Oxygen Vacancy Enables Markedly Enhanced Magnetic Resonance Imaging-Guided Photothermal Therapy of a Gd3+-Doped Contrast Agent

Gd3+-based contrast agents (CAs) are the most prevailing and widely used for enhanced magnetic resonance imaging (MRI). Numbers of approaches have been developed to regulate the key parameters in order to obtain high-relaxivity CAs, according to the classic Solomon-Bloembergen-Morgen theory. Herein, a method of controlling oxygen vacancies in inorganic nanosized CAs has been developed for largely accelerated proton relaxation to obtain a high r(1) value. Such a strategy is verified on oxygen-deficient PEG-NaxGdWO3 nanorods, which exhibit a remarkable r(1) value up to 80 naM(-1) s(-1) (at 0.7 T) and a high r1 value of 32.1 mM(-1) s(-1) on a clinical 3.0 T scanner, offering an excellent blood pool MRI performance at a low dose. Meanwhile, free electrons and/or oxygen-vacancy-induced small polarons can endow PEG-(NaGdWO3)-Gd-x nanorods with significant photothermal conversion for MRI-guided photothermal therapy.