A split G-quadruplex DNAzyme based magnetic graphene oxide platform for sensitive authentication of Pseudostellaria heterophylla

Abstract

Based on the different affinities of graphene oxide (GO) toward ssDNA and dsDNA, a fluorescence assay using split G-rich probes and magnetic GO (Fe₃O₄/GO) was developed for authentication of Pseudostellaria heterophylla based on the ITS sequences. In this assay, the probes mixed with Fe₃O₄/GO nanoparticles, hybridize with T-DNA for a double-stranded structure and then their G-rich sequences can fold into a G-quadruplex which combines hemin for DNAzyme. After magnetic separation, the DNAzyme supernatant can catalyze 2′,7′-dichlorodihydrofluorescein diacetate (H₂DCFDA) oxidation with H₂O₂ and release a fluorescence signal. Herein, the Fe₃O₄/GO nanoparticles play an important role in decreasing the background signal by absorbing the excess probes and hemin. This assay allows the analysis of T-DNA in the range of 1.0 × 10⁻¹⁴ to 1.0 × 10⁻⁷ mol L⁻¹ with a low detection limit of 1.87 × 10⁻¹⁵ mol L⁻¹. In addition, this newly designed assay allows specific authentication of Pseudostellaria heterophylla from different provenances.