[Barret]

I am trying to create Chitosan nanoparticles using the "emulsion crosslinking method".

I create an emulsion of Chitosan (3%wt in 1%ac.acid) in mineral oil (CS:OIL = 6:1), using span 80 as the surfactant, sonication and later adding glutaraldehyde saturated toluene for crosslinking.

My problem is that the particles created range in size from a few nanometers to micrometeres.
How can I make them monodisperse nanoparticles ONLY???

Could it be because of the high ratio of chitosan/ oil used? ...

...Or the high viscosity of the Chitosan solution?  I ve seen in literature up to 10% wt solution used but I cant dissolve more than 3% and that by using lots of sonication and heating (~70 C).

Thanks in advance for any answers!