Composite nanoparticles with discrete domains of different materials, which are fused by solid-state interfaces, represent an emerging class of multifunctional lab-on-a particle architectures that underpin future advances in diverse applications.This type of nanostmcture combines materials with distinct physical and chemical properties to yield a unique hybrid nanosystem having multifunctional capabilities and tuned or enhanced useful properties, which may not be attainable in individual materials.