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Integrating T 1 -and T 2 -components of magnetic resonance (MR) imaging into a single particle has been demonstrated to be effective for improving the diagnostic accuracy. However, a T 1 -T 2 dual modal MR contrast agent with glioma targeting ability remains unexplored. In this study, we prepared gourd-shaped Fe 3 O 4 /MnO hybrid NPs with a size of 25 nm through a thermal decomposition method. The water dispersibility was then obtained via a ligand exchange process with carboxylic acid-terminated silane.The sequential conjugation of chlorotoxin (CTX) and Cy5.5 on the carboxyl groups of attached silane endowed Fe 3 O 4 /MnO hybrid NPs with near-infrared fluorescence and glioma-targeting characteristics.The in vitro studies confirmed the targeting ability of Fe 3 O 4 /MnO-Cy5.5-CTX NPs toward C6 glioma cells. The in vivo T 1 -T 2 dual modal MR imaging of glioma-bearing brain verified that the CTX conjugation led to a better contrast enhancement of the tumour tissue from the normal tissue both in T 1 and T 2 imaging, comparing to unconjugated NPs, which could enable more accurate diagnosis of gliomas.

The authors describe MnO nanoparticles (NPs) with unique excitation-dependent fluorescence across the entire visible spectrum. These NPs are shown to be efficient optical nanoprobe for multicolor cellular imaging. Synthesis of the NPs is accomplished by a thermal decomposition method. The MnO NPs exhibit a high r relaxivity of 4.68 mM s and therefore give an enhanced contrast effect in magnetic resonance (MR) studies of brain glioma. The cytotoxicity assay, hemolysis analysis, and hematoxylin and eosin (H&E) staining tests verify that the MnO NPs are biocompatible. In the authors' perception, the simultaneous attributes of multicolor fluorescence and excellent MR functionality make this material a promising dual-modal nanoprobe for use in bio-imaging. Graphical abstract A direct method to synthesize fluorescent MnO NPs is reported. The NPs are biocompatible and have been successfully applied for multicolor cellular imaging and MR detection of brain glioma.

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