Temperature-responsive nanoparticles used in conjunction with hyperthermia promise to provide synergistic effects for increasing drug efficacy. We propose a near-infared (NIR) fluorescent system based on a upper critical solution temperature (UCST) polymer, ISP2, integrated with a NIR fluorescent dye HITC for in vivo tracking. The system forms a nanoparticle that increases its volume as temperature increases, similar to the expansion of a Hoberman sphere. The nanospheres nearly doubled in size, from 80 nm to 140 nm, during a temperature increase from 40°C to 60°C.