Colorimetric Biosensors Of Gold Nanoparticles For Rapid Detection Of Fish Pathogen Streptococcus Iniae

In purpose of valid Streptococcus iniae detection,we have established two colorimetric biosensors which are Gold nanoparticle lateral flow test strip(LFTS)and LAMP-AuNPs detection biosensor.Gold nanoparticles lateral flow test strip was based on the principle of sandwich combination containing antibodies and second antibodies.AuNPs material was used for antibodies labelling and visual result exhibition.Monoclonal antibody(MAbs)was obtained by spleen cell of immunized mice and Sp2/0 cell fusion as well as positive samples screening.Through this whole procedure,there are 11 positive hybridoma cell lines of S.iniae and two types of S.iniae MAbs 6C11 and 6G8 with favorable potency and specificity.The LFTS that pairs MAbs 6C11 and E1H8 reaches a test limit of 2x105 CFU/ml.However,this LFTS system has a poor specificity for showing positive results with 3 gram-positive bacteria strains in the cross detection.Therefore,the LFTS detection biosensor needs further development and optimization.LAMP-AuNPs is an effective observable detection assay depends on AuNPs that labelled with dual functional probes and along with LAMP assay.Based on the characteristics of self-aggregation and bio-conjugation with ligands,AuNPs is chosen for observable color change in tandem with LAMP amplification method to reach high sensitivity and easy operation.Meanwhile,the improvement of dual probes that fully utilize the LAMP product gives the biosensor a stable result exhibition.For specific test of S.iniae,ftsB,one of a ATP transporters related gene,is the target gene of this LAMP-AuNPs system that is able to distinguish it with other fish pathogens.The detect limit of 102 CFU reveals a better sensitivity compared with polymerase chain reaction(PCR)method and AuNPs lateral flow test strip(LFTS).It is also proved to be effective by fish infection model trials with less than 2 h time consuming and barely no devices which make it a convenient biosensor for point-to-care detection.