A study of the interactions between nanocrystals in supercritical fluids for the solvophobic and solvophilic cases is presented. The model for the nanocrystal consists of a highly polarizable core and a passivation layer, both of which are uniformly composed of Lennard-Jones particles. A nonlocal integral equation theory is applied to study the excess and total potential of mean force between the nanocrystals. The effects of solvent density, and thickness and density of passivation layer, on the total potential of mean force and on solubility of nanocrystals in solutions is discussed. Important differences observed between solvophobic and solvophilic cases are analyzed in terms of the local solvent density profile around the nanocrystals. Interesting characteristic features, such as the disappearance of anomalous behavior previously reported by us for nonpassivated attractive solutes, are predicted. Certain qualitative feature observed in experimental studies of nanocrystal interactions in supercritical solvents are well reproduced within the model.