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.