Periodic Reporting for period 1 - AutoPolymer (Autocatalytic Self-Synthesising Polymersomes)
Reporting period: 2020-08-01 to 2022-07-31
Is there life beyond biology? How does chemistry become biology? Beyond formulating questions that are intellectually challenging, the main objective of this proposal was to find features of life in artificial synthetic constructs to generate technologies at the Living/Non-Living interface. The work employed cell units as a source of inspiration, which act as highly cooperative machinery to work in unison and produce cellular functions such as growth, communication, nourishment, or reproduction. In order to stay alive and produce their complex functions, they continuously produce energy gradients and metabolite transport in a state that is out-of-equilibrium with their environment. The overall goal of AutoPolymer has been to generate polymeric nanoparticles with capacity to undergo these out-of-equilibrium states and perform functions that remind us to living systems. For example, predatory particle populations that could feed from prey particle populations were explored in an aim to establish systems that could self-synthesise in the near future. In another example, the project took inspiration from the circadian rhythm which uses day and night cycles to regulate the alternation of metabolic activity. In these processes, the oscillation of metabolite concentrations is controlled by chemical hierarchical networks of independent oscillators that communicate and regulate each other to adapt to light intensity. By generating out-of-equilibrium polymer-enzyme hybrids that could catalyse antagonistic reactions in response to light, oscillations of chemical concentrations could be achieved. Overall, these results establish the developed chemical platform as a highly promising proof-of-concept to achieve systems at the Living/Non-Living interface that can manipulate cell activity finding applications in the modulation of bioreactors for the synthesis of compounds of industrial interest, or to generate motile, self-adaptive biomedical implants.
The multidisciplinary nature of this highly ambitions project was strongly supported by its localisation within the world-renowned Stevens Group at Imperial College London. The diverse nature of the project required input from a number of personnel within the Group with research backgrounds across chemistry, materials science, cell biology, molecular dynamics simulations, and spectroscopy and was crucial to meeting project outcomes. Ongoing collaborations which have been established as a result of this fellowship will continue to drive this work towards future applications.
The multidisciplinary nature of this highly ambitions project was strongly supported by its localisation within the world-renowned Stevens Group at Imperial College London. The diverse nature of the project required input from a number of personnel within the Group with research backgrounds across chemistry, materials science, cell biology, molecular dynamics simulations, and spectroscopy and was crucial to meeting project outcomes. Ongoing collaborations which have been established as a result of this fellowship will continue to drive this work towards future applications.
The following summarizes the main research tasks and results from this fellowship so far:
A. Out-of-equilibrium polymersome membranes that accept external polymers to enlarge in surface area:
1. The understanding of parameter landscape that allows the incorporation of external polymer chains to polymersome membranes.
2. Mechanistic insights of the physical phenomena that allows the incorporation of polymer chains to polymer membranes via microscopy, spectroscopy, and molecular dynamics simulations.
B. Out-of-equilibrium communication networks between polymersome populations:
1. Novel polymersomes containing light responsive motifs that allow the permeation of compounds to their inner cavity. This allows small molecules to encounter enzymes and to be transformed into products controlled by light.
2. Esterases encapsulated in the polymersomes produce acids from esters in presence of light. When the systems are kept in darkness the reactions are interrupted.
3. A second population of polymersomes containing an antagonistic enzyme, urease, was exposed to the light-responsive polymersomes and produced base when acid was formed by light. The delay of this reaction allowed to generate oscillations in the acidity of the medium. The process was regulated by the presence of a photomask that limited the amount of acid that could be generated given the light intensity during the irradiation process.
4. The oscillations of the medium pH, were transduced chemomechanically by controlling the swelling state of a pH-responsive hydrogel as a rudimentary example of the implementation of artificial circadian rhythms in the modulation of materials.
5. The processes were possible in biologically relevant buffers showing promise in their use for the modulation of cell behaviour. We are currently exploring suitable in vitro models to continue this work beyond the end of this Marie Curie fellowship.
