Enhancing catalase-like activity of Prussian blue nanozyme by gadolinium-doping for imaging-guided antitumor amplification via photodynamic therapy and chemotherapy

Deprivation of O 2 in most solid tumors greatly limits the effectiveness of photodynamic therapy. Prussian blue nanozyme (PBzyme) are reported to possess catalase-like (CAT) activity to alleviate tumor hypoxia . However, the low catalytic activity is far from satisfactory. Metal doping may improve the catalytic activity of PBzyme, but there are few reports in this regard. Herein, by a screening of metal dopants , Gd-doped PB with enhanced CAT activity is constructed on the basis of small-sized hollow mesoporous silica nanoparticles . Theoretical calculation demonstrates that Gd regulates the state density population of Fe in PBzyme and reduces the Gibbs free energy of CAT catalytic cycle, thus improving its CAT activity (approximately 4 times higher than that of pure PBzyme). After conjugated with photosensitizer Ce6 and tumor-targeted molecule folic acid and loaded with chemotherapy drug doxorubicin , the nanoplatform displays dual-enhanced T 1 and T 2 imaging capacity simultaneously. Upon high accumulation in tumors, the nanoplatform demonstrates augmented antitumor effects by combining enhanced photodynamic therapy and doxorubicin-mediated chemotherapy both in vitro and in vivo . This work demonstrates that the integration of Gd into PBzyme is an effective strategy to improve the catalytic activity of PBzyme and further potentiate the effectiveness of tumor theranostics.