Synthesis of Multifunctional Mn 3 O 4 -Ag 2 S Janus Nanoparticles for Enhanced T 1 -Magnetic Resonance Imaging and Photo-Induced Tumor Therapy.

The global burden of cancer is increasing rapidly, and nanomedicine offers promising prospects for enhancing the life expectancy of cancer patients. Janus nanoparticles (JNPs) have garnered considerable attention due to their asymmetric geometry, enabling multifunctionality in drug delivery and theranostics. However, achieving precise control over the self-assembly of JNPs in solution at the nanoscale level poses significant challenges. Herein, a low-temperature reversed-phase microemulsion system was used to obtain homogenous Mn 3 O 4 -Ag 2 S JNPs, which showed significant potential in cancer theranostics. Structural characterization revealed that the Ag 2 S (5-10 nm) part was uniformly deposited on a specific surface of Mn 3 O 4 to form a Mn 3 O 4 -Ag 2 S Janus morphology. Compared to the single-component Mn 3 O 4 and Ag 2 S particles, the fabricated Mn 3 O 4 -Ag 2 S JNPs exhibited satisfactory biocompatibility and therapeutic performance. Novel diagnostic and therapeutic nanoplatforms can be guided using the magnetic component in JNPs, which is revealed as an excellent T 1 contrast enhancement agent in magnetic resonance imaging (MRI) with multiple functions, such as photo-induced regulation of the tumor microenvironment via producing reactive oxygen species and second near-infrared region (NIR-II) photothermal excitation for in vitro tumor-killing effects. The prime antibacterial and promising theranostics results demonstrate the extensive potential of the designed photo-responsive Mn 3 O 4 -Ag 2 S JNPs for biomedical applications.