Ultrasensitive enzyme-free electrochemical immunosensor based on hybridization chain reaction triggered double strand DNA@Au nanoparticle tag.
An ultrasensitive enzyme-free electrochemical immunoassay was developed for detection of the fg/mL level carcinoembryonic antigen (CEA) by using a double strand DNA@Au nanoparticle (dsDNA@AuNP) tag and hexaammineruthenium(III) chloride (RuHex) as the electroactive indicator. The dsDNA@AuNP was synthesized by one-pot hybrid polymerization of dsDNA on initiator DNA modified AuNPs via hybridization chain reaction. The immunosensor was prepared by covalently cross-linking capture antibody on chitosan/AuNP nanocomposite modified glass carbon electrode. The AuNPs accelerated the electron transfer and led to high detection sensitivity. With a sandwich-type immunoreaction and a biotin-streptavidin affinity reaction, the dsDNA@AuNP tag was conjugated on the immunocomplex to bring a high amount of RuHex to the electrode surface via electrostatic interaction, resulting in an amplified electrochemical signal. Under optimal conditions, the proposed sensing platform showed a wide linear detection range from 10 fg/mL to 10 ng/mL along with a detection limit of 3.2 fg/mL for CEA. The immunosensor exhibited high sensitivity and good stability, showing a promising application in early cancer diagnosis and could be extended to sensitive electrochemical biosensing of other analytes.
State Key Laboratory of Analytical Chemistry for Life Science, Department of Chemistry, Nanjing University, Nanjing 210093, PR China; School of Chemistry, Dalian University of Technology, Dalian 116023, PR China.
Yanqiu
Y
Ge
State Key Laboratory of Analytical Chemistry for Life Science, Department of Chemistry, Nanjing University, Nanjing 210093, PR China. Electronic address: wujie@nju.edu.cn.
Jie
J
Wu
State Key Laboratory of Analytical Chemistry for Life Science, Department of Chemistry, Nanjing University, Nanjing 210093, PR China.
Huangxian
H
Ju
School of Chemistry, Dalian University of Technology, Dalian 116023, PR China. Electronic address: wushuo@dlut.edu.cn.
Shuo
S
Wu
D000818:Animals; D055910:Antibodies, Immobilized / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods; D002272:Carcinoembryonic Antigen / Q000032:analysis*; D048271:Chitosan / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay / Q000379:methods; D057230:Limit of Detection; D053758:Nanoparticles / Q000737:chemistry*; D009693:Nucleic Acid Hybridization / Q000379:methods; D017975:Ruthenium Compounds / Q000737:chemistry
D055910:Antibodies, Immobilized; D002272:Carcinoembryonic Antigen; D017975:Ruthenium Compounds; C031584:hexammineruthenium; D006046:Gold; D004247:DNA; D048271:Chitosan
Carcinoembryonic antigen; Electrochemical immunosensor; Hexaammineruthenium; Hybridization chain reaction; Signal amplification