一种低pH响应的新型近红外菁类荧光探针

A Novel Heptamethine Cyanines Near-Infrared Fluorescent Probe for Low pH Monitoring

开发一种快速、准确的pH测定方法对研究生命体系内的理化环境具有重要意义。以糠醛化合物为起始原料合成了两个水溶性良好的七甲川菁pH荧光探针I-1及I-2。光学性能研究表明,这两个探针都能在低pH条件发出较强的近红外荧光,最大发射波长分别为749、753 nm,且其荧光强度分别在pH 1.69~3.38、1.78~2.52时与pH值呈良好线性关系,pKa值分别为2.82、2.40,因此可用于该范围内pH值的定量检测。它们对pH值的响应非常迅速、灵敏、可逆,并且响应前后荧光强度变化达20倍以上。另外,探针I-1及I-2在体外模拟胃液的低pH检测中同样显示出了良好的荧光响应以及稳定性。因此,探针I-1及I-2在低pH生物体系的pH值检测与荧光成像上具有较佳应用潜力。

It is of great significance to develop a rapid and accurate pH detecting method for the study of physicochemical environment inside the living systems.In this article,we synthesized two water soluble heptamethine cyanine probes I-1 and I-2 from furfural derivatives.The investigation on their optical properties shows that both probes emit strong near-infrared fluorescence in low pH value environment.The maximum emission wavelengths of I-1 and I-2 were 749 nm and 753 nm,respectively.The fluorescent intensity of I-1 and I-2 are in good linear relationship with the pH value within the range of respectively 1.69~3.38 and 1.78~2.52,with the pKa value of 2.82 and 2.40,respectively.Thus,the probes can be employed for the quantitive detection of pH value in these range.The pH response of the probes was very rapid,sensitive and revisable.The fluorescence intensity changed more than 20 times before and after the response.Besides,the probe I-1 and I-2 also showed great fluorescence response and stability in simulate gastric low pH detection.Therefore,the probe I-1 and I-2 exihibit great potential for the application in detecting the pH value in low pH living systems.