Nanoparticle-Functionalized Cellulose Through Biosynthesis-Only Approach

Bacterial cellulose (BC) is a natural polymer produced by microorganisms, while carbon dots (CDs) are carbon-based nanoparticles with biocompatibility and unique optical properties. Herein, nanoparticles, glucose-modified CDs (Glu-CDs), into cellulose chains using only microbial fermentation is introduced. This is the first time that nanoparticles, other than small molecules, have been biochemically incorporated into cellulose chains by forming covalent bonds in BC synthases. This biosynthesis method overcomes drawbacks associated with traditional physical and/or chemical synthetic methods, such as the easy detachment of functional groups and environmentally harmful processes. The resulting Glu-CDs functionalized BC (Glu-CDs-BC) exhibits distinctive cyan fluorescence with notable changes in the micro-structures of the pristine BC, creating plenty of protrusions on the cellulose nanofibers. Additionally, both the crystallinity and thermal stability are significantly reduced compared to the pristine BC. All these property changes cannot be achieved by simply physically attaching CDs to the BC. This study demonstrates that cellulose can be in situ functionalized through a microbial synthesis system with nanoparticles, opening up possibilities for creating functional nanoparticle-living organism composites through solely microbial biosynthesis.