Abstract: A laser-induced fluorescence (LIF) combined with magnetic separation sensing method was established for the online detection of the CP4-5-enol acetate-3-phosphate synthase gene (CP4-EPSPS). Amino magnetic nanoparticles (MNPs) were used as the vector to modify cDNA, construct gene capture probes, and design 5-carboxyfluorescein (FAM)-labeled signal gene probes (sDNA). In the presence of the CP4-EPSPS gene probe (tDNA), cDNA and sDNA combined with tDNA to form a double-stranded structure through complementary base pairing. The construction could be enriched and separated by a magnetic field when passing through the capillary, and then its fluorescence signal could be detected online by a laser-induced fluorescence detector. At optimized concentrations of MNPs, cDNA and bovine serum protein, the concentration of the CP4-EPSPS gene in the range of 1.0 × 10-11–2.0 × 10-7 mol/L had a good linear relationship with the fluorescence peak area, and the limit of detection (LOD) was 4.0 × 10-12 mol/L (RSN = 3). This method could be successfully applied to the detection of polymerase chain reaction (PCR) amplification products of genetically modified soybeans.

Key words: laser-induced fluorescence; CP4-EPSPS gene; genetically modified soybean