A　sensitive　electrochemical　approach　for　the　detection　of　thrombin　was　designed　by　using　densely　packed　hierarchical　dendritic　gold　microstructures　(HDGMs)　with　secondary　and　tertiary　branches　as　matrices,　and　thionine-functionalized　mesoporous　silica　nanospheres　as　signal　tags.　To　prepare　the　signal　tags,　the　positively　charged　thionine　(as　an　indicator)　was　initially　adsorbed　onto　the　mesoporous　silica　nanoparticles　(MSNs).　Then　[AuCl4](-)　ions　were　in　situ　reduced　on　the　thionine-modified　MSNs　by　ascorbic　acid　to　construct　nanogold-decorated　MSNs　(GMSNs).　The　formed　GMSNs　were　employed　as　label　of　the　aminated　aptamers.　The　assay　was　carried　out　in　PBS,　pH　7.4　with　a　sandwich-type　assay　mode　by　using　the　assembled　thionine　in　the　GMSNs　as　indicators.　Compared　with　the　pure　silica　nanoparticles,　mesoporous　silica　could　provide　a　larger　surface　for　the　immobilization　of　biomolecules　and　improve　the　sensitivity　of　the　aptasensor.　Under　optimal　conditions,　the　electrochemical　aptasensors　exhibited　a　wide　linear　range　from　0.001　to　600　ng　mL(-1)　(i.e.　0.03　pM　to　0.018　mu　M　thrombin)　with　a　low　detection　limit　(LOD)　of　0.5　pg　mL(-1)　(approximate　to　15　fM)　thrombin　at　3　sigma.　No　obvious　non-specific　adsorption　was　observed　during　a　series　of　analyses　to　detect　target　analyte.　The　precision,　selectivity　and　stability　of　the　aptasensors　were　acceptable.　Importantly,　the　methodology　was　evaluated　with　thrombin　spiked　samples　in　blank　fetal　calf　serum,　and　the　recoveries　were　94.2-112%.　indicating　an　exciting　potential　for　thrombin　detection.　(C)　2012　Elsevier　B.V.　All　rights　reserved.