Abstract: A nanoparticle comprising a ternary core comprising Cd, Zn and Se; and a shell comprising Zn and Y, wherein Y is Se or S or a combination thereof. The Cd and Zn are non-homogenously distributed in the ternary core such that the nanoparticle exhibits continuous photoluminescence for extended periods of time. Also provided are methods for preparing and methods of using the nanoparticles which exhibit continuous photoluminescence.