Application of Polydimethylsiloxane/Glass Microchips for Fast Electrophoretic Separation of Serum High-density Lipoprotein Subclasses

When isolated on the basis of density by ultracentrifugation, high-density lipoprotein (HDL) can be separated into two major subfractions: HDL2 and HDL3. The inhibition of oxidative modification of low-density lipoprotein (LDL) by HDL2 is believed to play a central role in coronary heart disease (CHD), so HDL subclasses separation is necessary for CHD prediction and diagnosis. In this study, a polydimethylsiloxane (PDMS)/glass microchip was used to separate HDL subclasses. We chose n-Dodecyl beta-D-maltoside (DDM), sodium dodecylsulfonate (SDS) and hydroxypropylcellulose (HPC) to modify both lipoprotein and the channel surface to reduce lipoprotein adsorption and improve the resolution of lipoprotein separation. Under optimal conditions, HDL2 and HDL3 were baseline separated with high reproducibility. The RSD values of the migration time and peak areas of HDL2 and HDL3 were 2.05% and 2.71% and 1.98% and 2.89%, respectively. The serum HDL subclasses of healthy ones and patients with CHD were separated by the PDMS-based microchip. Two peaks (HDL2 and HDL3) were detected in the serum samples of healthy ones, while HDL2 peaks almost disappeared in patients' entire serum samples. These results suggested that PDMS/glass microchip-based HDL subclasses assay is a simple, rapid and highly efficient technique for the analysis of CHD risk factors.