Recent Advances in Metal–Organic Framework-Based Luminescent Sensors toward 3-Nitrotyrosine Biomarker

3-Nitrotyrosine (3-NT), as a specific biomarker of protein oxidative stress damage, is of great significance in the early diagnosis of various diseases. This review systematically summarizes the latest research progress and specific applications of metal–organic framework (MOF)-based luminescent sensors for detecting 3-NT in aqueous media and biological samples. It focuses on the classification and detection capacity of MOF-based 3-NT luminescent sensors. Besides, the main sensing mechanisms, including structural collapse (SC), photoinduced electron transfer (PET), fluorescence resonance energy transfer (FRET), competition absorption (CA), internal filtration effect (IFE), and dynamic quenching effect (DQE), are analyzed in depth. This review critically assesses current research progress, challenges, and future directions of MOF-based 3-NT detection, offering valuable insights for developing highly sensitive and selective MOF-based luminescent sensors. These insights will be instrumental in steering the field toward innovative and practical solutions, facilitating the design of sensors with enhanced performance and broader applicability.