Microfluidic dialysis device fabrication for protein solution enrichment and its enrichment enhancement by plasma surface treatment of a membrane

In this work, we fabricated and characterized a microfluidic dialysis device for sample enrichment and improved enrichment performance by surface modification of a regenerated cellulose (RC) membrane using an oxygen plasma. The microfluidic dialysis device was developed with PDMS (polydimethylsiloxane) for protein solution enrichment. A PDMS mold with a microchannel was formed by using a contact photolithography process. The microfluidic dialysis device based on the RC membrane involves protein solution flow on the donor side and a flow of polyethyleneglycol (PEG) on acceptor side. The concentration was determined by using UV-spectrophotometer and high performance liquid chromatography (HPLC). The enrichment factor was characterized by varying the sample solution flow rate, the PEG flow rate and the PEG concentration. The bovine serume albumine (BSA) solution concentration was enriched to 116 μg/mℓ from 20 (μg/mℓ with the microfluidic dialysis device. The enrichment efficiency was further improved by plasma surface modification of the membrane. The modified membrane surface became highly hydrophilic after oxygen plasma treatment, resulting in fouling reduction. The enrichment efficiency was improved by 7.2 times after the oxygen plasma surface treatment. The surface chemical composition and surface morphology were analyzed with X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM).