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

Abstract

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.