Electrostatic Self-Assembly of Protein Cage -Based Hybrid Materials

Antti Korpi

Research output: ThesisDoctoral ThesisCollection of Articles


Supramolecular self-assembly is a modern tool for development of materials with well-defined nanostructure. The process is simple and has low energy requirements, making it appealing as aproduction method. Electrostatic interaction is a versatile driving force for self-assembly due to the quantity of applicable components and environmental sensitivity of the phenomenon. Protein cages are a subclass of proteins characterized by a hollow interior, which can store smaller particles within. The cages have well-defined and symmetric structures, making them optimal particles for self-assembling systems. In this thesis, electrostatic self-assembly of two protein cages, apoferritin (aFT) and cowpea chlorotic mottle virus (CCMV), and synthetic molecules as well as inorganic particles is studied by focusing on both the assembly process itself and the obtained structures. In publication I, aFT is complexed with synthetic block copolymers with cationic and thermoresponsive segments. The obtained systems are multi-responsive and can be assembled or disassembled by changing temperature or electrolyte concentration. In publication II, CCMV is used to form aggregates with cationic colloidal lignin particles (c-CLPs).Significance of the charged nature of lignin is quantified and c-CLPs are found effective in removing virus particles from water as aggregates by sedimentation or filtration. Publication III demonstrates self-assembly of aFT and CCMV structures with green fluorescent protein (GFP) carrying a cationic polypeptide tail. GFP is successfully incorporated in the assemblies and the order of the obtained structures varies with the dimensions of the assembling protein cage In publication IV, aFT is complexed with various cationic cyclophanes to initiate self-assembly. With optimisation of cyclophane structure, charge density and solution conditions, highly ordered crystal structures are obtained. In publication V, properties of aFT with open and close cage morphology are compared. Both selfassemble with cationic gold nanoparticles, but the closed cages are found to reach higher level of order. Publication VI demonstrates production of mesoporous silica using aFT crystals as templates. The crystals are encased in silica and removed by calcination to yield mesoporous material, where the order of the crystals is retained in orientation of the pores. The research shows that protein cages are versatile particles for self-assembling systems and electrostatic interactions are an applicable driving force for their construction. Combination of different cages and synthetic co-assembly agents enables design of specific hybrid materials for targeted applications.
Translated title of the contributionProteiinihäkkeihin Pohjautuvien Hybridimateriaalien Elektrostaattinen Itsejärjestyminen
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
  • Kostiainen, Mauri, Supervising Professor
  • Kostiainen, Mauri, Thesis Advisor
Print ISBNs978-952-64-0227-7
Electronic ISBNs978-952-64-0228-4
Publication statusPublished - 2021
MoE publication typeG5 Doctoral dissertation (article)


  • protein cages
  • self-assembly
  • electrostatic interaction
  • hybrid materials


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