Expanding the Enzymatic Polymerization Landscape by Lipid Mesophase Soft Nanoconfinement.

Soft nanoconfinement can increase chemical reactivity in nature and has therefore led to considerable interest in transferring this universal feature to artificial biological systems. However, little is known about the underlying principles of soft nanoconfinement responsible for the enhancement of biochemical reactions. Herein we demonstrate how enzymatic polymerization can be expanded, optimized, and engineered when carried out under soft nanoconfinement mediated by lipidic mesophases. By systematically varying the water content in the mesophase and thus the diameter of the confined water nanochannels, we show higher efficiency, turnover rate, and degrees of polymerization as compared to the bulk aqueous solution, all controlled by soft nanoconfinement effects. Furthermore, we exploit the unique properties of unfreezing soft nanoconfined water to perform the first enzymatic polymerization at -20 °C in pure aqueous media. These results underpin lipidic mesophases as a versatile host system for chemical reactions and promote them as an original and unexplored platform for enzymatic polymerization.

2D foam film coating of antimicrobial lysozyme amyloid fibrils onto cellulose nanopapers.

Amyloid fibrils made from inexpensive hen egg white lysozyme (HEWL) are bio-based, bio-degradable and bio-compatible colloids with broad-spectrum antimicrobial activity, making them an attractive alternative to existing small-molecule antibiotics. Their surface activity leads to the formation of 2D foam films within a loop, similar to soap films when blowing bubbles. The stability of the foam was optimized by screening concentration and pH, which also revealed that the HEWL amyloid foams were actually stabilized by unconverted peptides unable to undergo amyloid self-assembly rather than the fibrils themselves. The 2D foam film was successfully deposited on different substrates to produce a homogenous coating layer with a thickness of roughly 30 nm. This was thick enough to shield the negative charge of dry cellulose nanopaper substrates, leading to a positively charged HEWL amyloid coating. The coating exhibited a broad-spectrum antimicrobial effect based on the interactions with the negatively charged cell walls and membranes of clinically relevant pathogens (Staphylococcus aureus, Escherichia coli and Candida albicans). The coating method presented here offers an alternative to existing techniques, such as dip and spray coating, in particular when optimized for continuous production. Based on the facile preparation and broad spectrum antimicrobial performance, we anticipate that these biohybrid materials could potentially be used in the biomedical sector as wound dressings.