The rapid and sensitive detecting technique for subgroup J of avian leukosis viruses (ALVs-J) needs to be developed as soon as possible in order to not only reduce economic losses but also ensure the food safety. In this paper, a novel electrochemical immunosensor was built based on mesoporous graphitic carbon nitride (mpg-C 3 N 4 ). Mpg-C 3 N 4 was used as the sensor platform to bond with the primary antibodies (Ab 1 ). The compound of thionine and mpg-C 3 N 4 (Th-mpg-C 3 N 4 ) was synthesized for the first time to serve as the electroactive probe as well as the carrier of secondary antibodies (Ab 2 ). Compared to bulk g-C 3 N 4 , mpg-C 3 N 4 possesses larger specific surface area, smaller electrochemical resistance and abundant active sites. So the proposed electrochemical immunosensor exhibited amplified detective signals which realized the sensitive detection of ALVs-J. Under the opitimized conditions, the immunosensor exhibited outstanding analytical performance for the detection of ALVs-J whose titer ranged from 10 2.08 to 10 4.0 TCID 50 /mL (TCID 50 : 50% tissue culture infective dose) with a low detection limit of 120 TCID 50 /mL (S/N = 3). The sensitivity of the immnosensor was 6.15 μA/(TCID 50 /mL). This high sensitive immunosensor also displayed good selectivity, reproducibility and stability. Last but not least, this new strategy may be of great promise for clinic application in the future.
Chao Liu,Jing Dong,Geoffrey I.N. Waterhouse,Ziqiang Cheng,Shiyun Ai
A sensitive sandwich-type electrochemical immunosensor was developed for the detection of avian leukosis virus subgroup J (ALV-J), which benefitted from multiple signal amplification involving graphene-perylene-3,4,9,10-tetracarboxylic acid nanocomposites (GR-PTCA), nanocellulose-Au NP composites (NC-Au) and the alkaline phosphatase (ALP) catalytic reaction . GR-PTCA nanocomposites on glassy carbon electrodes served as the immunosensor platform. Due to their excellent electrical conductivity and abundant polycarboxylic sites, the GR-PTCA nanocomposites allowed fast electron transfer and good immobilization of primary antibodies, thereby affording a strong immunosensor signal in the presence of ALV-J. The detected signal could be further amplified by the introduction of NC-Au composites as a carrier of secondary antibodies (Ab 2 ) and by harnessing the catalytic properties of Au and ALP. Under optimized testing conditions, the electrochemical immunosensor displayed excellent analytical performance for the detection of ALV-J, showing a linear current response from 10 2.08 to 10 4.0 TCID 50 /mL (TCID 50 : 50% tissue culture infective dose) with a low detection limit of 10 1.98 TCID 50 /mL (S/N = 3). In addition to high sensitivity, the immunosensor showed very good selectivity, reproducibility and operational stability, demonstrating potential application for the quantitative detection of ALV-J in clinical diagnosis.
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