Hollow SiO2 Microspheres Produced by Coating Yeast Cells

Hollow silica microspheres were produced by coating yeast cells with amorphous SiO 2 . In the precipitation reaction, yeast cells of Saccharomyces cerevisiae were used as a biological template. The silica shell was synthesized by the hydrolysis of tetraethylorthosilicate (TEOS) in water−alcohol mixtures as solvent using ammonia as a catalyst according to the Stoeber process. The hollow microspheres were characterized by means of scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Both smooth and textured coatings were prepared. The biological template can be removed by calcining, after which the particle morphology persists. Additionally, density and light scattering coefficients of the pigment were measured.