(468h) Robust Membraneless Polyelectrolyte Complex Coacervate Bioreactors without Molcecular Stabilizer

Although recent interests in polyelectrolyte coacervates have shown their advanced applications such as microscale bioreactors with enhanced transcription rates, these applications are, however, usually limited to spatially isolated coacervate droplets or those with liposome or polymer membrane because of membraneless droplets’ instability towards coalescence. In this experimental work, we systematically explored the interfacial properties of droplets prepared in controlled saline environment. We worked with a well-studied LLPS system: PDDA – ATP, without any additional molecular stabilizer. These droplets were found to be very stable; for more than weeks and were quite robust against sheer mixing induced by vortexing, which was confirmed by fluorescent microscopy. Surface charge analysis using zeta potential measurements indicated a steric stabilization rather than charge-based repulsion. We looked at the diffusion of small molecule (~ 5 Å) and macromolecules (~10 nm) in and out of these stable droplets as well as localization of protein molecules in the droplets. Consequently, we used these droplets as stable micro bioreactors by performing enzymatic catalysis where the enzyme-encapsulated droplets were found capable of doing reactions even after a week of synthesis. This work has an important consequence as this analysis allows us to understand the stability of various phase-separated liquid systems formed in vivo which finds applications ranging from protein storage to neurodegenerative diseases.