Enzyme-Instructed Self-Assembly for Spatiotemporal Profiling of the Activities of Alkaline Phosphatases on Live Cells

Alkaline phosphatase (ALP), an ectoenzyme, plays important roles in biology. But there is no reliable activity probe for imaging ALPs on live cells because of 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 significantly higher activity of ALP on cancer cells than on stromal cells in co-cultures and shows an inherent and dynamic difference in ALP activity between drug-sensitive and drug-resistant cancer cells and 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 the activity of ALPs on live cells at the single-cell level. The activity probes for ALP contribute to our understanding of reversible phosphorylation-dephosphorylation in extracellular domains, an emerging frontier in biomedicine.