A rapid and sensitive chemiluminescence immunoassay (CLIA) based on magnetic nanoparticles (MNPs) was developed to detect aflatoxin B1 (AFB1), which is a potent carcinogen in nature. We prepared monodisperse MNPs (300 nm in diameter) according to the solvothermal synthesis reaction and the MNPs were coated with silica by the Stöber method. Triethox was used as a one-step carboxylation reagent, and 3-aminopropyltriethoxysilane (APTES) an amination reagent, to modify the MNPs. We prepared two types of solid phase antigens using the above synthesized functionalized MNPs coupled with the later prepared AFB1-oxime active ester and the purchased BSA-AFB1 respectively. 2',6'-dimethylcarbonylphenyl-10-sulfopropylacridinium-9-carboxylate 4'-N-hydroxysuccinimide (4'-NHS) ester (NSP-DMAE-NHS), as a novel luminescent reagent, was used to label anti-AFB1 antibodies. The two CLIA calibration curves based on the two types of solid phase antigens were obtained and compared. The acquired limit of detection (LOD) was about 0.001 ng/mL for the two functionalized MNPs-based immunoassays, and the half maximal inhibitory concentration (IC ) was 0.51 ng/mL for the MNPs-AFB1-based method and 0.72 ng/mL for the MNPs-BSA-AFB1-based method.

A strategy has been applied to chloramphenicol (CAP) detection with chemiluminescence immunoassays (CLIA) based on cheap functionalized Fe O @SiO magnetic nanoparticles (Fe-MNPs). The strategy that bovine serum albumin (BSA) was immobilized on cheap functionalized Fe-MNPs and that the CAP molecules were then immobilized on BSA, avoided the long process of dialysis for preparation of the BSA-CAP conjugates. The samples were detected for both methods that utilized two different kinds of functionalized Fe-MNPs (amine-functionalized Fe O @SiO and carboxylic acid-functionalized Fe O @SiO ). The sensitivities and limits of detection (LODs) of the two methods were obtained and compared based on inhibition curves. The 50% inhibition concentrations (IC ) values of the two methods were about 0.024 ng ml and 0.046 ng ml respectively and LODs were approximately 0.0002 ng ml and 0.001 ng ml respectively. These methods were much more sensitive than that of any traditional enzyme-linked immunosorbent assay (ELISA) previously reported. Therefore, such chemiluminescence methods could be easily adapted for small molecule detection in a variety of foods using Fe-MNPs.