Quantification of Amino Groups on Solid Surfaces using

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1 Supporting Information Quantification of Amino Groups on Solid Surfaces using Cleavable Fluorescent Compounds Saori Shiota, Shunsuke Yamamoto, Ayane Shimomura, Akio Ojida, Takashi Nishino, Tatsuo Maruyama * Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe , Japan Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka , Japan Experimental Materials. Methyl methacrylate (MMA), 2,2 -azobisisobutyronitrile (AIBN), triethylamine, chloroform, ethanol, methanol, dichloromethane (DCM), dimethyl sulfoxide (DMSO), ethyl acetate, hexane, acetonitrile, tetrahydrofuran (THF), N-hydroxysuccinimide (NHS) and 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride n-hydrate (DMT-MM) were purchased from Wako Pure Chemical Industries Ltd. (Osaka, Japan). 2-Aminoethyl methacrylate hydrochloride (AEMA HCl) and fluorescein isothiocyanate (FITC) were purchased from Sigma (St Louis, MO). 3-[(2-Aminoethyl)dithio]propionic acid (AEDP) was purchased from Toronto Research Chemicals (Toronto, Canada). 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) was purchased from Dojindo Molecular Technologies Inc. (Kumamoto, Japan). 2-Dimethylaminobenzoic acid was purchased from Alfa Aesar (Heysham, UK). S1

2 Tris(2-carboxyethyl)phosphine hydrochloride (TCEP), 2,4-dihydroxybenzaldehyde, 2,2-dimethyl-1,3-dioxane-4,6-dione, piperidinium acetate, 5-formylsalicylic acid and di-tert-butyl dicarbonate were purchased from Tokyo Chemical Industry (Tokyo, Japan). Silica particles (Sicastar, NH 2, 1 m, nonporous) were purchased from Micromod Partikel Technologie GmbH (Rostock, Germany). N,N-Dimethylformamide (DMF) and NH 2 -PEG resin (1 m) were purchased from Watanabe Chemical Industries Ltd. (Hiroshima, Japan). Inhibitor was removed from MMA using activated alumina prior to use; other reagents were used without further purification. High-quality deionized water (DI water, >15 M cm) produced by an Elix-5 system (Millipore, Molsheim, France) was used in experiments. Poly(methyl methacrylate) (PMMA) substrates (.5 mm thick) were obtained from Nitto Jushi Kogyo Co., Ltd. (Tokyo, Japan). Substrates were cleaned by sonication in water and then cut into 1 1 cm pieces prior to use. Synthesis of cleavable FITC. AEDP (.55 mmol) was dissolved in THF/water (4 ml, 1:1 volume ratio) containing.1 vol % triethylamine. FITC (.5 mmol) was added to the solution, which was then stirred for 3 h at room temperature. After the solvent was evaporated, the solid residue was dissolved in 1 wt % Na 2 CO 3 aqueous solution, and 1 M HCl aqueous solution was added to adjust the ph of the solution to 1. The precipitate obtained was centrifuged, washed with 1 mm HCl aqueous solution twice and then freeze-dried overnight. The yield of cleavable FITC was 78%. The compound was characterized by 1 H NMR spectroscopy (Varian Gemini 3) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) (UltrafleXtreme, Bruker, Billerica, MA). 1 H NMR (3 MHz, DMSO-d 6 ): (ppm) 1.4 (t, 2H, J=6.6 Hz), 2.63 (t, 2H, J=6.6 Hz), (m, 4H), (m, 9H). MALDI-TOF/MS (m/z): [M+H] + calcd for C 26 H 22 N 2 O 7 S 3, 57.7; found, Synthesis of 7-hydroxycoumarin-3-carboxylic acid. 1 2,4-Dihydroxybenzaldehyde (5 mmol), S2

