当前位置： SCI文献检索 > PHOTOCHEMISTRY AND PHOTOBIOLOGY期刊下所有文献 > Carotenohematoporphyrins as tumor-imaging dyes. Synthesis and in vitro photophysical characterization.

Carotenohematoporphyrins as tumor-imaging dyes. Synthesis and in vitro photophysical characterization.

Abstract：

:Multichromophoric dyes for use in tumor imaging have been synthesized and photophysically characterized. Structurally, these dyes are dyads and triads that consist of one or two carotenoid polyenes covalently attached to hematoporphyrin (HP) or hematoporphyrin dimethyl ester (HPDME) moieties via ester linkages. The ground-state absorption of each compound shows that the electronic interaction between the chromophores is small. The fluorescence quantum yield for the dyad monocaroteno-HPDME is 0.033 and the dicaroteno-HPDME triads have yields between 0.016 and 0.007, all of which are reduced with respect to the parent compound HPDME (0.09). Global analysis of the transient fluorescence decays of the dyads and triads requires two exponential components (approximately 5-6 ns and approximately 1-2 ns) to fit the data, while a single exponential component with a lifetime of 9.3 ns describes the decay data of the parent HPDME. Possible mechanisms for the observed porphyrin fluorescence quenching by the nearby carotenoid are discussed. Nanosecond transient absorption reveals a carotene triplet with maximum absorption at 560 nm and a 5.0 microsecond lifetime. No transient was detected at 450 nm, indicating rapid (< or = 10 ns) triplet energy transfer from the hematoporphyrin to the carotenoid moieties in fluid as well as in rigid media. The yield of triplet energy transfer from the porphyrin to the carotenoid moiety is unity. Singlet oxygen (O2(1 delta g), studies support the transient absorption data, as none of these compounds is capable of sensitizing O2(1 delta g). Liposome vesicles were used to study the photophysical characteristics of the dyes in phospholipid membranes. Singlet oxygen was not sensitized by the dyads and triads in liposomes. Transient absorption measurements suggest that the triads are substantially aggregated within the phospholipid bilayer, whereas aggregation in the dyads is less severe.

journal_name

Photochem Photobiol

journal_title

Photochemistry and photobiology

authors

Tatman D,Liddell PA,Moore TA,Gust D,Moore AL

subject

Has Abstract

pub_date

1998-10-01 00:00:00

pages

459-66

issue

eissn

0031-8655

issn

1751-1097

journal_volume

pub_type

杂志文章

在线工具

Carotenohematoporphyrins as tumor-imaging dyes. Synthesis and in vitro photophysical characterization.