Preliminary investigation of nitric oxide release from upconverted nanoparticles excited at 808 nm near-infrared for brain tumors

Upconverted UCNPs@mSiO 2 -NH 2 nanoparticles were synthesized via thermal decomposition while employing the energy resonance transfer principle and the excellent near-infrared (NIR) light conversion property of up-conversion. The 808 nm NIR-excited photocontrolled nitric oxide (NO) release platform was successfully developed by electrostatically loading photosensitive NO donor Roussin's black salt (RBS) onto UCNPs@mSiO 2 -NH 2 , enabling the temporal, spatial, and dosimetric regulation of NO release for biological applications of NO. The release of NO ranged from 0.015⁓0.099 mM under the conditions of 2.0 W NIR excitation power, 20 min of irradiation time, and UCNPs@mSiO 2 -NH 2 &RBS concentration of 0.25⁓1.25 mg/mL. Therefore, this NO release platform has an anti-tumor effect. In vitro experiments showed that under the NIR light, at concentrations of 0.3 mg/mL and 0.8 mg/mL of UCNPs@mSiO 2 -NH 2 &RBS, the activity of glioma (U87) and chordoma (U–CH1) cells, as measured by CCK8 assay, was reduced to 50 %. Cell flow cytometry and Western Blot experiments showed that NO released from UCNPs@mSiO 2 -NH 2 &RBS under NIR light induced apoptosis in brain tumor cells. In vivo experiments employing glioma and chordoma xenograft mouse models revealed significant inhibition of tumor growth in the NIR and UCNPs@mSiO 2 -NH 2 &RBS group, with no observed significant side effects in the mice. Therefore, NO released by UCNPs@mSiO 2 -NH 2 &RBS under NIR irradiation can be used as a highly effective and safe strategy for brain tumor therapy.