2024 AIChE Annual Meeting
Rapid Phase Separation Driven Formation of Biomimetic 2D Nanosheets
Biomimetic materials, such as membrane proteins, exhibit intriguing potential as membrane materials due to their fast transport rates and high selectivity. When membrane proteins are self-assembled into 2D nanosheets with block copolymers and deposited onto membranes, the resulting membranes have exhibited exceptional performance for nanofiltration. However, the methods required to create these self-assembled 2D nanosheets can take up to multiple days to complete. In this work, we leverage detergent solution phase separation to achieve a rapid self-assembly of membrane proteins and block copolymers. To create the 2D nanosheets, Outer Membrane Protein F (OmpF), poly(butadiene-b-ethylene oxide) (PB-PEO), and n-octyl-oligo-oxyethylene (Octyl POE) detergent were mixed and then heated to 60°C for varying durations. After heating, the solution was diluted to lower the Octyl POE concentration below its critical micelle concentration. To analyze the structures that were formed, Transmitting Electron Microscopy (TEM) was utilized. Fast-Fourier-Transform analysis of TEM images revealed the formation of 2D nanosheets with a trigonal packing of OmpF proteins in PB-PEO, the same structure that was formed using previous methods. We hypothesize that the 2D nanosheet formation was caused by the aggregation of Octyl POE micelles containing OmpF and PB-PEO at 60°C, which happens within seconds. These sheets were formed in as little as five minutes, which is about 2,100 times faster than the conventional method for 2D nanosheet synthesis. Additionally, many of these nanosheets were found to be nearly an order of magnitude larger in size than the largest OmpF nanosheet synthesized by the conventional method. This method was scaled up in volume 30x and continued to produce similar quality 2D nanosheets, indicating scalability potential. Ultimately, the method reported here eliminates the time and material constraints previously associated with 2D nanosheet formation from membrane proteins while maintaining nanosheet quality, critical factors for achieving scalability of 2D nanosheet biomimetic membranes.