Tumor microenvironment responsive nanozymes for multimodal imaging of tumors

Nanozymes exhibit immense potential and promising prospects in the realm of diagnostic imaging and tumor therapy, owing to their inherent physicochemical properties and enzymatic activities. With the further development and application of nanotechnology, nanozymes are expected to become an important tool in the field of medicine, providing new solutions for disease diagnosis and treatment. This review provides an overview of recent studies over the past five years on the application of nanozymes capable of responding to the tumor microenvironment (TME) in multimodal imaging, with a focus on hypoxia, acid pH, excess GSH and ROS. In addition, we present the current status of the development of several common multimodal imaging and related contrast agents, such as MRI/CT, MRI/PET, MRI/SPECT, PET/CT. Moreover, some thoughts on the challenges, future development, and clinical translation of tumor microenvironment-responsive nanozymes in the field of multimodal imaging are shared. This review aims to provide an up-to-date theranostic nanomedicine reference for those who focus on related fields, promote the progress of this interdisciplinary subject, and accelerate clinical translation.