A　new　anodic-stripping　voltammetric　immunoassay　protocol　for　detection　of　IgG1,　as　a　model　protein,　was　designed　by　using　CdS　quantum　dot　(QD)　layer-by-layer　assembled　hollow　microspheres　(QDHMS)　as　molecular　tags.　Initially,　monoclonal　anti-human　IgG1　specific　antibodies　were　anchored　on　amorphous　magnetic　beads　preferably　selective　to　capture　Fab　of　IgG1　analyte　from　the　sample.　For　detection,　monoclonal　anti-human　IgG1　(F　c-specific)　antibodies　were　covalently　coupled　to　the　synthesized　QDHMS.　In　a　sandwich-type　immunoassay　format,　subsequent　anodic-stripping　voltammetric　detection　of　cadmium　released　under　acidic　conditions　from　the　coupled　QDs　was　conducted　at　an　in　situ　prepared　mercury　film　electrode.　The　immunoassay　combines　highly　efficient　magnetic　separation　with　signal　amplification　by　the　multilayered　QD　labels.　The　dynamic　concentration　range　spanned　from　1.0　fg　mL-1　to　1.0　μg　mL-1　of　IgG1　with　a　detection　limit　of　0.1　fg　mL-1.　The　electrochemical　immunoassay　showed　good　reproducibility,　selectivity,　and　stability.　The　analysis　of　clinical　serum　specimens　revealed　good　accordance　with　the　results　obtained　by　an　enzyme-linked　immunosorbent　assay　method.　The　new　immunoassay　is　promising　for　enzyme-free,　and　cost-effective　analysis　of　low-abundance　biomarkers.　A　sandwich-type　immunoassay　for　ultrasensitive　detection　of　low-abundance　proteins　was　developed　by　using　mAb2-functionalized　quantum　dot　aggregated　hollow　microspheres　(QDHMS),　as　tags　on　an　mAb1-functionalized　magnetic-bead　(MB)-based　platform.　In　the　immunoassay,　square-wave　anodic-stripping　voltammetric　(SWASV)　detection　of　Cd　released　under　acidic　conditions　from　the　coupled　QDs　was　conducted.　Copyright　©　2013　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim.