Computer tomography (CT) and magnetic resonance imaging (MRI) are noninvasive
cancer imaging methods in clinics. Hence, a material that enables MRI/CT dual-modal imaging-guided
therapy is in high demand. Currently, the available materials lack active
tumor targeting, deep
tumor penetration, and ultralong
tumor retention and may lose their imaging elements. To overcome these drawbacks, herein, nanoparticles (NPs) were deveopled by integrating an MRI contrast-enhancing chelated
gadolinium (Gd) complex within a
doxorubicin (DOX)-loaded protective
silica shell as well as a CT imaging/photothermal biocompatible
bismuth (Bi) nano-core, which surface-displayed an MCF-7
breast tumor-homing
peptide (AREYGTRFSLIGGYR, termed AR); we found that the resultant NPs AR-Bi@SiO2-Gd/DOXNPs could home to and penetrate deep into the
tumors with the unexpected ultralong retention of at least 14 days (as determined by CT/MRI imaging) and the
tumor retention half-life of 104.5 h (as determined by ICP-MS analysis) under the guidance of the AR
peptide. These NPs can be further used to image
tumors with significantly increased sharp contrasts via both CT and MRI, which are much better than the commercial standard
contrast agents; moreover, they significantly inhibit
tumor growth via the synergistic action of both Bi-enabled
photothermal therapy and DOX-induced
chemotherapy. The NPs are cleared by the spleen, liver and kidney and then excreted from the body along with faeces and urine. The precise
tumor targeting and ultralong
tumor retention of these unique NPs would enable both precise
tumor detection for early diagnosis and signal-persistent
tumor tracking for monitoring the treatment with only a single injection of these NPs.