To prepare spotting solutions, oligonucleotides were diluted in a solution of 150 mM sodium phosphate buffer containing 0.01% sucrose monolaurate at pH 8.5. After spotting, chips were stored overnight in a sealed chamber filled at the bottom with sodium chloride saturated solution (40 g/100 mL, 65% humidity). Finally, chips were treated with a blocking solution containing ethanolamine (50 mM in 0.1 M Tris/HCl buffer pH 9 and 2 mM MgCl2) at room temperature for 1 h, rinsed with MgCl2 2 mM and dried.