A new water-soluble cationic polyfluorene with boronate-protected fluorescein (peroxyfluor-1) covalently linking to the polymer backbone (PF-FB) was synthesized as a fluorescence probe to optically detect hydrogen peroxide (H2O2) and glucose in serum. The peroxyfluor-1 exists as a lactone form which is colorless and non-fluorescent. Without addition of H2O2, the fluorescence resonance energy transfer (FRET) from fluorene units (donor) to peroxyfluor-1 (acceptor) is absent and only blue donor emission is observed upon excitation of the fluorene units. In the presence of H2O2, the peroxyfluor-1 can specifically react with H2O2 to deprotect the boronate protecting groups and to generate green fluorescent fluorescein. The absorption of fluorescein overlaps the emission of polyfluorene, which encourages efficient FRET from the fluorene units to the fluorescein. By triggering the shift in emission color and the ratio change of blue to green emission intensities, it is possible to assay H2O2 and its concentration change in buffer solution and in serum. The PF-FB probe can detect H2O2 in the range from 4.4 to 530 µM. Since glucose oxidases (GOx) can specifically catalyze the oxidation of β-D-(+)-glucose to generate H2O2, glucose detection is also realized with the PF-FB probe as the signal transducer. Thus, an optical assay for hydrogen peroxide (H2O2) and glucose in serum was created which combines a fluorescent ratiometric technique based on FRET with the light-harvesting properties of conjugated polymers.
我们合成了一种新型
水溶性阳离子聚
芴,其聚合物主链上共价连接有
硼酸盐保护的
荧光素(过氧
氟-1)(PF-FB),可作为荧光探针光学检测血清中的
过氧化氢(
H2O2)和
葡萄糖。过氧
氟-1 以内酯形式存在,无色无荧光。在不加入 的情况下,
芴单元(供体)与过氧
氟-1(受体)之间不会发生荧光共振能量转移(FRET),在
芴单元被激发时只能观察到蓝色的供体发射。在 存在的情况下,过氧
氟-1 可以与 发生特异性反应,使
硼酸保护基团脱保护,生成绿色
荧光素。
荧光素的吸收与聚
芴的发射相重叠,从而促进了
芴单元与
荧光素之间有效的 FRET。通过触发发射颜色的转变和蓝绿发射强度的比例变化,可以检测缓冲溶液和血清中的 及其浓度变化。PF-FB 探针可检测 4.4 至 530 µM 范围内的 。由于
葡萄糖氧化酶(GOx)能特异性地催化 β-D-(+)-
葡萄糖氧化生成 ,因此
葡萄糖检测也可以用 PF-FB 探针作为信号转换器来实现。这样,一种检测血清中
过氧化氢( )和
葡萄糖的光学测定方法就诞生了,它将基于 FRET 的荧光比率测定技术与共轭聚合物的光收集特性结合在一起。