MnO 2 -Nanosheet-Modified Upconversion Nanosystem for Sensitive Turn-On Fluorescence Detection of H 2 O 2 and Glucose in Blood

Transcription

1 Supporting Information MnO 2 -Nanosheet-Modified Upconversion Nanosystem for Sensitive Turn-On Fluorescence Detection of H 2 O 2 and Glucose in Blood Jing Yuan, Yao Cen, Xiang-Juan Kong, Shuang Wu, Chen-Liwei Liu, Ru-Qin Yu, and Xia Chu* State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha , P. R. China xiachu@hnu.edu.cn. S-1

2 ADDITIONAL EXPERIMENTAL DETAILS Characterization of the Materials. Dynamic light scattering (DLS) experiments were carried out on a Malvern Zetasizer (Nano-ZS, USA). Fourier transform infrared spectroscopy (FT-IR) spectra were recorded on a Nicolet Nexus 670 FT-IR spectrometer by using pressed KBr tablets. The energy dispersive X-ray spectroscope (EDS) spectrum was collected using Environmental Scanning Electron Microscope (FEI QUANTA 200, USA) with energy dispersive X-ray spectroscope (EDAX genesis xm-2). The X-ray photoelectron spectroscopy (XPS) analysis was performed by an X-ray photoelectron spectroscope (Thermo Fisher Scientific, USA) using an unmonochromated Al KαX-ray source ( ev). Mn 2+ Detection. Mn 2+ ions produced from the reduction of MnO 2 by H 2 O 2 can be detected according to the method described by literature µl of MnO 2 -nanosheet-modified UCNPs aqueous solution first reacted with enough H 2 O 2 in phosphate buffer solution at 37 C for 40 min. After centrifugation and collection of the supernatant, 2.5 µl of phosphoric acid (85%) and 20 µl of sodium periodate (1 M) were added into 50 µl of the above supernatant. The mixed solution was then incubated at room temperature for 30 min. After that, the resulting mixture was diluted to a final volume of 100 µl with ultrapure water, and the UV-vis absorption spectra were recorded on a UV-2450 UV-vis spectrometer. L-Lactic Acid Detection. In a typical assay of L-lactic acid, 10 µl of 10 U ml -1 lactate oxidase, 50 µl of MnO 2 -nanosheet-modified UCNP aqueous solution (0.03 mg ml -1 ) and different concentrations of L-lactic acid solution (30 µl) were added into 10 µl of 100 mm phosphate buffer solution (ph 7.0). The mixed solution was incubated at 37 C for 40 min. Then, the upconversion fluorescence spectra were recorded under the excitation of 980 nm laser. REFERENCES (1) Willard, H. H.; Greathouse, L. H. The Colorimetric Determination of Manganese by Oxidation with Periodate. J. Am. Chem. Soc. 1917, 39, S-2

3 Figure S1. TEM image of azelaic acid-capped hydrophilic 4 core-shell nanoparticles. S-3

4 Figure S2. Dynamic light scattering (DLS) of oleic acid-capped UCNPs in cyclohexane (black) and azelaic acid-capped UCNPs in water (red). S-4

5 Figure S3. FT-IR spectra of oleic acid-capped (top, black) and azelaic acid-capped (bottom, red) NaYF 4 :Yb,Tm@NaYF 4 core-shell nanoparticles. The absorption bands around 2925 and 2854 cm -1, attributed to C-H stretching, are observed to decrease with a concomitant increase in the O-H stretching band around ~3450 cm -1 in the azelaic acid-capped UCNPs as compared to the OA-capped UCNPs. This indicates the oxidation cleavage of C=C bond of OA. We also observe that the absorption band around 1463cm -1, ascribed to C=C stretching, for the OA-capped UCNPs is diminished in the azelaic acid-capped UCNPs, further confirming the oxidation cleavage of C=C bond of OA. S-5

6 Figure S4. (A) XPS spectra of NaYF 4 :Yb,Tm@NaYF 4 core-shell UCNPs (red line) and MnO 2 -nanosheet-modified UCNPs (black line). (B) High resolution Mn (2p) XPS spectra of NaYF 4 :Yb,Tm@NaYF 4 core-shell UCNPs. (C) High resolution Mn (2p) XPS spectra of MnO 2 -nanosheet-modified NaYF 4 :Yb,Tm@NaYF 4 UCNPs. S-6

7 Figure S5. UV-vis absorption spectra of (A) KMnO 4 (black) and MnO 2 nanosheets (red); (B) NaYF 4 :Yb,Tm@NaYF 4 core-shell UCNPs (black) and MnO 2 -nanosheet-modified UCNPs (red). S-7

8 Figure S6. Upconversion emission spectra of (a) NaYF 4 :Yb,Tm@NaYF 4 core-shell UCNPs (black); (b) mixing solution of core-shell UCNPs and pre-synthesized MnO 2 nanosheets (red); (c) MnO 2 - nanosheet-modified UCNP assemblies (pink). Note that a physical mixing of pre-synthesized MnO 2 nanosheets and the core-shell UCNPs did not lead to a significant change in emission intensity. Inset showed the photographs of the corresponding upconverted visible fluorescence under 980 nm laser illumination (right). S-8

9 Figure S7. TEM images of MnO2-nanosheet-modified UCNP assemblies formed at different KMnO4 concentrations of (A) 0.2 mm, (B) 0.6 mm, and (C) 1.2 mm. S-9

10 Figure S8. The reduction of MnO 2 to Mn 2+ by H 2 O 2 can be verified by a highly specific reaction for Mn 2+ as following equation: 2Mn 2+ +5IO H 2 O 2MnO IO H + (A) UV-vis absorption spectra of the reaction mixture of sodium periodate under the acidic conditions with supernatant of the MnO 2 -modified UCNPs treated with (black curve) and without enough H 2 O 2 (red curve), and KMnO 4 aqueous solution (blue curve). Inset: Photographs of the reaction mixture of sodium periodate with supernatant of the MnO 2 -modified UCNPs treated with (right) and without (left) enough H 2 O 2. (B) Photographs of UCNPs (a), MnO 2 -modified UCNPs (b), and MnO 2 -modified UCNPs treated with enough H 2 O 2 (c). S-10

11 Figure S9. Effects of incubation temperature (A) and reaction time (B) on the upconversion fluorescence response of MnO 2 -modified UCNPs to 100 µm glucose. S-11

12 Figure S10. Upconversion fluorescence spectra of MnO 2 -nanosheet-modified NaYF 4 :Yb,Tm@NaYF 4 UCNPs (90 µl) after incubation with (a) 10 µl human serum in the present of mg ml -1 GOx; (b) 10 µl human serum pre-treated with 0.3 mm NEM in the presence of mg ml -1 GOx; (c) 10 µl human serum; (d) 10 µl human serum pre-treated with 0.3 mm NEM; (e) MnO 2 -modified NaYF 4 :Yb,Tm@NaYF 4 UCNPs (90 µl) after dispersion in 10 µl phosphate buffer. S-12

13 Figure S11. (A) Upconversion fluorescence response of MnO 2 -nanosheet-modified NaYF 4 :Yb,Tm@NaYF 4 UCNPs after incubation with L-lactic acid of varying concentrations (0-800 µm) in phosphate buffer (ph 7.0) containing 1 U ml -1 lactate oxidase. (B) Plot of fluorescence intensity at 450 nm against the L-lactic acid concentration. Error bars represented standard deviation of three repetitive experiments. S-13