Monitoring DNA adducts in human blood samples using magnetic Fe3O4@graphene oxide as a nano-adsorbent and mass spectrometry.

DNA adducts usually occur at a level of 0.1-1 adducts per 108 unmodified DNA bases, which can cause many adverse health effects if not normally repaired. Using microgram amounts of DNA to detect DNA adducts remains challenging due to the extremely low levels. Commercial solid phase extraction is the most widely used method for extracting DNA adducts from biological samples, but it is time consuming and costly, and the hydrophobic interactions between various alkyl-bonded phases and analytes typically lack selectivity when used to extract DNA adducts. Therefore, an effective method for DNA adducts analysis based on Fe3O4@graphene oxide (GO) nano-adsorbent and ultra-performance liquid chromatography-triple quadrupole mass spectrometry detection was developed in this study, in which the selectivity may also be increased by π-π stacking interactions between GO and adduct molecules. Several variables, including the extraction time, extraction pH, nano-sorbent amount and elution solvent were optimized, to achieve the best extraction efficiency using the proposed method. A small amount of Fe3O4@GO (2.5 mg) exhibited a good adsorption performance for the model DNA adducts, and butanol containing 4% NH3·H2O showed good elution effects. Under the optimized conditions, satisfying recoveries (78-107%) from calf thymus DNA samples were achieved, and 2 adducts were detected in only 2 μg of blood DNA. This method can be used as an effective strategy for DNA adduct analysis, and can be extended to other biological samples.