Controllable construction of micro/nanostructured NiO arrays in confined microchannels via microfluidic chemical fabrication for highly efficient and specific absorption of abundant proteins

Abstract

Three kinds of micro/nanostructured NiO arrays were constructed in confined microchannels via a facile and template-free microfluidic chemical fabrication method. Bovine serum albumin (BSA) and bovine hemoglobin (BHb) with different isoelectric points (IEPs) were chosen as the model proteins to test the absorption ability of NiO-modified microchannels for abundant proteins via electrostatic interaction and affinity interaction. The influences of the pH and ionic strength of the protein solution, the residence time of protein solution in the microchannels, zeta potentials and morphologies of nickel oxide on the protein absorption behavior of the modified microchannels were all studied. The NiO nanosheet array-modified microchannels could almost absorb all of the target proteins when the protein solution (500 μg mL⁻¹) resided in the microchannel for 120 s without separation. The excellent protein absorption ability of NiO nanosheet array-modified microchannels could be attributed to their high zeta potential and more absorption sites induced by the macroporous structure consisting of large nanosheets. Moreover, the NiO nanosheet array-modified microchannels also exhibited excellent selective absorption ability for hemoglobin from a protein mixture and human blood samples owing to the strong affinity interaction between nickel and the histidine residues of hemoglobin. Therefore, the NiO nanosheet array-modified microchannels showed promise for application in proteomics.