Mix-and-Read No-Wash Fluorescence DNA Sensing System Using Graphene Oxide: Analytical Performance of Fresh Versus Aged Dispersions

Simple and sensitive assays for DNA detection still represent a highly pursued research area with important implications in biomedical-related sciences. Graphene oxide (GO) is a highly efficient quenching platform for fluorophore-tagged DNA, which is why its use for fluorescent sensing has been widespread over the past decade. GO-based biosensing systems frequently rely upon the isolation of biomolecule–material complexes prior to detection via hybridization-induced desorption of the fluorescent dye. Simple mix-and-read detection formats that do not require purification/isolation/wash steps are envisioned as promising schemes for decentralized analysis, with potential for commercial scalability. For GO-based mix-and-read assays, the aging process of the quenching material in aqueous media can be a crucial parameter affecting the analytical performance, which has so far not been addressed in the literature. To get this goal, top–down characterization microstructures to atomic levels is needed. Herein, we revisit GO as a well-known quenching system, aiming at a centrifugation-free, mix-and-read, no-wash format, toward the detection of an apolipoprotein-E-encoding DNA sequence as a model analyte. We look into the progression of GO aging in water medium through a top–down characterization and investigate the analytical performance of fresh versus aged dispersions in terms of hybridization-based detection. We found that aged GO, while still retaining a high quenching efficiency, undergoes morphological changes over time with concomitant detrimental effects on its analytical performance toward DNA detection.