Does anyone have experience with preparation of chitosan nanoparticles encapsulating plasmid? I’m following a protocol where I heat up chitosan dissolved in acetic acid/sodium acetate (ph5.5) and pDNA in sodium sulfate up to 55°C. I mix both solutions to a 1:1 volume after 30 min of heating up in water bath and vortex for 30s at 2500rpm. Upon centrifugation at 12,000xg for 10 min there’s a translucent film like pellet observed. However, when I tried doing the same process without using plasmid to make blank chitosan NPs, there’s no pellet observed after centrifugation.
additionally is it better to dissolve chitosan in acetic acid by stirring without any heating up as it can change it's molecular weight/viscosity?
this film appears because of the antibacterial property of chitosan, increase the temperature this will obviously decrease the viscosity , it is recommended not to increase the temperature
Makhlouf Mohammed Rabeh
Mr. Makhlouf, do you mind elaboration on how antibacterial properties of chitosan is forming the film like substance after centrifugation?
forgive me if i'm wrong but i'm assuming that the nanoparticles formation by coacervation is based primarily on two ion interactions:
1) the sulfate anions from sodium sulfate cross links with chitosan that is positively charged.
Article Properties of Chitosan Nanoparticles Formed Using Sulfate An...
and
2) the positively charge amino group of chitosan with phosphate group of nucleic acid.
My question initially was also trying to understand if the lack of nucleic acid in the coacervation process leads to less formation of nanoparticles thus the lack of translucent film which represents the nanoparticles after centrifugation.
Thank you.
in microencapsulation, tiny solid particles or liquid droplets (your case is the plasmid) are covered with a thin film or coating material (chitosan in your case), if any of these are missing the process cannot occur, so logical that you did not find a pallet , when you use chitosan alone .
he coating is carried out through the NH3 + of chitosan which is positively charged in the acidic medium (this is a unified characteristic for a polymer) with the anio of the nucleaic acid, I think you will notice this
Hope the best for you .
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