Dear Stella Dozie,

I would think about creation of repulsive force on the surface of nano particles by addition of organic steric hindrance  and deaglomeration by ultrasonic treatment.

Faithfully yours,

B. Djuricic

thank you sir, i will try centrifuging at a low speed  and then try your other reccommendations.

Stella Dozie may i ask u if u solved the problem?

if yes, would u please tell me how?