Borosilicate glass coverslips

Borosilicate glass coverslips (12 mm in diameter; Corning) were modified with synthetic IKVAV peptide following a technique described previously ^{105 (link)}. Borosilicate glass coverslips were cleaned with 2 % (v/v) micro-90 detergent (Sigma Aldrich, Z281565) for 30 min at 60 °C, rinsed six times with distilled water, rinsed with ethanol and then dried. Coverslips were plasma-etched (Harrick Plasma PDC-001-HP) with O₂ for 30 s, then immediately incubated in a 2 % (v/v) solution of (3-aminopropyl) triethoxysilane (Sigma Aldrich) in ethanol for 15 min. Coverslips were then rinsed twice with ethanol and twice with water and then dried in the oven. IKVAV peptide was then prepared at 50 nmol/mL in a 1.25 mg/mL solution of 1-ethyl-3-(dimethyl-aminopropyl) carbodiimide (Arcos Organics) with 2 % DMF (Dimethylformamide, Sigma Aldrich). Coverslips were incubated with this solution for 3.5 hrs at 40 °C. After incubation, coverslips were washed successively with 100 % acetic anhydride (Fisher Chemical), 2 M hydrochloric acid (Fisher Chemical), and 0.2 M sodium bicarbonate. After rinsing with an excess amount of water, samples were sonicated in 4 M urea for 10 min followed by 1 M NaCl for 10 min and then rinsed with an excess amount of water and dried at 100 °C for 1 h.