I am trying to make PLGA nanoparticles, I need it to be ~100nm.
I am using different methods, with the nanoprecipitation, this is the protocol:
76mg of PLGA (MW 12 kDa, 50:50 lactide/glycolide molar ratio). Prepared in 5mL of acetone. I heat with stirring for moments to dissolve the polymer. Then, I add 14mg of Pluronic1 F-108. Add them to aqueous (50 ml) solution under vigorous magnetic stirring and left to stir overnight (rate of addition of organic phase (1 mL/min) to aqueous phase).
The next day, I centrifuge at 10,000 rpm for 20 minutes (Not sure if I should convert that to xg or not), wash twice with diH2O (I get a problem in resuspend them, they adhere too much to the wall of the tube (50mL tube)). I found aggregations when I used higher speed and removed them by quick spin the sample and take the supernatant.
Then, I snap freeze them using liquid nitrogen, and finally lyophilized under vacuum for 48 hours.
For the characterization part: I am using Malvern Zetasizer ZS90. Reconstitute them after lyophilization in PBS "also tired diH2O". I add around 2-5mL. Then, serial dilution, 10uL of the sample into 990uL, the second is 20uL of the diluted into 980uL.
Every time I try different SOP, I got a very poor sample, either the Z-average (88-900) Or PDI which is always above 0.1 (0.3-0.8). And most of the time it stop and asks me to change the sample because it's poor.
I tried two samples and changed the following:
Speed of adding organic phase, it was drop-wise and 1mL/min
Speed of stirring during addition of organic phase, I used 360rpm
What should I change? The concentrations? The characterization part? Should I try different solvent or surfactant? The speed of centrifuge?
"""76mg of PLGA (MW 12 kDa, 50:50 lactide/glycolide molar ratio). Prepared in 5mL of acetone. I heat with stirring till it's clear"""
As I understand from what you have written that the 5mL acetone which dissolved the PLGA is evaporated before incorporate it to the aqueous !!
However, Your compound in which phase is dissolved !!
Please paraphrase your question so the researchers may help you !
I don't quite understand. But, I meant by clear that "no visible solid parts of PLGA" i.e. dissolved, not evaporation. The heating was momentary. I still have 5mL before continue the protocol.
I think the problem is with the Plutonic F-108. I have changed it and waiting to see the results.
Dear Ahmed,
I synthesized PLGA nanoparticles by the nanoprecipitation method without surfactant.
Please check my publication on Polymer for details.
Carina
Hi Ahmed
what is the size of your nanoparticles before freeze drying?
You could try with Tween 80 or Vitamin E TPGS instead of P-F 108, as surfactants.
Also try to reduce the time you leave the particles under stirring before centrifugation ( I used to go for 1 hour).
Also, I used to do 2 centrifugation steps, the first at lower speed (around 8000 rpm) to collect the first pellet,, followed by centrifugation of the supernatant at higher speed (11000 rpm).
Hope this helps
best
Clara
Thank you Dr. Mattu, I didn't check the size before freeze drying. I read about using Vitamin E TPGS. I will check that with your suggestions. That's very helpful, thank you.