Design of near-infrared light induced functionalized upconverting nanoparticles as support in enzyme immobilization: Enhanced biocatalyst activity and stability.

In this study, we hypothesized that the emission of upconverted nanoparticles (UCNP) can trigger PEG-L-ASNase (P-Lase) activity through Förster Resonance Energy Transfer under near-infrared (NIR) irradiation. To enhance stability and activity of P-Lase, it was immobilized on functionalized NaYF4:Yb3+, Er3+, Nd3+. Upon immobilization, the obtained NaYF4:Yb3+, Er3+, Nd3+/GPTMS-P-Lase exhibited excellent pH stability, thermal stability, metal ions or organic solvent tolerance, and storage stability. The relative activity of NaYF4:Yb3+, Er3+, Nd3+/GPTMS-P-Lase had about 65 % after 20 cycles and maintained 68 % and 59 % at +4 and 25 °C, respectively, after 4 weeks. Furthermore, in vitro cytotoxicity and hemolysis tests confirmed that the synthesized UCNPs were biocompatible. Most importantly, the activity of P-Lase was enhanced ≥4-fold under suitable NIR irradiation. It is reasonable to believe that this investigation may supply a novel technique to trigger the catalytic efficiency of P-Lase and may have promising application in leukemia treatment.