Precise microcasting revealing the connectivity of bamboo pore network

Abstract

Bamboo is a short-rotation crop yet with high stem strength, possessing evolved pore network with considerable potential in porous functional material fields. While limited understanding and complex anatomical properties of this pore network require reliable and effective methods to systematically characterize the overall architecture, to further promote its industrial applications. Here an improved microcasting approach is proposed, in which maleic anhydride pre-treatment ensures a close fit between the cell wall and casting resin and toughens the final casts. The bamboo tissue was then dissolved and removed by digestion, leaving only accurate resin replicas of the entire pore network. Precise microcasting allows simultaneous measurements of various structures to explore their correlations, which is hard by previous methods. The smallest replicated conduits 40−100 nm in diameter exposed diverse pit membrane microstructures (“connecting valves” in the network). The hitherto undocumented compensatory system, xylem polymorphism, high abundance of parenchyma, pit distribution rules, and network connecting patterns are revealed, aiding improved understanding of the biomechanics and fluid transport efficiency/safety coordination. Simplicity, reliability, and quantifiability make this method an effective technique to study complex pore systems in biomaterials, and enlighten studies on structure-function relationships and bio-inspired designs.