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Magnetic Graphene Oxide-Based Affinity Surface-Assisted Laser Desorption/Ionization Mass Spectrometry for Screening of Aflatoxin B1 from Complex Samples.

Aflatoxin B1 (AFB1), commonly found in agriculture products, has been considered as a carcinogen. Thus, to develop analytical methods that can be used to rapidly screen the presence of AFB1 in complex samples is important. Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) uses inorganic materials as assisting materials to facilitate desorption/ionization of analytes. The feasibility of using GO as the affinity probe against AFB1 and as the assisting material in SALDI-MS analysis was first demonstrated. We also explored a facile method to impose magnetism on GO to generate magnetic GO (MGO) nanoprobes by simply incubating GO in aqueous FeCl3 under microwave heating. The generated MGO nanoprobes possessed magnetism and were capable of enriching trace AFB1 from complex samples. AFB1 enrichment took only 6 min by incubating MGO with samples under microwave heating (power = 90 W). Followed by magnetic isolation, the isolated conjugates were ready for SALDI-MS analysis. The enrichment steps including trapping and isolation can be completed within ∼10 min. The lowest detectable concentration of our method toward AFB1 was ∼1 nM. Results also showed that AFB1 can be selectively detected from complex samples, including cell lysates of fungal spores, AFB1-spiked peanut, and wheat samples, by using the developed method. The selectivity of our method against AFB1 from the samples containing other toxins including aflatoxin G1 and ochratoxin A was also examined. According to these results, we believe that the developed method should have the potential to be used for rapid screening of AFB1 from real-world samples.