Electrostatic interplay: The interaction triangle of polyamines, silicic acid, and phosphate studied through turbidity measurements, silicomolybdic acid test, and ²⁹Si NMR spectroscopy

• Anne Jantschke,
• Katrin Spinde and
• Eike Brunner

Beilstein J. Nanotechnol. 2014, 5, 2026–2035, doi:10.3762/bjnano.5.211

• silica. Keywords: phosphate; self-assembly; silica–polyamine interactions; silicomolybdic acid test; 29Si NMR; turbidity measurements; Introduction Long-chain polyamines (LCPAs) were previously found biomolecules that are tightly associated to the biosilica of various diatom species [1][2][3][4][5

• analysis of the influence of the polyamine structure and charge upon the polycondensation of silicic acid in the absence and presence of phosphate. The kinetics of the aggregation and silica polycondensation processes were studied by a combination of turbidity measurements and silicomolybdic acid test [31

• represents the so-called “soluble silica” and can be detected by the silicomolybdic acid test reaction [31][33][34]. In the basic solution, practically all silica is soluble, i.e., molybdate-reactive. For this reason, our experiments were carried out starting from a basic sodium metasilicate solution. Figure