A microcolumn coated with polydimethylsiloxane functionalized by graphene oxide quantum dots for the gas chromatographic separation of characteristic markers of advanced fibrosis

In this paper, the serpentine-shaped semi-packed chromatographic columns embedded with the micro-post array were developed to separate the characteristic markers of advanced fibrosis. The 3 m long micro separation columns with a rectangular channel cross-sectional dimension of 250 μm × 200 μm and the micropost diameter of 30 μm were prepared by the micro-electromechanical system (MEMS) technology. Based on the static coating process, two kinds of microcolumns (Sp1 and Sp2) with different stationary phase coatings were prepared for comparison. In detail, the Sp1 column was only coated with polydimethylsiloxane (PDMS), and the Sp2 column was coated with PDMS functionalized by graphene oxide quantum dots (GOQDs). GOQDs is a carbon-based nanomaterial that had similar properties to graphene oxide (GO). Moreover, the microcolumns are connected to a conventional gas chromatograph for testing. Alkanes (C5-C14) and benzene series (benzene, toluene, o-xylene, 1,3,5- trimethylbenzene) were used to evaluate the separation characteristics of microcolumns, and the effect of constant column temperature and heating rate on chromatographic performance was studied. The experimental results show that the potential characteristic markers of advanced fibrosis (pentane and benzene) could be effectively separated in alkanes and benzene series, respectively, and the separation effect of Sp2 was better than that of Sp1. In addition, the Sp2 column also showed good repeatability. Therefore, the GOQDs-functionalized PDMS coated column could assist the microdetector of the microsystem under development to rapidly, accurately and effectively distinguish the markers, and is expected to become a candidate for micro gas chromatography (μGC) column for micro-system integration.