3 2,2-dimethyl-1,3-dioxane-4,6-dione (5 mmol) and piperidinium acetate (1 mmol) were dissolved in dehydrated ethanol (25 ml), then stirred for 1 min at room temperature and subsequently for 3 h under reflux. The reaction mixture was cooled to room temperature, and then further cooled in an ice bath for 3 min. The precipitate was collected by filtration and washed with ethanol three times, then dried in a vacuum desiccator overnight. The yield of 7-hydroxycoumarin-3-carboxylic acid was 71%. 1 H NMR (3 MHz, DMSO-d 6 ): (ppm) 6.74 (d, 1H, J= 1.8 Hz), 6.85 (dd, 1H, J= 2.1, 8.4 Hz), 7.75 (d, 1H, J=8.7 Hz), 8.68 (s, 1H). Anal. calcd for C 1 H 6 O 5 : C, 58.3; H, 2.9. Found: C, 58.3; H, Synthesis of N-succinimidyl-7-hydroxycoumarin-3-carboxylate. 7-Hydroxycoumarin-3-carboxylic acid (1.36 mmol) was dissolved in DMF (7 ml) and then cooled in an ice bath. EDC (1.63 mmol) and NHS (1.36 mmol) were added to the solution. The mixture was stirred for 2 h in an ice bath. After returning to room temperature, the reaction mixture was diluted with ethyl acetate (2 ml) and washed with water (5 ml) twice. The organic phase was dried with magnesium sulfate anhydride overnight. The solution was filtered and then the solvent was evaporated. The solid residue was suspended in ethyl acetate (15 ml), and then the solution was filtered. The residue was washed with 5 ml of ethyl acetate/hexane (1:4 volume ratio) and freeze-dried overnight. The yield of N-succinimidyl- 7-hydroxycoumarin-3-carboxylate was 65%. 1 H NMR (3 MHz, DMSO-d 6 ): (ppm) 2.89 (s, 4H), 6.77 (d, 1H, J= 1.8 Hz), 6.9 (dd, 1H, J=1.8, 8.4 Hz), 7.88 (d, 1H, J=9 Hz), 9.2 (s, 1H), (bs, 1H). ESI-MS (m/z): [M-H] - calcd for C 14 H 9 NO 7, 33.2; found, ESI-MS was performed using a JMS-T1LP AccuTOF LC-plus spectrometer (JEOL, Tokyo, Japan). Synthesis of cleavable coumarin. AEDP (.55 mmol) and triethylamine (1.43 mmol) were dissolved in water (4 ml) and then DMF (1.98 ml) was added to the aqueous solution. DMF (5.2 ml) containing.1 M N-succinimidyl-7-hydroxycoumarin-3-carboxylate was added dropwise to the S3

4 aqueous solution, which was subsequently stirred at room temperature overnight. The solvent was evaporated, and the residue was washed with.1 M HCl aqueous solution (1 ml) and then 1 mm HCl aqueous solution (1 ml) twice. The resulting solid residue was collected by centrifugation, recrystallized from methanol and dried in a vacuum desiccator overnight. The yield of cleavable coumarin was 64%. 1 H NMR (3 MHz, DMSO-d 6 ): (ppm) 2.63 (t, 2H, J=7.1 Hz), (m, 4H), 3.62 (q, 2H, J=6.5 Hz), 6.8 (d, 1H, J= 2.1 Hz), 6.88 (dd, 1H, J= 1.8, 8.4 Hz), 7.82 (d, 1H, J=8.4 Hz), 8.8 (s, 1H). MALDI-TOF/MS (m/z): [M+H] + calcd for C 15 H 15 NO 6 S 2, 369.4; found, Synthesis of N-succinimidyl-2-dimethylaminobenzoate. 2-Dimethylaminobenzoic acid (1.21 mmol) was dissolved in DCM (6 ml). EDC (1.57 mmol) and NHS (1.21 mmol) were added to the solution. The reaction mixture was stirred at room temperature overnight. The solution was washed with water (6 ml) three times and then the organic phase was dried with magnesium sulfate anhydride overnight. The solution was filtered and the solvent evaporated. The residue was freeze-dried overnight. The yield of N-succinimidyl-2-dimethylaminobenzoate was 55%. 1 H NMR (3 MHz, CDCl 3 ): (ppm) 2.89 (d, 4H, J=2.7 Hz), 2.92 (s, 6H), 6.85 (t, 1H, J=7.5 Hz), 6.97 (d, 1H, J= 8.4 Hz), 7.44 (t, 1H, J= 8. Hz), 7.96 (d, 1H, J=7.8 Hz). MALDI-TOF/MS (m/z): [M+H] + calcd for C 13 H 14 N 2 O 4, 262.3; found, Synthesis of cleavable anthranilate. AEDP (.72 mmol) and triethylamine (1. mmol) were dissolved in water (5.6 ml). Then,.8 M N-succinimidyl-2-dimethylaminobenzoate solution in THF (8.4 ml) was added dropwise to the solution. The solution was stirred at room temperature overnight and then the solvent was evaporated. The residue was purified by silica-gel column chromatography using methanol/hexane (2:1 volume ratio) as the eluent. The yield of cleavable anthranilate was 28%. 1 H NMR (3 MHz, CDCl 3 ): (ppm) 2.74 (s, 6H), 2.79 (t, 2H, J=6.6 Hz), S4

