Aptasensor for amplified IgE sensing based on fluorescence quenching by graphene oxide

Water-soluble graphene oxide (GO) with a two-dimensional layered nanostructure was synthesized and used as a quencher to construct a highly sensitive and selective fluorescence resonance energy transfer (FRET) aptasensor for sensing Immunoglobulin E (IgE). The fluorescein isothiocyanate (FITC)-labeled aptamer could be adsorbed stably onto the surface of GO via pi -> pi stacking interaction, which led to the occurrence of FRET from FITC to GO, and the fluorescence of FITC-labeled aptamer was quenched by GO via energy transfer. In the presence of IgE, the fluorescence was recovered due to a higher affinity between the aptamer and IgE compared with interactions between GO and the aptamer, leading to a high signal-to-background ratio. The fluorescence intensity of the aptamer increased in proportion to the amount of IgE in the sample, so that IgE could be detected with a linear range of 60-225 pM and a detection limit of 22 pM. The assay was highly selective because the aptamer was unaffected by the presence of immunoglobulin G (IgG), human serum albumin (HSA) and bovine serum albumin (BSA). The practical application of the proposed aptasensor was successfully carried out for the determination of IgE in human serum samples. Copyright (c) 2012 John Wiley & Sons, Ltd.