A　new　sandwich-type　electrochemical　immunosensor　based　on　nanosilver-doped　bovine　serum　albumin　microspheres　(Ag@BSA)　with　a　high　ratio　of　horseradish　peroxidase　(HRP)　and　detection　antibody　was　developed　for　quantitative　monitoring　of　biomarkers　(carcinoembryonic　antigen,　CEA,　used　in　this　case)　by　coupling　enzymatic　biocatalytic　precipitation　with　tyramine　signal　amplification　strategy　on　capture　antibody-modified　glassy　carbon　electrode.　Two　immunosensing　protocols　(with　and　without　tyramine　signal　amplification)　were　also　investigated　for　the　detection　of　CEA　and　improved　analytical　features　were　acquired　with　tyramine　signal　amplification　strategy.　With　the　labeling　method,　the　performance　and　factors　influencing　the　electrochemical　immunoassay　were　studied　and　evaluated　in　detail.　Under　the　optimal　conditions,　the　electrochemical　immunosensor　exhibited　a　wide　dynamic　range　of　0.005-80　ng　mL(-1)　toward　CEA　standards　with　a　low　detection　limit　of　5.0　pg　mL(-1).　Intra-　and　inter-assay　coefficients　of　variation　were　below　11%.　No　significant　differences　at　the　0.05　significance　level　were　encountered　in　the　analysis　of　6　clinical　serum　specimens　and　6　spiked　new-born　cattle　serum　samples　between　the　electrochemical　immunoassay　and　the　commercialized　electrochemiluminescent　immunoassay　method　for　the　detection　of　CEA.　(C)　2013　Elsevier　B.V.　All　rights　reserved.