A smart FRET probe exhibiting a molecular keypad lock device based on rapid detection of nitric oxide mediated by Cu~(2+) ion

摘要

A rhodamine-dansyl conjugate (RPD) has been synthesized for rapid FRET-based ratiometric detection of nitric oxide (NO) up to nM level mediated by the Cu2+ ions. The emission band of dansyl centered at 481 nm showed quenching upon addition of Cu2+ and further addition of NO, showed a decrease at dansyl emission band and ratiometrically generate a new band at 580 nm corresponding to the open spirolactam derivative of rhodamine. Subsequent chemical inputs of Cu2+ and NO generate a smart molecular level security device with a unique set of inputs to unlock the device. The rapid detection of NO is devoid of false signalling, as the detection is dependent on sequence-based two input correct combination. The [RPD-Cu2+] solution was also highly efficient to detect NO in solution by a visual change in colour: i.e. colourless to pink and pale green to orange under naked eye and UV-light respectively. The probe-Cu2+ solution exhibits excellent NO imaging in HeLa cells with low cytotoxicity and the lower level of emission in the presence of probe-Cu2+ which is advantageous to see the initial incubation of probe inside the live cells. The applicability of [RPD+Cu2+] has been proven by efficient detection of NO in HeLa cells by dual enhanced emissions in green/red channels.