Summary
Alkaline phosphatase (ALP), an ectoenzyme, plays important roles in biology. But
there is no activity probes for imaging ALPs in live cell environment due to the diffusion
and cytotoxicity of current probes. Here we report the profiling of the activities of ALPs
on live cells by enzyme-instructed self-assembly (EISA) of a D-peptidic derivative that
forms fluorescent, non-diffusive nanofibrils. Our study reveals the significantly higher
activities of ALP on cancer cells than on stromal cells in their co-culture and shows an
inherent and dynamic difference in ALP activities between drug sensitive and resistant
cancer cells or between cancer cells with and without hormonal stimulation. Being
complementary to genomic profiling of cells, EISA, as a reaction-diffusion controlled
process, achieves high spatiotemporal resolution for profiling activities of ALPs of live
cells at single cell level. The activity probes of ALP contribute to understanding the
reversible phosphorylation/dephosphorylation in the extracellular domains that is an
emerging frontier in biomedicine.