-808 nm-activated Ca²⁺doped up-conversion nanoparticles that release no inducing liver cancer cell (HepG2) apoptosis

A near-infrared (NIR) light-triggered release method for nitric oxide (NO) was developed utilizing core/shell NaYF₄: Tm/Yb/Ca@NaGdF₄: Nd/Yb up-conversion nanoparticles (UCNPs) bearing a mesoporous silica (mSiO₂) shell loaded with the NO donor S-nitroso-N-acetyl-DL-penicillamine (SNAP). To avoid overheating in biological samples, Nd³⁺was chosen as a sensitizer, Yb³⁺ions as the bridging sensitizer, and Tm³⁺ions as UV-emissive activator while co-doping with Ca²⁺was done to enhance the luminescence of the activator Tm³⁺. NO release from SNAP was triggered by an NIR-UV up-conversion process, initiated by 808 nm light absorbed by the Nd³⁺ions. NO release was confirmed by the Griess method. Under 808 nm irradiation, the viability of the liver cancer cell line HepG2 significantly decreased with increasing UCNPs@mSiO₂-SNAP concentration. For a UCNPs@mSiO₂-SNAP concentration of 200μg ml^-1, the cell survival probability was 47%. These results demonstrate that UCNPs@mSiO₂-SNAP can induce the release of apoptosis-inducing NO by NIR irradiation.