2011 年 9 巻 2 号 p. 64-70
The zeta potential of the surface of anatase-form titania particles modified by ultraviolet (UV)-irradiation or cold-plasma O2 treatment was investigated and compared with that of unmodified titania particles.
Zeta potential was first determined after suspension in 10 mM sodium chloride and then with exposure to various concentrations of sodium hydroxide. The charge shifted from positive with a low pH to negative and finally zero with increase in pH. The pH of the solution at which the zeta potential was zero was determined as the isoelectric point (pI). The pI of unmodified titania particles was 6.5. After UV-irradiation, the pI shifted with increase in alkalinity (pI=9.2). Cold-plasma O2 modification of the titania particles also yielded a shift in pI with increase in alkalinity (pI=8.9). These findings showed that physicochemical surface modification of anatase-form titania particles by UV-irradiation or cold-plasma O2 treatment resulted in a change in surface charge.
This indicates that such treatment could be used to control adsorption and desorption of specific molecules to titania surfaces. Further research is needed, however, to determine the applicability of such treatment to other metals. These findings are useful in controlling the physicochemical nature including the surface electrical charge, and in surface modification of the titanium scaffolds for tissue engineering.