Sticky Business: Investigating “velcro” gelators in the Netherlands


By LifETIME CDT Student: Chloe Wallace (University of Glasgow)

In March I travelled to the Netherlands to undertake a three-month placement at the University of Technology in Eindhoven (TUE), working with Professor Patricia Dankers’ group. Here, I learned all about their self-assembling ureido-pyrimidinone (UPy) functionalised polymers and their potential as biomaterials. These UPy-units act as a “molecular velcro” by driving self-assembly via fourfold hydrogen bonding (Figure 1). The incorporation of the supramolecular group alters the mechanical properties of the polymer network1 and the non-covalent nature of the assembly mimics the hierarchal nature of the extracellular matrix formation.2 The group has already shown the outstanding potential of these systems as biomaterials for applications such as kidney organoid growth3 and drug delivery.4

The goal for my project was to combine these materials with the low molecular weight gelator I work with in Glasgow (2NapFF) and characterise the new systems (Figure 1). Previous work from the Dankers group has found that altering the ratio of how the ratio of different UPy-polymers determines the viscoelastic properties of the hydrogel.2 With this in mind, we were keen to investigate the effect adding our gelator would have on the systems.

Figure 1. Schematic outlining the project investigating the two gelators in water both alone and as multi-component systems for cell culture.

Figure 1. Schematic outlining the project investigating the two gelators in water both alone and as multi-component systems for cell culture.

During the placement I had the chance to get acquainted with several new techniques such as Cryo-TEM, with the help of Riccardo Bellan from the Dankers group. I learned about how samples were processed before imaging could be carried out and gained high-resolution images of the fibrous networks at a micrometer scale. I was also lucky enough to submit samples for small-angle neutron scattering (SANS) scattering data from ISIS neutron and muon source in the UK. SANS is another method of probing the structure of the fibres present in the system which allows us to compare the data with information obtained by Cryo-TEM.

I also carried out rheology on the gels to probe their mechanical properties such as strength and stiffness, to investigate the effect of including different components into the network. As well as this I tested the biocompatibility of the networks individually

and combined at different concentrations. This was done by culturing human fibroblast cells on top of the network. For this aspect, I also added a UPy-functionalised biological motif to help the cells stick to our hydrogels more efficiently.

My time at TUE was one of the highlights of my PhD and underlined the potential that can be unlocked by combining these types of materials for biological purposes. I would like to thank Professor Dankers for this opportunity, as well as her support and ideas throughout the placement. Furthermore, I could not have wished for a more welcoming group who made my experience so memorable. I am so grateful for all their help in the lab and for making my time in the Netherlands so memorable. In particular, for introducing me to traditional Dutch activities, such as dinner at the pancake restaurant (pictured below). I now look forward to applying what I learned during my placement throughout the remainder of my PhD at the University of Glasgow.

Group photo of Chloe with her placement colleagues. 10 people all sit around a round garden table with a red umbrella above them, there is grass, trees and fairy lights in the background and the weather looks warm and sunny.



  1. J. Kang, D. Miyajima, T. Mori, Y. Inoue, Y. Itoh and T. Aida, Science, 2015, 347, 646-651.
  2. M. Diba, S. Spaans, S. I. S. Hendrikse, M. M. C. Bastings, M. J. G. Schotman, J. F. van Sprang, D. J. Wu, F. J. M. Hoeben, H. M. Janssen and P. Y. W. Dankers, Adv Mater, 2021, 33, e2008111.
  3. P. Y. Dankers, J. M. Boomker, A. Huizinga-van der Vlag, E. Wisse, W. P. Appel, F. M. Smedts, M. C. Harmsen, A. W. Bosman, W. Meijer and M. J. van Luyn, Biomaterials, 2011, 32, 723-733.
  4. M. J. G. Schotman and P. Y. W. Dankers, Advanced Materials Interfaces, 2022, 9, 2100942.