Engineering the interfacial behavior of self-propelled yeast/nanocellulose supraparticles by tailoring the surface chemistry of cellulose nanofibrils

Abstract

This research is devoted to the development of living materials using biorenewable colloids. Basically, cellulose nanofibrils (CNF) are combined with Saccharomyces cerevisiae cells and dried in a controlled fashion into supraparticles that combine the binding capacity of the interlocked CNF matrix and the enclosed yeast cells that retain their metabolic function. The microbial metabolism, though, is strongly tethered to the position of this living supraparticle within an aqueous culture medium, whether in high redox potential (respiration) close to the air/water interface or in its low redox analogue (fermentation) submerged in the culture medium. The interfacial behavior of the supraparticles is then of utmost importance to control their CO2 production rate, which in turn affects their buoyancy/sedimentation balance and therefore their vertical motility. Taking advantage of the high chemical reactivity of CNF, this research is set to achieve different levels of surface energy by the functionalization with hydrophobic moieties onto CNF surface, which is proposed herein to be carried out via regioselective esterification reactions. The pristine and surface-hydrophobized building blocks as well as their assembled supraparticles will be extensively characterized as far as morphological, structural, mechanical, and metabolic properties towards self-propelled yet sustainable constructs. (AU)