Table 1.

Comparison of in vitro cell-free systems and traditional in vivo cell systems.

Feature	In vitro cell-free system	In vivo cell system
Manipulation of transcription and translation	Easy to control in an open environment	Hard because of cell membrane as the barrier
Post-translational modification	Hard	Easy
Self-replication	Hard	Easy
DNA template	Plasmids or PCR products	Plasmids or genomes
Synthesis of membrane proteins and complex proteins	Easy synthesis by adding surfactants or adjusting the system environment	Hard synthesis due to limited intracellular environment
Incorporation of unnatural amino acids into proteins	Easy	Hard
Ability to only produce the desired products	Easy achievement by focusing on the target metabolic pathways	Hard achievement due to complicated cellular metabolism
Toxic tolerance	High	Low
Integration with materials	Easy	Hard
Design-build-test-learn cycle	Two days	Two weeks
Biomanufacturing	High production rate	Modest production rate
	High product yield	Modest product yield
	Easy purification process without cell lysis	Cell lysis prior to product purification
Cost	Modest to high	Low to modest