| Aflatoxin B1(AFB1) is one of the most compelling mycotoxins and listed as a Group I carcinogen by the International Agency for Research in Cancer. Many countries have established regulations to govern the AFB1 level in agricultural products to avoid overexposure of humans and animals. In the present study, highly luminescent quantum dot beads(QBs) were used for the first time as immunochromatographic strip signal probe for detection of small molecule and established a quantitative detection model based on FIT/FIC for detection of AFB1 in maize.The QBs were synthesized by encapsulating CdSe/ZnS quantum dots(QDs), the average diameter of these submicrobeads is 247 nm ±13 nm and for same number of QB/QD particles, luminescence intensity of QBs was presumably 2863 times higher than QDs. The optimal parameters of the strip were as follows: The sample pads were saturated with 20 mmol/L sodium borate buffer(pH 8.0) containing 1.0%(w/v) BSA,0.25% Tween-20, and 0.1%(w/v) NaN3. 1 mg of QBs were conjugated to 150 μg anti-AFB1 ascites. The AFB1-BSA(0.4 mg/mL) and donkey anti-mouse IgG antibodies(1 mg/mL) were dispensed onto the NC membrane as test and control lines.In addition, pH value, methanol content of the sample extract, and interpretation time could influence the sensitivity and reproducibility of the QB-ICA sensor, immune reaction kinetics was used to explore the influence of the environment. Results indicated that the quantitative detection model based on FIT/FIC could elaborate the effects of the above factors. The regression equation could be represented by y =-0.28ln(x) + 1.25, where y is the competitive inhibition rate and x is the AFB1 concentration. The IC50 of the QB-ICA sensor was achieved at 13.87 ± 1.54 pg/mL(n=3), which is significantly higher(39-fold) than that of the QDs as a signal probe(IC50 = 0.54 ± 0.06 ng/mL). Besides, the QB-based ICA sensor exhibited dynamic linear detection of AFB1 in maize extract from 5 pg/mL to 60 pg/mL.The specificity of the QB-ICA sensor was evaluated by running four structurally related analogs(AFG1, AFG2, AFM1, and AFB2) and other five common mycotoxins(citrinin, patulin, ochratoxin A, deoxynivalenol, and zearalenone). The results show that the developed method exhibited 51.6%, 0.2%, 1.73%, and 5.58% Cr to AFG1,AFG2, AFM1, and AFB2, respectively, and negligible(< 0.01%) Cr to the other fivemycotoxins. The LOD was calculated at 0.42 pg/mL. the recoveries for the intra-assay ranged from 97.89% to 105.70%, with a CV ranging from 3.64% to 8.52%. The results for the inter-assay ranged from 96.32% to 110.30% and 4.34% to 6.36%,respectively. The variations for intra- and inter-assay using QB-ICA sensor are acceptable levels for AFB1 quantitative analysis.40 maize samples were chosen as real samples for quantitative analysis and verification of the correlation between commercialized ELISA kit and the strips.Results indicated a good correlation(R2=0.9391) between the two methods. The performance and practicability of our QB-ICA sensor were further confirmed with liquid chromatography tandem mass spectrometry(LC-MS/MS). Given its efficient signal amplification performance, the proposed QBs-ICA offers great potential for rapid, sensitive, and cost-effective quantitative detection of analytes in food safety monitoring. |
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