According to some articles results the relationship between the size of nanoparticles and their adjuvant is mysterious and often mirrored, some researchers showed that larger particles are more potent than smaller particles , while others showed the opposite. There were also data showing that the size of particles did not affect the resultant immune responses

thanks dear dr.Dhyaa

Please read the paper below

Article Relationship between the size of nanoparticles and their adj...

thanks dr.Mohamed

The required size depends on the field of  application,for instance applications based on the surface area and dispersion prefer nano sizes.

thanks dr.Hassan

Hi

Please see the link below i hope to be helpful for you.

https://www.google.iq/url?sa=t&source=web&rct=j&url=http://www.sciencedirect.com/science/article/pii/S0939641110003358&ved=0ahUKEwi146fY3rfYAhUMOJoKHayjBAkQFggaMAA&usg=AOvVaw0OQ_gO9dlILdRwfo4wYccT

Very good question, and I'm agree with Dr. Dhyaa A Abood

thanks for all answer