A new bio-based nanomaterial: Fundamental understanding of xylan single crystals for functional applications

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The world's population is expected to increase by a billion people in the next dozen years and these people will need food and energy, along with materials that can be returned to the earth without landfilling or littering the world's oceans. For the latter, we can use resources from agricultural straw, wood fibre, and other plant biomass for many innovative applications. However, the practicality is that the components within the plants are extremely complex, making them hard to use industrially, as nature utilizes complex biopolymers to achieve properties and desired traits of biological materials. In our research program, we extract biopolymers with specialized processing methods that limit the inherent variability of the material and we characterize the structure and resulting properties in order to transform them into useful, and importantly, uniform, materials. Previous examples of materials include carbon aerogels for supercapacitor applications, flexible lignin sponges for oil/water separation, and simple lignin esters for hydrophobic coatings. Supported in the most recent DG period, we created polysaccharide nanofibres spun from water solutions with controlled hydrophilicity by simple thermal treatment. In addition, we were able to isolate heteropolysaccharides and transform them into single crystal nanoparticles, revealed by cryo-electron microscopy. We also unexpectedly found that xylan could crystallize at interfaces. In this proposal, we are expanding the concept of conversion of complicated hetero-polysaccharides from plant resources into homogeneous nanoparticles of controlled size and surface chemistry. We will utilize the single-crystal methods developed in synthetic chemistry to help achieve xylan crystals of defined dimensions. We will also exploit the ability to crystallize at interfaces to establish two-dimensional membranes and investigate methods to form ultra-stable emulsions to potential edible coatings to extend the shelf life of foods. The xylan nanoparticles will be surface functionalized to form compounds that can reduce silver salts into nanoparticles or adsorb gold nanoparticles that would be able to serve as surface enhanced Raman spectroscopy substrates for diagnostics for chemical and biological sensing. The “we” in the program represents the talented and curious students and post-doctoral fellows that generate significant findings and work together for the research program. The proposed research will provide opportunity for outstanding training where trainees will become experts in lignocellulose biomass structure and processing, giving them analytical skills that includes spectroscopy, thermal analysis, and advanced nanoscale imaging methods. With outstanding equipment resources in the group, 2 PhD students and 10 undergraduate students supported will be well prepared by this grant to have outstanding careers in important nanotechnology field anchored by sustainable approaches and green chemistry.