Tunable Hierarchically Porous Gadolinium‐Based Metal‐Organic Frameworks for Bacteria‐Targeting Magnetic Resonance Imaging and In Situ Anti‐Bacterial Therapy

Abstract Currently, there are no non‐invasive tools to accurately diagnose deep surgical site bacterial infections before they cause significant anatomical damage in the clinic. An urgent need exists for bacteria‐targeting bifunctional probes for the detection of deep bacterial infections and precise in situ treatment. Herein, the bacteria‐targeting 1‐borono‐3,5‐benzenedicarboxylic acid (BBDC) ligand and paramagnetic Gd 3 + into one single metal‐organic frameworks (MOFs) are integrated, synergistically realizing bacteria‐specific magnetic resonance imaging (MRI) diagnosis and MRI‐guided antibacterial treatment. Molecular simulations and nitrogen adsorption‐desorption experiments demonstrate that a hierarchical porous structure can be constructed by tuning the Gd 3 + /BBDC ratio, which endows the Gd‐BBDC1.25 MOFs with an impressive longitudinal proton relaxivity of 15.81 mM −1 s −1 . In particular, the bacteria‐targeting boronic acid group in BBDC remained intact during the MOF synthesis, ensuring that Gd‐BBDC1.25 MOFs have a unique combination of high sensitivity and specificity for bacteria. Through an in situ reduction reaction, silver nanoparticles （Ag NPs）‐modified Gd‐BBDC1.25 MOFs to form Ag@Gd‐BBDC1.25, an interfacial Schottky heterojunction nanozyme, which enhances their peroxidase (POD)‐catalyze activity. Furthermore, it is demonstrated that the bacteria‐targeting Ag@Gd‐BBDC1.25 bifunctional probe can image as few as 10 5 colony‐forming units (cfu) in vivo and effectively eradicate the bacteria in situ.