Visual bio-detection and versatile bio-imaging of zinc-ion-coordinated black phosphorus quantum dots with improved stability and bright fluorescence

Zero-dimensional black phosphorus quantum dots (BPQDs) have unique structural characteristics and excellent properties for promising applications over other BP structures. With the decrease of BP stacked layers, BP becomes much unstable and is easy to be oxidized and degraded in air and water. To prevent BP oxidation and degradation is crucial during the preparation process of highly stable BPQDs with strong fluorescence (FL). Herein, we explored a zinc-ion-coordinated strategy to achieve the emerging [email protected] with improved colloidal and FL stabilities. Zn ions can be adsorbed on BP surface via cation-π interactions, which passivates lone pair electrons of phosphorus and makes BP much stable upon exposure to air and water. [email protected] were prepared through sonication-assisted liquid-phase exfoliation of bulk BP crystals in the presence of Zn ions and solvothermal reaction of exfoliated few-layer [email protected] nanosheets. Experimental results confirm the preparation of [email protected] with improved stability and high FL. [email protected] were used for both FL spectral detection and naked-eye visual FL detection of glutathione in practical samples. As emerging FL reagents, biocompatible [email protected] were further used for efficient in-vitro cell imaging and in-vivo imaging in natural plants and living aquatic animals.