Badugu Ramachandram, Lakowicz Joseph R, Geddes Chris D
Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, Medical Biotechnology Center, University of Maryland School of Medicine, 725 West Lombard St, Baltimore, MD 21201, USA.
Institute of Fluorescence and Center for Fluorescence Spectroscopy, Medical Biotechnology Center, University of Maryland Biotechnology Institute, 725 West Lombard St, Baltimore, MD 21201, USA.
Dyes Pigm. 2004 Jun;61(3):227-234. doi: 10.1016/j.dyepig.2003.10.011. Epub 2003 Dec 13.
We characterize a new water soluble fluorescent probe sensitive to changes in pH. The new probe shows spectral shifts and intensity changes in different pH media, in a wavelength ratiometric and colorimetric manner. Subsequently, changes in pH can readily be determined around the physiological level. The new probe's response is based on the ability of the boronic acid group to interact with strong bases like OH, changing from the neutral form of the boronic acid group [R-B(OH)] to the anionic R-B(OH) form, which is an electron donating group. The presence of an electron deficient quaternary heterocyclic nitrogen center and a strong electron donating amino group in the 6-position, on the quinolinium backbone, provides for the spectral changes observed upon OH complexation. In addition, the presence of the amino group in the 6-position of the quinolinium backbone, suppresses the response of the boronic acid containing probe towards mono saccharides such as glucose and fructose, which are present in many biological fluids, allowing for the predominant pH sensitivity. Finally we compare our findings to those of a control compound that does not contain the boronic acid group.
我们表征了一种对pH变化敏感的新型水溶性荧光探针。这种新型探针在不同pH介质中呈现光谱位移和强度变化，以波长比率法和比色法的方式表现。随后，在生理水平附近可以很容易地测定pH的变化。新型探针的响应基于硼酸基团与诸如OH等强碱相互作用的能力，从硼酸基团的中性形式[R-B(OH)]转变为阴离子形式R-B(OH)，这是一个供电子基团。喹啉鎓主链上6位存在缺电子的季杂环氮中心和强供电子氨基，导致在OH络合时观察到光谱变化。此外，喹啉鎓主链6位存在氨基，抑制了含硼酸探针对许多生物流体中存在的单糖如葡萄糖和果糖的响应，从而实现了主要的pH敏感性。最后我们将我们的发现与不含硼酸基团的对照化合物的发现进行了比较。
