Biomineralization\nSynthesis of HoMn Nanoparticles\nfor Ultrahigh-Field-Tailored and T1–T2 Dual-Mode MRI-Guided\nCancer Theranostics

Ultrahigh field magnetic resonance imaging (UHF-MRI)\n(≥7\nT) can dramatically boost image resolution and signal-to-noise ratio,\nwhich have distinct advantages in multifunctional imaging. However,\ntheir research and application are currently limited by the absence\nof high-field contrast agents (CAs) and the low sensitivity and accuracy\nof T1/T2 single-modality CAs. Therefore, the development of T1–T2\ndual-mode CAs that respond to UHF-MRI and nanoformulations with therapeutic\nsensitization can bring ideas for the integrated application of precise\nand synchronous tumor theranostics. Herein, we present a biomimetic\nmineralization strategy for synthesizing holmium/manganese oxide–bovine\nserum albumin–photosensitizer chlorin e6 nanohybrids. The hybrid\nnanoparticles exhibited better tumor accumulation, a suitable time\nimaging window, and excellent pH-response T1–T2 dual-mode UHF-MRI\nperformance. The antitumor effect comes from the amelioration of the\nhypoxic tumor microenvironment to promote the synergistic effect of\nphotodynamic therapy and radiotherapy, along with negligible acute\ntoxicity. Undoubtedly, this work not only provides a different perspective\nfor developing multifunctional nanotherapeutics but also promotes\nthe potential clinical exploitation and translation of UHF CAs.