Periodic Reporting for period 4 - STORM (Signal Transduction in Organic Materials) Reporting period: 2021-10-01 to 2022-03-31 Summary of the context and overall objectives of the project The aim of the STORM project is to make soft polymer materials think for themselves. In a nutshell, we try to make these materials responsive to signals coming from something inside or outside the material, and then respond with a pre-programmed action. Such an action could be for instance movement, or changing color, or releasing a drug, or fixing damage. Crucial to this signal detection and response are catalysts that can change their activity when reacting with the signal. Over the past few years, we've developed several of such catalysts, because these were previously unknown. We made versions of these catalysts that can respond to specific (often biological) signals, including catalysts that can be used as such repeatedly. We made polymer particles and gels that can respond to these catalysts or to signals, for instance by falling apart or by contracting. In parallel, we have discovered an entirely new signal-responsive cascade of reactions (a 'chemical reaction network') that can be built into all sorts of polymers quite easily, can amplify very small signals, and can be used in biological environments (hopefully even in the body in the future). Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far Over the course of the entire project, we performed the following work and achieved the following results.We developed two classes of signal responsive catalysts: one class where the catalyst is inactivated by being chemically blocked by a protecting group or 'cage', the other class where the catalyst is blocked by being sequestered inside a molecular container. For the latter, we demonstrated that concept for organometallic catalysts as well as organocatalysts. We also extended the concept to enable repeated on/off switching of activity and control over the time-domain of activity by coupling catalyst activity to a chemical reaction network. For the caged catalysts, we demonstrated their application in soft polymer materials (gel formation) and how to make their activation specific to certain chemical signals. We have subsequently worked on coupling catalysis and signal response to chemical reaction networks, to achieve repeated and temporary responses to specific signals. These networks were then coupled to polymer materials such as micelles (nanometer sizes particles) and polymer gels. With those, we showed how signals and catalysis can change material behaviour, for instance in gel contraction, polymer conformation, and gel destruction. We also coupled these types of behaviour to alternative signals such as light and radioactivity. For the combination of catalysis and reaction networks, we developed theoretical models to predict their behaviour. In the context of chemical reaction networks, we discovered a new type of network by surprise, and then explored its use in making signal responsive polymer materials. There, we made polymer gels and particles that can disintegrate in response to slight damage (a case of very efficient signal amplification), gels that can release chemotherapeutics drugs, and injectable gels. Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) Responsive artificial catalysts are rare and their development in this project goes beyond the state of the art. Besides, we have found a new class of chemical reaction network that holds great promise for application in many different fields. Currently we are exploring these possibilities, including in drug delivery and in protein structure analysis. project summary
