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.