Gadolinium Doped Layered Double Hydroxides for Simultaneous Drug Delivery and Magnetic Resonance Imaging

In this study, gadolinium (Gd) doped MgAl layered double hydroxides (LDHs) were synthesized via a 'bottom-up' method and fully characterized by X-ray diffraction, infrared spectroscopy and relaxivity measurements. Two cytotoxic agents were then intercalated via ion-exchange. X-ray diffraction patterns exhibit expanded interlayer spacings as a result of successful drug intercalation. Infrared spectra also showed characteristic peaks of the incorporated methotrexate (MTX) or 5-fluorouracil (5-FU). The LDHs were found to be highly stable under physiological conditions, while in acidic conditions a small proportion of Gd was freed into the immersion medium. Dissolution tests revealed that both 5FU and MTX were rapidly released from the LDH carrier. The longitudinal relaxivity of Gd-LDHs remains largely stable during drug release over 24 h, and was higher in acidic environments. Overall, the drug-loaded Gd-LDH systems prepared in this study could serve as pH-sensitive theranostic platforms for MRI-guided anti-cancer therapy.