Fluorescent Boron Oxide Nanodisks as Biocompatible Multi-messenger Sensors for Ultrasensitive Ni$^{2+}$ Detection

Boron-based nanocomposites are very promising for a wide range of technological applications, spanning from microelectronics to nanomedicine. A large variety of B-based nanomaterials has been already observed, such as borospherene, B nanotubes and nanoparticles, and boron nitride nanoparticles. However, their fabrication usually involves toxic precursors or leads to very low yields or small boron atom concentration. In this work, we report the synthesis of nanometric B$_{2}$O$_{3}$ nanodisks, a family of nanomaterials with a quasi-2D morphology capable of intense fluorescence in the visible range. Such as boron-based nanomaterial, which we synthesized by pulsed laser ablation of a boron target, is water-dispersible and nontoxic, and displays a highly crystalline structure. Moreover, its bright blue photoluminescence is highly sensitive and selective for the presence of Ni$^{2+}$ ions in solution, down to extremely small concentrations in the picomolar range. The results are very promising in view of the use of such novel B$_{2}$O$_{3}$ nanodisks as ultrasensitive multi-messenger Ni$^{2+}$ nanosensors.