Two fluorescent probes were designed by connecting indomethacin to coumarin through different linkers. The introduction of indomethacin quenched the fluorescence of coumarin-based probes with apparent red-shifts in the absorption and emission maxima, probably due to the photoinduced electron transfer (PET) from the indomethacin to the fluorophore and the formation of folding conformation. The addition of human serum albumin (HSA) triggered about 40-fold fluorescence enhancements of ADC-IMC-2 and ADC-IMC-6 with 85 nm blue-shifts. The probe with longer spacer ADC-IMC-6 exhibited ratiometric fluorescent response toward HSA, and that with shorter linker showed “off-on” fluorescence response to HSA. However, insignificant spectral changes of the reference compounds (ADC-6 and ADC-2) initiated by HSA implied that indomethacin played critical role in the identification of HSA. The competitive assays and molecular docking results reveal that the indomethacin in ADC-IMC-6 could tightly combine at drug site I of HSA. Fluorescence bio-imaging experiments show that both probes could distinguish cancer cells from normal cells.

通过将吲哚美辛通过不同的接头连接至香豆素，设计了两种荧光探针。消炎痛的引入使香豆素基探针的荧光猝灭，吸收和发射最大值出现明显的红移，这可能是由于从消炎痛到荧光团的光致电子转移（PET）以及折叠构象的形成。人血清白蛋白（HSA）的添加引发ADC-IMC-2和ADC-IMC-6荧光增强约40倍，蓝移为85 nm。间隔较长的探头ADC-IMC-6表现出对HSA的比例荧光响应，而连接子越短则显示对HSA的“关闭”荧光响应。但是，由HSA引发的参考化合物（ADC-6和ADC-2）的光谱变化不明显，这表明吲哚美辛在HSA的鉴定中起着关键作用。竞争性测定和分子对接结果表明，ADC-IMC-6中的消炎痛可在HSA的药物位点I紧密结合。荧光生物成像实验表明，两种探针均可将癌细胞与正常细胞区分开。