Acid-Base Properties and Biological Activity of Starch Phosphate Microgels

The apparent ionization constants have been determined for phosphate groups of phosphorylated starch microgels with particle sizes of 300-500 mu m. It has been shown that hydrogen bonds formed by phosphate and carbamate groups play an essential role in the acid-base equilibrium of starch phosphorylated in an orthophosphoric acid-urea system. It has been found that the acidic properties of starch phosphate microgels are almost independent of the ionic strength of a solution (0.05-0.5) and the concentration of phosphate groups (2.0-3.8 mmol/g). The cytostatic activity of starch phosphate microgels has been revealed in vitro using the HeLa cell culture.