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@mSiO2) 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.