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　mu　mol　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.