Celik, Y. et al. Proc. Natl. Acad. Sci. USA 110, 1309–1314 (2013).

Organisms that live in extremely cold temperatures express antifreeze proteins (AFPs), which bind to ice crystals and inhibit their growth by driving a difference between the melting and freezing temperatures of ice. The detailed mechanism of action of AFPs has not been determined because the interactions between such proteins and the ice-water interface pose great experimental challenges. Celik et al. report a microfluidic device that incorporates a sensitive temperature-controlled system and allows removal of GFP-tagged AFPs from the solution surrounding individual ice crystals without perturbing the ice or changing the temperature. The device allowed them to observe that the binding of AFPs to ice is irreversible and inhibits ice growth even when AFPs are depleted from the surrounding solution, in contrast to the mechanism that had been previously suggested.