A colorimetric and electrochemical immunosensor for point-of-care detection of enterovirus 71

Point-of-care detection of human enterovirus 71 (EV71), the major pathogen that causes hand, foot, and mouth disease (HFMD) among children, is urgently needed for early diagnosis and control of related epidemics. A colorimetric and electrochemical immunosensor for point-of-care detection of EV71 has been developed based on dual-labeled magnetic nanobeads amplification. The dual-labeled magnetic nanobeads (DL-MBs) are fabricated by simultaneous immobilization of EV71 monoclonal antibody (mAb) and horseradish peroxidase (HRP) on magnetic nanobeads. By capturing EV71 virions in 20μL sample on mAb modified AuNPs-coated ITO electrode and subsequently binding with DL-MBs, with the addition of TMB and H₂O₂, colorimetric signals corresponding to EV71 with a concentration of 1.0ngmL^-1 can be directly read out by naked eyes, making it possible towards point-of-care detection of the virus. Furthermore, on the reduction of oxidized TMB on the electrode, electrochemical signal can be detected in the same detection cell without solution transfer, with a detection limit of 0.01ngmL^-1. Validated with clinical samples, the colorimetric and electrochemical immunosensor shows a complete consistency with reverse transcription-polymerase chain reaction (RT-PCR) results. So far as we know, this is the first report on EV71 detection using electrochemical method. The merits of this assay, including high sensitivity, ability for colorimetric detection and easy to operation, ensure a promising future in point-of-care diagnostics of virus related diseases.