▎ 摘　　要

In this study, we developed a novel particle-type material comprised of graphene and polyethylene glycol (PEG) to solve the slow response problem of the previously reported microdevice for single-step immunoassay. Characterization of these graphene/PEG hybrids (GPH) was carried out using a transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, and fluorescence analysis. We found that PEG attached to graphene surfaces behave like molecular sieves to separate free fluorescently-labeled antibodies from antigen-bound antibody immunocomplexes. The free antibody is PEG-permeable and directly adsorbs onto the graphene surface, where fluorescence is quenched by fluorescence resonance energy transfer. On the contrary, immunocomplexes are PEG-impermeable; thus, as the concentration of the antigen increases, the concentration of PEG-impermeable immunocomplexes also increases; consequently, increasing the fluorescence intensity of the solution. After characterizing GPH, single-step immunoassay microdevices were prepared by separately immobilizing the GPH and fluorescently-labeled antibodies on two independent microchannel arrays and combining them. Finally, we tested the proposed immunoassay microdevices with various known concentrations of C-reactive protein (CRP), an inflammatory marker protein, and successfully measured CRP concentration within an approximate time of 2 min by monitoring the fluorescence intensity change.