Johansson PK , Jullesson D , Elfwing A , Liin SI , Musumeci C , Zeglio E , Elinder F , Solin N , Inganäs O .

	Figure 1. Characterization of the PEDOT-S@alkyl-ammonium complexes.(a) i) The monomer of PEDOT-S, ii) dioctyl-ammonium chloride, the alkyl-ammonium molecule used in subsequent experiments, iii) DOPC, the molecule used to create P-S@dioct:DOPC structures, iv) the presumed structure of the PEDOT-S@dioctyl-ammonium complex. (b) PEDOT-S is soluble in water (top), but precipitates in 2.5 mM dioctyl-ammonium (middle) and the precipitate is soluble in chloroform (bottom). (c) UV-vis spectra of PEDOT-S@alkyl-ammonium complexes dissolved (100 μg/mL based on PEDOT-S), in chloroform:methanol (2:1) after being precipitated from water solutions at pH 4 (solid) or pH 9 (dashed), corresponding to doped and dedoped PEDOT-S respectively. The alkyl-ammonium salts used were tetrabutyl-ammonium (green), hexadecyl-trimethyl-ammonium (red), dioctyl-ammonium (blue) and nonyl-ammonium (black). PEDOT-S@dioctyl-ammonium (d) and PEDOT-S@hexadecyl-trimethyl-ammonium (e) complexes dissolved (100 μg/mL based on PEDOT-S) in chloroform:methanol (2:1) were characterized after being precipitated from water solutions with pH in the range 9–4. The arrows indicate increased doping as the pH is decreased.
	Figure 2. Characterization of P-S@dioct:DOPC interactions with supported lipid bilayers.(a) 100 nm DOPC liposomes (500 μg/mL) reach the SiO2 QCM-D sensor at 6 min and a lipid bilayer is formed at about 9 min (A). P-S@dioct:DOPC structures (500 μg/mL DOPC, 50 μg/mL PEDOT-S) were introduced and reached the sensor at 19 min (B) which caused shifts in frequency and dissipation indicative of structure adsorption. After additional 18 min, rinsing with pure PBS started (C) and the curves returned to the values for a clean lipid bilayer. b) P-S@dioct:DOPC structures (500 μg/mL DOPC, 50 μg/mL PEDOT-S) were introduced directly and reached the SiO2 QCM-D sensor at 5 min. A lipid bilayer was formed at about 11 min (D) and the shifts in dissipation and frequency remained high, which indicated presence of P-S@dioct:DOPC structures on the surface. Rinsing with PBS started after additional 16 min (E) and continued for 50 min, but the shifts of the curves remained high. c) AFM image of the P-S@dioct:DOPC structures adsorbed onto a supported lipid bilayer prepared on a SiO2 substrate.
	Figure 3. Electrical characterization of P-S@dioct:DOPC structures.a) Supported lipid bilayers were prepared on nano-electrodes with 100 nm gaps, and 100 nm P-S@dioct:DOPC structures (500 μg/mL DOPC, 50 μg/mL PEDOT-S) prepared at pH 7.4 were then adsorbed. A time-series during 300 s with 0.5 V applied voltage show stable electronic currents (A). References with either only lipid bilayers (B) or lipid bilayers treated with PEDOT-S dissolved in MilliQ (100 μg/mL) during 15 min (C) were not conductive and the measurements were terminated after 7 s. (D) shows a voltage sweep for the P-S@dioct:DOPC structures between 0–1 V. b) 400 nm P-S@dioct:DOPC structures (500 μg/mL DOPC, 50 μg/mL PEDOT-S) were applied on Pt substrates and measured on by C-AFM. i) shows two representative 400 nm structures that had collapsed on the surface and had heights of 17 nm and 21 nm respectively. ii) shows the various spots that were measured and iii) shows the average currents in voltage sweeps between −100 to 100 mV for the two structures (17 nm black, 21 nm red), the surrounding lipid bilayer (green) and the clean Pt substrate (blue).
	Figure 4. PEDOT-S quenches the fluorescent dye Nile Red in the P-S@dioct:DOPC structures.a) When the P-S@dioct:DOPC structures are prepared together with Nile Red, the fluorescence is significantly decreased compared with reference DOPC liposomes stained with Nile Red but without PEDOT-S@dioctyl-ammonium. b) The fluorescence decay of Nile Red is quicker (multiexponential) for P-S@dioct:DOPC structures than the monoexponential decay for Nile Red in DOPC liposomes (τ = 3.5 ns), which indicates quenching. Excitation wavelength was 550 nm in a) and 500 nm in b).
	Figure 5. P-S@dioct:DOPC structures affect the voltage dependence of the Shaker K channel.(a) 0.33 μM P-S@dioct:DOPC applied to the extracellular solution increases the steady-state K+ current at −20 mV. (b) Current traces at −20 mV from a holding voltage of −80 mV. Same recording as in (a). (c) Steady-state K+ conductance vs. membrane voltage. (d) Dose-response curve of the induced shift. The best-fitted curve is ΔV = ΔVmax / (1 + (KD/c)n), where ΔVmax = −5.0 mV, KD = 0.30 μM, and n = 3.2. Neither control samples with DOPC liposomes without PEDOT-S@dioctyl-ammonium nor PEDOT-S added to the water phase, resulted in significant shifts. Data shown as mean ± SEM, n = 4 − 10. All concentrations given are based on the PEDOT-S monomer and the pH was 7.4 for all experiments.

