Fluorescent reversible regulation based on photoinduced electron transfer from DNA to quantum dots and intercalation binding of DNA intercalator to DNA

Source：Talanta, 2018, 188: 7-16.

DOI：10.1016/j.talanta.2018.05.034

• Fluorescence
• Reversible regulation
• DNA intercalator
• DNA
• Quantum dots

Based on the fluorescent reversible regulation, a novel sensor platform was designed for the detection of DNA intercalators utilizing the intercalation binding of DNA intercalators to DNA as an inherent exhibition and the fluorescence change of quantum dots (QDs) as an external manifestation. To prove its feasibility, acridine orange (AO) was chosen as an example of DNA intercalator. When different concentrations of herring sperm DNA (hsDNA) were added to cysteamine (CA)-capped ZnSe QDs solution, the hsDNA bound with the QDs through electrostatic interaction due to the photoinduced electron transfer from hsDNA to QDs and formed QDs-hsDNA complexes with 1:1 ratio, leading to the fluorescence quenching of the QDs; and upon addition of different concentrations of AO to the QDs-hsDNA complex system, the AO first caused the release of the hsDNA from the complexes and concomitantly bound with them through intercalation binding and formed AO-hsDNA complexes with 1:3 ratio on account of the fact that the intercalation binding constant between AO and hsDNA (1.932 × 105 L/mol) was greater than the electrostatic interaction constant between QDs and hsDNA (7.874 × 104 L/mol), resulting in the fluorescence recovery of the QDs. Therefore, the detection of AO could be achieved through the relationship between the fluorescence recovery yield of the QDs and the concentration of AO added. The results illustrated that the fluorescence recovery yield of the QDs-hsDNA system was linearly dependent to the concentration of AO in the range of 5.0–75.0 × 10−5 mol/L with a detection limit (3σ/K) of 1.5 × 10−5 mol/L. This dual-directional fluorescent regulation provided a novel method for the detection of DNA intercalators such as polycyclic aromatic hydrocarbons and drugs interfering with DNA-synthesis and possessed some potential applications in the investigation of the interactions between DNA intercalators and DNA.
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