DNA nanotechnology NANPs RNA RNA aptamers RNA interference RNA logic RNA nanoparticle RNA nanotechnology RNA self-assembly aggregation aptamers biological media biosensors conditional activation conditionally activated contrast variation cotranscriptional folding cytosine rich sequences dynamic fluorescence fluorogenic RNA functional RNA ganciclovir gene delivery gene therapy glioblastoma multiforme i-motif DNA immunostimulation light-up aptamer live-cell imaging