# Nano-Fibrous Networks from Co-Assembly of Amphiphilic Peptide and Polyelectrolyte
## 2 Materials and Methods
### Methods  
PA synthesis. Fmoc Rink amide resin (1.15 g, 0.87 mmol/g loading, 1 mmol) was used after removing of the fmoc protecting group using a mixture of piperidine/DBU/DMF (2:2:96) following by several rinsing steps with dichloromethane and methanol. In a SPPS glass reactor charged with deprotected resin was added 1-Hydroxybenzotriazole (HOBt) (0.41 g, 3 mmole), N,N\({}^{\prime}\)-Dhisopropylcarbodiimide (DIC) (0.5 mL, 3 mmole) and 3 mmol of the Fmoc Amino acid in DMF. The coupling reaction was carried out for 3 h followed by several rinsing steps with dichloromethane and methanol. At the end of each coupling step, a Kaiser test was performed to ensure the completion of the reaction. After the removal of the Fmoc protecting group, this coupling step was repeated to obtain H-Val-Val-Ala-Ala-Ala-Lys-Lys-Lys-Gly-resin sequence. A last acylation step was carried out on the peptide-resin with a solution of palmitoyl chloride in dichloromethane (10% \(v/v\), 8 mL) for 1 h. The resin bound protected peptide chain was then treated with a mixture (6 mL) of trifluoroacetic acid (TFA) containing 5% (\(v/v\)) of distilled water. After 5 h the resin was filtered off and the solution was precipitated in diethylether. The resulting PA (Mw = 1207.66 g/mol) was collected, dried, resolubilized in distilled water and lyophilized (yield 90%). After characterization by MS (MH\({}^{\prime}\) = 1207.93 g/mol), PA was used without further purification step. Membrane preparation. Tape-casting: 300 \(\mu\)L of solution are deposited with a knife 250 \(\mu\)m high. The speed of movement of the knife is 1 cm/s. The solutions are applied using a syringe to form a strip of 3 mm wide and 18 mm long. This solution is spread either directly on a glass slide or on a hydrophilic PVDF filter 25 mm in diameter (Durapore Membrane, hydrophilic PVDF, 0.45 \(\mu\)m, 25 mm, Millipore). The tape-casting was performed on an Elcometer 4350. Spray-coating. The PSSNa solution injected is 6 g/L. The deposition pattern is a rectangle 30 mm by 75 mm. This rectangle is divided into three sections in the width (30 mm). The nozzle passes through each section. The nozzle is located 60 mm from the sample, the speed 250 mm/min and the flow is set to 100 mL/h. The spray-coating was carried out on a ND-SP from Nadetech. Scanning electron microscopy. SEM analyses were performed using a Hitachi S-4500 instrument operating at a spatial resolution of 1.50 nm at an energy of 15 kV. The samples were dried and covered with an ultra thin layer of electrically conductive Platinum deposited by high vacuum evaporation. Rheology. The rheology analyzes were carried out on a Physica MCR 301 from [PERSON] with a conical spindle: CP50-1. The mixtures are carried out directly on the rheometer stage to minimize changes in the medium. Water permeation. The filtration studies were performed in a 10 mL filtration cell with 25 mm diameter. The fluid is pressurized through the membrane using compressed air. The pressure drops studied are between 0 and 3 bar. For the filtration tests, the prepared membrane (d = 2.5 cm) was placed in a 10 mL filtration cell (Amicon 8010 stirred cell). Then, the filtration cell was connected to a water tank and a compressed air line. The mass of water passing through the membrane (permeate) was recorded with SartoConnect software during 20 min for each pressure drop. All filtration experiments were performed at 25 \({}^{\circ}\)C with dust free ultrapure water (filtered through a 400 \(\upmu\)m filter). AFM. AFM images were taken with tips oscillating at a frequency of 300 kHz in intermittent contact mode. The scan speed is 0.74 lines per second. Parameters such as gain, setpoint or drive are determined for each image and no value is preset. However, a low setpoint and drive are favored, as well as a gain close to 30% for the integral and proportional values. The approach percentage is set at 90%. AFM analyzes were performed on a PicoSPM II. Circular dichroism (CD) spectroscopy. Circular dichroism solutions were performed in mQ water.