344
J. Ma et al. / Spectrochimica Acta Part A 94 (2012) 340–345
(b)
18
(a)
-
RuL + OH,O2 , O 2-, NO3- ,
RuL
.
.
1.0
0.8
0.6
0.4
0.2
0.0
NO-2, H2O2, 1O2
16
14
12
10
RuL+NO
8
6
4
2
0
RuL+ONOO-
-
O2- NO3- NO2-
ROS/RNS
1O2 O2-
RuL OH
H2O2
NO
ONOO
550
600
650
700
750
Wavelength /nm
Fig. 6. (a) Fluorescence spectra of RuL (10 M, 1% CH3OH, 10 mM sodium phosphate buffer, pH 7.6) before and after •OH, O2−, NO3−, NO2−, H2O2, 1O2, •O2−, NO, ONOO−
were added with an excitation at 468 nm. (b) Fluorescence intensity specific value at 600 nm RuL solution before and after different kinds of ROS/RNS was added.
suitable pH range for the detection of ONOO− because in this region
the addition of ONOO− results in the most remarkable changes
conditions (pH 7.5) and the sensing sensitivity, all spectroscopic
data were determined at pH 7.6 in sodium phosphate buffer solu-
tion (0.1 M, 1% CH3OH).
Fig. 4a shows variations of the fluorescence spectra of RuL
ranged from 10 to 100 M, and the fluorescence intensity at 600 nm
was gradually quenched upon addition of ONOO−. When the con-
centration of ONOO− was 100 M, the fluorescence intensity was
quenched by 90%. As shown in Fig. 4b, the plot profile of fluores-
cence intensity at 600 nm against ONOO− concentration exhibits
a nice linear relationship (R2 = 0.992) at the concentration ranged
from 0 to 50 M, indicating a quantitative response of RuL to
ONOO−.
4. Conclusion
In summary, we have presented a new fluorescent sensor RuL
based on the oxidative O-dealkylation reaction, which could rec-
ognize ONOO− specifically among ROS/RNS. This probe shows
favorable water-solubility and biocompatibility, rapid reaction
with ONOO− and good linear relationship in the range of 10–50 M.
The present result provides an alternative method to explore the
design of fluorescent sensors for ONOO− in aqueous solution.
Acknowledgments
This work was supported by the NNSF of China (Grant Nos.
21173244, 21073213, 20903110), and the Main Direction Program
of Knowledge Innovation of Chinese Academy of Sciences.
In order to determine the fluorescence quenching kinetics of
RuL/ONOO− system, the time-dependent fluorescence changes of
RuL after addition of ONOO− were recorded. As shown in Fig. 5,
upon addition of 10 equiv of ONOO−, the fluorescence intensity
of RuL (10 M) at 600 nm decreased rapidly, and achieved a
steady value in a very short time (about 10 s). This result indi-
cates that the reaction velocity between RuL and ONOO− is very
fast, and the observed rate constant (kobs) under the pseudo first-
order reaction conditions is estimated to be 0.5 s−1 (t1/2 = 1.5 s), in
which the reaction time is close to the half-time of ONOO− (1.9 s)
[1].
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