pH-Reversible, High-Capacity Binding of Proteins on a Substrate with Nanostructure

In this letter, a pH-switchable system for protein adsorption and release is introduced. By combining the pH sensitivity of poly(methacrylic acid) (poly(MAA) chains and the nanoeffects of 3D nanostructured silicon nanowire arrays (SiNWAs), a poly(MAA)-modified SiNWAs material showed an extremely high capacity for binding lysozyme at pH 4 (an similar to 80-fold increase compared with that of smooth Si-poly(MAA)). Moreover, similar to 90% of the adsorbed lysozyme was released from SiNWAs-poly(MAA) by increasing the pH from 4 to 9, without a loss of enzyme activity.