Recent advances in matrix metalloproteinases-responsive nanoprobes for cancer diagnosis and therapy

Matrix metalloproteinases (MMPs), a class of zinc-contained endopeptidases, are closely involved in tumor growth, infiltration, metastasis, and angiogenesis. By virtue of the specifically enzymatic hydrolysis, MMPs have been widely used to turn on imaging and/or therapy function of elaborately designed enzyme-responsive nanoprobes, which is expected to realize precise diagnosis and treatment of cancer. This review systematically summarizes the classifications of MMPs, their substrates and recognized sequences, and overexpressed tumor types. The advances of MMPs-responsive nanoprobes for cancer diagnosis and therapy are focused, including trigger mechanism, design principle, and various imaging or therapy modes. Finally, this review analyzes the challenges of MMPs-responsive nanoprobes in clinical application, and provides constructive opinions for future study.