The Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu, 273165, Shandong, China.
The Key Laboratory of Pharmaceutical Intermediates and Analysis of Natural Medicine, Qufu Normal University, Qufu, 273165, Shandong, China.
Mikrochim Acta. 2021 Mar 6;188(4):113. doi: 10.1007/s00604-021-04770-9.
A fluorescence platform is designed based on aggregation-induced emission of Au/Cu nanoclusters (Au/Cu NCs) driven by pH value. When pH increases from 6.0 to 7.0, Au/Cu NCs change from aggregation to dispersion, accompanied by the oxidation of Cu cores. Under the catalysis of urease, urea is hydrolysed to release ammonia, which further undergoes a hydrolysis reaction to produce OH, causing the pH to increase. The fluorescence of Au/Cu NCs quenches linearly at 590 nm with the excitation wavelength at 320 nm when the concentration of urea varies from 5.0 to 100 μM. The limit of detection (LOD) and limit of quantification (LOQ) of urea are 2.23 and 7.45 μM, respectively. Combined with headspace single-drop microextraction technology, Au/Cu NCs are employed to monitor dissolved ammonia with low-cost and simple operation. The linear range of dissolved ammonia is from 20 to 300 μM. The LOD and LOQ of dissolved ammonia are 7.04 and 23.4 μM, respectively. The relative standard deviation (RSD) values of the intra-day and inter-day precision of urea are 2.4-3.0% and 3.0-3.7%, respectively, and those of dissolved ammonia are in the range 3.4-5.1% (intra-day precision) and 4.2-5.8% (inter-day precision). No interferences have been indentified in the determination of urea and dissolved ammonia. Finally, the proposed method has been applied to determine urea in human urine samples and dissolved ammonia in water samples with satisfactory results.Graphical abstract The pH increase produces the dispersion and decomposition of Au/Cu NCs, leading to the fluorescence quenching. Both urea and dissolved ammonia are detected successfully because they cause the pH change to alkaline.
基于 pH 值驱动的金/铜纳米团簇（Au/Cu NCs）的聚集诱导发射，设计了一个荧光平台。当 pH 值从 6.0 增加到 7.0 时，Au/Cu NCs 由聚集变为分散，同时铜核被氧化。在脲酶的催化下，尿素水解释放出氨，氨进一步发生水解反应产生 OH，导致 pH 值升高。当尿素浓度在 5.0 至 100 μM 范围内变化时，在 320nm 激发波长下，Au/Cu NCs 在 590nm 处的荧光强度呈线性猝灭。尿素的检测限（LOD）和定量限（LOQ）分别为 2.23 和 7.45 μM。结合顶空单滴微萃取技术，Au/Cu NCs 用于监测溶解氨，操作简单，成本低。溶解氨的线性范围为 20 至 300 μM。溶解氨的 LOD 和 LOQ 分别为 7.04 和 23.4 μM。尿素日内和日间精密度的相对标准偏差（RSD）值分别为 2.4-3.0%和 3.0-3.7%，溶解氨的 RSD 值分别在 3.4-5.1%（日内精密度）和 4.2-5.8%（日间精密度）范围内。在测定尿素和溶解氨时，未发现干扰。最后，该方法成功应用于人尿样中尿素和水样中溶解氨的测定，结果令人满意。
