Metal-Doped Boron Quantum Dots for Versatile Detection of Lactate and Fluorescence Bioimaging
Meng Yang, Hui Jin, Rijun Gui
Abstract
To improve the stability and fluorescence (FL) of monoelemental boron nanomaterials, this work put forward a metal-coordination strategy to explore emerging metal-doped boron quantum dots, Co@BQDs. Through theoretical calculations, B–Co bonding as predicted can suppress the B–O reaction and protect the electronic structures of exfoliated two-dimensional (2D) boron from oxidation and decomposition upon exposure to oxygen. In experimental studies, Co2+ was added into a dispersion liquid of bulk boron and subjected to probe sonication to promote Co2+ adsorption on the surface of exfoliated 2D boron, followed by Co2+ coordination with exposed boron atoms. Solvothermal treatment of exfoliated 2D boron resulted in the generation of Co2+-doped 0D boron Co@BQDs. Experimental results confirm that Co@BQDs have higher colloidal and FL stability than BQDs as a reference. B–Co bonding formation to suppress the B–O reaction ensures the high stability of exfoliated boron structures. A dispersion liquid of Co@BQDs with stable and bright FL was used for visual FL imaging of solutions and solid substrates. Based on enzymatic and cascade oxidation-induced FL quenching of Co@BQDs, a novel FL bio-probe of lactate was explored. This bio-probe, with a broad detection range of 0.01–10 mM and a low detection limit of 3.1 μM, enables FL sensing of lactate in biosamples and shows high detection recoveries of 98.0–102.8%. Moreover, this bio-probe realized versatile FL imaging and visual detection of lactate in liquid/solid-phase systems. These results demonstrate great prospects of Co@BQDs as emerging and efficient imaging reagents for long-term tracking and bioimaging applications.