A STAINING AGENT FOR BIOLOGICAL SILICA

The use of bis (cytopentadienyl) titanium dichloride, TiCp2Cl2, as a surface hydroxyl staining agent for biological silicas has been investigated by optical density measurements and electron microscopy including X-ray microanalysis. For synthetic silica samples agreement exists between optical density measurements on bulk samples and X-ray analytical data on microscopic sample regions. Studies on heterogeneous biological silicas have, therefore, allowed identification of structural motifs by the level of titanium 'stain' incorporation. The variation in surface hydroxyl concentration for silica motifs within a single cell sample suggests a high level of biological control over both polymerization and aggregation of silica.