Construction of spidroin coacervate microdroplets and regulation of their morphology

Abstract

In recent years, developing artificial cells of higher complexity has emerged as being key to simulating advanced life behaviors, among which coacervate microdroplets are a promising kind of model artificial cell. Constructing simple coacervate systems in vitro which can subsequently achieve specific responses to environmental stimuli to form coacervate microdroplet communities are fundamental for studying the interactions between liquid–liquid phase separated molecules and the way such interactions determine material properties, composition and phase behavior. Herein, we propose a membrane-free artificial cell based on recombinant spidroin, NT2RepCT, which utilizes the complex structure of spidroin to provide coacervate microdroplets with a unique population morphology in response to environmental stimuli. By changing the environmental conditions such as protein concentration, pH and temperature, the coacervate microdroplets of single-type, regular adhesion-type and irregular adhesion-type were statistically generalized, and it is highlighted that the adhesion-type of coacervate microdroplets depended on the α-helical percentage, complex folding degree of spidroin and internally hydrophobic environment of the coacervate, while it was inversely proportional to the surface hydrophobic environment. Much more interesting, regulation of the non-enzymatic polymerization reaction of oligonucleotides was successfully achieved by adjusting the population morphology of coacervate microdroplets.