Periodic Reporting for period 1 - ARC-for-CORE (Artificial Compartment for Coenzyme Regeneration)
Reporting period: 2019-03-18 to 2021-03-17
Rebuilding the cell or matching the certain cell functions can be the way we understand how real cells work and even go beyond for intelligent production. Over the last decade, the EU has invested heavily in searching for cell alternatives to impact pharmaceutics, therapeutics, agriculture, and more general chemical processing. The technological possibilities of relevant research are now at a tipping point and will lead to a revolution in medicine, food and sustainability in the next 5 to 20 years. We noticed that most works focused on proof-of-concept research of compartmentalised/localised reactions and mass transfer among/within cells. Given that the cell wall is equally important like other organelles to the cell’s space-sensitive activities, a robust, function-tuneable artificial envelop is highly needed. As far as we know, the effort to build an artificial cell wall is far from enough. The state-of-art knowledge of man-made shell, from material selection, interfacial assembly kinetics to tailoring functionality, is limited. Therefore, a systematic exploration concentrating on building blocks of the artificial cell wall can bridge the gap of EU in the progress of this field. Due to the Covid lockdown, we had to reconsider the methodologies, e.g. we developed the Genetic Algorithm to accelerate material optimisation, and replaced the collaborative microfluidics with the extensive emulsion stability study. However, the overall goal has not been changed. The bonus of the smartly optimised shell candidate is that we know much clearer than before about the physical chemistry at the complex interface. Therefore, the significance of our updated project even broadened the horizon to the basic interfacial science and methodology advancement, which would pave the way for the community to understand the behaviour of low-dimensional materials at the interface. Arc-for-Core project contributes to developing novel candidates for artificial compartment by investigating low-dimensional materials as building blocks. We demonstrate high versatility of low dimensional materials in forming a composite shell, which manifests tailorable mechanical properties, conductance, stimuli-response, and potential of interfacial assembly. Furthermore, through the updated methodology of processing, the 2D materials in the latter case offer us the chance to investigate their behaviour at the complex and multiphasic interface.
The role of different polymers in stabilising 2D materials was investigated. We confirmed that glycol-chitosan and PVP-10k were the best positively and negatively charged polymer to stabilise 2D materials, including graphene, MoS2 and MXene. But isothermal titration calorimetry (ITC) clued that precise control of intermolecular attraction cannot be applicable in our case. We also optimised the consecutive process of exfoliation. We coded customised genetic algorithm (GA) and drove the optimisation of liquid phase exfoliation of 2D materials, aiming at the optimal width-to-thickness (L-to-H) ratio. We found the optimised exfoliation enabled the progressive thinning, which not only enrich monolayers but also preserve the 2H phase. This led to less charged monolayers, and consequently, the ideal candidate for interface trapping. We further investigated the surface energy of exfoliated 2D materials by using contact angle and calculated surface energy using van Oss-Chaudhury-Good thermodynamic approach. We have also probed the functional groups or adsorbates on the exfoliated samples by Fourier transform infrared spectrometry (FTIR) and Sum frequency generation spectroscopy (SFG). . All of these results indicate that the monolayer is the ideal candidate for stabilising emulsions because of the amphiphilic properties.
We realised o-w, w-o, o-w-o and w-w emulsions by using home-made microfluidic devices. Time-lapse fluorescence imaging of droplets can track the change of PL intensity which parallelises the period for diffusion-limited mass transfer of intermediate phase or formation of pseudophase. Therefore, the interfacial immobilisation kinetics were obtained and modelled by Michaelis–Menten kinetics. We conclude that the interfacial energy is still playing the major role for the interfacial immoblisation of 2D flakes. In addition, the investigation of emulsion stability were examined intensively by using phase diagraph. As compared with other candidates, monolayers led to a compositional range for stable emulsion that extend to the region containing NMP less than 5%. The above results support our anticipation that monolayer-rich flakes can be interface trapped because of their low affinity to the polar phase and high atomic efficiency.
