Enhanced persistent luminescence of MgGeO3: Yb3+ nanoparticles via substitution of Ge4+ by Ga3+ ions for biological applications

The emission of persistent luminescence nanoparticles (PLNPs) is in the second near infrared region (NIR-II, 1000–1700 nm), considered as ideal fluorescence imaging materials because of their special characteristic consist of no autofluorescence, weak scattering and deep tissue penetration depth in biological tissues. However, it is still a great challenge to enhance their persistent luminescence intensity. Herein, we reported a new MgGe 0.8 Ga 0.2 O 3 : Yb 3+ (MGGO: Yb 3+ ) PLNPs, which were synthesized through solvothermal liquid-solid-solution and salt microemulsion method. We found that partially replacing Ge 4+ with Ga 3+ ions in MgGeO 3 host can increase the density of traps, thus significantly improving the NIR-II persistent luminescence intensity of Yb 3+ ions (the decay time is more than 33 min). Moreover, X-ray could be used to repeatedly stimulate the NIR-II persistent emission of MGGO: Yb 3+ , which is pivotal for deep tissues long term imaging. The optical penetration length of Yb 3+ ions persistent luminescence was assessed to be 3.9 mm via capping tissue. The above results reveal that MGGO: Yb 3+ PLNPs are promising material to be applied to deep-tissue imaging field.