DNA colloids for interpenetrating gels

Hybrid materials are all around us, from ice-cream to the cytoskeleton in living cells. The mechanical behaviour of hybrid materials is completely different than the behaviour of their individual components. Many hybrid materials have features far smaller than the diffraction limit of light making it extremely difficult to study them with microscopy. Colloidal gels however consist of particles that can be visualized with for example confocal microscopy. Hybrid colloidal gels have only just recently been synthesized1 but the optical properties of these state-of the art materials make it impossible to quantitatively study their structure and local dynamics.

To quantitatively understand the interaction between interpenetrating networks you will synthesize refractive index-matched colloids (See Reference 2) that can specifically self-assemble into interpenetrating networks. This will be achieved by exploiting the extreme specificity of DNA hybridisation.

Once synthesized you will explore the structure, dynamics and mechanics of your newly-made material with optical tweezers and high-speed confocal microscopy. Results will be analysed with new methods which have recently been developed at the sprakellab.



  • Investigating DNA hybridisation in solvents suitable for refractive index matching.
  • Synthesis of refractive index-matched colloids coated with DNA.
  • Inducing the formation of interpenetrating colloidal gels.
  • If all goes well and time allows quantitative measurements and analysis of newly formed material.


  • Synthesis
  • Differential scanning calorimetry (DSC)
  • Quantitative high speed 3D confocal microscopy
  • Optical tweezers
  • Matlab



  1. Varrato, Francesco, et al. "Arrested demixing opens route to bigels." Proceedings of the National Academy of Sciences 109.47 (2012): 19155-19160.
  2. Kodger, Thomas E., Rodrigo E. Guerra, and Joris Sprakel. "Precise colloids with tunable interactions for confocal microscopy." Scientific reports 5 (2015).