Alkaline Hydrolysis Behavior of Metal-Organic Frameworks NH2-MIL-53(Al) Employed for Sensitive Immunoassay via Releasing Fluorescent Molecules

Nanosized metal-organic frameworks (MOFs) NH2-MIL-53(Al) were synthesized from 2-aminoterephthalic acid (NH2 center dot H2BDC) and AlCl3 by a facile hydrothermal method. The synthesized MOFs displayed good stability and a uniform particle size in a netural medium and were hydrolyzed in alkaline medium to release a large amount of fluorescent ligand NH2 center dot H2BDC. Therefore, they can act as large-capability nanovehicles to load signal molecules for investigating various biorecognition events. In this work, based on the alkaline hydrolysis behavior of MOFs NH2-MIL-53(Al), a sensitive immunoassay method was developed for the detection of aflatoxin B-1 (AFB(1)) by employing them as fluorescent signal probes. With a competitive immunoassay mode on microplate, AFB(1) can be detected within a linear range of 0.05-25 ng mL(-1). The method was successfully employed to detect AFB(1) spiked in Job tears, Polygala tenuifolia and with acceptable recovery values of 83.00-114.00%. The detection results for moldy Fructus xanthii displayed an acceptable agreement with those from the high-performance liquid chromatography method, with relative errors of -14.21 to 3.49%. With the merits of high sensitivity, facile manipulation, and ideal reliability, the approach can also be extended to other areas such as aptasensor and receptor-binding assay.