Electronic Supplementary Material (ESM)
A regenerable fluorescent quantum dots based nanoprobe for zinc(II), and the design of
a molecular logic gate
Chenxia Hao, Shaopu Liu, Wanjun Liang, Dan Li, Linlin Wang, Youqiu He
Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of
Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China
Optimization of reaction conditions
Influence of acidity
The influence of acidity of Britton-Robinson, Phosphate, Hasting-Sendroy and Tris-HCl
buffer on the fluorescence intensity of GSH-CdTe Q-dots-DTPA system was investigated.
According to the experimental results, the Britton-Robinson buffer was selected to control the
acidity of the solution. The effect of pH in a range between 6.0 and 9.0 was studied in order to
achieve an optimal reaction pH. As can be seen in Fig. S1a, maximal fluorescent change of
DTPA-induced the fluorescence quenching of GSH-CdTe Q-dots was obtained at pH of 7.0.
Hence, the pH of the solution was set at 7.0 in order to achieve a low detection limit for Zn 2+.
At the same time, the effect of the dosage of Britton-Robinson buffer on the fluorescence
intensity of GSH-CdTe Q-dots-DTPA system was also discussed. Fig. S1b revealed that the
optimal dosage of Britton-Robinson was 1.0 mL.

Corresponding author, Tel.: +86 23 68367475; fax: +86 23 68254000, E-mail address:
heyq@swu.edu.cn (Y.Q. He)
Influence of aqueous GSH-CdTe Q-dots concentration
The effect of GSH-CdTe Q-dots concentration on the fluorescence intensity of GSH-CdTe
Q-dots-DTPA system was explored by keeping the DTPA concentration and the pH constant
while changing the GSH-CdTe Q-dots concentration. As shown in Fig. S2, the optimal
concentration of GSH-CdTe Q-dots was 1.0×10−4 mol·L-1, namely, 0.5 mL above prepared
GSH-CdTe Q-dots.
Influence of incubation time
Fig. S3 showed the impact of incubation time on the fluorescence intensity of GSH-CdTe
Q-dots-DTPA system. It was observed that the reaction was finished completely in 20 minutes
and the fluorescence intensity remained stable for at least 1 h. Therefore, the time scale of 20
minutes was adopted in the following experiments.
1500
1500
1450
900
F0-F
F0-F
1200
600
1400
1350
300
1300
6.0 6.4 6.8 7.2 7.6 8.0 8.4 8.8 9.2
pH
(A)
0.4
0.6
0.8
1.0
1.2
1.4
V/mL
(B)
Fig. S1. Effect of acidity on the fluorescence intensity of GSH-CdTe Q-dots-DTPA system in
the presence (F) and the absence (F0) of DTPA (a) effect of pH of buffer; (b) effect of dosage
of buffer. (GSH-CdTe Q-dots, 1.0×10-4 mol·L-1; DTPA, 6.0×10-5 mol·L-1)
1600
1400
F0-F
1200
1000
800
600
0.8
1.0
1.2
1.4
1.6
-4
C/(10 mol/L)
Fig. S2. Effect of GSH-CdTe Q-dots concentration on the fluorescence intensity of
GSH-CdTe Q-dots-DTPA system in the presence (F) and the absence (F0) of DTPA. (DTPA,
6.0×10-5 mol·L-1; Britton-Robinson buffer, 1.0 mL, pH=7.0)
Fluorescence intensity
2700
2400
2100
1800
1500
0
10
20 30 40
Time (min)
50
60
Fig. S3. Effect of incubation time on the fluorescence intensity of GSH-CdTe Q-dots-DTPA
system in 1.0 mL Britton-Robinson buffer at pH=7.0 (GSH-CdTe Q-dots, 1.0×10-4 mol·L-1;
DTPA, 6.0×10-5 mol·L-1)
(A)
(B)
Fig. S4. Molecular electrostatic potential maps of (a) DTPA and (b) a fragment of GSH.
Fluorescence intensity
a
2400
b
2000
1600
1200
800
400
0
450
500
550
600
650
/nm
Fig. S5. Fluorescence spectra of GSH-CdTe Q-dots in the absence (a) and presence (b) of
Zn2+ in Britton-Robinson buffer at pH 7.0 (GSH-CdTe Q-dots, 1.0×10-4 mol·L-1; Zn2+
5.0×10-5 mol·L-1).
Table S1. Stern-volmer quenching constants for the interaction of GSH-CdTe Q-dots with
DTPA at different temperature.
Temperature (K)
Stern-volmer linear equation
Ksv (L·mol-1)
Ra
S.Db
279
F0/F=0.9999+1.265×104 [Q]
1.265×104
0.9985
0.0191
298
F0/F=0.9919+1.015×104 [Q]
1.015×104
0.9986
0.0149
4
0.9973
0.0128
309
a
4
F0/F=0.9881+0.631×10 [Q]
0.631×10
R is the correlation coefficient
b
S.D. is the standard deviation for the Ksv values
Table S2. Results for the determination of Zn2+ in real water samples. (n=5).
Samples
Added Zn2+ (μM)
Found (n=5, μM)
Recovery (n=5, %)
R.S.D. (n=5, %)a
Tap water 1
0.3
0.2982
99.39
1.2
Tap water 2
0.5
0.4936
98.72
1.5
Jialing River 1
0.2
0.2037
101.84
2.1
Jialing River 2
0.4
0.4043
102.08
3.8
a
The relative standard deviation (RSD) was calculated as (SD/mean)×100%.