We addressed the nano- and microstructural control of inorganic crystal materials by nature-inspired aqueous route. Multi-layered WO₃·H₂O plates were obtained from (NH₄)₁₀W₁₂O₄₁·5H₂O aqueous solutions containing gelatin at 60°C. The nanostructured WO₃·H₂O precursors were converted to WO₃ particles by heating at 600°C. Nanostructured SnO particles were produced by aging Sn₆O₄(OH)₄ in HCl solutions containing biological polymers at 60°C, where the branching of SnO crystals was promoted with decreasing pH value and with increasing biological polymer contents. Hureaulite (Mn₅(PO₃OH)₂(PO₄)₂·4H₂O) single crystals were obtained from aqueous precursor solutions by keeping at 80°C, where the crystal size of the hureaulite products increased by addition of citric acid. These results suggested that nature-inspired aqueous route was effective for making hierarchical architectures of inorganic materials.

Guanine molecule is one of DNA base molecules and is utilized for a material controlling the strong light reflection on body surface of animals, such as fish, frog, spider, chameleon and plankton. This review summarizes general features of fish guanine platelets, and focuses on the recent topic of novel optical properties of the platelets. In addition, utilization of bio-reflecting biomaterials for light control is discussed. Investigating dynamic optical phenomenon which can be observed in living creature may provide more attractive nature of micro-particles. Particularly, fish guanine platelets exhibit a specific directionality in light reflection and diffraction. This novel optical behavior can be applied for micro-imaging of dynamic motions.

Ciliates are swimming microorganisms living in aquatic environments. It has been known that they prefer fields as their habitats near nutrient-rich solid-liquid interfaces such as pond bottom walls and waterweed surfaces. We investigated the interaction dynamics of the behavior of ciliates beside a solid surface without nutrients. The ciliates start sliding on the flat wall of glass substrate after collision. Based on the experimental results on the cilia motions of the surface of the cell, we found that the ciliary thrust force becomes asymmetric due to stop ciliary beating caused by the steric interaction between the wall and the cilium, and the asymmetry of the thrust force results in the cell sliding on the wall. Interestingly, this mechanism brings several behaviors of the ciliate known as habitats, cell accumulation on a solid wall and rheotaxis behavior which is swimming ability toward upstream direction. The accumulated cells form a self-crowded granular system.

Sessile organisms cause significant economic losses on submerged artificial surfaces such as ships. The use of tributyltin (TBT)-based antifouling paint for underwater ship hulls was banned due to its high toxicity to marine organisms. Therefore, it is necessary to develop low environmental impact antifouling technologies. Previously, antifouling studies focusing on the physiological and ecological understanding of fouling organisms has been conducted. And antifouling materials inspired by surface properties of marine organisms were developed in recent years. This review introduces the settlement selectivity and behavior of barnacle cypris larvae on the surfaces with different surface properties, such as micro-structures and functional groups.

Adhering different materials poses a significant challenge in various fields. Taking inspiration from aquatic organisms such as barnacles and mussels, which adhere to a variety of materials in high-salinity seawater, this paper introduces catechol-containing amphiphilic polymers mimicking the adhesive proteins of mussels developed and discusses their functionalities.