Viral protein cages as building blocks for functional materials

In this thesis strategies are described in order to take full advantage of virus protein capsids, to develop functional materials. ‘Proteins assemble in a well-defined way, making them very interesting in nanotechnology and in materials science,’ Aijie Liu explains.

‘They may serve as building blocks,’ she says. ‘Especially virus particles have shown great advantages, as they exist in various sizes and shapes, with high mono-dispersity and symmetry. They can be easily produced using various methods. The resultant products can potentially be scaled up for daily life applications.’

Nature builds up proteins bottom-up, from the amino acids to large protein chains with tertiary three dimensional structures. Nature uses proteins as highly efficient molecular machines which control many functions within the living cell. Because of their natural properties, virus coat proteins are widely used for controlled drug loading and delivery, and also as size-selective catalyst platforms, and as confined nanoreactors for controlled growth of inorganic and organic materials.

‘In my PhD work supramolecular chemistry, surface chemistry and the role of enzymes and catalyst functional materials, were combined,’ Aijie says. ‘For example the catalytic properties of thin films I studied for potential application in bio-sensors. The biocompatibility of these films was studied to reveal the possibility of in vivo applications, in future photo-thermotherapy.’

In the last chapters of her thesis work, Aijie collaborated with Dutch based Royal DSM.

‘We had annual meetings as well as progress meetings along the year,’ Aijie says. ‘I find it important for my work to contribute to the common good. I hope to find that feature of work in my future job in Research & Development, be it in Europe or in my home country China.’

Hybrid nanoparticles

In these two chapters hybrid nanoparticles based on the virus capsid and gold were studied.

The protein cages were also used as templates for controlled synthesis of inorganic silica particles. ‘The growth was finetuned by controlling the pH,’ Aijie says. ‘In the end gold core-silica hollow shell nanostructures were formed. Also I demonstrated that virus particles can be used as environmental friendly porogens, for the fabrication of anti-reflective coatings.’


In earlier chapters of her work, Aijie believes her findings could be used, one day, in novel sensor systems, as well as in solar cells and electronic devices.

For example gold/protein hybrid nanoparticles were immobilized in flow channels. Further crosslinking of gold loaded proteins on a liquid-liquid interface, cages resulted in free standing thin films. The catalytic properties were studied for potential application in bio-sensors.


Aijie: ‘While working at Mesa+ I felt very privileged, being able to use the equipment and the Nanolab. Also it was great to collaborate. Colleagues were very flexible to make an appointment, and always willing to share knowledge and think along with me. What especially stood out for me, was the organization of the labs: the nice chemical arrangements, with very clean working environments. No unusual smells were present. All the time, I perceived the working atmosphere as very inspiring.’