Microemulsion-Confined Assembly of Magnetic Nanoclusters for pH/H2O2Dual-Responsive T2–T1Switchable MRI

In this work, a T2–T1switchable superparamagnetic iron oxide nanoprobe with a pH/H2O2dual response was obtained using a microemulsion method. This novel method for the controllable assembly of small iron clusters followed by their independent modification was reported, which could not be prepared by common synthetic methods. The size of the assembled nanoprobe was uniform and controllable, with a stable T2magnetic resonance imaging (MRI) signal under a single condition. When the nanoprobe was exposed to the tumor environment, the higher H+and H2O2concentrations at the tumor site could dissociate the nanoprobe and redisperse into small iron clusters. When this occurred, the T2MRI signal was converted into a T1MRI signal, achieving specific detection of tumors by a pH/H2O2dual-response T2–T1MRI.