A diffusion-driven mineralization approach for the fabrication of calcium carbonate on and in regenerated and functionalized cellulose membranes was investigated. Calcium dichloride was used as the cation source. Ammonium carbonate was applied in a gas-phase diffusion and sodium carbonate in a liquid continuous-flow setup. Calcium carbonate was obtained solely on the membrane surfaces from the gas-diffusion approach, whereas by applying continuous-flow diffusion, crystals were obtained throughout the membranes.[a]

Biomacromolecules control and direct the formation of biominerals and hard tissues in nature. In many cases, polysaccharides are involved during the assembly of the inorganic phase as template. Natural and regenerated polysaccharides exhibit a hierarchical multiscale order as well as self-assembly properties and they appear in a large variety of accessible structures. Therefore, the application of polysaccharide-based structures and composites is a promising approach for the formation of patterned and hierarchically structured inorganic functional and structural materials. The authors report on recent advancements on the biotemplated formation of inorganic functional materials using polysaccharides. Owing to their structural diversity, polysaccharides can be used at various levels from the molecular scale up to complex three-dimensional parts. The versatility of polysaccharide templating is shown on one-dimensional (1D) cellulose nanocrystals for formation of inorganic nanotubes. Two-dimensional (2D) Langmuir–Blodgett films of cellulose and cellulose derivatives are used as reference templates to investigate the mineralization behaviour of inorganic phases from supersaturated solutions. The development of optical and photocatalytic materials from plant tissues (wood and Juncaceae) is presented. In innovative route, phototactic microalgae are used as biotemplates for the mineralization of inorganic phases on their exopolysaccharides, which provide novel pathways for the fabrication of a variety of functional materials.

A composite material consisting of cellulose and HAp was prepared using coagulation of a native cellulose suspension. Composite tapes with a HAp content below 50 vol.% exhibit a gradient of filler particles across the cross-section of the sample due to gravity force that causes sedimentation of HAp, as long as the viscosity of the suspension is below a critical level during the coagulation process. According to gravimetric and solution analysis as well as SEM, the filler content influences the amount and uniformity of HCA precipitated in the surface of the tape. With increasing content of filler in the cellulose matrix, the apatite growth from SBF is promoted, due to a higher amount of HAp particles that serve as nucleation sites.

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