A　new　electrochemical　immunoassay　was　designed　for　the　sensitive　detection　of　prostate-specific　antigen　(PSA)　via　a　pyrophosphatase　(PPase)-hydrolysed　Cu(ii)-coordinated　pyrophosphate　ion　(Cu2+-PPi)　complex,　accompanying　the　release　of　Cu(ii)　ions　and　capture　on　a　negatively　charged　electrode.　This　system　involved　a　sandwiched　immunoreaction　with　nanogold-labeled　PPase/detection　antibodies　on　a　polystyrene　microplate,　enzymatic　hydrolysis,　Cu(ii)　release　and　voltammetric　measurement.　The　voltammetric　signal　is　derived　from　the　as-released　Cu(ii)　ions　within　the　applied　potential　on　the　electrode.　Under　optimum　conditions,　our　strategy　exhibited　a　good　voltammetric　response　for　the　analyte,　and　allowed　determination　of　PSA　at　a　concentration　as　low　as　5.2　pg　mL-1.　Good　precision,　high　specificity　and　acceptable　accuracy　were　achieved　for　the　detection　of　PSA.　This　journal　is　©　2020　The　Royal　Society　of　Chemistry　and　the　Centre　National　de　la　Recherche　Scientifique.