Construction and investigation of a DNA sensing system based on a magnetic molecular beacon probe

We presented a fast, specific, and sensitive DNA sensing system, which composed of a CdTe/Fe₃O₄ magnetic core-shell quantum dots (energy donor), a commercial quencher (BHQ₂; energy acceptor), and a designed single strand Toxoplasma gondii DNA. The designed single strand Toxoplasma gondii DNA was applied to link the energy donor and acceptor, and target DNA was detected based on mechanism of fluorescence resonance energy transfer. The CdTe quantum dots, Fe₃O₄ magnetic nanoparticles, CdTe/Fe₃O₄magnetic core-shell quantum dots, and sensing probe were step-wisely prepared. Properties of synthesized quantum dots were investigated by transmission electron microscopy and fluorescence spectrum, respectively. Specificity and sensitivity of sensing probe was determined by measuring the recovery of fluorescence intensity. The resulting data revealed the sensing system was successfully fabricated, and which has relative high sensitivity and specificity. Moreover, a simple modeling of the current sensing system/probe was primarily created, and which was utilized to theoretically illustrate and quantitatively investigate some surface properties of the sensing probe. We expect the current modeling can profit the current research and promote the sensitivity and specificity of the sensing system.