Bio‐Inspired Microreactors Continuously Synthesize Glucose Precursor from CO2 with an Energy Conversion Efficiency 3.3 Times of Rice

Abstract Excessive CO2 and food shortage are two grand challenges of human society. Directly converting CO2 into food materials can simultaneously alleviate both, like what green crops do in nature. Nevertheless, natural photosynthesis has a limited energy efficiency due to low activity and specificity of key enzyme D‐ribulose‐1,5‐bisphosphate carboxylase/oxygenase (RuBisCO). To enhance the efficiency, many prior studies focused on engineering the enzymes, but this study chooses to learn from the nature to design more efficient reactors. This work is original in mimicking the stacked structure of thylakoids in chloroplasts to immobilize RuBisCO in a microreactor using the layer‐by‐layer strategy, obtaining the continuous conversion of CO2 into glucose precursor at 1.9 nmol min−1 with enhanced activity (1.5 times), stability (≈8 times), and reusability (96% after 10 reuses) relative to the free RuBisCO. The microreactors are further scaled out from one to six in parallel and achieve the production at 15.8 nmol min−1 with an energy conversion efficiency of 3.3 times of rice, showing better performance of this artificial synthesis than NPS in terms of energy conversion efficiency. The exploration of the potential of mass production would benefit both food supply and carbon neutralization.

).After PEI deposition, new peaks appear at around 3200-3500 cm -1 corresponding to the N-H stretching vibration of amine groups in PEI, around 2800-3000 cm -1 corresponding to the C-H stretching vibration of methylene groups in PEI and around 1400-1600 cm -1 corresponding to the N-H/C-H bending.(b) CD spectra of PDMS film (red line), RuBisCO solution (purple line), and (PEI/RuBisCO)n assembly deposited on PDMS films.The spectrum of the PDMS thin film shows no peak (red line).But the RuBisCO solution has the peak at ~220 nm (purple line), indicating the secondary structure of RuBisCO [1] .The spectra of the (PEI/RuBisCO)n assembly deposited on the PDMS thin film also present the similar negative peak at ~ 220 nm, which confirms the immobilization of RuBisCO on PDMS.It is noticed that the peak intensity increases with the increasing number of the PEI/RuBisCO bilayer, suggesting the increasing amount of the immobilized RuBisCO on PDMS film, which is consistent with the ATR-FTIR spectra.Reader).BSA solutions at different concentrations were selected as standards to plot the calibration curve. [2](a) BSA at 0.125-1 mg mL -1 for the microplate standard assay and (b) BSA at 1.25-25 g mL -1 for the microplate micro-assay.2a, 3] Table S2.Performance comparison of the immobilized RuBisCO and the free RuBisCO.Free in solution c) 10% 47% 6% -a)c) The data are collected from the previous studies using the same detection method; [2a, 3] d) Thermal stability is the remained relative activity after the incubation at 70 °C for 10 min; e) Long-term thermal stability is the remained relative activity after the incubation at 50 °C for 60 min; f) Storage stability is defined as the remaining relative activity after 15 days; g) Reusability is the remained relative activity after 10 cycles of reuse at the flow rate of 7 μL min −1 ; h) Post-immobilization leakage rate is determined by the slope of the linearly fitted line of the relative activities retained after each cycle of reuse.

Figure S1 .
Figure S1.Process flow of the fabrication of PMRs by the soft photolithography, including

Figure S2 .
Figure S2.Detailed dimensions of the microchannels as shown by the gray-blue area.The unit

Figure S5 .
Figure S5.Calibration of protein amount determined from BSA solutions by the Bradford

Figure S7 .
Figure S7.(a) SDS-PAGE analysis of RuBisCO in the reaction buffer for the confirmation of

Figure S8 .
Figure S8.Visualization of the charge distribution on the surface of the RuBisCO under pH of

Figure S9 .
Figure S9.Relative activities of (PEI/RuBisCO)4-PMRs retained after a prolonged incubation time up to 60 min at 50 o C. RuBP concentration is 0.5 mM and HCO3 -is 66 mM.RuBP and

Figure S10 .
Figure S10.Comparsion of the relative activity remained after each cycle of reuse and the

Table S1 .
Measured kinetic parameters of the immobilized RuBisCO and the free RuBisCO a) .