Diacyl disulfides as the precursors for hydrogen persulfide (H2S2).

While hydrogen polysulfides (H2Sn, n ≥ 2) are believed to play regulatory roles in biology, their fundamental chemistry and reactivity are still poorly understood. Compounds that can produce H2Sn are useful tools. In this work we found that H2S2 could be effectively produced from diacyl disulfide precursors, triggered by certain nucleophiles, in both aqueous solutions and organic solvents. This method was used to explore redox reactions of H2S2, such as scavenging 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and reduction of tetrazines.

Metabolism Control in 3D-Printed Living Materials Improves Fermentation.

The three-dimensional (3D) printing of cell-containing polymeric hydrogels creates living materials (LMs), offering a platform for developing innovative technologies in areas like biosensors and biomanufacturing. The polymer material properties of cross-linkable F127-bis-urethane methacrylate (F127-BUM) allow reproducible 3D printing and stability in physiological conditions, making it suitable for fabricating LMs. Though F127-BUM-based LMs permit diffusion of solute molecules like glucose and ethanol, it remains unknown whether these are permissible for oxygen, essential for respiration. To determine oxygen permissibility, we quantified dissolved oxygen consumption by the budding yeast-laden F127-BUM-based LMs. Moreover, we obtained data on cell-retaining LMs, which allowed a direct comparison between LMs and suspension cultures. We further developed a highly reliable method to isolate cells from LMs for flow cytometry analysis, cell viability evaluation, and the purification of macromolecules. We found oxygen consumption heavily impaired inside LMs, indicating that yeast metabolism relies primarily on fermentation instead of respiration. Applying this finding to brewing, we observed a higher (3.7%) ethanol production using LMs than the traditional brewing process, indicating improved fermentation. Our study concludes that the present F127-BUM-based LMs are useful for microaerobic processes but developing aerobic bioprocesses will require further research.