Supramolecularly Multicolor DNA Decoding Using an Indicator Competition Assay

Relative to the individual intensity-dependent strategy, the multicolor fluorescence sensor has promise to achieve a high signaling contrast. In this work, we develop a cucurbituril-based supramolecular and multicolor DNA recognition rationale via indicator competition assay (ICA). Alkaloids of coptisine (COP) and palmatine (PAL) are identified as the proof-of-principle indicators with a lighting-up fluorescence upon supramolecular complexation to cucurbit[7]uril (CB[7]). With an introduced abasic site (AP site) as the contestant, DNAs having pyrimidines opposite this site can compete for COP with CB[7] to bring an emission color change from green to yellow brown, while those having purines opposite the AP site do not compete for COP and still have the green emission, indicative of a high selectivity for the multicolor nucleotide transversion recognition. However, because of the relatively weaker binding of PAL with CB[7], the AP site-containing DNA can take away PAL from its CB[7] complex and resultantly bring a blue-to-green emission color change independent of the AP site-opposite nucleotide identity, dissimilar to the remaining blue color for the fully matched DNA without the AP site, suggesting a preferable strategy for the AP site biomarker detection. Our method demonstrates a new way to develop an ICA-based multicolor DNA sensor with the supramolecular cucurbituril complexation to ensure a highly selective performance.