We describe a simple and effective strategy to construct a molecular imprinting ratiometric fluorescence sensor (MIR sensor) for the visual detection of bovine hemoglobin (BHb) used as a model protein. The sensor was prepared by simply mixing the solution of green and red CdTe quantum dots (QDs), which were embedded in core–shell structured molecularly imprinted polymers and silica nanoparticles, respectively. The resultant hybrid MIR sensor can selectively bind with BHb and thus quench the fluorescence of the green QDs, while the red QDs wrapped with silica are insensitive to BHb with the fluorescence intensity unchanged. As a result, a continuous obvious fluorescence color change from green to red can be observed by naked eyes, with the detection limit of 9.6 nM. Moreover, the MIR sensor was successfully applied to determine BHb in bovine urine samples with satisfactory recoveries at three spiking levels ranging from 95.7 to 101.5%, indicating great potential application for detecting BHb in real samples. This strategy of using different fluorescence emission materials incorporated to construct a ratiometric fluorescence sensor is reasonable and convenient, which can be extended to the preparation of other ratiometric fluorescence systems for targeted analytes.

中文翻译：

---

基于分子印迹的混合比例荧光传感器可视化测定牛血红蛋白

我们描述了一种简单有效的策略来构建分子印迹比率荧光传感器（MIR传感器），用于视觉检测用作模型蛋白的牛血红蛋白（BHb）。通过简单地混合绿色和红色CdTe量子点（QDs）溶液即可制备传感器，它们分别嵌入核-壳结构分子印迹聚合物和二氧化硅纳米颗粒中。所得的混合MIR传感器可以选择性地与BHb结合，从而淬灭绿色QD的荧光，而包裹有二氧化硅的红色QD对BHb不敏感，荧光强度不变。结果，可以用肉眼观察到从绿色到红色连续的明显荧光颜色变化，检测极限为9.6 nM。而且，MIR传感器成功应用于牛尿样品中BHb的测定，回收率令人满意，三种加标水平从95.7到101.5％，这表明在实际样品中检测BHb具有巨大的潜力。使用掺入的不同荧光发射材料构建比例荧光传感器的这种策略是合理且方便的，可以扩展到针对目标分析物的其他比例荧光系统的制备。