Copper-Based Metal-Organic Framework Nanoparticles. with Peroxidase-Like Activity for Sensitive Colorimetric. Detection of Staphylococcus Aureus

Transcription

1 Supporting Information For Copper-Based Metal-Organic Framework Nanoparticles with Peroxidase-Like Activity for Sensitive Colorimetric Detection of Staphylococcus Aureus Shuqin Wang, Wenfang Deng, Lu Yang, Yueming Tan, * Qingji Xie, and Shouzhuo Yao Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha , China. address: tanyueming0813@126.com; tanyueming0813@hunnu.edu.cn S1

2 EXPERIMENTAL SECTION Instrumentation. Scanning electron microscopy (SEM) studies were performed on a Hitachi S4800 scanning electron microscope. Transmission electron microscopy (TEM) studies were performed on a TECNAI F-30 high-resolution transmission electron microscope operating at 300 kv. X-ray photoelectron spectroscopy (XPS) was recorded on a PHI QUANTUM 2000 X-ray photoelectron spectroscopic instrument. UV-Vis absorption spectra an the absorption values at a given wavenumber were recorded using a plate reader (Infinite M1000, Tecan, Switzerland). Fourier transform infrared (FT-IR) spectra were collected on a Nicolet Nexus 670 FT-IR instrument (Nicolet Instrument Co., USA) in its transmission mode. Chemicals. Bovine serum albumin (BSA), 2-aminoterephthalic acid, 3,3,5,5 -tetramethylbenzidine (TMB), and polyvinyl pyrrolidone (PVP) were purchased from Aladdin Chemistry Co., Ltd. N, N-dimethylformamide (DMF), CuNO 3 3H 2 O and glutaraldehyde (50 wt.%) were purchased from from Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China). Hydrogen peroxide (30 wt.%), ethanol, hydrochloric acid (36 wt.%) were purchased Tianjin Kemiou Chemical Reagent Co., Ltd. (Tianjin, China). Strains of S. aureus, S. dysenteriae, S. typhimurium, and E. coli O157:H7 were obtained from American Type Culture Collection. Amino functionalized Fe 3 O 4 nanoparticles with a diameter of nm were purchased from Aladdin Chemistry Co., Ltd. The S. aureus aptamer sequence was 5 -NH 2 -GCA ATG GTA CGG TAC TTC CTC GGC ACG TTC TCA GTA GCG CTC GCT GGT CAT CCC ACA GCT ACG TCA AAA GTG CAC GCT ACT TTG CTA A-3. 1 The S. aureus aptamer was purchased from Shanghai Sangon Biological Science & Technology Company (Shanghai, China). S2

3 Synthesis of Cu-MOF g PVP was dissolved into the mixed solvent containing 4 ml DMF and 4 ml ethanol, and then 24.2 mg CuNO 3 3H 2 O (0.1 mmol) and 5.43 mg 2-aminoterephthalic acid (0.03 mmol) dissolved in 4 ml DMF were added into the above solution. After that, the solution was treated under ultrasonication for 20 min. Subsequently, the solution was transferred into a Teflon-lined stainless steel autoclave and heated at 100 o C for 8 h. Finally, the obtained product was collected by centrifugation, water-rinsed, and dried in a vacuum freeze drier. Modification of aptamer on Cu-MOF. 6 mg of Cu-MOF nanoparticles was dispersed in 6 ml glutaraldehyde (2.5 wt. %). After reacting for 2 h, the Cu-MOF nanoparticles were collected by centrifugation, water-rinsed, and re-dispersed in 6 ml 0.01 M phosphate buffer solution (PBS, ph 7.4). Subsequently, 12 µl of 10-4 M amino-terminated S. aureus aptamer was added. The mixture was incubated at 37 C for 24 h. The reaction product was centrifuged at 4,000 rpm for 10 min to remove the excess aptamer. Then, the nanoparticles were blocked with 1% BSA in PBS for 1 h at room temperature to avoid the nonspecific absorption. Finally, the product was collected by centrifugation, water-rinsed, and re-dispersed in 10 ml 0.01 M PBS, ph 7.4 and stored at 4 C for further use. Modification of aptamer on Fe 3 O 4. 3 mg of Fe 3 O 4 nanoparticles was dispersed in 6 ml glutaraldehyde (2.5 wt. %). After reacting for 2 h, the Cu-MOF nanoparticles were collected by centrifugation, water-rinsed, and re-dispersed in 6 ml 0.01 M PBS (ph 7.4). Subsequently, 12 µl of 10-4 M Amino-terminated S. aureus aptamer was added. The mixture was incubated at 37 C for 24 h. The reaction product was centrifuged at 4,000 rpm for 10 min to remove the excess aptamer. Then, the nanoparticles were blocked with 1% BSA in PBS for 1 h at room S3

