Final Report Summary - COLSTRUCTION (Numerical Design of Self Assembly of Complex Colloidal Structures)
Biological systems are capable of assembling functional structures of great complexity: many distinct building blocks (including proteins, lipids and DNA) can, together form structures that can perform specific tasks that are essential for life. One of the key challenges in nano-materials science is to uncover the design principles that would allow us to copy nature in the sense that we mix a large number of distinct components in a test tubes and have these components self-assemble into complex `devices' that would process chemical, optical or electrical information.
This holy grail seemed far away when I started on my ERC project in 2008. Now, having completed the project, I am confident that the door is open to a new and exciting field of research that will see the creation of such structures.
My own contribution has been to understand the factors that hampered earlier developments and to uncover principles that will allow experimentalists to move forward. My project has therefore centred on theory and modelling, but always with an eye on the experimental realisations.
Specifically, I have used numerical simulations to explore how self-assembly can be used to make truly complex materials. The idea was that the selectivity of NDA hybridization would make it possible to create so-called `addressable' structures, i.e. structure where many (hundreds or thousands) distinct building blocks are arranged in a pre-determined pattern. At the very end of the project, we got to the stage where we could formulate the design rules that will make this possible, It is one of the most exciting pieces of research that I have ever done.
On the way to this final result, we gained insight in the factors that had hampered experimental progress in the field. It turned out that the strong cooperativity of DNA-mediated binding between colloids was at the root of the problem. If colloids can form a large number of DNA contacts, there is a well defined temperature below which these colloids can no longer unbind. From that moment on, complex target structures can no longer anneal. The result is that, upon cooling, the system does not form the target structure but some disordered `off-pathway' aggregate. This suggested to us that effective self assembly requires only few (ideally, only one) bonds between neighbouring particles.
In 2012, the group of Peng Yin at Harvard reported exciting experiments that show that very complex (hundreds to thousands of building blocks) structures could be form from specially designed DNA strands. We were able to elucidate the mechanism by which this self-assembly can succeed where earlier experiments failed. Using these insights we are now at the stage where we can start designing truly complex structures containing colloidal building blocks. As these final results have only been published very recently, follow-up experiments are still lacking.
Surprisingly, the very same physical phenomena that hamper the kinetics of self-assembly of colloids coated with many DNA strands, can be harnessed to achieve highly selective drug delivery of vesicles coated with many ligands to targeted cells that over-express complementary receptors. This work has been taken up by several experimental groups.
This holy grail seemed far away when I started on my ERC project in 2008. Now, having completed the project, I am confident that the door is open to a new and exciting field of research that will see the creation of such structures.
My own contribution has been to understand the factors that hampered earlier developments and to uncover principles that will allow experimentalists to move forward. My project has therefore centred on theory and modelling, but always with an eye on the experimental realisations.
Specifically, I have used numerical simulations to explore how self-assembly can be used to make truly complex materials. The idea was that the selectivity of NDA hybridization would make it possible to create so-called `addressable' structures, i.e. structure where many (hundreds or thousands) distinct building blocks are arranged in a pre-determined pattern. At the very end of the project, we got to the stage where we could formulate the design rules that will make this possible, It is one of the most exciting pieces of research that I have ever done.
On the way to this final result, we gained insight in the factors that had hampered experimental progress in the field. It turned out that the strong cooperativity of DNA-mediated binding between colloids was at the root of the problem. If colloids can form a large number of DNA contacts, there is a well defined temperature below which these colloids can no longer unbind. From that moment on, complex target structures can no longer anneal. The result is that, upon cooling, the system does not form the target structure but some disordered `off-pathway' aggregate. This suggested to us that effective self assembly requires only few (ideally, only one) bonds between neighbouring particles.
In 2012, the group of Peng Yin at Harvard reported exciting experiments that show that very complex (hundreds to thousands of building blocks) structures could be form from specially designed DNA strands. We were able to elucidate the mechanism by which this self-assembly can succeed where earlier experiments failed. Using these insights we are now at the stage where we can start designing truly complex structures containing colloidal building blocks. As these final results have only been published very recently, follow-up experiments are still lacking.
Surprisingly, the very same physical phenomena that hamper the kinetics of self-assembly of colloids coated with many DNA strands, can be harnessed to achieve highly selective drug delivery of vesicles coated with many ligands to targeted cells that over-express complementary receptors. This work has been taken up by several experimental groups.