Development of a Photoactivatable Phosphine Probe for Induction of Intracellular Reductive Stress with Single-Cell Precision

Photoactivatable phosphines that induce intracellular reductive stress are reported. The design of these probes takes advantage of the conjugate addn. of trialkylphosphines to carbocyanine dyes, which can be reverted photochem. to produce the trialkylphosphine and a fluorescent reporter. The photochem. release depends on the efficiency of photoinduced electron transfer from the indolenine arm of the probe to the coumarin acceptor. These probes readily permeate the mammalian plasma membrane and can be photoactivated in live cells. Upon irradn. of the probe, the released trialkylphosphine induces intracellular reductive stress, which ultimately leads to formation of thioflavin-pos. intracellular protein aggregates. These effects could be induced in individual cells within a monolayer, with minimal disturbance of neighboring cells.