Abstract
The controllable production of microparticles with complex geometries is useful for a variety of applications in materials science and bioengineering. The formation of intricate microarchitectures typically requires sophisticated fabrication techniques such as flow lithography or multiple-emulsion microfluidics. By harnessing the molecular interactions of a set of artificial intrinsically disordered proteins (IDPs), we have created complex microparticle geometries, including porous particles, core-shell and hollow shell structures, and a unique ‘fruits-on-a-vine’ arrangement, by exploiting the metastable region of the phase diagram of thermally responsive IDPs within microdroplets. Through multi-site unnatural amino acid (UAA) incorporation, these protein microparticles can also be photo-crosslinked and stably extracted to an all-aqueous environment. This work expands the functional utility of artificial IDPs as well as the available microarchitectures of this class of biocompatible IDPs, with potential applications in drug delivery and tissue engineering.
Highlights
The controllable production of microparticles with complex geometries is useful for a variety of applications in materials science and bioengineering
Because Elastin-like polypeptides (ELPs) and partially ordered polymers (POPs) exhibit highly controllable, thermally responsive phase separation and share sufficient sequence homology to be partially miscible, we show that mixtures of the two types of artificial intrinsically disordered proteins (IDPs) can be used to create complex microarchitectures using only simple droplet microfluidics and stepwise heating and cooling
The Tcp of POPs and ELPs are tunable by the identity and mole fraction of the guest residue (X) in the VPGXG repeat unit, and the Tcps of POPs are further tunable by the mole fraction of embedded oligoalanine helices
Summary
The controllable production of microparticles with complex geometries is useful for a variety of applications in materials science and bioengineering. Because ELPs consist of VPGXG repeats (Fig. 1a) found in tropoelastin, they are non-toxic and biocompatible, leading to their extensive application in drug delivery and tissue engineering[40,41,42] When heated above their cloud point temperature (Tcp), they form ELP rich, insoluble coacervate droplets in an ELP poor aqueous phase (Fig. 1b, c). Though the disordered regions of IDPs are considered the primary driving force for phase separation, we recently established that periodically spaced structurally ordered domains within an IDP can alter the internal microarchitecture of the coacervate without loss of control over Tcp[48] These partially ordered polymers (POPs) utilize ELPs as the structurally disordered backbone and incorporate oligoalanine helices—reminiscent of those within tropoelastin—that are periodically spaced within the ELP sequence (Fig. 1a). Because ELPs and POPs exhibit highly controllable, thermally responsive phase separation and share sufficient sequence homology to be partially miscible, we show that mixtures of the two types of artificial IDPs can be used to create complex microarchitectures using only simple droplet microfluidics and stepwise heating and cooling
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
