一个基于NBD-NH2荧光团的增强型pH荧光探针及其细胞造影研究

A Turn-on pH Fluorescent Probe Based on NBD-NH_2 Fluorophore and Its pH_i Imaging Application

本文以NBD-NH2荧光团偶联N-(4-吡啶甲基)乙二胺质子受体构建了基于光致电子转移(PET)机制的pH探针NBD-Py。探针在pH 5.0～8.5范围内显示pH降低导致的荧光增强响应,pK a为6.48。该响应不受胞内常见金属离子干扰且有良好的可逆性。研究表明质子受体中引入4-甲基吡啶修饰乙二胺是探针实现对弱酸/近中性pH响应的关键。HeLa细胞中的造影证实了探针的pHi造影能力和溶酶体靶向性能,为溶酶体pH相关的生理过程研究提供了新的可靠手段。

A fluorescent probe of PET mechanism, NBD-Py, was constructed by coupling fluorophore NBD-NH2 with a proton receptor N-（4-pyridylmethyl）ethylene diamine. This probe displays the pH decrease-induced emission enhancement in pH range from 5.0 to 8.5, with a pKa of 6.48. This sensing behavior is reversible and not interfered by normal intracellular metal cations such as Na＋, K＋, Ca2＋, Mg2＋ and other transition metal cations. Comparison between the pH sensing behaviors of NBD-Py and its analogue without the N-（4-pyridyl） methyl group disclosed that the pyridylmethyl group is essential its pH sensing ability for weak acidic and near neutral pH, which is important for cell biology. Confocal imaging in HeLa cells confirmed the pHi imaging ability and the lysosome-targetability of NBD-Py, which is valuable for lysosome cell biology.