AuNPs labeled antisera improve the visualization of direct agglutination and sensitivity of agar double immunodiffusion test

Abstract

Poor visualization of direct agglutination test (DAT) and low sensitivity of agar double immunodiffusion (ADID) test severely hindered their applications in large-scale sample screening. This study aims to develop a facile method of Au nanoparticles (AuNPs) tagged Riemerella anatipestifer (RA) antisera that can improve these drawbacks. Results demonstrated that citrate-reduction method synthesized AuNPs with an average of 5.0 nm takes a strong extinction band with a maximum absorption peak at 518 nm. 1.0 mM MUA can be coupled onto AuNPs under ultrasonic processing. The carboxylated AuNPs can covalently tagged with RA antisera with the activation of EDC/NHS for acquisition of AuNPs/RA antisera immunoprobe. Results of DAT and ADID tests affirmed that visualization and sensitivity (at least one concentration gradient) were effectively improved, respectively. The proposed method may offer a new way for large-scale screening of samples.

Keywords:

• AuNPs
• immunodiffusion
• visualization
• sensitivity

Additional information

Funding

Thanks to NSF of Chongqing (cstc2019jscx-msxm0366), Open Fund of Chongqing Key Laboratory of Industrial Fermentation Microorganism (GYFJWSW-201905), Project of Scientific and Technological Research Program of Chongqing Municipal Education Commission (KJZD-K201806401, KJZD-K201906401, KJQN201801528) and graduate Innovation Fund of CQUST(YKJCX2020509, YKJCX2120502, YKJCX2120541).