Electrochemical reactions involving NAD(P)H as alternative to the SECM were performed. We designed the porous structure with 2D materials as building blocks. The low overpotential of defective MoS2 in hydrolysis encouraged us introduce 2D materials as both supporter and mediator for the coenzyme regenerations. The porous film served as a working electrode. The kinetics were detected by a rotary disk electrode. The progress of the NAD+ reduction reaction was monitored by UV-Vis spectrophotometry.
As an overview of the result, we have explored the interfacial behaviour of 2D materials. The effort to exploit 2D materials as “Arc” for the “Core” (biological reactions) generated pioneering experience in optimising the size and thickness of 2D materials by using genetic algorithm. The stability of emulsion has been deeply investigated more through the thermodynamics. The fellow, therefore, further enhance the skills that will help further success in the field of colloids and interfaces. Although the planed collaboration and secondment cannot be realised due to the covid crisis, the fellow had some more chances to develop other critical complementary skills, such as computation and microfluidics. The results of the fellowship also pave a way for 2D surfactant, which will be a brand-new family of surfactant impacting widely on the industry and society.
We realised o-w, w-o, o-w-o and w-w emulsions by using home-made microfluidic devices. Time-lapse fluorescence imaging of droplets can track the change of PL intensity which parallelises the period for diffusion-limited mass transfer of intermediate phase or formation of pseudophase. Therefore, the interfacial immobilisation kinetics were obtained and modelled by Michaelis–Menten kinetics. We conclude that the interfacial energy is still playing the major role for the interfacial immoblisation of 2D flakes. In addition, the investigation of emulsion stability were examined intensively by using phase diagraph. As compared with other candidates, monolayers led to a compositional range for stable emulsion that extend to the region containing NMP less than 5%. The above results support our anticipation that monolayer-rich flakes can be interface trapped because of their low affinity to the polar phase and high atomic efficiency.
Electrochemical reactions involving NAD(P)H as alternative to the SECM were performed. We designed the porous structure with 2D materials as building blocks. The low overpotential of defective MoS2 in hydrolysis encouraged us introduce 2D materials as both supporter and mediator for the coenzyme regenerations. The porous film served as a working electrode. The kinetics were detected by a rotary disk electrode. The progress of the NAD+ reduction reaction was monitored by UV-Vis spectrophotometry.
As an overview of the result, we have explored the interfacial behaviour of 2D materials. The effort to exploit 2D materials as “Arc” for the “Core” (biological reactions) generated pioneering experience in optimising the size and thickness of 2D materials by using genetic algorithm. The stability of emulsion has been deeply investigated more through the thermodynamics. The fellow, therefore, further enhance the skills that will help further success in the field of colloids and interfaces. Although the planed collaboration and secondment cannot be realised due to the covid crisis, the fellow had some more chances to develop other critical complementary skills, such as computation and microfluidics. The results of the fellowship also pave a way for 2D surfactant, which will be a brand-new family of surfactant impacting widely on the industry and society.
We demonstrated the high versatility of low dimensional materials in forming a composite shell, which manifests tailorable mechanical properties, conductance, stimuli-response, and the potential of interfacial assembly. We innovatively explain the interface energy of exfoliated transition metal dichalcogenide flakes with the van Oss-Chaudhury-Good thermodynamic approach, revealing that the hydrophobicity of 2D materials depends on the surface defect. We updated the methodology with a genetic algorithm for the exfoliation of layered materials so that the optimised 2D materials offered the chance to investigate their behaviour at the complex and multiphasic interface. The monolayer MoS2 has been developed as a very promising 2D surfactant to stabilise the o-in-w emulsion with an ultrahigh atomic efficiency. Microfluidics was mastered and employed to investigate the interfacial immobilisation of 2D materials and their favourable impact on the enzymatic activities. The regeneration of coenzyme has been studied via an electrochemical approach. We believe that building the compartments with monolayer MoS2 will have 2-folds advantages: 1) stabilises the compartment with a high atomic efficiency, 2) facilitates the mediated NAD(P)+ reduction by MoS2-catalysed generation of active absorbed hydrogen.