Dendritic Fibrous Nanosilica-Based Inorganic–Organic Composite Fluorescent Probes for the Detection and Removal of Pb2+ and Hg+ Ions

Dendritic fibrous nanomaterials play an important role in the adsorption of heavy metals. The introduction of fluorescent groups on the dendritic fibrous nanosilica (DFNS) will endow it with the ability to recognize and adsorb heavy metals. In this work, DFNS was first prepared as starting materials. Then, it was chemically modified with vinyltriethoxysilane (VTES) to make its surface rich in C═C double bonds. At the same time, the RAFT reagent (Br-CTA-CH═CH₂) containing -Br and C═C double bond was synthesized. In addition, fluorescent monomers Naph-CH═CH₂ and BT-CH═CH₂ were synthesized by introducing C═C double bonds on naphthalimide and benzothiazole, respectively. Then, Naph-CH═CH₂, BT-CH═CH₂, and Br-CTA-CH═CH₂ were subjected to RAFT polymerization to obtain fluorescent hyperbranched polymers (FL-HBPs) containing Br groups. Finally, FL-HBPs were loaded onto the surface of CH₂═CH-DFNS by Heck reaction to obtain organic–inorganic composite microspheres (FL-HBP-DFNS). The microspheres can sensitively identify and efficiently separate Pb²⁺/Hg⁺. The probe exhibits fluorescence enhancement of the Pb²⁺/Hg⁺ ions. The limit of detection (LOD) reaches 1.04 nM and 2.46 nM, respectively. Moreover, the adsorption efficiency of Pb²⁺ reaches 99.7%, and the adsorption capacity is 157.5 mg/g. Therefore, FL-HBP-DFNS can play effective roles in the identification and removal of heavy metals.