Glutamic acid (Glu) is the most abundant excitatory neurotransmitter in the central nervous system, and an elevated level of Glu may indicate some neuropathological diseases. Herein, three isomorphic microporous lanthanide metal–organic frameworks (MOFs) [(CH₃)₂NH₂]₂[Ln₆(μ₃-OH)₈(BDC-OH)₆(H₂O)₆]·(solv)_x (ZJU-168; ZJU = Zhejiang University, H₂BDC-OH = 2-hydroxyterephthalic acid, Ln = Eu, Tb, Gd) were designed for the detection of Glu. ZJU-168(Eu) and ZJU-168(Tb) suspensions simultaneously produce the characteristic emission bands of both lanthanide ions and ligands. When ZJU-168(Eu) and ZJU-168(Tb) suspensions exposed to Glu, the fluorescence intensity of ligands increases while the emission of lanthanide ions is almost unchanged. By utilizing the emission of ligands as the detected signal and the emission of lanthanide ions as the internal reference, an internal calibrated fluorescence sensor for Glu was obtained. There is a good linear relationship between fluorescence intensity ratio and Glu concentration in a wide range with the detection limit of 3.6 μM for ZJU-168(Tb) and 4.3 μM for ZJU-168(Eu). Major compounds present in blood plasma have no interference for the detection of Glu. Furthermore, a convenient analytical device based on a one-to-two logic gate was constructed for monitoring Glu. These establish ZJU-168(Tb) as a potential turn-on, ratiometric, and colorimetric fluorescent sensor for practical detection of Glu.

中文翻译：

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高度稳定的镧系金属有机骨架，可作为谷氨酸（一种神经病生物标记物）的内部校准发光传感器。

谷氨酸（Glu）是中枢神经系统中最丰富的兴奋性神经递质，而Glu的升高可能表明某些神经病理疾病。这里，3同构微孔镧系金属-有机骨架（MOF）[（CH ₃）₂ NH ₂ ] ₂ [LN ₆（μ ₃ -OH）₈（BDC-OH）₆（H ₂ O）₆ ]·（SOLV）_x（ZJU-168; ZJU =浙江大学，H ₂BDC-OH = 2-羟基对苯二甲酸，Ln = Eu，Tb，Gd）用于检测Glu。ZJU-168（Eu）和ZJU-168（Tb）悬浮液同时产生镧系元素离子和配体的特征发射带。当ZJU-168（Eu）和ZJU-168（Tb）悬浮液暴露于Glu时，配体的荧光强度增加，而镧系元素离子的发射几乎不变。通过利用配体的发射作为检测信号，并利用镧系元素离子的发射作为内部参考，获得了用于Glu的内部校准荧光传感器。ZJU-168（Tb）的检出限为3.6μM，ZJU-168（Eu）的检出限为4.3μM，荧光强度比与Glu浓度之间存在良好的线性关系。血浆中存在的主要化合物对Glu的检测无干扰。此外，构建了基于一到两个逻辑门的便捷分析设备来监控Glu。这些将ZJU-168（Tb）确立为用于实际检测Glu的潜在开启，比例和比色荧光传感器。