Photoluminescence Lifetime of Black Phosphorus Nanoparticles and Their Applications in Live Cell Imaging.

Black phosphorus (BP) has attracted much attention as a new member of 2D materials due to its unique electronic and optical properties and a wide range of promising applications. Here, for the first time, we report the photoluminescence lifetime of BP nanomaterial and its applications as an efficient agent for live cell imaging. With a lateral size of ∼35 nm and a thickness of ∼6 nm, the fabricated BP nanoparticles (BPNPs) exhibited a unique photoluminescent (PL) emission at ∼690 nm. The photoluminescence lifetime (PLT) of BPNPs was determined to be 110.5 ps. Coating a layer of mesoporous silica on the surface of BPNPs (BPNPs@mSiO) extended the lifetime to 267 ps, suggesting a change in the microenvironment. The lifetime was also influenced by ionic strength and intracellular microenvironment, which implies BPNPs as valuable probes for sensing variations in the microenvironment. Live cell imaging was achieved via directly probing the photoluminescence intensity or the photoluminescence lifetime. Our findings are significant, implying that BPNPs can be of large value in sensing variations of the cellular microenvironment and in probing cells with distinct cytosolic contents. This research leads to promising prospects for BPNPs in multiple biomedical applications.