Investigation of a halloysite-based fluorescence probe with a highly selective and sensitive “turn-on” response upon hydrogen peroxide†
Abstract
Inorganic halloysite nanotubes (HNTs) were modified with an organic fluorescein derivative (PA) to prepare HNTs-based hybrid fluorescence probe (HNTs-PA). Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), solid-state 13C NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), energy dispersive spectrum (EDS) and transmission electron microscopy (TEM) confirmed that PA was successfully grafted onto the lumen of HNTs to obtain HNTs-PA with a grafting degree of 6.0%. The established B–C bond endows a selective fluorescence response toward hydrogen peroxide (H2O2) to HNTs-PA. The new hybrid probe exhibited a highly specific “turn-on” fluorescence response to H2O2 over other reactive oxygen species (ROS) and common ions owing to their chemoselective boronate-to-phenol switch. The “turn-on” response could even be tracked when the additional amount of H2O2 was limited to 1 × 10−7 mol. Moreover, human lung cancer cells (A549 cells) were successfully stained and the staining intensity enhanced as time prolongs, which can be due to the overexpressed H2O2 of cancer cells. Thus, the as-prepared organic–inorganic hybrid fluorescence probe can have a broad range of applications for identification and diagnosis.