Design of controlled multi-probe coupled assay via bioinspired signal amplification approach for mercury detection

摘要

We have designed and synthesized off–on fluorometric probes, 7-(but-3-yn-1-yloxy)-8-(difluoromethyl)-2 H -chromen-2-one (AYF) and 7-((4-( tert -butyldiphenylsilyloxy)benzyl)oxy)-8-(difluoromethyl)coumarin (DPF _(1) ), by incorporating the concept of biological signal transduction strategy into their molecular design and present their proof-of-concept demonstration for mercury (Hg ~(2+) ) detection. AYF undergoes a cascade of self-immolative reactions in the presence of Hg ~(2+) and unmasks fluorogenic coumarin 1 and releases two latent fluoride ions. These fluorides initiate the removal of silyl protecting trigger group on DPF _(1) which directs another cascade of self-immolative reactions. The fluoride ions (amplifiers) are continuously activating the cascade reaction, and, as a result, coumarin 1 progressively accumulates in the reaction medium and the whole process accelerates an amplified signal for Hg ~(2+) . For detection of Hg ~(2+) , the limit of detection of the two-probe coupling assay (AYF and DPF _(1) ) is 0.51 ppb which is more than 2000 times lower than that of AYF alone. Besides, 3-(benzothiazol-2-yl)-4-carbonitrile-7-((4-( tert -butyldiphenylsilyloxy)benzyl)oxy)coumarin (DCC), a long-wavelength probe, was coupled with AYF and DPF _(1) in order to shift the emission to a higher wavelength region. Negative control studies revealed that the probes undergo controlled and organized sensing pathways as we designed.