Selective fluorescence lighting-up recognition of DNA abasic site environment possessing guanine context
DNA abasic site (apurinic/apyrimidinic (AP) site) has received much attention due to its involvement in diseases and development of selective genetic drugs. Fluorescence technique has been widely used in identifying the AP sequence environment with a fluorophore being the AP site-targeting probe. However, fluorescence enhancement for signal-on response with no need of labeling procedure still remains a challenge, especially for the AP site flanked by guanine context. Usually, the excited state of the AP site-targeting fluorophore is deactivated by electron transfer with the context guanine, the most oxidizable base in DNA. In this work, we found that 9-dicyanovinyljulolidine (DCVJ) can selectively target the apurinic site (namely, the orphan base is pyrimidine) and its fluorescence is significantly enhanced only when the flanking base is guanine. According to dependence of the fluorescence responses on base’ redox properties and base stacking-determined electronic properties, we proposed that the comparable electron energy levels of the DCVJ excited state and the flanking base are responsible for the observed fluorescence enhancement, although DCVJ has been reported as a molecular rotor-based probe. This turn-on fluorescence probe for the flanking guanine environment of the AP site exhibits a better selectivity in comparison with the previously used turn-off probe.
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