Protein cages are common structures in biology that can have profoundly different functional properties.The majority of these icosahedral organized particles is found in viruses,structures designed to hijack the molecular machinery of the host cell,while in a variety of bacteria these protein cages have organelle-like functions.In our group we aim to design and control the assembly of proteins into materials of well-defined nano-scale dimensions,to use these e.g.as a nanoreactor and scaffold for functional materials.For this we employ techniques for biomolecular engineering with tools from supramolecular and polymer chemistry.