Powdered sodium alginate

Powdered sodium alginate (Mn = 357,475, Mn/Mw = 1.392, M/G = 0.32) was purchased from Sigma Aldrich from the United States. Poly (3,4-ethylene dioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) was bought from Osila, USA. Starch from wheat (C₆H₁₀O₅)_n containing moisture content of about 8.8–11.5%, protein ≤ 0.3%, and particle size ≥95% (−120 mesh) was obtained. High amylopectin content in starch makes it easier to graft more acrylonitrile side chains, whereas high amylose content in starch decreases the grafting ratio of acrylonitrile. Dimethyl sulfoxide DMSO (CH₃)₂SO (assay 99.9%; Sigma Aldrich (Gillingham, UK)) and sulfuric acid H₂SO₄ were purchased from Sigma Aldrich, UK. The activated carbon (surface area: 1800–2000 m²/g, particle size: 5–20 m) coating was applied to the graphite conductive substrate, which was used as an electrode. This substrate was purchased from Sigma Aldrich. The solvent used was deionized water (DI).

Powdered sodium alginate (#71238, Sigma) was used to make 1.5% solution in sterile filtered water and heated at 65°C for 4 hours to facilitate dissolution. Stock solutions of gel were pasteurized at 100°C for 30 minutes, and stored at 4°C until further use. Immediately prior to microsphere synthesis, 50 ml of gel was filtered through 1.2 μm syringe filter and UV irradiated for 10 minutes (Stratalinker 1800, distance of 1 cm from the light source, and intensity of 1500 μJ/cm².)