Tumor microenvironment-responsive contrast agents for specific cancer imaging: A narrative review

Abstract

Molecular imaging is of great significance for early diagnosis and timely treatment of cancer and disease, as well as basic medical and biological research. As personalized cancer treatment has become increasingly popular, the demand for more advanced imaging technologies has also significantly increased. Taking advantage of differences between the tumor microenvironment and normal tissue cells, tumor microenvironment-responsive or "turn-on" contrast agents have a higher signal-To-noise ratio and lower background interference compared with "turn-off" probes, which can remarkably improve the performance of tumor diagnostics. Thus, tumor microenvironment-responsive contrast agents can not only detect changes in the tumor microenvironment, but also have important significance for tumor diagnosis, prediction of invasion potential, evaluation of treatment effectiveness, planning of therapeutic regimens, and tumor prognosis. Herein, this review focuses on recent research progress of tumor microenvironmentresponsive intelligent probes, and highlights future research directions of tumor microenvironment-responsive contrast agents for precision diagnostics.