Yttrium Oxide as a Strongly Adsorbing but Nonquenching Surface for DNA Oligonucleotides

A large number of nanomaterials can strongly adsorb DNA and quench fluorescence, such as graphene oxide, gold nanoparticles, and most metal oxides. On the other hand, noncationic nanomaterials that adsorb DNA but cannot quench fluorescence are less known. These materials are attractive for studying the mechanism of DNA-based surface reactions. Y₂O₃ was found to have this property. Herein, we used fluorescently labeled oligonucleotides as probes to study the mechanism of DNA adsorption. The fluorescence was quenched at low concentrations of Y₂O₃ and then recovered and even enhanced with higher Y₂O₃ concentrations. The reason was attributed to the intermolecular quenching by the DNA bases of the neighboring strands. The fluorescence enhancement was due to breaking of the intramolecular fluorophore/DNA interactions, and the most enhancement was observed with a Cy3-labeled DNA. DNA adsorption followed the Langmuir isotherm on Y₂O₃. Desorption experiments suggested that DNA was adsorbed through the phosphate backbone, with FAM-G₁₅ and FAM-C₁₅ adsorbed more strongly than the other two DNA homopolymers. With a high salt concentration, no fluorescence change was observed, suggesting that the DNA adsorbed in a folded state reducing intermolecular quenching. Overall, Y₂O₃ might be useful as a model surface for investigating DNA hybridization on a surface.