Photocatalytic cleavage of single TiO2/DNA nanoconjugates.
TiO(2)/DNA nanoconjugates were successfully fabricated by using the catechol moiety as a binding functional group, which was confirmed by steady-state absorption and fluorescence spectroscopies. Upon UV irradiation, the photocatalytic cleavage of the TiO(2)/DNA nanoconjugates was observed at the single-molecule level by using wide-field fluorescence microscopy. The decrease in the number of conjugates, which was estimated from the luminescent spots due to semiconductor quantum dots modified at the DNA strand, was significantly inhibited by a single A/C mismatch in the DNA sequences. This result strongly suggests that the migration of holes, which are injected from the photoexcited TiO(2) into the DNA, through the DNA bases plays an important role in the photocatalytic cleavage of the conjugates. The influences of the photogenerated reactive oxygen species (ROS) on the cleavage efficiency were also examined. According to the experimental results, it was concluded that oxidation of the catechol moiety and/or the DNA damage are key reactions in this process.
The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, Japan.
Takashi
T
Tachikawa
Yoshiaki
Y
Asanoi
Kiyohiko
K
Kawai
Sachiko
S
Tojo
Akira
A
Sugimoto
Mamoru
M
Fujitsuka
Tetsuro
T
Majima
D000225:Adenine / Q000737:chemistry; D001483:Base Sequence; D002384:Catalysis; D002396:Catechols / Q000737:chemistry / Q000528:radiation effects*; D003596:Cytosine / Q000737:chemistry; D004247:DNA / Q000737:chemistry / Q000528:radiation effects*; D004249:DNA Damage; D008956:Models, Chemical; D010084:Oxidation-Reduction; D045663:Quantum Dots; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000528:radiation effects*; D012666:Semiconductors; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014025:Titanium / Q000737:chemistry / Q000528:radiation effects*; D014466:Ultraviolet Rays
D002396:Catechols; D017382:Reactive Oxygen Species; C009495:titanium dioxide; D003596:Cytosine; D004247:DNA; D014025:Titanium; D000225:Adenine; C034221:catechol