A　new　signal　amplification　strategy　based　on　mesoporous　carbon-enriched　palladium　nanostructure　(MSC-PdNS)　was　designed　for　enzyme-free　electrochemical　immunoassay　of　brevetoxin　B　(BTB)　in　marine　toxins.　The　assay　was　carried　out　on　a　BTB-bovine　serum　albumin-functionalized　electrode　by　using　monoclonal　mouse　anti-BTB-labeling　MSC-PdNS　as　the　signal-transduction　tag.　A　competitive-type　assay　protocol　was　successfully　introduced　to　develop　a　high-efficiency　enzyme-free　immunoassay　accompanying　the　doped　palladium　nanostructure　into　MSC-PdNS　toward　reduction　of　H2O2.　Under　the　optimal　conditions,　the　catalytic　current　decreased　with　the　increment　of　BTB　concentration　in　the　range　from　0.01　to　10　ng　mL(-1)　with　a　detection　limit　(LOD)　of　5.0　pg　mL(-1)　BTB　at　the　3s(blank)　criterion.　The　selectivity　and　precision　were　acceptable.　In　addition,　the　methodology　was　further　validated　for　assaying　spiked　seafood　samples,　and　consistent　results　between　the　electrochemical　immunoassay　and　the　referenced　enzyme　immunoassay　were　obtained.　Importantly,　the　enzyme-free　electrochemical　immunoassay　provides　a　promising　approach　for　rapid　screening　of　marine　toxin　because　of　its　simplicity,　low　cost,　sensitivity,　specificity　and　without　the　need　of　sample　pretreatment.　(C)　2015　Elsevier　B.V.　All　rights　reserved.