This　work　reports　a　photoelectrochemical　(PEC)　biosensing　platform　for　the　sensitive　and　specific　screening　of　thrombin　by　using　graphene　oxide-coated　copper-doped　zinc　oxide　quantum　dots　(Cu0.3Zn0.7O-GO　QDs)　as　the　photoactive　materials　and　glucose　oxidase-encapsulated　DNA　nanoflowers　(GOx-DFs)　for　signal　amplification.　Interestingly,　the　coated　graphene　oxide　nanosheets　on　the　surface　of　the　Cu0.3Zn0.7O　QDs　could　cause　the　charge　to　transfer　rapidly　and　ameliorate　the　photocorrosion.　The　doped　copper　into　the　quantum　dots　could　enhance　the　absorption　of　visible　light　by　tuning　the　band　gap　of　ZnO　QDs,　therefore　increasing　the　photocurrent　under　visible　irradiation.　Upon　addition　of　target　thrombin,　a　sandwiched　reaction　was　carried　out　between　thrombin　aptamer　and　GOx-DFs,　accompanying　the　formation　of　nanocomposites　with　the　magnetic　microparticles　(MMPs)/thrombin/GOx-DFs.　Followed　by　magnetic　separation,　the　carried　GOx　oxidized　glucose　to　H2O2,　thus　resulting　in　the　increasing　photocurrent　of　the　Cu0.3Zn0.7O-GO　QD-modified　electrode.　Under　optimum　conditions,　the　developed　PEC　biosensing　platform　exhibited　good　analytical　performance　with　a　linear　range　of　50-10 000　fM　thrombin　and　a　limit　of　detection　of　29　fM.　Impressively,　our　strategy　offers　a　new　horizon　in　developing　bridge-connected　graphene-coated　nanomaterials　and　novel　signal　amplification　strategy　for　the　development　of　PEC　biosensors.　©　The　Royal　Society　of　Chemistry　2021.