Figure 1.
A schema showing oxidation of a sterically hindered amine TPC (2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide) by singlet oxygen to give rise to the nitroxide radical, and representative ESR spectra of the laser-irradiated mixtures containing rose bengal and a sterically hindered amine TPC.
The mixture containing 450 mM TPC and 0, 1 or 10 µM rose bengal was irradiated by the laser light with a wavelength of 532 nm for 60 s. Open circle and closed circle indicate Mn2+ marker and the nitroxide radical, respectively.
Figure 2.
The yields of the nitroxide radical from the laser-irradiated photosensitizers.
The mixture containing 450 mM TPC and 10 µM photosensitizer was irradiated by the laser light with a wavelength of 532 nm for 15, 30, 45 and 60 s. Each value represents the mean of triplicate determinations with standard deviation. The slope and intercept of each regression line are expressed as the mean with standard error.
Figure 3.
Number of viable S. mutans in the suspension after each treatment.
P(+)L(+), P(+)L(−), P(−)L(+), and P(−)L(−) stand for laser irradiation of each photosensitizer, photosensitizer alone, laser irradiation alone, and no treatment, respectively. Under the conditions of P(+)L(+) and P(+)L(−), the suspension contained 10 μM rose bengal, phloxine, or erythrosine. Each value represents the mean of nonuplicate determinations.
Figure 4.
Incorporation rates of photosensitizers into the bacterial cells.
The bacterial suspension containing 10 μM rose bengal, phloxine, or erythrosine was incubated at room temperature for 3 min. Each value represents the mean of triplicate determinations with standard deviation. Statistically significant differences between the two groups are shown as * (p<0.05).
Figure 5.
Influence of L-histidine, a singlet oxygen quencher, on the bactericidal effects of laser-irradiated photosensitizers.
L-Histidine (25 and 100 mM) was added to the bacterial suspension containing 10 μM rose bengal, phloxine, or erythrosine, followed by laser-irradiation for 60 s. Each vealue represents the mean of nonuplicate determinations with standard deviation. Statistically significant differences from the corresponding P (−)L(−) group are shown as ** (p<0.01).