Detection of DNA damage by exploiting the distance dependence of the electrochemiluminescence energy transfer between quantum dots and gold nanoparticles

We have developed a platform to detect DNA damage induced by perfluorooctanoic acid (PFOA) by measuring the electrochemiluminescence (ECL) of a layer-by-layer electrostatic assembly. Gold nanoparticles were electrodeposited on a glassy carbon electrode (GCE) and then drop coated with calf thymus DNA. The surface of the GCE was then modified by sequential drop coating with polyethyleneimine and CdSe quantum dots (QDs). The electrode surface was characterized by atomic force microscopy and electrochemical impedance spectroscopy. DNA damage was determined by measuring the ECL of the QDs, which decreases when exposed to PFOA. This is because DNA damage decreases the distance between the QDs and gold nanoparticles. Eventually, this leads to the energy transfer of ECL. The process is highly sensitive to distance. ECL intensity is logarithmically related to the concentration of PFOA in the range from 10 μmol L−1 to 10 pmol L−1, and the detection limit is 10−12 mol L−1 (at an S/N ratio of 3). This ECL-based sensor represents a powerful tool for detecting PFOA and for fabricating in vitro gene vector platforms to study DNA damage.