One of the most interesting questions for chemists is how bioinspired or biomimetic properties can arise from the interactions of relatively simple molecules. Taking inspiration from Alan Turing’s pioneering computational work in 1952, chemists demonstrated in experiments that “simple” chemical systems can produce complex spatio-temporal phenomena or stationary patterns that may play a role in morphogenesis and the growth of form in living systems. This work highlighted the important role of feedback loops in the reaction networks for the emergence of periodicity that plays such an important role in biology.
More recently, the interplay between chemistry and mechanical forces in heterogeneous media including membranes, micelles, hydrogels etc is of increasing importance in this exciting research area. As was noted by Gregoire Nicolis in 2001 “elucidating the mechanisms of mechano-chemical couplings should lead not only to the elaboration of interesting new materials but also to the understanding of a number of biological processes of great concern.”
However, many of the systems under investigation suffer from drawbacks including lack of biocompatibility or unstable components that lead to degradation and loss of behaviour. While computational models are advanced, experimental realization remains challenging and necessitates solid experience in quite different fields as nonlinear science, polymer (physical) chemistry and enzyme reactions.
Therefore, the objectives of this project were to unite the host`s and the researcher`s previous experiences and to develop new biologically relevant systems capable of chemomechanical oscillations with chemistry open to diversification. The approach could thus be generalized, opening the path for the development of many new stable systems with regulatory functions, such as the ability to periodically open a valve. Such systems show features in common with biological machines and are of interest in soft robotics, with applications, for example, in drug delivery.
The original focus of the project was an enzymatic reaction – the urease reaction – that could form the basis of a self-oscillating enzyme-containing hydrogel. Another important aspect of the project was comparison with known chemical oscillators and identification of stability and toxicity issues. To this end, a chemical system was identified and modified such that its stability and general applicability were greatly improved.
Creating biocompatible (but not necessarily enzymatic) oscillatory reactions remains an interest for a much broader group within the community of nonlinear and materials scientists. The easy handling and stability of the chemical reaction has priority, and the possibility of combining with delicate biomaterials (natural polymers) widens the perspectives. Understanding biological processes (that are too complex to overview intuitively or analytically) can happen only by studying simplified artificial subsystems that reproduce certain characteristic but general behaviours. Periodicity is one of them.