Boesen, Molecular dissection of bacterial nanowires. 2013, Pubmed

Boesen, Molecular dissection of bacterial nanowires. 2013, Pubmed
Bond, On electron transport through Geobacter biofilms. 2012, Pubmed
Bubnova, Semi-metallic polymers. 2014, Pubmed
Börjesson, Electrostatic tuning of cellular excitability. 2010, Pubmed , Xenbase
Börjesson, Structure, function, and modification of the voltage sensor in voltage-gated ion channels. 2008, Pubmed
Börjesson, Lipoelectric modification of ion channel voltage gating by polyunsaturated fatty acids. 2008, Pubmed , Xenbase
Börjesson, An electrostatic potassium channel opener targeting the final voltage sensor transition. 2011, Pubmed , Xenbase
Chan, Model membrane systems and their applications. 2007, Pubmed
Charych, Direct colorimetric detection of a receptor-ligand interaction by a polymerized bilayer assembly. 1993, Pubmed
Cho, Quartz crystal microbalance with dissipation monitoring of supported lipid bilayers on various substrates. 2010, Pubmed
Du, Increased ion conductance across mammalian membranes modified with conjugated oligoelectrolytes. 2013, Pubmed
Elinder, Metal ion effects on ion channel gating. 2003, Pubmed
Greenspan, Nile red: a selective fluorescent stain for intracellular lipid droplets. 1985, Pubmed
Hamedi, Electrochemical devices made from conducting nanowire networks self-assembled from amyloid fibrils and alkoxysulfonate PEDOT. 2008, Pubmed
Hamedi, Electronic polymers and DNA self-assembled in nanowire transistors. 2013, Pubmed
Hamill, Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. 1981, Pubmed
Heeger, Semiconducting and Metallic Polymers: The Fourth Generation of Polymeric Materials (Nobel Lecture) Copyright(c) The Nobel Foundation 2001. We thank the Nobel Foundation, Stockholm, for permission to print this lecture. 2001, Pubmed
Heeger, Semiconducting and Metallic Polymers: The Fourth Generation of Polymeric Materials (Nobel Lecture). 2001, Pubmed
Hinks, Modeling cell membrane perturbation by molecules designed for transmembrane electron transfer. 2014, Pubmed
Hoshi, Biophysical and molecular mechanisms of Shaker potassium channel inactivation. 1990, Pubmed , Xenbase
Hou, Conjugated oligoelectrolytes increase power generation in E. coli microbial fuel cells. 2013, Pubmed
Jiang, Kinked p-n junction nanowire probes for high spatial resolution sensing and intracellular recording. 2012, Pubmed
Kamb, Molecular characterization of Shaker, a Drosophila gene that encodes a potassium channel. 1987, Pubmed
Karam, Unraveling electronic energy transfer in single conjugated polyelectrolytes encapsulated in lipid vesicles. 2010, Pubmed
Keller, Surface specific kinetics of lipid vesicle adsorption measured with a quartz crystal microbalance. 1998, Pubmed
Kim, Interfacing silicon nanowires with mammalian cells. 2007, Pubmed
Kucherak, Switchable nile red-based probe for cholesterol and lipid order at the outer leaflet of biomembranes. 2010, Pubmed
Mata, Interaction of cationic surfactants with carboxymethylcellulose in aqueous media. 2006, Pubmed
Matulis, Thermodynamics of cationic lipid binding to DNA and DNA condensation: roles of electrostatics and hydrophobicity. 2002, Pubmed
Muzzalupo, Interactions between gemini surfactants and polymers: thermodynamic studies. 2007, Pubmed
Ottosson, Drug-induced ion channel opening tuned by the voltage sensor charge profile. 2014, Pubmed , Xenbase
Persson, Electronic control over detachment of a self-doped water-soluble conjugated polyelectrolyte. 2014, Pubmed
Persson, Electronic control of cell detachment using a self-doped conducting polymer. 2011, Pubmed
Prylutska, Effect of iron-doped multi-walled carbon nanotubes on lipid model and cellular plasma membranes. 2012, Pubmed
Prylutska, Water-soluble pristine fullerenes C60 increase the specific conductivity and capacity of lipid model membrane and form the channels in cellular plasma membrane. 2012, Pubmed
Richter, Following the formation of supported lipid bilayers on mica: a study combining AFM, QCM-D, and ellipsometry. 2005, Pubmed
Rutten, Selective electrical interfaces with the nervous system. 2002, Pubmed
Thaning, Stability of poly(3,4-ethylene dioxythiophene) materials intended for implants. 2010, Pubmed
Thomas, Synthesis, characterization, and biological affinity of a near-infrared-emitting conjugated oligoelectrolyte. 2014, Pubmed
Vargas, Aromatic amino acids required for pili conductivity and long-range extracellular electron transport in Geobacter sulfurreducens. 2013, Pubmed
Wang, Uncovering alternate charge transfer mechanisms in Escherichia coli chemically functionalized with conjugated oligoelectrolytes. 2014, Pubmed
Widge, Computational modeling of poly(alkylthiophene) conductive polymer insertion into phospholipid bilayers. 2007, Pubmed
Xu, Design and synthesis of diverse functional kinked nanowire structures for nanoelectronic bioprobes. 2013, Pubmed
Yoshimura, Interactions of quaternary ammonium salt-type gemini surfactants with sodium poly(styrene sulfonate). 2004, Pubmed