Abstract: Objective To investigate the physicochemical features of glucose oxidase-loaded and manganese-based mesoporous silica nanoparticles (MSN@Mn-GOx) and its antitumor effect against gastrointestinal cancer. Methods The morphology, particle size and Fenton-like properties of MSN@Mn-GOx nanoparticles were analyzed using transmission electron microscopy (TEM), dynamic light scattering (DLS), Zeta potential analysis, ultraviolet absorption spectroscopy, energy dispersive spectroscopy and X-ray photoelectron spectroscopy. A mouse model bearing human colon cancer HT-29 xenograft was established to examine the antitumor effect of MSN@Mn- GOx using MRI imaging. Reactive oxygen species (ROS) production assay, CCK-8 assay and EdU assay were used to evaluate the in vitro anti-tumor effect of the nanoparticles. Results MSN@Mn-GOx nanoparticles were solid spheres with a diameter of about 100 nm and a Zeta potential of -35 mV. MSN@Mn-GOx had a higher H2O2 catalytic efficiency in glucose containing solution than in glucose-free solution, and showed a stronger Fenton-like properties at pH6.0 than at pH7.4 (P<0.05). In the tumor-bearing mice, MSN@Mn-GOx treatment dose-dependently enhanced T1 imaging of the tumor (P<0.01). Compared with the control group and MSN@Mn group, MSN@Mn-GOx induced a significantly higher level of ROS production and a stronger inhibitory effect on the proliferation of gastric and colon cancer cells (P<0.05). Conclusion MSN@Mn-GOx nanoparticles have good chemodynamic properties and a strong anti- tumor effect and provide a potential therapeutic option for gastric cancer.

Key words: manganese-based nanomaterials; nanoparticles; gastrointestinal cancer; chemodynamic therapy