Modular surface chemistry of green nanoparticles for the next generation of functional materials

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This proposal aims to tune the interfacial properties of green nanoparticles (gNPs) to develop the next generation of functional micro/nanostructured materials. The demand for environmental sustainability makes renewable materials key to the development of future consumer products. Plant-derived NPs (e.g, cellulose nanocrystals - CNCs) are especially attractive because they have unique properties that can lead to new materials. However, a key obstacle to the widespread use of gNPs is their lack of reactivity. While many approaches to functionalize gNPs exist, they are expensive, require harsh processing, or limit functional diversity. This has severely hindered the use of gNPs in consumer products. Recently, our group proposed to use triazinyl chemistry for the modular functionalization of nanocellulose and showed that its interfacial properties can be readily tailored. Key advantages of this chemistry are that the reactions are done in mild conditions, the functionalization is efficient, and the reagents are inexpensive. The current challenge, which this proposal addresses, is to expand the range of functionalities that can be introduced onto gNPs. We will accomplish this by creating a library of triazinyl derivatives that will be grafted onto renewably-sourced gNPs, rendering them functional, reactive, and/or compatible with a variety of solvents. These new gNPs will be a platform for the development of new materials and products. We will use modified gNPs to develop green photopolymerizable 3D printing bioinks that have tuneable mechanical properties and porosity, and that can be modified post-printing to incorporate biochemical motifs in a spatially and temporally controlled way. 3D printed scaffolds produced using such bioinks will be tested for their suitability in cell culture and tissue engineering. We will also use modified nanomaterials to develop ultraporous microparticles capable of absorbing contaminants or releasing drugs. This will be accomplished by using gNPs bearing two functionalities: on one hand, complementary reactive groups will promote efficient crosslinking, and on the other, binding moieties will allow scavenging heavy metals or slowly releasing antimicrobial agents. Finally, we will use triazinyl chemistry to develop a reactive paper platform that enables the fabrication of complex paper-based microanalytical or electronic devices. This will be done by installing reactive groups on paper that allow us to directly print and covalently immobilize a variety of small molecules, polymers, peptides and nanoparticles, and demonstrating the use of the printed functionalities in the fabrication of sensing devices. The proposed research, including organic synthesis, characterization, and fabrication, and interactions with industrial partners, will provide trainees a rich multidisciplinary environment and highly transferrable skills in chemistry, materials science, micro/nanotechnology, and knowledge translation.**