Supporting Information

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1 Supporting Information Construction and biological applications of electrochemically active, anti-biofouling polymer adlayers on transparent electrode surfaces Eun Jeong Kim, a Hee-Young Shin, a Sang-Jin Park, b Daekyung Sung, b Sangyong Jon, b, * Srinivasa-Gopalan Sampathkumar, c Kevin J Yarema, c Sung-Yool Choi, d Kyuwon Kim e, * a Korea Research Institute of Standards and Science, b Gwangju Institute of Science and Technology, c The Johns Hopkins University, d Electronics and Telecommunications Research Institute, e University of Incheon Materials. N-acryloxysuccinimide (NAS; 99%) was purchased from ACRS rganics (Noisy-le-Grand, France). -(Trimethoxysilyl)propyl methacrylate (TMSMA), poly(ethylene glycol) methyl ether methacrylate (PEGMA, average M n = ca. 475), 4-aminophenol, and 2,2 -azobisisobutyronitrile (AIBN) were purchased from Aldrich Chemical Co. (Milwaukee, WI). All organic solvents were used as received without further purification. Regenerated cellulose acetate membrane, molecular weight cut-off 8000, was purchased from Spectra/por -Spectrum Labs Inc. (Rancho Dominguez, CA). 1

2 Measurements. 1 H NMR (00 MHz) spectra was recorded on a JEL JNM-LA00WB FT-NMR (Tokyo, Japan). X-ray photoelectron spectroscopy (XPS) spectra were obtained using a Kratos AXIS Ultra Imaging X-ray Photoelectron Spectrometer with a monochromatized Al K X-ray source. Synthesis of poly(tmsma-r-pegma-r-nhp). The poly(tmsma-r-pegma-r-nas) was synthesized by a previously reported method (M n = 15,784 with M w /M n = 1.58). To a solution of poly(tmsma-r- PEGMA-r-NAS) (0.507 g, mmol of an NAS) in tetrahydrofuran was added 4-aminophenol (0.981 g, 9 mmol, equiv) and the mixture was stirred at room temperature for 12 h. The reactive part of the polymer, NAS, was converted into an NHP. The reaction mixture was dissolved in distilled water and then was dialyzed against distilled water for 24 h to remove excess of 4-aminophenol to yield a hydrolyzed form of poly(tmsma-r-pegma-r-nhp). The hydrolyzed form of poly(tmsma-r-pegma-r-nhp) was characterized by 1 H NMR. Actual ratios of three monomer units incorporated in the final copolymer were calculated from comparison of the integration values of the peaks at δ = 4.1 (C 2 -CH 2 at PEGMA) and at δ =.92 (C 2 -CH 2 at TMSMA) with that of the peak at δ = 6.48 and 6.8 (phenyl ring) in 1 H NMR spectra. The ratio of electroactive part (NHP) in the polymer was ~17%. 1 H NMR (00 MHz, D 2 ): δ = 8.4 (br, 1H of phenolic H), 6.48 (s, 2H of phenyl ring), 6.8 (s, 2H of phenyl ring), 4.1 (br, 2H, C 2 - CH 2 of PEGMA),.92 (br, 2H, C 2 -CH 2 of TMSMA),.66 (s, 0H), (s, 9H; m, 2H),.40 (s, H), 2.82 (br, 4H, C-CH 2 CH 2 -C of NAS), (br, 6H), 1.04 (br, 2H), 0.87 (br, 4H), 0.66 (br, 2H). Table S1. Elemental compositions of PAs on an IT electrode measured by XPS. C N Si In Sn Elemental composition (%)

3 Figure S1. High resolution XPS spectra of PAs on an IT electrode.

4 Figure S2. N(1s) XPS intensities of bare IT (100% as a control) and PAs on an IT measured after incubation with BSA solution (0.1 mg/ml in phosphate buffered saline, ph 7.4) for 2 h Current (μa) V/sec 0.2 V/sec 0. V/sec 0.4 V/sec 0.5 V/sec Anodic peak current (μa) Potential (V vs Ag/AgCl) Scan rate (V/sec) Figure S. Cyclic voltammetric results as a function of scan rates. S(2p) XPS intensity (a.u.) (a) (b) ev Figure S4. S(2p) XPS results for PAs-modified surfaces react with hexanedithiol (a) before and (b) after electrochemical treatments. 4

5 Incorporation of thiol into cell surface. Jurkat lymphocytes (human acute T-cell leukemia) were treated with Ac5ManNTGc (10 mm in ethanol) at a concentration of 100 μm to generate thiols on the cell surfaces. The cells were cultured in RPMI 1640 media supplemented with 10% FBS and antibiotics (100 units/ml penicillin, 100 μg/ml streptomycin) in culture flasks (7 C, 5% C 2 ). Stock solution of Ac5ManNTGc (10 mm) ware prepared in ethanol and added into culture plate prior to cell seeding at concentration of 100 μm. To detect and quantify the cell surface thiols, ~ cells/ml were harvested after day 2 culture and resuspended in PBS supplemented with 10 μl of tris-(2-carboxyethyl) phosphine (TCEP, 10 mm) to attain a reduced form of the cell surface thiols that subsequently rendered react with a maleimide bearing-conjugated biotin (5 mm, 100 μl). The biotinylated cell surfaces were stained with streptavidin-conjugated quantum dot for 0 min and then analyzed by fluorescence microscope. nly Ac5ManNTGc-treated cells showed highly fluorescent images, indicating that the desired thiols were properly expressed on cell surfaces (Figure S5). quantum dot H HN S N + H H (PE) 2 N + HS H H H HN H - 2C cell streptavidin maleimide-conjugated biotin a c b d Figure S5. (a) ptical, (b) fluorescence image of cell treated with Ac5ManNGc, and (c) optical, (d) fluorescence image of cell treated with Ac5ManNTGc. (Scale bars, 100 μm). 5