Polymer brushes tethered onto various surfaces and interfaces with specified functionalities have advanced surface modification in various applications including drug delivery, surface coatings, implantable-devices, flexible electronics, surfactancy, and sensing. Their properties can be tuned in response to different environments involving solvents, salts, pH,  and temperature by adopting multiple conformational states.  In this talk, I will present our efforts to develop fluorescent, polyelectrolyte decorated nanoparticles and discuss their surface and interfacial properties.