I conjugated 10mg carboxylatad graphene oxide with 2ml polyethyleneimine (2KDa) and zeta potential raised from -20 to -10. Have you done a similar reaction and what is your response in relate to zeta potential?
You had nanoparticles with negative -СOO- groups. You added an imine with positive -NH2- groups. The proton of water forms a bond by means of non-covalent nitrogen electrons of the imino group. Therefore, the zeta potential of nanoparticles varies.
Thanks for your attention. I know but I want to know that its zeta potential after conjugation with graphene oxide must be positive or negative in other words polyethyleneimine 2 KDa is able to raise zeta potential from -10 to for example +20.