4 temperature to avoid the nonspecific absorption. Finally, the product was collected by centrifugation, water-rinsed, and re-dispersed in 10 ml 0.01 M PBS (ph 7.4) and stored at 4 C for further use. Colorimetric detection of S. aureus. 100 µl of 0.01 M PBS (ph 7.4) containing 0.6 mg ml -1 aptamer modified Cu-MOF nanoparticles was first mixed with 100 µl of 0.01 M PBS containing 0.3 mg ml -1 aptamer modified Fe 3 O 4 nanoparticles, and the mixture was incubated with 50 µl of S. aureus suspension for 70 min at 37 o C. Note that here the concentrations of aptamer modified Cu-MOF nanoparticles and aptamer modified Fe 3 O 4 nanoparticles are optimal to achieve an optimal colorimetric effect and a complete magnetic separation. Then magnetic separation was carried out to remove Fe 3 O 4 and Cu-MOF nanoparticles bound to S. aureus. Subsequently, 200 µl of the supernatant containing residual Cu-MOF nanoparticles was mixed with 200 µl of 0.2 M HCl solution containing 160 µm and 20 mm H 2 O 2, and the mixture was incubated in a 45 C water bath for 10 min. Finally, color photograph was taken immediately and 200 µl of the resulting solution was transferred to a 96-well plate to measure UV-Vis absorption spectrum of using a multifunctional microplate reader. S4

5 Figure S1. FT-IR spectra of Cu-MOF and organic link 2-aminoterephthalic acid. The stretching vibration peaks of amino group for 2-aminoterephthalic acid are observed at 3500 and 3400 cm -1. The stretching vibration peaks of amino group for Cu-MOF shift to 3452 and 3351 cm -1, due to the formation of intra-framework hydrogen bonding of amine group with an electron donating oxygen from the carboxylic group. 2-aminoterephthalic acid shows a large peak at 2970 cm -1, assigned to stretching vibration of OH. For Cu-MOF, the stretching vibration peak of OH at 2970 cm -1 disappears, confirming the occurrence of coordination interaction between Cu 2+ and -COOH of 2-aminoterephthalic acid. S5

6 Figure S2. UV-Vis absorption spectra of TMB-H 2 O 2 solutions (10 mm H 2 O 2 and 80 µm TMB in 0.1 M HCl) incubated with different catalysts at 45 o C for 10 min. S6

7 Figure S3. Effects of H 2 O 2 concentration (a) and TMB concentration (b) on the Cu-MOF catalyzed chromogenic reaction. Effects of H 2 O 2 concentration and TMB concentration on the Cu-MOF catalyzed chromogenic reaction were studied. As shown in Figure S3a, with the increase of H 2 O 2 concentration from 0 to 10 mm, the absorbance at 450 nm increases sharply. The absorbance shows no obvious increase when the H 2 O 2 concentration is higher than 10 mm. Thus 10 mm H 2 O 2 is selected for colorimetric analysis. As shown in Figure S3b, the absorbance increases sharply with the increase of TMB concentration from 0 to 80 µm. The absorbance showes no obvious increase when the TMB concentration is higher than 80 µm. Thus 80 µm TMB is selected for colorimetric analysis. S7

8 Figure S4. Effects of ph (a), reaction temperature (b), and reaction time (c) on the Cu-MOF catalyzed chromogenic reaction. Effects of ph, reaction temperature, and reaction time on the Cu-MOF catalyzed chromogenic reaction were studied. As shown in Figure S4a, the highest absorbance is obtained in 0.1 M HCl aqueous solution. Thus the Cu-MOF-catalyzed chromogenic reaction was conducted in 0.1 M HCl aqueous solution. As shown in Figure S4b, the absorbance at 450 nm increases sharply with the increase of reaction temperature up to 45 o. The absorbance showed no obvious increase when the reaction temperature is higher than 45 o. Thus the Cu-MOF-catalyzed chromogenic reaction was conducted at 45 C. As shown in Figure S4c, the absorbance increases sharply with the increase of reaction time up to 10 min. The absorbance showed no obvious increase when the reaction time is higher than 10 min. Thus the optimal reaction time is 10 min. S8

