For AEX, a TSKgel DNA-STAT column (4.6 x 100 mm, 5 µm dp) (P/N: 0021962)) from TOSOH Bioscience was used. The eluent was generated by mixing 20 mM Tris-HCl (pH 8) in ACN-water (10:90, v/v) (A) and 20 mM Tris-HCl (pH 8) with 2 M of NaCl in ACN-water (10:90, v/v). The gradient program started with a 1-min hold at 35% B, followed by a linear increase of 35% to 55% B in 20 min and a hold of 2 min at 55% B. The flow rate was 0.4 mL/min and the column oven temperature was 25 °C.