Electronic Supplementary Information
MoS
2
quantum dots with upconversion
fluorescence
based
aptasensor
for
microcystin-LR detection via the inner filter
effect
Haiyan Caoa*, Wenfei Donga, Tianli Wangb, Wenbing Shia, Cuicui Fua,Yan Wua
aThe Key Laboratory of Chongqing Inorganic Special Functional Materials; College
of Chemistry and Chemical Engineering, Yangtze Normal University, Chongqing 408100, China. E-mail: [email protected]
bCollege of Chemistry and Chemical Engineering, Southwest University, Chongqing
400715, China.
Number of Pages: 12 Number of Figures: 14 Number of Tables: 1
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Materials and reagents. Ammonium molybdate, thiourea, N-acetyl-L-cysteine
(NAC), and citrate sodium were purchased from Aladdin Reagent Co. Ltd (Shanghai, China). Sodium chloride (NaCl), HAuCl4.4H2O was obtained from Sinopharm
Chemical Reagent Co. (Shanghai, China). Single-stranded DNA (ssDNA) aptamer for MC-LR (5′- GGC GCC AAA CAG GAC CAC CAT GAC AAT TAC CCA TAC CAC CTC ATT ATG CCC CAT CTC CGC -3′) selected on the basis of previous literatures 1 were obtained from Shanghai Sangon Biotechnology Co., Ltd.,
(Shanghai, China). Microcystin-LR (MC-LR), Microcystin-YR (MC-YR) and Microcystin-RR (MC-RR) was bought from Sigma–Aldrich (USA). All regents were of analytical grade and all solutions were freshly prepared by ultra-pure water (18.2 MΩcm).
Apparatus and characterization. The fluorescence spectra and UV-Vis
absorption spectra were recorded on a Hitachi F-7000 fluorescence spectrophotometer (Tokyo, Japan) and a U-4100 spectrophotometer (Hitachi, Japan), respectively. Both the excitation and emission slit widths were 20.0 nm with the PMT voltage of 800 V on a Hitachi F-7500 fluorescence spectrofluorometer (Kyoto, Japan). The scanning electron microscopy (SEM) and the transmission electron microscopy (TEM) images were carried on a S-4800 field emission scanning electron microscope (Hitachi, Japan) and a Talos F200S (FEI, USA), respectively. The X-ray photoelectron spectroscopy (XPS) was performed on a VG Multilab 2000X instrument (Thermal Electron, USA). The fluorescence lifetime were measured on a full-functional steady/transient FLs980 fluorescence spectrophotometer (Edinburgh, UK) with a laser
at 980 nm excitation (Malvern, UK). The pH values of solution were performed on a PHS-3D pH meter (Shanghai Precision Scientific Instrument Co. Ltd., China). Dynamic light scattering (DLS) was carried out with a Malvern Instruments Zetasizer Nano-ZS (Malvern, UK) instrument for characterization of the size distribution of Au NPs in solution.
Reference:
(1) Andy, N.; Raja, C.; Shimaa, E.; Hechun, L.; Chaker, T.; Mohammed, Z. Selection, characterization, and biosensing application of high affinity congener-specific microcystin-targeting aptamers. Environ.
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Table S1. Characterization results of so-obtained Au NPs
*Obtained by TEM measurement. **Obtained by dynamic light scattering measurement. Solution HAuCl4 (mM) Sodium citrate (mM) λabs (nm) Average sizes* (nm) Average sizes** (nm) Au NPs-1 1.00 0.7760 542 55.11±18 53.19±19 Au NPs-2 1.00 1.552 536 33.6±5.7 31.6±5.7 Au NPs-3 1.00 3.104 526 20.57±4.7 16.7±2.0 Au NPs-4 1.00 3.880 518 12.6±1.7 11.1±0.9
Figure S1. (A) The corresponding particle size distribution histogram (middle) of
MoS2 QDs; (B) EDX analysis of MoS2 QDs.
Figure S2. The impact of various solvents on DLS of MoS2 QDs.
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Figure S3. High-resolution XPS spectra of (A) Mo 3d, (B) S 2p, and (C) C1s.
A B
Figure S4. (A)XRD patterns of MoS2 QDs. XRD patterns at the bottom show MoS2
(JCPDS NO. 17-0744). (B) Raman spectrum of MoS2 QDs. (C) The
three-dimensional stereogram obtained by AFM of the as-prepared MoS2 QDs. (D)
AFM image of MoS2 QDs and height measurement (inset) across MoS2 QDs.
Figure S5. The excitation spectra at the emission wavelength of 509 nm (red line) and
A B
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Figure S6. Emission spectra of MoS2 QDs at excitation wavelengths from 835 to 885
nm.
Figure S7. The fluorescence spectra of (A) 1.0 mL MoS2 QDs at different time
indicating the high stability of QDs; (B) 25 μL MoS2 QDs with different
concentrations NaCl (0-10 mM); (C) 25 μL MoS2 QDs with different concentrations
H2O2 (0-200 μM); (D) 25 μL MoS2 QDs under continuous irradiation indicating the
high photostability of QDs in the system of 25 μL MoS2 QDs, 25 μL MoS2 QDs +
14.4 nM Au NPs, and 25 μL MoS2 QDs + 14.4 nM Au NPs +13 nM MC-LR,
respectively.
A B
Figure S8. The TEM images of the synthesized Au NPs with different sizes: (A) Au
NPs-1; (B) Au NPs-2; (C) Au NPs-3; (D) Au NPs-4.
Figure S9. The UV-Vis spectra of the synthesized Au NPs with different sizes.
A B
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Figure S10. The impact of the Au NPs’ size on the fluorescent response of MoS2
QDs.
Figure S11. Fluorescence decay curves of MoS2 QDs with upconversion fluorescence
Figure S12. (A) FL responses of the sensing system in different reaction time in the
presence of 30.15 nM MC-LR; (B) FL responses of MoS2 QDs-Au NPs at 505 nm in
the absence (black line) and presence (red line) of 30.15 nM MC-LR at different concentration aptamers. Relative fluorescence intensities [(I-I0)/I0] at 505 nm of
MoS2 QDs-Au NPs in the presence (blue) of 30.15 nM MC-LR at different
concentration aptamers; (C) The effect of different dilution ration of MoS2 QDs on
the performance of MC-LR probe; (D) The effect of the Au NPs’ concentrations on the performance of MC-LR determination.
A
B
C D
B A
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performance of the sensing system in the presence of 40.19 nM MC-LR. Blank-the sensing system without MC-LR; Sample-the sensing system with MC-LR. The pH of solution was controlled by the citric acid/ sodium citrate buffer.
Figure S14. The relative fluorescence intensities ([(I-I0)/I0]) at 509 nm of MoS2
QDs-aptamer-Au NPs after the addition of MC-LR and its analogues, other common metal ions and anions in the complex environmental water samples, including 29 nM MC-LR, MC-YR, MC-RR, 1 mM Na+, K+, CO
32-, PO43-, 200 μM
Cl-, NO
3-, 100 μM Ca2+, Mg2+, Cu2+, Zn2+, SO42-, 50 μM Al3+, Cd2+, 10 μM Fe3+, Cr3+,