I think you can perform Zeta potential analysis and adjust pH (if required) to select the right surfactant for the stability of nanofluids. Zetal potenial vs pH graph can give you a wide range of different types surfactants with their required concentration then you can choose the suitable one.

Zeta potential maybe only useful in case of electrostatic stabilization. Further in the nano-range there might be additional problems in using Zeta potential for orientation.

See also

Evaluation of particle interactions by in situ visualization of separation behaviour

http://www.sciencedirect.com/science/article/pii/S0927775712006917

Titus you are right.