Theranostic agents based on inorganic
nanomaterials are still suffered
from the nonbiodegradable substances with long-term retention in body
and unavoidable biological toxicity, as well as nonspecificity biodistribution
with potential damage toward normal tissues. Here, we develop magnetic
ions (FeIII, FeII, GdIII, MnII, and MnIII) coordinated nanoplatform (MICN) with
framework structure and modify them with PEG (MICN-PEG). Notably,
MICN-PEG demonstrates hydroxide ions (OH–) triggered
the structure collapse along with responsive near-infrared photoacoustic
(PA) signal, magnetic resonance imaging (MRI), and photothermal therapy
(PTT) performances. Thereby, MICN-PEG is able to remain stable in
tumors and exert excellent PA/MRI and PTT effects for multimodal imaging-guided
cancer treatment. In contrast, MICN-PEG is gradually collapsed in
normal tissues, resulting in the significant improvement of imaging
accuracy and treatment specificity. MICN-PEG is gradually cleared
after administration, minimizing concerns about the long-term toxicity.