Production of a monoclonal antibody against aflatoxin M1 and its application for detection of aflatoxin M1 in fortified milk

AbstractAflatoxin M1 (AFM1) is a toxic metabolite of the fungal product aflatoxin found in milk. For food safety concern, maximum residual limits of AFM1 in milk and dairy products have been differently enforced in many countries. A suitable detection method is required to screen a large number of product samples for the AFM1 contamination. In this study, monoclonal antibodies (MAbs) against AFM1 were generated using a conventional somatic cell fusion technique. After screening, five MAbs (AFM1-1, AFM1-3, AFM1-9, AFM1-11, and AFM1-17) were obtained that showed cross-reactivity with aflatoxin B1 (AFB1) and aflatoxin G1 (AFG1) but with no other tested compounds. An indirect competitive enzyme-linked immunosorbent assay (ELISA) using a partially purified MAb and antigen-coated plates yielded the best sensitivity with the 50% inhibition concentration (IC50) and the limit of detection (LOD) values of 0.13 ng/mL and 0.04 ng/mL, respectively. This indirect competitive ELISA was used to quantify the amount of fortified AFM1 in raw milk. The precision and accuracy in terms of % coefficient of variation (CV) and % recovery of the detection was investigated for both intra- (n = 6) and inter- (n = 12) variation assays. The % CV was found in the range of 3.50–15.8% and 1.32–7.98%, respectively, while the % recovery was in the range of 92–104% and 100–103%, respectively. In addition, the indirect ELISA was also used to detect AFM1 fortified in processed milk samples. The % CV and % recovery values were in the ranges of 0.1–33.0% and 91–109%, respectively. Comparison analysis between the indirect ELISA and high performance liquid chromatography was also performed and showed a good correlation with the R2 of 0.992 for the concentration of 0.2–5.0 ng/mL. These results indicated that the developed MAb and ELISA could be used for detection of AFM1 in milk samples

Integrated lateral flow immunoassays using trimethylsilyl cellulose barriers for the enhanced sensitivity of COVID-19 diagnosis

Lateral flow immunoassays (LFIAs) serve as rapid and convenient tools for disease screening. However, there is room for enhancing diagnostic sensitivity. Therefore, this paper introduces a novel material combined with lateral flow immunoassays to improve the sensitivity of COVID-19 detection and diagnosis. Trimethylsilyl cellulose (TMSC) was printed on the device between the test and control line to delay the flow of the solution, which resulted in a more excellent binding of the immunoassay. These delay-LFIAs (d-LFIAs) were developed for the diagnosis of COVID-19, targeting the detection of immunoglobulins G and M, as well as the COVID-19 antigen. Under optimized conditions, the d-LFIA increased the sensitivity by up to 5 times compared to that of conventional LFIAs. Moreover, it exhibited the ability to detect IgG, IgM, and SARS-CoV-2 antigens as low as 1 ng/mL (limit of detection) by the naked eye. In addition, the application of this device to real samples yielded highly consistent results with those obtained from other LFIAs and standard SARS-CoV-2 diagnostic methods (such as enzyme-linked immunosorbent assay and reverse transcription polymerase chain reaction) diagnosis. Therefore, we expect this device to be a new platform for highly sensitive, easy, and affordable immunoassay strip testing to certify future emerging diseases