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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.

No MeSH data available.


Fluorescence emission spectra of Cro/MgChl with excitation at 536 nm (solid line) and 660 nm (dashed line). The dotted line is the emission spectrum of crocetin solution in the presence of CTAB micelles.
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f3-2_57: Fluorescence emission spectra of Cro/MgChl with excitation at 536 nm (solid line) and 660 nm (dashed line). The dotted line is the emission spectrum of crocetin solution in the presence of CTAB micelles.

Mentions: Figure 3 shows the fluorescence emission spectra of Cro/MgChl (solid line) MgChl-a/b (dashed line), and crocetin (dotted line) solution. When crocetin is excited with 536 nm due to the absorption band, fluorescence is observed at 572 and 645 nm, as shown in Figure 3 (dotted line). The fluorescence emission spectrum of Cro/Mgchl with excitation attributed to the absorption band of crocetin (536 nm) is shown in Figure 3 (solid line). Fluorescence at 680 and 700 nm due to MgChl-a and b is observed. However, the fluorescence at 572 and 645 nm due to crocetin has disappeared. In contrast, fluorescence is also observed at 680 and 700 nm with excitation due to the absorption band of MgChl-a and b (660 nm), as shown in Figure 3 (dashed line). Moreover, the weak fluorescence at 680 nm is observed with 536 nm excitation in the CATB micellar medium including MgChl-a and b without crocetin (MgChl-a/b). The shape of the excitation spectrum of Cro/MgChl is similar to that of the UV-vis absorption spectrum, as shown in Figure 2, and a peak around 536 nm due to crocetin is observed. Thus, the fluorescence of crocetin is quenched by MgChl-a/b, and photoinduced energy transfer from the photoexcited state of crocetin onto the surface of micelles to the MgChl-a and b in the hydrophobic site of CTAB micelles occurs, as shown in Scheme 2.


Photochemical and photophysical properties of carotenoid immobilized on a surfactant micellar medium including chlorophyll as an artificial photosynthesis system
Fluorescence emission spectra of Cro/MgChl with excitation at 536 nm (solid line) and 660 nm (dashed line). The dotted line is the emission spectrum of crocetin solution in the presence of CTAB micelles.
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Related In: Results  -  Collection

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f3-2_57: Fluorescence emission spectra of Cro/MgChl with excitation at 536 nm (solid line) and 660 nm (dashed line). The dotted line is the emission spectrum of crocetin solution in the presence of CTAB micelles.
Mentions: Figure 3 shows the fluorescence emission spectra of Cro/MgChl (solid line) MgChl-a/b (dashed line), and crocetin (dotted line) solution. When crocetin is excited with 536 nm due to the absorption band, fluorescence is observed at 572 and 645 nm, as shown in Figure 3 (dotted line). The fluorescence emission spectrum of Cro/Mgchl with excitation attributed to the absorption band of crocetin (536 nm) is shown in Figure 3 (solid line). Fluorescence at 680 and 700 nm due to MgChl-a and b is observed. However, the fluorescence at 572 and 645 nm due to crocetin has disappeared. In contrast, fluorescence is also observed at 680 and 700 nm with excitation due to the absorption band of MgChl-a and b (660 nm), as shown in Figure 3 (dashed line). Moreover, the weak fluorescence at 680 nm is observed with 536 nm excitation in the CATB micellar medium including MgChl-a and b without crocetin (MgChl-a/b). The shape of the excitation spectrum of Cro/MgChl is similar to that of the UV-vis absorption spectrum, as shown in Figure 2, and a peak around 536 nm due to crocetin is observed. Thus, the fluorescence of crocetin is quenched by MgChl-a/b, and photoinduced energy transfer from the photoexcited state of crocetin onto the surface of micelles to the MgChl-a and b in the hydrophobic site of CTAB micelles occurs, as shown in Scheme 2.

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.