Autonomous bottom-up fabrication of three-dimensional nano/microcellulose honeycomb structures, directed by bacterial nanobuilder

https://doi.org/10.1016/j.jbiosc.2014.04.002Get rights and content

We investigated the autonomous bottom-up fabrication of three-dimensional honeycomb cellulose structures, using Gluconacetobacter xylinus as a bacterial nanoengine, on cellulose honeycomb templates prepared by casting water-in-oil emulsions on glass substrates (Kasai and Kondo, Macromol. Biosci., 4, 17–21, 2004). The template film had a unique molecular orientation state along the honeycomb frames, but was non-crystalline. When G. xylinus, used as a nanofiber-producing bacterium, was incubated on the honeycomb scaffold in a culture medium, it secreted cellulose nanofibers only on the upper surface of the honeycomb frame. The movement was regulated by a selective interaction between the synthesized nanofiber and the surface of the honeycomb frames of the template. The relationship between directed deposition of synthesized nanofibers and ordered fabrication from the nano- to the micro-scale could provide a novel bottom-up methodology, using bacteria, for the design of three-dimensional honeycomb structures as functional materials with nano/micro hierarchical structures, with low energy consumption.

Section snippets

Materials

Cellulose triacetate (80–110 cP) provided by Wako Pure Chemical Industries Ltd. (Osaka, Japan) was used as the starting material for fabricating honeycomb-patterned cellulose films. The water used was purified using a NANOpure Diamond Ultrapure Water System (Barnstead International, Dubuque, IA, USA). All solvents were reagent grade and were used without further purification.

Preparation and characterization of honeycomb-patterned films

Honeycomb-patterned films were prepared as described in our previous report (9). Polarized microscopic images were

Characterization of honeycomb-patterned cellulose triacetate and cellulose films

The orientations of the cellulose molecular chains in honeycomb-patterned cellulose triacetate films were examined using a polarized microscope equipped with a compensator, as shown in Fig. 1. The interference color shifts from yellow to blue on rotating the specimen through 90° (Fig. 1C and D). When the yellow color of the specimen is perpendicular to the Z-axis of the compensator, the molecular orientation within the honeycomb structure is perpendicular to the Z-axis (Fig. 1C, white circle).

Acknowledgments

We would like to thank Prof. R. Malcolm Brown, Jr. at the University of Texas at Austin for valuable comments. We thank Mr. T. Mitsunaga and Ms. A. Takase of the X-ray Research Laboratory, Rigaku Corporation for advice on X-ray diffractometry. Dr. W. Kasai is partly supported by a Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists. This study is also partially supported by the MAFF Nanotechnology Project of the Agriculture, Forestry, and Fisheries

References (14)

There are more references available in the full text version of this article.

Cited by (8)

View all citing articles on Scopus
View full text