Multiscale Simulations of Colloidal Nanostructures: Self-assembly, Ligand activity and Molecular delivery Petr Král Departments of Chemistry and Physics, University of Illinois at Chicago We present our collaborative experimental and theoretical studies of colloidal nanostructures. Structures and properties of these systems are simulated with quantum, atomistic, coarse-grained and mean-field computational methods. First, we discuss the selfassembly of colloidal nanoparticles of different sizes, shapes, material compositions, ligands and solvents in external fields. We illustrate that the lattice types and configurations of the self-assembled superstructures critically depend on the delicate balance of forces (vdW, Coulombic, magnetic, etc.) acting between the nanoparticles. Second, we discuss how the ligand nature determines the particle solvation, self-assembly, bioactivity, etc. Finally, we describe nanomedicines based on micelles with linear and branched copolymer monomers. We show their properties, discuss how they can deliver drugs, peptides, and nucleic acids, and clarify how they interact with biological membranes. In all these cases, detailed simulations are used to reveal the parameters of the studied systems with the goal to optimize them for numerous potential applications.