Development of FRET biosensor based on aptamer/functionalized graphene for ultrasensitive detection of bisphenol A and discrimination from analogs

Abstract

We report an ultrasensitive, effective and efficient platform for small molecule bisphenol A (BPA) detection based on Förster resonance energy transfer (FRET) between functionalized graphene (graphene oxide; GO and reduced GO; rGO) as acceptor and fluorescently tagged BPA specific aptamer (5’-FAM-tagged single-stranded DNA; FAM-ssDNA) as donor design. Due to noncovalent assembly and specific adsorption, fluorescent quenching of FAM probe takes place due to good overlap between FAM emission and the GO (and rGO) absorption spectrum. On addition of BPA analyte, the aptamer preferentially bounds to BPA, forming FAM-ssDNA–aptamer–BPA complexes, the FRET is disrupted possibly by switching its configuration or re-hybridization preventing aptamer from molecular adsorption on or away from GO or rGO surface and the fluorescence signal is restored (turn-on’ bioassay). This method relies upon competitive interaction between two hydroxyphenyl groups of BPA and “cytosine–cytosine” mismatches in ssDNA. The intensity of optical fluorescence signal was changed in linear proportion to BPA concentration ranging 50 pg/mL − 100 ng/mL, with low limit of detection <10 pg/mL. The sensitivity and specificity of biosensor toward BPA was demonstrated viaseveral BP, BPB, BPC, DES analogs. The developed aptasensor assay is successfully implemented for real water (tap, bottled and river) samples and recovery rate is between 96.0% and 104% indicative of higher accuracy. These remarkable findings are attributed to interplay of large surface area and topologically interconnectedness provided by functional moieties in graphene scaffolds thus favorable interaction with FAM-ssDNA. This strategy can be extended to detection of other molecules by simply substituting the aptamer.