Controllable coacervation of recombinantly produced spider silk protein using kosmotropic salts

Pezhman Mohammadi*, Jonkergouw Christopher, Grégory Beaune, Peter Engelhardt, Ayaka Kamada, Jaakko V.I. Timonen, Tuomas P.J. Knowles, Merja Penttila, Markus B. Linder

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)
181 Downloads (Pure)


Recent developments suggest that the phase transition of natural and synthetic biomacromolecules represents an important and ubiquitous mechanism underlying structural assemblies toward the fabrication of high-performance materials. Such a transition results in the formation of condensed liquid droplets, described as condensates or coacervates. Being able to effectively control the assembly of such entities is essential for tuning the quality and their functionality. Here we describe how self-coacervation of genetically engineered spidroin-inspired proteins can be preceded by a wide range of kosmotropic salts. We studied the kinetics and mechanisms of coacervation in different conditions, from direct observation of initial phase separation to the early stage of nucleation/growth and fusion into large fluid assemblies. We found that coacervation induced by kosmotropic salts follows the classical nucleation theory and critically relies on precursor clusters of few weak-interacting protein monomers. Depending on solution conditions and the strength of the supramolecular interaction as a function of time, coacervates with a continuum of physiochemical properties were observed. We observed similar characteristics in other protein-based coacervates, which include having a spherical-ellipsoid shape in solution, an interconnected bicontinuous network, surface adhesion, and wetting properties. Finally, we demonstrated the use of salt-induced self-coacervates of spidroin-inspired protein as a cellulosic binder in dried condition.

Original languageEnglish
Pages (from-to)149-160
Number of pages12
JournalJournal of Colloid and Interface Science
Publication statusPublished - 15 Feb 2020
MoE publication typeA1 Journal article-refereed


  • Classical nucleation theory
  • Coacervate
  • Genetic engineering
  • Kosmotropic salt
  • Liquid-liquid phase transition
  • Protein engineering
  • Salting out
  • Silk-like protein


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