As the colloidal synthesis techniques of functional nanostructures are advancing at a fast pace, the systematic organization of these nanostructures for their optimal activity is also becoming equally important. Thus, in the last decades, self-assembly of nanostructures has been developing as an independent sub-field of colloidal synthesis methods. However, many challenges still remain to be solved for self-assembly to be a mature nanofabrication technology. The primary challenge is posed by the surface chemistry of the nanostructures. The wet chemical methods for colloidal nanostructure synthesis usually involve intricate chemistry of organic and inorganic reagents for shape and size control, and stabilization in the following chemical/physical processes. Colloidal nanostructures are often stabilized by organic ligands, surfactants, polymers, etc., that determine the surface chemistry. As most self-assembly techniques involve surface functionalization for hydrophobization, surfacecharge/pH control, further reactions, and so on, the surface molecules carried over from the wetchemical synthesis should facilitate the chemistry. For example, citrate capped Au nanoparticles can be easily replaced by thiol ligands. However, these thiol ligands once grafted onto the nanoparticle surface cannot be replaced by an amine ligand. For a certain material, it is not possible to define a fixed chemistry as different shapes and sizes of nanoparticles require different surface molecules in the synthesis process. The invention of compatible chemistry for different surface functionalization of different nanostructures synthesized via different routes remains the biggest challenge in the selfassembly techniques. This challenge is further compounded for hybrid nanostructures such as Janus structures, core-shell structures and so on. On this front, significant attention has been given to clickchemistry driven processes as a versatile route for joining nanoparticles with desired functionalizing molecules/groups. On a final note, self-assembly is a powerful technique complementary to wetchemical synthesis techniques towards functional interfaces. With the desired progress in this field, one can foresee a new paradigm in nanofabrication techniques which will enable tailor-made nanostructures to be used as building blocks of large-scale functional interfaces as well as bulk phases. R.B. acknowledges financial support from the University of Antwerp Special Research Fund (BOF) for a DOCPRO4 doctoral scholarship.