Colorful packages : fluorescent proteins in complex coacervate core micelles

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This thesis explores the encapsulation of fluorescent proteins (FPs) into complex coacervate core micelles (C3Ms) and features the impact of this encapsulation on the biophysical properties of the FPs. In total eight different FPs were investigated originating from two different classes (Hydrozoa: SBFP2, mTurquoise2, EGFP, mEGFP, and SYFP2; and Anthozoa: mKO2, mCherry, and TagRFP), thereby covering the whole visible spectrum. As enveloping material the diblock copolymer poly(2-methyl-vinyl-pyridinium)n-b-poly(ethylene-oxide)m (P2MVPn-b-PEOm) of two different lengths (P2MVP41-b-PEO205 and P2MVP128-b-PEO477) was used. The research was focused on the formation, composition, dynamics, and stability of the FP-containing C3Ms, but it also gave us insights into the structural and spectral properties of the encapsulated FPs. We showed the successful encapsulation of about 500 EGFP molecules per C3M using both diblock copolymers. This high amount of FPs per C3M promoted dimerization of EGFP, resulting in a somewhat stronger acid character of its chromophore. By using seven other FPs, the effect of encapsulation on the structure and spectral properties of these proteins was systematically investigated. Hydrozoa FPs were more efficiently encapsulated than Anthozoa FPs, and the latter proteins were subject to di- or tetramerization in C3Ms. Finally, fast exchange dynamics of C3Ms were detected using FRET. Combining the insights presented in this thesis with sophisticated protein engineering and bioconjugation procedures, may lead in the near future to C3M-based protein nanoparticles that can be used for food and pharmaceutical applications.