The Detection Of Human Chorionic Gonadotropin By New Electrochemical Immunosensors Based On Nanocomposites

Human chorionic gonadotropin?hCG?is a glycoprotein hormone that was synthesized and secreted by human placental syncytiotrophoblast cells.hCG detection has been widely used in the diagnosis of early pregnancy,ectopic pregnancy,trophoblastic disease diagnosis,prenatal screening and pregnancy-induced hypertension.So it had great significance to develop rapid,selective and sensitive methods to detect hCG.Electrochemical immunosensors had a good application foreground in detection of hCG because of its high selectivity,fast responding speed,low cost,and easy operating with relatively small equipment.In this paper,several kinds of new nanocomposites,such as LPCs-SnS₂,MWCNTs-COFs and PEDOT-AuNFs,were used to constructed electrochemical immunosensors for sensitive detection of hCG.Some researches were made as follows:1.A novel label-free electrochemical immunosensor based on the composite of LPCs-SnS₂ and AuNPs for the detection of human chorionic gonadotropin:In this study,a novel label-free electrochemical immunosensor was constructed with new layered SnS₂functionalized lignin-based porous carbons?LPCs-SnS₂?and gold nanoparticles?AuNPs?as substrates for the sensitive and fast detection of human chorionic gonadotropin?hCG?.Vertical SnS₂ nanosheet arrays were orderly loaded on LPCs via a facile hydrothermal route,which resulted in a 3D conduction architecture and a large surface area.Based on the high performance of the AuNPs/LPCs-SnS₂ composite,an hCG electrochemical immunosensor was successfully fabricated with a wide linear response in the range of 0.5-50 ng/mL and a limit of detection of 6.4 pg/mL.The proposed immunosensor displayed good specificity,reproducibility and stability.And finally,it was successfully used for the detection of hCG in a real human serum sample.2.Label-free electrochemical immunosensor based on the MWCNTs-COFs and AuNPs for the detection of hCG:In this work,a novel signal amplification strategy based on multiwalled carbon nanotube-covalent organic frameworks?MWCNTs-COFs?and AuNPs was used to prepared a label-free electrochemical immunosensor for ultrasensitive detection of hCG.For MWCNTs-COFs,COFs wrapped outside of MWCNTs through?-?interaction.The presence of a large amount of N in COFs not only improved the dispersion of carbon nanotubes,but also facilitated the further adsorption of gold nanoparticles.The AuNPs/MWCNTs-COFs composite owned high specific surface area,which could greatly accelerate electron transfer and increase active site for immobilization of antibody.Under optimal experimental conditions,the sensor showed a relatively wide linear range?0.1-60 ng/mL?with a low detection limit?7.3 pg/mL?.The immunosensor also exhibited high stability,specificity,and reproducibility,and was successfully used for actual sample detection.3.Ultrasensitive electrochemical immunosensor based on sandwich architecture for selective detection of hCG:A simple and sensitive sandwich electrochemical immunosensor was constructed for the detection of hCG by using ferrocene carboxylic acid?Fc?as signal trace.In this work,1-methyl-3-octyl-imidazolium chloride?[OMIM][Cl]?,one of imidazolium ionic liquids,was chosen to act as template to prepare PEDOT nanospheres and gold nanoflowers?PEDOT-AuNFs?composite.The PEDOT-AuNFs presented high specific surface area,which could greatly accelerate electron transfer and increase active site for immobilization of antibody.In sandwich immunosensor assembling,capture antibodies?Ab₁?were immobilized by PEDOT-AuNFs/LPCs complex film which decorated on the surface of electrode;detection antibodie?Ab₂?labeled with?Fc?were combined with COFs-AuNPs and used as signal tag.Under optimal experimental conditions,the sensor has a wide linear range from 0.01 to 500 ng/mL with a detection limit of 3.2 pg/mL?S/N=3?.The constructed immunosensor offered the superiorities of good stability,specificity and reproducibility.Furthermore,the resulting immunosensor was successfully applied for hCG detection in human serum.