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Photochemical and photophysical properties of carotenoid immobilized on a surfactant micellar medium including chlorophyll as an artificial photosynthesis system

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ABSTRACT

To develop an artificial photosynthesis model, the anionic water-soluble carotenoid dye crocetin was electrostatically immobilized onto the surface of cationic surfactant cetyltrimethylammonium bromide (CTAB) micellar medium including Mg chlorophyll-a and b (MgChl-a and b) (Cro/MgChl), and its photophysical properties were studied using UV-vis absorption and fluorescence spectroscopy. The fluorescence of MgChl-a and b was observed, with the excitation wavelength attributed to the absorption band of crocetin, indicating that photo-induced energy transfer from the photoexcited state of crocetin to MgChl-a and b occurs. The photostability of MgChl-a and b in Cro/MgChl was investigated under continuous irradiation. After 60 min irradiation, the absorbance decreases at 660 nm Cro/MgChl and MgChl-a/b, without crocetin, were 3.0 and 17%, respectively. These results indicate that the photo-bleaching rate of MgChl-a/b in Cro/MgChl on irradiation is suppressed by the crocetin molecule on the surface of micelles.

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Time dependence of absorbance changes at 660 nm attributed to MgChl-a and b in Cro/MgChl (circle) and MgChl (square) with irradiation.
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f4-2_57: Time dependence of absorbance changes at 660 nm attributed to MgChl-a and b in Cro/MgChl (circle) and MgChl (square) with irradiation.

Mentions: Figure 4 shows the absorbance changes at 660 nm attributed to the absorption band of MgChl-a/b in Cro/MgChl (circle) and in MgChl-a/b (square) with irradiation time. After 60 min irradiation, the absorbance decreases at 660 nm in Cro/MgChl and MgChl-a/b were 3.0 and 17%, respectively. The decrease in the rate of absorbance of MgChl-a/b in Cro/MgChl is slower than that of MgChl. These results indicate that the photo-bleaching rate of MgChl-a/b in Cro/MgChl on irradiation is suppressed by the crocetin molecule on the surface of micelles. As shown in Figure 2, crocetin absorbs light at wavelengths less than 400 nm and 536 nm on the surface of CTAB micelles, including MgChl-a/b. From the fluorescence of Cro/MgChl, the photoinduced energy transfers from crocetin to the MgChl-a/b via the interface of CTAB micelles, as shown in Scheme 2. Since the crocetin molecule on the surface of micelles acts as a cut-off filter, the degradation of MgChl-a/b is suppressed.


Photochemical and photophysical properties of carotenoid immobilized on a surfactant micellar medium including chlorophyll as an artificial photosynthesis system
Time dependence of absorbance changes at 660 nm attributed to MgChl-a and b in Cro/MgChl (circle) and MgChl (square) with irradiation.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC5036646&req=5

f4-2_57: Time dependence of absorbance changes at 660 nm attributed to MgChl-a and b in Cro/MgChl (circle) and MgChl (square) with irradiation.
Mentions: Figure 4 shows the absorbance changes at 660 nm attributed to the absorption band of MgChl-a/b in Cro/MgChl (circle) and in MgChl-a/b (square) with irradiation time. After 60 min irradiation, the absorbance decreases at 660 nm in Cro/MgChl and MgChl-a/b were 3.0 and 17%, respectively. The decrease in the rate of absorbance of MgChl-a/b in Cro/MgChl is slower than that of MgChl. These results indicate that the photo-bleaching rate of MgChl-a/b in Cro/MgChl on irradiation is suppressed by the crocetin molecule on the surface of micelles. As shown in Figure 2, crocetin absorbs light at wavelengths less than 400 nm and 536 nm on the surface of CTAB micelles, including MgChl-a/b. From the fluorescence of Cro/MgChl, the photoinduced energy transfers from crocetin to the MgChl-a/b via the interface of CTAB micelles, as shown in Scheme 2. Since the crocetin molecule on the surface of micelles acts as a cut-off filter, the degradation of MgChl-a/b is suppressed.

View Article: PubMed Central - PubMed

ABSTRACT

To develop an artificial photosynthesis model, the anionic water-soluble carotenoid dye crocetin was electrostatically immobilized onto the surface of cationic surfactant cetyltrimethylammonium bromide (CTAB) micellar medium including Mg chlorophyll-a and b (MgChl-a and b) (Cro/MgChl), and its photophysical properties were studied using UV-vis absorption and fluorescence spectroscopy. The fluorescence of MgChl-a and b was observed, with the excitation wavelength attributed to the absorption band of crocetin, indicating that photo-induced energy transfer from the photoexcited state of crocetin to MgChl-a and b occurs. The photostability of MgChl-a and b in Cro/MgChl was investigated under continuous irradiation. After 60 min irradiation, the absorbance decreases at 660 nm Cro/MgChl and MgChl-a/b, without crocetin, were 3.0 and 17%, respectively. These results indicate that the photo-bleaching rate of MgChl-a/b in Cro/MgChl on irradiation is suppressed by the crocetin molecule on the surface of micelles.

No MeSH data available.


Related in: MedlinePlus