Used for rapid synthesis of proteins without the need for living cells, enabling expression of toxic or unstable proteins that are difficult to produce in cell-based systems. Ideal for high-throughput screening, functional genomics, and production of isotopically labeled proteins for NMR studies. Commonly applied in drug discovery, enzyme engineering, and personalized medicine research due to fast reaction times and open accessibility to the reaction environment. Enables on-demand protein production in field settings or point-of-care diagnostics where cell culture infrastructure is unavailable.