High‐Loading L‐Arginine Stabilized in an Oxygen‐Rich Lanthanide Metal–Organic Framework Capable of NO Release and Self‐Quantifying Luminescence Detection

Abstract Exogenous supplementation of L‐arginine (L‐Arg) facilitates the release of nitric oxide (NO) for gas therapy applications in tumor microenvironments rich in H 2 O 2 . However, direct administration inevitably leads to the premature release of hydrophilic L‐Arg in the bloodstream, potentially resulting in unstable plasma L‐Arg concentrations and subsequent adverse reactions. Therefore, it is crucial to identify efficient and stable high‐dose L‐Arg delivery carriers, albeit challenging. Here, the study has achieved high (≈94 mg g −1 ) and stable L‐Arg loading within a 12‐coordinated Yb‐based lanthanide metal‐organic framework (named Yb‐DOBDC, where DOBDC is 2,5‐dihydroxyterephthalic acid). Yb‐DOBDC features size‐matched apertures and oxygen‐rich pore microenvironments, securely entrapping L‐Arg through electrostatic interactions and conjugation effects, thereby enhancing the biostability of the drug during delivery. In vitro experiments demonstrate that L‐Arg‐loaded Yb‐DOBDC (L‐Arg@Yb‐DOBDC) promotes NO release upon H 2 O 2 stimulation, and the Yb‐DOBDC framework exhibits good biocompatibility within cells. More interestingly, the near‐infrared‐luminescence‐emitting Yb‐DOBDC exhibits a “turn‐off” behavior upon gradual loading of L‐Arg, enabling self‐quantifying luminescence detection during the encapsulation process. Consequently, the L‐Arg@Yb‐DOBDC system designed in this work, with its high/stable loading capacity and self‐quantifying luminescence detection capability, holds theoretical research value and potential practical application prospects.