A folic acid-functionalized dual-emissive nanoprobe for "double-check" luminescence imaging of cancer cells.

Development of luminescent probes for rapid and effective discrimination and detection of cancer cells has the potential to address the current challenges in early diagnosis and treatment monitoring of cancer diseases. In this work, we report the preparation of a unique folic acid (FA)-functionalized dual-emissive nanoprobe, CTMR@BHHBCB-Eu-FA, for steady-state and time-gated luminescence "double-check" imaging of cancer cells. The nanoprobe was engineered by covalently doping two luminescent dyes, 5-carboxytetramethylrhodamine (CTMR) and BHHBCB-Eu, in core and shell of silica nanoparticles, followed by surface modification of the nanoparticles with FA, a cancer cell-targeting molecule. As-prepared nanoprobe is monodisperse and highly stable in buffer displaying two strong emissions, short-lived emission from CTMR at 584 nm and long-lived emission from BHHBCB-Eu at 612 nm. The nanoprobe is biocompatible, and can specifically recognize folate receptor (FR)-overexpressed cancer cells through the FA-FR binding interaction. Using the nanoprobe, the "double-check" imaging of HeLa cells was successfully achieved at steady-state and time-gated luminescence modes, indicating the capability of the nanoprobe for cancer cell imaging.