e., cannot be completely dissolved in the continuous phase), the initial rate of mass loss will be zero-order (due to volatile solvent evaporating under saturating conditions), first-order (due to volatile solvent evaporating under non-suturing conditions), then zero-order (due to evaporation of aqueous dispersed phase).
If you can use nanomagnetic particles to attach your drug then simple magnetic separation will serve the purpose. Place steel wool between ploes of an electromagnet and allow to flow your sample through it. Drug attahced nanomagnetic particles will stick to the steel wool and drug etc will flow.
Maruthi Prasanna did u get the problem solved?
if yes, plz tell me how?
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