Supporting Information Fluorescence Regulation of Copper Nanoclusters via DNA Template Manipulation toward Design of a High Signal-to-Noise Ratio Biosensor Junyao Li, Wenxin Fu, Jianchun Bao, Zhaoyin Wang*, and Zhihui Dai*,, Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing, 210023, P. R. China Nanjing Normal University Center for Analysis and Testing, Nanjing, 210023, P. R. China * E-mail: daizhihuii@njnu.edu.cn; Tel./Fax: +86-25-85891051. (Z. Dai) * E-mail: zywang@njnu.edu.cn. (Z. Wang) List of contents: 1. Absorption and Excitation Spectra of CuNCs (Figure S1). 2. Effect of Exo I on Fluorescence Intensity of CuNCs (Figure S2). 3. The Detailed Description of LOD Calculation. 4. Comparison of Analytical Performances of Different Hg 2+ Biosensors (Table S1). 5. Related References for Supporting Information (Reference (1) - (9)). S-1
1. Absorption and Excitation Spectra of CuNCs Figure S1. (A) The absorption spectra of (a) poly(30t)-templated CuNCs and (b) Hg 2+ -treated poly(30t)-templated CuNCs. (B) The excitation spectra of (a) poly(30t)-templated CuNCs and (b) Hg 2+ -treated poly(30t)-templated CuNCs. S-2
2. Effect of Exo I on Fluorescence Intensity of CuNCs Figure S2. Effect of exo I on fluorescence intensity of CuNCs. The excitation wavelength is 340 nm. S-3
3. The Detailed Description of LOD Calculation The calculation method for LOD is based on the IUPAC formula: LOD = 3σ/k, where σ is the measured standard deviation of twenty blank assays, and k is the slope of the calibration curve. Taking the Hg 2+ biosensor as an example, twenty blank assays were accomplished in the absence of Hg 2+ ions. The signal of each blank sample is recorded as x i. On a basis of the formula: σ= ( ), (µ is the mean of the twenty x i ), it can be obtained that the σ is 43.76. In light of the regression equation F 650 nm = 34.2lg[Hg 2+ ] (nm) - 100, the k is 34.2. Since the detection signal and the logarithm of the concentration of Hg 2+ reveal linearity (lg LOD = 3σ/k), the calculated LOD is 6.9 µm. S-4
4. Analytical Performances of Different Hg 2+ Biosensors Table S1. Comparison of analytical performances of different Hg 2+ biosensors. Method Signal probe Detection limit Electrochemistry Thymine-functi onalized silver nanoparticle Linear range 5 pm 50 pm 50 nm Real sample detection Lake water, well water, tap water Process complexity Cost Time Ref. + + + + + + + + (1) Colorimetry Amphiphilic Ag nanoclusters 30 nm 10 nm 2.5 µm Lake water, soil solution + + + (2) Electrochemilum inescence Dual-function oligonucleotide probe 5.1 pm 50 pm 10 nm Tap water, lake water + + + + + + + + (3) Photoelectroche mistry Nanogold 2 pm 5 pm 500 pm Tap water, river water + + + + + + + + (4) Impedance Fe(CN) 6 4- /Fe(C N) 6 3-100 pm 100 pm 10 µm 10% newborn calf serum, lake water + + + + + + + + (5) Room-temperatu re phosphorescence CTAB-capped Mn-doped ZnS quantum dots 1.5 nm 50 nm 800 nm Tap water, river water + + + + + (6) Surface enhanced Raman spectroscopy Tryptophan-pro tected popcorn shaped gold nanoparticles 5 ppb 5 ppb 1000 ppb Old alkaline battery + + + + + + + + + (7) Fluorescence Graphene oxide 300 pm 300 pm 1 nm Drinking water + + + + + + + (8) Fluorescence Copper nanocluster 3.3 nm 10 nm 10 µm Water sample, food stuff + + + + (9) Fluorescence Copper nanoclusters 16 pm 50 pm 500 µm Lake water + + + This work We used + to represent the simplest operation, the cheapest expenditure and the shortest time. On the contrary, we used + + + to represent the most complicated operation, the most expensive cost and the longest time. S-5
5. References (1) Wei, T.; Dong, T.; Wang, Z.; Bao, J.; Tu, W.; Dai, Z. Aggregation of Individual Sensing Units for Signal Accumulation: Conversion of Liquid-Phase Colorimetric Assay into Enhanced Surface-Tethered Electrochemical Analysis. J. Am. Chem. Soc. 2015, 137, 8880-8883. (2) Xia, N.; Yang, J.; Wu, Z. Fast, High-Yield Synthesis of Amphiphilic Ag Nanoclusters and the Sensing of Hg 2+ in Environmental Samples. Nanoscale 2015, 7, 10013-10020. (3) Huang, R. F.; Liu, H. X.; Gai, Q. Q.; Liu, G. J.; Wei, Z. A Facile and Sensitive Electrochemiluminescence Biosensor for Hg 2+ Analysis Based on a Dual-Function Oligonucleotide Probe. Biosens. Bioelectron. 2015, 71, 194-199. (4) Li, J.; Tu, W.; Li, H.; Han, M.; Lan, Y.; Dai, Z.; Bao, J. In Situ-Generated Nano-Gold Plasmon-Enhanced Photoelectrochemical Aptasensing Based on Carboxylated Perylene-Functionalized Graphene. Anal. Chem. 2014, 86, 1306-1312. (5) Lin, Z.; Li, X.; Kraatz, H. B. Impedimetric Immobilized DNA-Based Sensor for Simultaneous Detection of Pb 2+, Ag +, and Hg 2+. Anal. Chem. 2011, 83, 6896-6901. (6) Xie, W.; Huang, W.; Luo, H.; Li, N. CTAB-Capped Mn-Doped ZnS Quantum Dots and Label-Free Aptamer for Room-Temperature Phosphorescence Detection of Mercury Ions. Analyst 2012, 137, 4651-4653. (7) Senapati, T.; Senapati, D.; Singh, A. K.; Fan, Z.; Kanchanapally, R.; Ray, P. C. Highly Selective SERS Probe for Hg(II) Detection Using Tryptophan-Protected Popcorn Shaped Gold Nanoparticles. Chem. Commun. 2011, 47, 10326-10328. (8) Huang, J.; Gao, X.; Jia, J.; Kim, J.-K.; Li, Z. Graphene Oxide-Based Amplified Fluorescent Biosensor for Hg 2+ Detection through Hybridization Chain Reactions. Anal. Chem. 2014, 86, 3209-3215. (9) Hu, X.; Wang, W.; Huang, Y. Copper Nanocluster-Based Fluorescent Probe for Sensitive and Selective Detection of Hg 2+ in Water and Food Stuff. Talanta 2016, 154, 409-415. S-6