5 (m, 4H), 3.81 (q, 2H, J=6.2 Hz), (m, 2H), 7.44 (t, 1H, J=8.1 Hz), 8.14 (d, 1H, J=7.5 Hz), 1.34 (bs, 1H). MALDI-TOF/MS (m/z): [M+H] + calcd for C 14 H 2 N 2 O 3 S 2, 328.5; found, Synthesis of 2-(tert-butoxycarbonylamino)ethyl methacrylate (Boc-AEMA). AEMA HCl (6.4 mmol) and triethylamine (12.1 mmol) were dissolved in chloroform (2 ml). Di-tert-butyl dicarbonate (6.64 mmol) was added to the solution, which was then stirred at 4 C overnight. Ethyl acetate (3 4 ml) was added to the solution, and the resulting precipitate was removed by filtration. The filtrate was evaporated, and the resulting residue was washed with water three times and then freeze-dried overnight. The yield of Boc-AEMA was 6%. 1 H NMR (3 MHz, CDCl 3 ): (ppm) 1.45 (s, 9H), 1.95 (s, 3H), 3.45 (q, 2H, J=5.1 Hz), 4.21 (t, 2H, J=5.4 Hz), 4.77 (bs), 5.59 (s, 1H), 6.13 (s, 1H). ESI-MS (m/z): [M+Na] + calcd for C 11 H 19 NO 4, 252.2; found, Synthesis of poly(mma-r-(boc)aema). MMA (31.4 mmol), Boc-AEMA (3.49 mmol) and AIBN (.6 mmol) were dissolved in acetonitrile (7.58 ml) that was subsequently purged with nitrogen gas. Polymerization was performed under a nitrogen atmosphere at 7 C overnight. The copolymer was precipitated by adding excess hexane, and then the precipitate was freeze-dried overnight. 1 H NMR (3 MHz, CDCl 3 ): (ppm) (m, 38H), 1.46 (s, 1H), (m, 18H), 3.6 (s, 31H). Gel permeation chromatography (GPC) suggested that poly(mma-r-(boc) AEMA) had M n of g/mol and M w /M n of 2.9. GPC was performed using a chromatograph (L-7, Hitachi, Japan) equipped with a GPC column (TSKgel H, mm, Tosoh, Tokyo, Japan). Chloroform was used as the eluent, and polystyrene molecular weight standards were used to obtain a standard curve. Quantification of amino groups using Orange II. 2 NH 2 -PEG resins in dry condition were S5

6 dispersed in water to prepare 1.54 mg/ml resin slurry. In a 2-mL tube, NH 2 -PEG resins (1 µl) were washed with water and added to 1 mm HCl aqueous solution containing Orange II, followed by gentle mixing for 3 min at 4 C. After centrifugation and removal of the supernatant, fresh HCl aqueous solution (1 mm) was added to the NH 2 -PEG resins and mixed for 3 min at 4 C to wash them. This washing procedure was repeated twice. After centrifugation and removal of the supernatant, the NH 2 -PEG resins were dispersed in NaOH aqueous solution (1 mm, 1 ml). After centrifugation, HCl aqueous solution (4.1 M, 1 µl) was added to the supernatant to adjust the ph to 3. The absorbance of the solution at 484 nm was then measured using a UV-vis spectrophotometer. S6

7 Fluorescence intensity [-] Fluorescence intensity [-] Results 1 a c 6 d Concentration of liberated fluorescence [ M] Figure S1. Standard curves of cleavable fluorescent compounds. (a) Cleavable FITC, (b) cleavable coumarin, and (c) cleavable anthranilate in phosphate buffer (67 mm, ph 8.) containing 2 mm TCEP. (d) 5-Formylsalicylic acid in phosphate buffer (67 mm, ph 7.4). b References 1. Gnaccarini, C.; Ben-Tahar, W.; Mulani, A.; Roy, I.; Lubell, W. D.; Pelletier, J. N.; Keillor, J. W., Site-specific protein propargylation using tissue transglutaminase. Org. Biomol. Chem. 212, 1 (27), Noel, S.; Liberelle, B.; Robitaille, L.; De Crescenzo, G., Quantification of primary amine groups available for subsequent biofunctionalization of polymer surfaces. Bioconjug. Chem. 211, 22 (8), S7