Lanthanide-Doped LiLuF4 Upconversion Nanoprobes for the Detection of Disease Biomarkers

Lanthanide-doped upconversion nanoparticles (UCNPs) have shown great promise in bioapplications. Exploring new host materials to realize efficient upconversion luminescence (UCL) output is a goal of general concern. Herein, we develop a unique strategy for the synthesis of novel LiLuF4:Ln(3+) core/shell UCNPs with typically high absolute upconversion quantum yields of 5.0% and 7.6% for Er3+ and Tm3+, respectively. Based on our customized UCL biodetection system, we demonstrate for the first time the application of LiLuF4:Ln(3+) core/shell UCNPs as sensitive UCL bioprobes for the detection of an important disease marker beta subunit of human chorionic gonadotropin (beta-hCG) with a detection limit of 3.8 ng mL(-1), which is comparable to the beta-hCG level in the serum of normal humans. Furthermore, we use these UCNPs in proof-of-concept computed tomography imaging and UCL imaging of cancer cells, thus revealing the great potential of LiLuF4:Ln(3+) UCNPs as efficient nano-bioprobes in disease diagnosis.