The assembly and confinement properties of the cowpea chlorotic mottle virus

In this thesis viruses are studied for the development of new materials. ‘These form a whole new set of building blocks which have already found application in materials science, nanotechnology and medicine,’ says Stan Maassen. ‘Their monodispersity and high degree of symmetry is unsurpassed. And a huge amount of different shapes and sizes can be found.’

Knowledge on viral assembly

By studying the assembly and confinement conditions of the cowpea chlorotic mottle virus (CCMV), the knowledge on viral assembly is extended within this PhD project. As a new angle of approach, microscale thermophoresis (MST) was introduced. ‘We can now study the assembly into virus-like particles more efficiently and precisely,’ says Stan. ‘For further insight into the energy involved in these processes, we also applied isothermal titration calorimetry.’ 

Using negatively charged, pH-reponsive fluorescent probes, Stan was able to study the pH-conditions inside CCMV-based capsids. ‘These shells protect, transport and release viral genetic material,’ Stan explains.

‘I was very excited when finding that the pH inside a protein cage, differs from the bulk solution in the order of 0,5 pH. Our colleagues were enthusiastic immediately about these experimental results. From there, we were able to construct a theoretical model which is of interest for many catalytic purposes and new virus-based materials. The findings were published in high impact journals, including Small.’

To aid in the development of new CCMV-based materials and applications, new methods for virus-like particle assembly and functionalization were developed.

‘The procedures for analysing assembly were shortened extremely,’ Stan says. ‘Also, we now have a great repertoire to study e.g. polymerization reactions inside CCMV-based capsids. However, for example, more knowledge on the interactions between various components is required, to be able to accurately design specific structures.’

Research skills

During his PhD working period Stan, coming from a chemical background, extended his knowledge and research skills in physics.

‘Also I developed my chemical synthesis skills, spending many hours in the lab,’ he says. ‘Most importantly, however, I value my improved abilities to analyse new research fields quickly and to be able to come to the core of the problem much faster nowadays. This I noticed while working on new expert fields together with master students with whom I collaborated. My academic skills grew gradually during the PhD project. I now know how to detect the tricky points of research and resolve these problems first, and then focus fully on the subject.’


In his future career, Stan favours a job in industry. ‘I like to see actual results of my work in an early phase of research,’ Stan says. ‘Research on polymers and fiber reinforced materials appeal to me, especially regarding to durability and environmental friendly products and processes.’

Stan enjoyed being part of Mesa+. ‘Our own Biomolecular NanoTechnology Group alone, houses many disciplines already,’ he says  ‘Also, we collaborated with other Mesa+ Groups, for example NanoBiophysics, making use of their expertise on SAXS measurements involving Small Angle X-Ray Scattering. With the Materials Science & Technology of Polymers Group we collaborated on polymerization processes, which were of crucial importance for my research outcomes.’

‘Further, we collaborated with Universities of Eindhoven and Utrecht, for example helping us with theoretical issues involving Ph measurements. Being part of Mesa+ helped me finding new contacts. While on conferences one perceives the Mesa+ research is well-known and is appreciated widely.’