Swimming supraparticles: controlling the motility of nanocellulose/yeast supraparticles through surface chemistry

• Grant number: 22/08780-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2022
• End date: January 31, 2025
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: Caio Gomide Otoni
• Grantee: Eduardo Mendes Daniel
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 21/12071-6 - Tailoring colloids through supramolecular interactions: from fundamentals to applications, AP.TEM
• Associated scholarship(s): 23/03442-6 - Engineering the interfacial behavior of self-propelled yeast/nanocellulose supraparticles by tailoring the surface chemistry of cellulose nanofibrils, BE.EP.IC

Abstract

The current state-of-the-art in materials science allows for a deep understanding of the microscopic level of matter, in addition to its manipulation with high modeling capacity. However, a technological bottleneck lies in bulk materials, such as particulates, whose macro compositions are associations between smaller building blocks. One of the sustainable and efficient ways to engineer bulk materials is the bottom-up assembly of nanofibrillated cellulose (NFC). Supraparticles - i.e. particles formed by smaller particles with supramolecular association - can be produced with CNF and different objects, including yeasts, whose metabolic capabilities are maintained for being packed within a complex CNF network, which in turn allows access to the nutrients needed for the fermentative process. Under suitable conditions, CNF supraparticles containing Saccharomyces cerevisiae produce, among other metabolites, carbon dioxide gas, which is retained in the supraparticle microstructure owing to its low solubility in the aqueous medium. The gas reduces the density of the supraparticle, which tends to float against the gravitational field, until it reaches the interface with air, where CO2 is soluble and then released, restoring the density of the supraparticle and leading to its sedimentation. Although promising for applications involving mass transport, as an example, this alternating upward/descending motion remains poorly described and explored. In this sense, a fundamental study of the motility of CNF/S. cerevisiae supraparticles is aimed herein, in order to elucidate efficient variables in modulating this behavior and in establishing correlations with the composition of the culture medium and the supraparticles, as well as the surface chemistry of the latter, plus fermentation kinetics and vertical movement profile.(AU)