I managed to make a suspensions of ZnO and TiO2 nanoparticles, in ethanol. I tried concentration of 5 mg/mL, it gave me the behaviour I expected, but you must try less concentrated, like 1 mg/mL and 0.5 to check the result. I would say to you test what suits best for your nanoparticle, and find out if there is any solvent that harm your compound. For ZnO I could use water, but for TiO2 water was not suitable, so I used ethanol.