Amperometric Immunosensor For Detection Of Tumor Marker Based On Nano-modified

In this article, some nano-modified amperometric immunosensors for Human chorionic gonadotropin (HCG), Carcino-embryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) tumor markers were investigated. Gold nanoparticles and gold-magnetic nanoparticles composite film coated antibody were modified electrode by self-assembly layer by layer, electroless plating and magnetic controllable. The main works are as follows:1. An Amperometric immunosensors for human chorionic gonadotrophin (HCG) in the saliva was established based on Mercapto Succinic Amide (HL)/gold nanoparticles (AuNPs) coated Antibody by layer-by-layer self assembly technology. Mercapto succinic amide and nano Au particles (AuNPs) monolayers were modified alternatively and formed multiple membranes, so the modified electrode could get more active site to adsorb HCG antibody (anti HCG). K3Fe(CN)6 was used as electron probe for detection. The antigen-antibody immune complex which formed on the electrode surface could hinder electron transport, so the redox current of K3Fe(CN)6 was decreased. The decreased value ofΔIp was related to the extent of immune reaction on membrane surface, which can be employed as quantitative basis of HCG content. The results showed that: a large number of AuNPs which can adsorb more anti-HCG and obviously broaden the linear detection range existed in the film. the studied immunosensor exhibited high sensitivity and could be used to screen detection of trace HCG in the saliva.2. A novel amperometric immunosensor for carcinoembryonic antigen (CEA) in human serum was established based on [Cu(bpy)2(ONO)]NO3 (CuL) and CEA antibody coated gold nanoparticles (AuNPs) composite film. The ammoniated electrode was soaked in CuL and electroless gold plating solution. Then CuL can be absorbed on GCE byπ-πstacking interaction and AuNPs film of 30~50 nm were formed by electroless gold plating to form GCE|CuL-AuNPs. This method simplifies the detection system without adding electron transfer media to solution with high sensitivity, wide detection range. It would be valuable for clinical immunoassay of CEA in patients'serums.3. A novel amperometric immunosensor for human serum carbohydrate antigen 19-9 (CA19-9) based on its antibody (anti CA19-9) coated Fe3O4(core)@Au(shell) gold-magnetic nanocomposites(GMP) modified electrode is investigated. Firstly, chitosan (CS) was adsorbed on the surface of Au electrode (Au|CS), then Fe (CN) 63– (FeCN) was connected to -NH3+ on the surface of chitosan film to form Au|CS-FeCN electrode by electrostatic attraction in acidic pH. FeCN can be employed as an electron transfer mediator. Furthermore anti CA19-9 coated GMP(GMP-anti CA19-9) was immobilized on the surface of Au|CS-FeCN by outside magnetic field adsorption to form one CA19-9 amperometric immunosensor (Au│CS-FeCN/GMP-anti CA19-9). The immunosensor combines many functions as separation, enrichment and determination in one, with high sensitivity and good stability. This method would be valuable for clinical immunoassay for CA19-9 in human serum.