9 Figure S5. SEM images (a, b) and FT-IR spectrum of amino functionalized Fe 3 O 4 nanoparticles. As shown in Figure S5a and b, spherical Fe 3 O 4 nanoparticles with a diameter of nm are observed. A sharp stretching vibration peak at 3400 cm -1 is observed (Figure S5c), confirming the presence of NH 2 on the surfaces of Fe 3 O 4 nanoparticles. S9

10 Figure S6. XPS survey spectrum (a) and P 2p peak (b) of aptamer modified Fe 3 O 4 nanoparticles. No P element is found in amino functionalized Fe 3 O 4 sample (data not shown). However, after modification of aptamer on Fe 3 O 4 nanoparticles, small P2p peak is observed, confirming that aptamer is successfully linked to Fe 3 O 4 nanoparticles. S10

11 Figure S7. XPS survey spectrum (a) and P 2p peak (b) of aptamer modified Cu-MOF nanoparticles. No P element is found in Cu-MOF sample (data not shown). However, after modification of aptamer on Cu-MOF nanoparticles, small P 2p peak is observed, confirming that aptamer is successfully linked to Cu-MOF nanoparticles. S11

12 Figure S8. Effect of incubation time on the absorbance changes at 450 nm of the resulting solutions for the detection of 10,000 CFU/mL S. aureus. S12

13 Figure S9. Results for detection of Staphylococcus aureus by colorimetric analysis of Cu-MOF nanoparticles bound to bacterial cells. UV-Vis absorption spectra (a), absorbance changes at 450 nm (b), typical photographs (c) of the resulting solutions for the detection of different concentrations (0, 50, 500, 1000, 3000, 5000, 7000, CFU ml -1 ) of S. aureus. Experimentally, Fe 3 O 4 and Cu-MOF nanoparticles bound to S. aureus were removed from the supernatant by magnetic separation and then re-dispersed in 200 µl water for colorimetric analysis. S13

14 Figure S10. Absorbance changes at 450 nm of the resulting solutions for the detection of S. aureus, S. dysenteriae, S. typhimurium, and E. coli O157:H7 (10,000 CFU ml -1 for each). S14

15 Table S1. The Comparison of the Determination of Pathogen in the Literature. Technique Label/Probe Target LOD (CFU ml -1 ) Ref. Colorimetry Antibody-gold nanoparticle-magnetic nanoparticle nanocomposites Staphylococcus aureus Colorimetry Streptavidin labeled Horseradish peroxidase Staphylococcus aureus Colorimetry Gold nanoprobe functionalized with specific fusion protein Staphylococcus aureus 19 4 Colorimetry D-amino acid covalently bound to a magnetic nanobead Listeria monocytogenes Fluorescent spectrometry Aptamers-modified upconversion nanoparticles labels Staphylococcus aureus 25 6 Fluorescent spectrometry fluorescein isothiocyanate-labeled porcin IgG Staphylococcus aureus Fluorescent spectrometry Vancomycin-stabilized fluorescent gold nanoclusters Staphylococcus aureus 16 8 Colorimetry Aptamer-modified Cu-MOF nanoparticles Staphylococcus aureus 20 This work S15

16 Table S1. Results of Determination Of S. Aureus in Real Samples. a Sample Milk Added (CFU ml -1 ) Found (CFU ml -1 ) RSD (%) Recovery (%) # # # a The milk samples from the local market were diluted for 20 times, and then S. aureus in the diluted milks was measured. REFERENCES (1) Cao, X. X.; Li, S. H.; Chen, L. C.; Ding, H. M.; Xu, H.; Huang, Y. P.; Li, J.; Liu, N. L.; Cao, W. H.; Zhu, Y. J.; Shen, B. F.; Shao, N. S., Combining Use of a Panel of ssdna Aptamers in the Detection of Staphylococcus Aureus. Nucleic Acids Res. 2009, 37, (2) Sung, Y. J.; Suk, H. J.; Sung, H. Y.; Li, T.; Poo, H.; Kim, M. G., Novel Antibody/Gold Nanoparticle/Magnetic Nanoparticle Nanocomposites for Immunomagnetic Separation and Rapid Colorimetric Detection of Staphylococcus Aureus in Milk. Biosens. Bioelectron. 2013, 43, (3) Yu, J.; Zhang, Y.; Zhang, Y.; Li, H.; Yang, H.; Wei, H., Sensitive and Rapid Detection of Staphylococcus Aureus in Milk via Cell Binding Domain of Lysin. Biosens. Bioelectron. 2016, 77, S16

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