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 fg/mL level carcinoembryonic antigen by using a double strand DNA@Au nanoparticle (dsDNA@AuNP) tag and hexaammineruthenium(III) chloride (RuHex) as the electroactive indicator.