The key concepts from this fellowship were presented at the American Chemical Society Spring Meeting 2022 in San Diego. Three publications (Najer et al. ACS Central Science, Kim and Yeow et al. Advanced Science, and Rifaie-Graham et al. Nature Chemistry) have reported findings of this project and 2 more publications are in preparation for submission. These publications have acknowledged and will acknowledge all European Commission funding and comply with EU open access policies. I have also participated in broader outreach activities such as Imperial College’s Great Exhibition Road Festival, to disseminate my research findings and general research interests to the general public. Although significant disruption to planned dissemination activities was incurred due to the COVID-19 pandemic, these will be greatly pursued as further opportunities become more available. Finally, the fundamental knowledge gained from this work has facilitated the training and project development of several research students and will result in further outcomes from this fellowship.
A. Out-of-equilibrium polymersome membranes that accept external polymers to enlarge in surface area:
1. The understanding of parameter landscape that allows the incorporation of external polymer chains to polymersome membranes.
2. Mechanistic insights of the physical phenomena that allows the incorporation of polymer chains to polymer membranes via microscopy, spectroscopy, and molecular dynamics simulations.
B. Out-of-equilibrium communication networks between polymersome populations:
1. Novel polymersomes containing light responsive motifs that allow the permeation of compounds to their inner cavity. This allows small molecules to encounter enzymes and to be transformed into products controlled by light.
2. Esterases encapsulated in the polymersomes produce acids from esters in presence of light. When the systems are kept in darkness the reactions are interrupted.
3. A second population of polymersomes containing an antagonistic enzyme, urease, was exposed to the light-responsive polymersomes and produced base when acid was formed by light. The delay of this reaction allowed to generate oscillations in the acidity of the medium. The process was regulated by the presence of a photomask that limited the amount of acid that could be generated given the light intensity during the irradiation process.
4. The oscillations of the medium pH, were transduced chemomechanically by controlling the swelling state of a pH-responsive hydrogel as a rudimentary example of the implementation of artificial circadian rhythms in the modulation of materials.
5. The processes were possible in biologically relevant buffers showing promise in their use for the modulation of cell behaviour. We are currently exploring suitable in vitro models to continue this work beyond the end of this Marie Curie fellowship.
The key concepts from this fellowship were presented at the American Chemical Society Spring Meeting 2022 in San Diego. Three publications (Najer et al. ACS Central Science, Kim and Yeow et al. Advanced Science, and Rifaie-Graham et al. Nature Chemistry) have reported findings of this project and 2 more publications are in preparation for submission. These publications have acknowledged and will acknowledge all European Commission funding and comply with EU open access policies. I have also participated in broader outreach activities such as Imperial College’s Great Exhibition Road Festival, to disseminate my research findings and general research interests to the general public. Although significant disruption to planned dissemination activities was incurred due to the COVID-19 pandemic, these will be greatly pursued as further opportunities become more available. Finally, the fundamental knowledge gained from this work has facilitated the training and project development of several research students and will result in further outcomes from this fellowship.
This fellowship has advanced the state-of-the-art across several areas in systems chemistry and nanotechnology. Whilst nature has shown the importance of compartmentalisation employing cell membranes as chemical gates, to date, the majority of out-of-equilibrium systems and materials have been built as non-compartmentalised assemblies. The results showcase the implementation of key features of life into membranous polymer nanoparticles, i.e. polymersomes: their ability to combine molecular assemblies and enzymatic reactions to generate chemical energy gradients and dissipation that is out-of-equilibrium with their environment. To date, the majority of the literature results showcase examples of achieving out-of-equilibrium states by feeding chemical fuels. The communication networks developed in this MSCA are initially in a dormant equilibrium state and display out-of-equilibrium activity when they are stimulated externally by light without requiring feeding of fuel, representing a major step forward in the field. Moreover, the predatory polymersomes studied in this MSCA unlock parameters for the conceptualisation of self-synthesising polymersomes that could be employed to generate bioreactors in synergy with living microorganisms for the production of chemical products of industrial interest. Taking biologically-derived materials and synthetic products as a model for the creation of a fossil-fuel-independent economy, this MSCA has provided novel technologies with stimuli-responsive and self-adaptive properties that take environmentally available energy as a source to power out-of-equilibrium functions.