Spiropyran as a biosensor for double-stranded RNA detection

Abstract

Spiropyrans are photochromic organic dyes whose molecular structures and properties vary between closed spiropyran and open merocyanine isoforms. Here, we show that merocyanine derivatives can interact with RNA base pairs, which alters the spectral property of the compound. By quantifying UVVis absorbance spectral change, we can detect and quantify dsRNAs, both synthetic and endogenous. By treating RNAs extracted from cells with endonucleases of different substrate specificities, we can isolate ds-RNAs and detect them. Particularly, we show that spiropyrans can robustly detect elevated dsRNA expression levels when colorectal cancer cells are treated with 5-aza-2'-deoxycytidine, a DNAdemethylating agent used during chemotherapy, and thus, spiropyrans can be used to predict the responsiveness of cells to the drug treatment. As dsRNAs are signature of virus and accumulation of dsRNAs is implicated in various degenerative diseases, our work establishes potential application of spiropyrans as a simple spectral biosensor to diagnose human diseases based on dsRNA expression and analytically monitor the progress of chemotherapy.