Session: Colloidal Hybrid Materials Intended for Biological Applications:

Complex coacervation between the enzyme catalase and oppositely charged weak polycations in the presence of hydrogen peroxide fuel is investigated. Catalase catalyzes the decomposition of hydrogen peroxide and causes an increase in the solution pH under certain reaction conditions. This increase in pH reduces the positive charge density of the polycation thus destabilizing the liquid-like coacervate (or amorphous precipitate). By coupling the pH-dependent assembly of coacervates with the metabolic activity of the enzyme, we demonstrate a pH-responsive active coacervate system based on negative feedback. Upon exposure to the fuel, micron-scale coacervates droplets containing catalase experience a localized pH increase, the magnitude of which depends on the size of the droplet. Our results indicate how enzymatic activity can be used to control the size of the coacervate droplets through engineered feedback loops. In the broader sense, our system explores how self-assembly coupled to chemical reactions can give rise to dynamic (dissipative) functionality found in living cells.

Nisha Modi

Appearances