(728b) Simplified Synthesis Methods for Membrane-Protein 2D Nanosheets

Membrane proteins and artificial channels are promising membrane materials due to their high throughput and precise selectivity. Incorporating these channels and amphiphilic block-copolymers into 2D nanosheets and depositing them onto porous membranes has yielded composite nanofiltration membranes with water permeances 1-2 orders of magnitude higher than commercial membranes of similar selectivity. However, synthesizing these 2D nanosheets involves time-consuming and/or complex methods. In this work, simplified synthesis methods for protein-block copolymer 2D nanosheets are investigated. 2D nanosheets containing Outer Membrane Protein F (OmpF) and poly(caprolactone-b-ethylene oxide) (PCL-PEG) were synthesized by mixing detergent-solubilized OmpF and PCL-PEG, fluctuating the temperature between 25°C and 60°C, and diluting the detergent (Octyl-POE) below its critical micelle concentration. TEM indicated the formation of 2D materials with a hexagonal crystal structure. Compared to materials prepared using the conventional detergent-dialysis method, these OmpF/PCL-PEG nanosheets were synthesized up to ~320x faster and were up to 1-2 orders of magnitude larger, having areas up to 390 µm². OmpF 2D nanosheets were formed for two PCL-PEG block copolymer with different block lengths as well as two poly(butadiene-b-ethylene oxide) (PB-PEO) block copolymers with different end functionalities, demonstrating the flexibility of this synthesis method. We hypothesize that the rapid formation of these 2D nanosheets was enabled by the temperature-driven phase separation of Octyl-POE. Overall, this simplified synthesis methods for 2D nanosheets represents an advancement in the scalability of nanosheet-based biomimetic membranes.