Zn2SiO4-coated microparticles with biologically-controlled 3D shapes

The synthesis of zinc silicate-coated microparticles with well-controlled three-dimensional (313) shapes, via chemical modification of the surfaces of diatom microshells, is demonstrated. ZnO nanoparticle-based coatings were first applied by exposing the microshells to a zinc acetate-bearing solution and then firing at 700 degrees C. The ZnO nanoparticles were then allowed to react with the underlying SiO2 micro-shells at 1050 degrees C. Thin (submicron), compact, and continuous Zn2SiO4 coatings were generated that conformed to the microshell surfaces. The Zn2SiO2-coated microparticles retained the starting 3D microshell shape. Given the wide range of microshell shapes available among different species of diatoms (or other SiO2-forming organisms), this simple and scalable microshell coating method may be used to synthesize functional microparticles with a variety of well-controlled 3D shapes and tailored silicate chemistries.(c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.