An Electrochemical Immunosensor Based on Gold Nanoparticles Decorated Cobalt Boride Nanosheet Arrays for Detection of Human Chorionic Gonadotropin

Human chorionic gonadotropin ( hCG) is a marker of early pregnancy and diseases such as ovarian cancer. Therefore, the rapid, accurate and real-time determination of hCG is of great significance. In this work , an electrochemical immunosensor for detection of hCG based on three-dimensional Au nanoparticles anchored on cobalt boride ( AuNPs/CoB ) nanosheet array electrode was developed. AuNPs/CoB nanosheet arrays were synthesized by an electrodeposition method , which was first explored for immunoassay of hCG. AuNPs/CoB nanosheeet arrays could enhance the perfkifmance of electrocatalytic reduction of thionine to amplify signal. Thionine ( Thi) was electro-polymerized on the AuNPs/CoB nanosheet arrays, thus forming Thi/AuNPs/CoB nanosheet array-electrode. HCG antibody ( anti-hCG) could be successfully attached to the Thi/AuNPs/Co-B nanosheet array-electrode by Au-N bond of AuNPs or the amino group of thionine, which caused an obvious decrease in the catalytic current due to the insulated anti-hCG. The current signal decreased linearly with the increase of hCG concentration due to the formation of antibody-antigen immunocomplex. The immunosensor possessed a good linearity with logarithm of hCG concentration in the range of 10-5. 0 x 10(4) pg/mL, and the detection limit was 2. 80 pg/mL ( S/N= 3). The immunosensor based on Thi/AuNPs/Co-B nanosheet arrays could exactly detect hCG in human serum samples, providing a simple and reliable evaluation method for the clinical diagnosis of early pregnancy and gynecological diseases.