Nanotech products are projected to account for 15% of products manufactured globally by 2014 with a large economic impact totaling ~ USD 2.6 trillion. There is a strong need to understand the stability of commercial nanomaterials (CNMs) in the environment upon disposal at the end of their useful life. It is however extremely challenging to simulate physical and chemical properties of CNMs after release into the environment. CNMs vary in composition, structure/morphology and surface coating/chemistry and their state of dispersion. We are investigating fundamental interaction of core-shell (coated) CNMs with dissolved organic matter (DOM) such as humic acid. We are developing optical-based model nanoprobes for studying interaction of DOM components with CNMs in real-time at the molecular/nanoparticle level.