Abstract
A highly sensitive aptasensor for aflatoxin M1 (AFM1) detection was constructed based on fluorescence resonance energy transfer (FRET) between 5-carboxyfluorescein (FAM) and palladium nanoparticles (PdNPs). PdNPs (33 nm) were synthesized through a seed-mediated growth method and exhibited broad and strong absorption in the whole ultraviolet-visible (UV-Vis) range. The strong coordination interaction between nitrogen functional groups of the AFM1 aptamer and PdNPs brought FAM and PdNPs in close proximity, which resulted in the fluorescence quenching of FAM to a maximum extent of 95%. The non-specific fluorescence quenching caused by PdNPs towards fluorescein was negligible. After the introduction of AFM1 into the FAM-AFM1 aptamer-PdNPs FRET system, the AFM1 aptamer preferentially combined with AFM1 accompanied by conformational change, which greatly weakened the coordination interaction between the AFM1 aptamer and PdNPs. Thus, fluorescence recovery of FAM was observed and a linear relationship between the fluorescence recovery and the concentration of AFM1 was obtained in the range of 5–150 pg/mL in aqueous buffer with the detection limit of 1.5 pg/mL. AFM1 detection was also realized in milk samples with a linear detection range from 6 pg/mL to 150 pg/mL. The highly sensitive FRET aptasensor with simple configuration shows promising prospect in detecting a variety of food contaminants.
Highlights
Aflatoxins (AFs), which are highly toxic mycotoxins produced by Aspergillus parasiticus, Aspergillus flavus and Aspergillus nomius, present in a wide range of food and feed commodities [1,2]
In the past few years, various testing methods have been developed for aflatoxin M1 (AFM1) detection, which includes thin-layer chromatography (TLC) [11,12], enzyme-linked immunosorbent assay (ELISA) [13,14], high-performance liquid chromatography (HPLC) [15,16], liquid chromatography-tandem mass spectrometry (LC-MS) [17,18] and immunosensors [19,20]
The AFM1 aptasensor was constructed based on aptamer-bridged fluorescence resonance energy transfer (FRET) between FAM and
Summary
Aflatoxins (AFs), which are highly toxic mycotoxins produced by Aspergillus parasiticus, Aspergillus flavus and Aspergillus nomius (rarely), present in a wide range of food and feed commodities [1,2]. In the past few years, various testing methods have been developed for AFM1 detection, which includes thin-layer chromatography (TLC) [11,12], enzyme-linked immunosorbent assay (ELISA) [13,14], high-performance liquid chromatography (HPLC) [15,16], liquid chromatography-tandem mass spectrometry (LC-MS) [17,18] and immunosensors [19,20] Compared with those mentioned above, the aptasensor, which exhibits unique advantages such as being less expensive, easier to operate and suitable for on-site analyses, has attracted increasing attention recently. We combined the excellent luminescence quenching ability of PdNPs towards fluorescent dyes with the highly specific binding ability of the AFM1 aptamer towards AFM1 to develop a highly sensitive PdNPs-based FRET aptasensor for AFM1 detection.
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