Bas van Ravensteijn

Bas van Ravensteijn
Bas van Ravensteijn

Bas van Ravensteijn is an Assistant Professor of Pharmaceutics, Utrecht University. He obtained his PhD at the Van 't Hoff Laboratory for Physical & Colloid Chemistry, Utrecht University in 2015 under supervision of Prof. Kegel. After completing a postdoctoral research project at the University of California – Santa Barbara (UCSB) in collaboration with Prof. Hawker and Prof. Helgeson, he joined the Self-Organising Soft Matter group of Prof. Voets at Eindhoven University of Technology as a Marie-Skłodowska-Curie research fellow. In 2021, he moved to the Utrecht Institute for Pharmaceutical Sciences (UIPS) where he, with the support of an ERC Starting Grant, combines fundamental physical & polymer chemistry with pharmaceutical science to rationally design and understand tomorrow's nano-pharmaceutics.

    Research

    The research of Bas van Ravensteijn operates on the boundaries of pharmaceutical science, soft matter chemistry, physical chemistry and polymer science. With this interdisciplinary approach we aim to develop new and fundamentally understand drug delivery systems. 

      1) Polymerization-Induced Assembly for Designer Drug Delivery Vehicles​

      Typically, block copolymer micelles  are prepared in two distinct steps. First, the polymers are synthesized and subsequently the micelles are formed and loaded with the pharmaceutical cargo. More recently, polymerization-induced self-assembly (PISA) routes were developed in which the block copolymer formation occurs simultaneously with higher order structure formation via self-assembly. Because the system is constantly evolving due to the ongoing polymerization, one can argue that PISA generate non-equilibrium structures.

      Although drug delivery has frequently being coined as one of the application areas for PISA, the impact of the non-equilibrium character of the micelles on their drug delivery properties and performance is yet to be elucidated . We attempt to do this by performing a direct comparison with micelles with the same chemical composition but prepared via the conventional two-step approach. With this we hope quantify how preparative pathways influence the physical chemical characteristics of the micelle and how this ultimately influences their performance in vitro. 

      Research team

      Collaborators

      2) Electrostatically Templated Polymerization

      Recently, we have introduced the concept of switchable templated polymerizations. Making use of a well-defined macromolecular template with tunable charge density, the rate of polymerization of an oppositely charge monomer and its maximum achievable conversion could be regulated by simply controlling pH and ionic strength. Electrostatic attraction between the monomer and the template causes a local increase in monomer concentration that enables polymerization at a pH-dependent rate. As the templating effect relies on non-covalent electrostatic forces, it can be switched ‘ON’ and ‘OFF’ on demand by pH and ionic strength as external triggers. The ability to modulate the templating effect, and hence the interaction strength between the polymers in situ, opens up new avenues in polymer synthesis and assembly, employing temporal control of the degree of structural rearrangement.

       We are currently extending this process to the controllable formation of polyplexes where one of the charged components is pharmaceutically-relevant genetic material. Additionally, we are starting to fundamentally understand these templated polymerizations by following the particle formation from molecular to colloidal length scales in situ. 

      Research team

      Collaborators

      3) Polymerization-Induced Colloidal Assembly

      In this project we would like to translate the concept of polymerization-induced self-assembly (PISA) to assembly block copolymers in an out-of-equilibrium fashion, to the colloidal size regime. The overall idea is that one starts with a dispersion of stable colloidal particles. By performing reaction on the surface of the particles or in the dispersing medium, the attractions between the colloids are gradually altered over time. This time dependent attraction triggers the assembly of the particles in higher-order structures. The exact time-dependency can be regulated by playing with the kinetics of the underlying attraction-inducing reaction.

      The fundamental question we would like to answer is how the final assembled structure depends on the time-dependency of the introduced attractions.

      Research team

      • Dr. Bas van Ravensteijn

      Collaborators

      Selected publications

      • E. G. Hochreiner, B. G. P. van Ravensteijn*, Polymerization-induced self-assembly for drug delivery: A critical appraisal. J. Polym. Sci. 2023, 61, 3186. (link)
      • M. Neumann, G. Di Marco, D. Iudin, M. Viola, C. F. van Nostrum, B. G. P. van Ravensteijn, T. Vermonden, Stimuli-responsive hydrogels: The smart biomaterials of tomorrow. Macromolecules 2023, 56, 8377. (link)
      • C. Li, J. R. Magana, F. Sobotta, J. Wang, M. A. Cohen Stuart, B. G. P. van Ravensteijn*, I. K. Voets*, Switchable electrostatically templated polymerization. Angew. Chem. Int. Ed. 2022, 134, e202206780. (link)
      • B. G. P. van Ravensteijn, P. A. Hage, I. K. Voets, Framed by Depletion. Nature Mater. 2020, 19, 1261. (link)
      • B. G. P. van Ravensteijn*, I. K. Voets, W. K. Kegel, R. Eelkema, Out-of-equilibrium colloidal assembly driven by chemical reaction networks. Langmuir 2020, 36, 10639. (link)
      • F. Chang, B. G. P. van Ravensteijn*, K. S. Lacina, W. K. Kegel, Bifunctional Janus spheres with chemically orthogonal patches. ACS Macro Lett. 2019, 8, 714. (link)
      • B. G. P. van Ravensteijn, R. Bou Zerdan, D. Seo, N. Cadirov, J. A. Gerbec, C. J. Hawker, J. N. Israelachvili, M. E. Helgeson, Triple function lubricant additives based on organic-inorganic hybrid star polymers. ACS Appl. Mater. Interfaces 2019, 11, 1363. (link)
      • B. G. P. van Ravensteijn, R. Bou Zerdan, M. E. Helgeson, C. J. Hawker, Minimizing star-star coupling in Cu(0)-mediated controlled radical polymerizations. Macromolecules 2019, 52, 601. (link)
      • B. G. P. van Ravensteijn, W. E. Hendriksen, R. Eelkema, J. H. van Esch, W. K. Kegel, Fuel-mediated transient clustering of colloidal building blocks. J. Am. Chem. Soc. 2017, 139, 9763. (link)
      • B. G. P. van Ravensteijn*, W. K. Kegel, Tuning particle geometry of chemically anisotropic dumbbell-shaped colloids. J. Colloid Interface Sci. 2017, 490, 462. (link)
      • B. G. P. van Ravensteijn*, M. Kamp, A. van Blaaderen, W. K. Kegel, General route toward chemically anisotropic colloids. Chem. Mater. 2013, 25, 4348. (link)