A Turn-On Fluorescent Sensor for Selective and Sensitive. Detection of Alkaline Phosphatase Activity with Gold

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1 Supporting Information A Turn-On Fluorescent Sensor for Selective and Sensitive Detection of Alkaline Phosphatase Activity with Gold Nanoclusters Based on Inner Filter Effect Haijian Liu a, Ming Li a, Yining Xia b *, Xueqin Ren a * a Department of Environmental Science and Engineering, College of Resources and Environmental Sciences, China Agricultural University, Beijing , China b Institute of Quality Standards and Testing Technology for Agro Products of Chinese Academy of Agricultural Sciences, Beijing , China *Corresponding author: Dr. Yining Xia Institute of Quality Standards and Testing Technology for Agro-Products of Chinese Academy of Agricultural Sciences, Beijing , China ynxia010@hotmail.com Prof. Xueqin Ren Department of Environmental Sciences & Engineering, College of Resources and Environmental Sciences, China Agricultural University, Beijing , P. R. China Tel: ; Fax: ; renxueqin@cau.edu.cn 1

2 Table of Contents: 1. Quantum yield measurement of AuNCs 2. Estimation of the concentration of the as-prepared AuNCs 3. Figure S1. The photostability of the AuNCs measured by fluorescence spectrophotometer every 5 min 4. Figure S2. Fluorescence intensity of AuNCs upon addition of various concentrations of PNPP from 0 to 1000 µm. 5. Figure S3. Effect of PNPP on the fluorescence lifetime of AuNCs 6. Figure S4. Detection of ALP in three adult volunteers serums by the clinic method and our method. 7. Table S1.Comparison of analytical performance of some assays for ALP detection 2

3 Quantum yield measurement The quantum yield (Φ) of AuNCs was determined by comparing the integrated fluorescent intensities (excitation at 330 nm) and absorbance values (at 330 nm) of the AuNC samples with those of rhodamine B. The quantum yield was calculated using equation (1), where Φ is the quantum yield, k is slope, η is the refractive index of the solvent, S is the standard and X is the sample. Φ Φ K K η η 1 Estimation of the concentration of the as-prepared AuNCs The number of Au in the HAuCl 4 solution: 0.005M 25 ml = According to previous literature 10, AuNCs stabilized with MUA consisted of 25 Au atoms. Therefore, mole of the as-prepared AuNCs can be estimated as below: (total number of Au atom in solution) 25 (number per AuNC) = mole Molar concentration of the as-prepared AuNCs can be calculated as below: mole ml = M Figure S1 The photostability of the AuNCs measured by fluorescence spectrophotometer every 5 min ( λ ex = 330 nm, λ em = 600 nm ) Figure S2 Fluorescence intensity of AuNCs upon addition of various concentrations of PNPP from 0 to 1000 µm. 3

4 Figure S3. Effect of PNPP on the fluorescence lifetime of AuNCs ( mol L 1, ph 9.0). (a) AuNCs (τ = 5.11 µs); (b) AuNCs in the presence of PNPP (τ = 4.85 µs). Figure S4. Detection of ALP in three adult volunteers serums by the clinic method and our method. A 50 µl of serum sample was added to Tris-HCl buffer solution (10 mm, ph 9.0) containing 1 mm PNPP and 0.1 µm MgSO 4 and then incubated at 37 C for 50 min. The reaction solution was mixed with 1 ml of AuNCs. The fluorescence spectrum was measured with the excitation at 330 nm. Table S1.Comparison of analytical performance of some assays for ALP detection Analysis methods Linear LOD range (U/L) (U/L) References cerium oxide nanoparticles-based colorimetric assay (1) CuInS 2 QDs-based fluorescence nu/ml nu/ml (2) CDs-based fluorescence (3) CDs-based fluorescence (4) Gold nanoclusters-based fluorescent probe mu/ml (5) 4

5 Gold nanoclusters-based fluorescent probe CDs-based fluorescence (6) (7) fluorescent dye fluorescence U/mL 0.06 U/mL (8) Betaine-modified PEI-based ratiometric fluorescent probe Gold nanoclusters-based fluorescent probe U/ml (9) This work 5

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