K+ concentration-based NMR-fluorescence dual-functional senescence sensing using graphene quantum dots with crown ether structure

Aging allows the occurrence and progression of cerebrovascular diseases, highlighting the importance of detecting senescent cells and tissues in the nervous system. Detecting senescent cells/tissues using nanoparticles as probes in the nervous system is desired with high sensitivity, high accuracy, and penetration of the blood-brain barrier. In response, we designed crown ether-based graphene quantum dots with fast proton transport channels to sense potassium ions, a significant differential indicator between healthy and senescent cells. Using the probe, we have achieved MRI-fluorescence dual-functional monitoring of potassium ion concentration in cells via fluorescent intensity and magnetic relaxation time. Importantly, we have further demonstrated the advantages of the crown ether-based graphene quantum dots in penetrating the blood-brain barrier, revealing their potential for diagnosing aging in the nervous system.