A Leaf out of Nature's Book: Hairy Nanocelluloses for Bioinspired Mineralization

The quest for designing new materials to unravel and mimic the biogenic mechanisms behind the formation of superior natural structures through biomineralization has stimulated interest in a broad range of disciplines. Here, we show that cellulose, the basic structural material of trees, and the most abundant yet inactive biopolymer in the world, can be chemically engineered to yield a new class of nanocelluloses with a ppm-level biomimetic effect. We introduce hairy nanocelluloses, namely, electrosterically stabilized nanocrystalline cellulose (ENCC) and dicarboxylated cellulose (DCC), as the first polysaccharide-based materials to address key biomimetic material design concerns, involving (i) an all-natural backbone, (ii) no anthropogenic effects such as eutrophication due to the N-, P-, and/or S-bearing groups, (iii) capability for macroscale mineralization, (iv) no extreme and/or controlled reaction condition requirements, (v) a high efficiency at extremely low concentrations, and (vi) a strong polymorph selectivity. In a model system under ambient conditions, the bioinspired mineralization of calcium carbonate with ENCC/DCC resulted in macroscale nacre-like sheets of vaterite, the least thermodynamically stable polymorph of CaCO₃, which were then decorated with stabilized microscale lenticular vaterite to unveil the biomimetic mineralization mechanism. The emergence of these advanced sustainable nanomaterials may open new horizons in the field of bioinspired nanoengineering for designing inorganic nanostructures and hybrid inorganic-organic nanocomposites.