DNA Conformation-Regulated\nHemin Switch for Lab-on-Chip\nChemiluminescent Detection of an Antibody Secreted from Hybridoma Cells

This work designed a DNA conformation-regulated hemin switch for rapid\nchemiluminescent (CL) detection of a monoclonal antibodies. This switch\nwas performed with an affinity probe and an inhibition probe, which\nwere conveniently prepared by hybridizing hemin-labeled DNA1 with\nKHL peptide-labeled DNA2 and binding biotin-labeled DNA3 to streptavidin,\nrespectively. In the absence of the target antibody, streptavidin-DNA3\ncould hybridize with hemin-DNA1/KHL-DNA2 to release KHL-DNA2, which\nled to the loss of hemin activity due to the affinity hindrance of\nstreptavidin-DNA3. After the KHL peptide was recognized by the target\nantibody, the strand replacement hybridization could be inhibited\nby the bound antibody, which retained the high catalytic activity\nof hemin overhung on the antibody-bound affinity probe for a CL reaction,\nleading to a “signal-on” process for CL antibody detection.\nUsing a KHL-specific antibody, anti-proprotein convertase subtilisin/kexin\ntype 9 antibody (PCSK9-Ab), as a target model and common L012–1,2,4-triazole–H<sub>2</sub>O<sub>2</sub> CL system, the designed switch showed a detection\nrange of 10 ng mL<sup>–1</sup> to 1 μg mL<sup>–1</sup> with a detection limit of 4.16 ng mL<sup>–1</sup> (56.2 pM)\nand a short analytical time of 6.5 min. The proposed quick method\ncould simply be used for lab-on-chip CL detection of PCSK9-Ab in situ-secreted\nfrom PCSK9-6E3 hybridoma cells, which\nshowed an accuracy of 90.2% compared with the statistical results\nfrom general fluorescence imaging, providing a potential technique\nfor screening specific hybridoma cells.