Comparison of lateral flow immunoassays based on oriented and nonoriented immobilization of antibodies for the detection of aflatoxin B1.

In recent years, some studies have found that oriented immobilization of antibodies to microspheres can fully expose the antigen binding sites of antibodies, which can improve the sensitivity of sandwich immunoassays for the detection of proteins. Can this antibody immobilization strategy also improve the sensitivity of competitive immunoassays for the detection of small molecules? To answer this question, the conjugate MS-SPG-Ab (oriented immobilization of aflatoxin B1 antibody to time-resolved fluorescent microspheres via streptococcal protein G) and the conjugate MS-Ab (nonoriented immobilization of aflatoxin B1 antibody to time-resolved fluorescent microspheres) were prepared, and a lateral flow immunoassay (LFIA) for the detection of aflatoxin B1 (AFB1) was established. The detection performance of the two methods was compared. The results showed that under the condition that the number of "effective" antibodies immobilized on TRF-MS was similar, compared with the nonoriented immobilization strategy (IC50 = 0.21 ng mL), the LFIA method established by the oriented immobilization strategy reduced the sensitivity of AFB1 detection (IC50 = 0.37 ng mL). However, this method can obtain higher detection precision for AFB1, the CV values were all below 8%. And it has stronger tolerance to the matrix of maize and peanut samples. The bias of LFIAs based on oriented immobilization technology (-14.93%-7.92%) was lower than nonoriented immobilization technology (28.16%-34.19%) for AFB1 detection in the two sample extracts. This study suggests that the LFIA method based on the oriented immobilization of antibodies can improve the accuracy of the detection results when performing rapid screening of small molecules.