Magnetic Quantum Dot Nanobead-Based Fluorescent Immunochromatographic Assay for the Highly Sensitive Detection of Aflatoxin B₁ in Dark Soy Sauce

Abstract

Herein, we synthesized bifunctional magnetic fluorescent beads (MFBs) with a distinct core/shell structure by encapsulating octadecylamine-coated CdSe/ZnS QDs (OC-QDs) and oleic acid-modified iron oxide nanoparticles (OA-IONPs) into two polymer matrixes with different hydrophobic properties. The OC-QDs and OA-IONPs were mainly distributed in the outer layer of MFBs. The resultant MFBs displayed ca. 226-fold stronger fluorescence emission relative to the corresponding OC-QDs and retained ca. 45.4% of the saturation magnetization of the OA-IONPs. The MFBs were used to purify and enrich aflatoxin B1 (AFB1) from dark soy sauce and then utilized as a fluorescent reporter of immunochromatographic assay (ICA) for the sensitive detection of AFB1. Under the optimal detection conditions, the MFB-based ICA (MFB-ICA) displayed a dynamic linear detection of AFB1 in sauce extract over the range of 5–150 pg/mL with a half maximal inhibitory concentration of 27 ± 3 pg/mL (n = 3). The detection limits for AFB1 in sauce extract and real dark soy sauce were 3 and 51 pg/mL, respectively, which are considerably better than those of the previously reported fluorescent bead-based ICA methods. The analytical performance of the proposed MFB-ICA in terms of selectivity and accuracy was investigated by analyzing AFB1-spiked dark soy sauce samples. The reliability of the proposed method was further confirmed by ultraperformance liquid chromatography with fluorescence detection. With the combined advantages of QDs and IONPs, the resultant MFBs offer great potential as reporters of ICA for the sensitive detection of trace pollutants in complex matrix samples.

Core–Shell‐Heterostructured Magnetic–Plasmonic Nanoassemblies with Highly Retained Magnetic–Plasmonic Activities for Ultrasensitive Bioanalysis in Complex Matrix

“…Among various self‐assembly systems, the directed self‐assembly of different NP components mediated by polymer compatibility has attracted wide interest in the field of multifunctional material fabrication because of its convenience and simplicity . Our previous work reported the successful self‐assembly synthesis of core–shell‐heterostructured magnetic‐fluorescent nanobeads (MFNBs), in which poly(maleicanhydride‐ alt ‐1‐octadecene) (PMAO) and poly(methyl methacrylate) (PMMA) were introduced to induce the phase separation of oleylamine‐coated CdSe/ZnS QDs (OA‐QDs) and OC‐IONPs on the basis of the solubility difference of OA‐QDs and OC‐IONPs in the polymer matrices of PMAO and PMMA . The results indicated that OA‐QDs and OC‐IONPs were mainly distributed in the outer layer of MFNBs.…”

Sensitive Immunochromatographic Assay Using Highly Luminescent Quantum Dot Nanobeads as Tracer for the Detection of Cyproheptadine Hydrochloride in Animal-Derived Food

“…For the best sensitivity and appropriate FI signal, the contents of QBs-mAb probe upon Hapten-OVA were optimized with a “checkerboard titration-like” tactic (Guo et al, 2019 ). The inhibition rate (IR) of CYP at 0.3 ng mL −1 are obtained by the formula: IR = (1− B / B 0 ) × 100%, where B represented FI T /FI C with CYP presence and B 0 represented FI T /FI C with the absence of CYP.…”

Progress on Structured Biosensors for Monitoring Aflatoxin B1 From Biofilms: A Review

“…Fluorescence Immunosensors Guo L. et al (2019) synthesized bi-functional magnetic fluorescent beads (MFBs) with a core/shell structure by using iron oxide nanoparticles and CdSe/ZnS QDs (Figure 4A). Anti-AFB1 antibody-labeled MFBs (MFB-mAbs) were used to fabricate MFB strips.…”