In this paper, we have designed long afterglow luminescent MgGeO3:Mn2+,Yb3+,Li+ (MGO) nanoparticles in the first (NIR-I) and second (NIR-II) biological windows. Yb3+
ions served not only as the trap center to enhance the NIR-I long afterglow emission of Mn2+ at 680 nm, but also as an emitting center to produce a NIR-II long afterglow emission at ∼1000 nm. Furthermore, we have found the addition of Li+ can greatly increase the NIR-II afterglow emission of Yb3+ and the optimal amount of Mn2+, Yb3+ and Li+ was found to be 0.1, 0.5 and 0.5 mol%, respectively. The MGO nanoparticles synthesized using
sol-gel methods showed a uniform morphology with a diameter of 50-100 nm, which were suitable for applications in bioimaging. More importantly, we have found MGO nanoparticles can be effectively excited to produce long persistent NIR-I and II luminescence using soft X-rays, suggesting that low dosage soft X-rays can also serve as a more powerful and deep tissue excitation source to recharge MGO nanoparticles. Furthermore, the MGO nanoparticles can also be re-excited to produce photo-stimulated emission under the irradiation of 650 and 808 nm NIR
lasers. The in vivo imaging results have shown that MGO nanoparticles modified with
folic acid (FA) can effectively realize super long-term targeted in vivo imaging of
inflammation with a high sensitivity via recharging using soft X-rays and NIR
lasers, which can provide not only an accurate diagnosis of
inflammation, but also long-term monitoring of possible changes in the focus of
inflammation in real time.