Fluorescent carbon quantum dots are emerging as a new class of fluorescent probes due to their unique optical properties . Herein, we presented a simple, one-pot and effective preparation strategy for copper-functionalized carbon quantum dots (Cu-CDs). The Cu-CDs demonstrated excitation-independent emissions, high fluorescent quantum yield (~ 24.4%) and excellent fluorescent stability. The fluorescence of Cu-CDs could be quenched efficiently in the presence of histidine (His) due to the coordination occurring between surface Cu and imidazole side chains of His. Thus, the Cu-CDs could be used as an efficient fluorescent probe for His detection. Under optimal conditions, the fluorescent signals of Cu-CDs decreased linearly with the concentrations of His over a range of 0.1–15 µM. The detection limit was 30 nM. The proposed method provided obvious advantages of rapid response, convenience, simplicity, high selectivity and sensitivity. Moreover, good results also have been obtained for His detection in real biological fluid samples.
Nan Lu,Xi Zhang,Ruiqi Na,Wendi Ma,Chongyang Zhang,Yuchao Luo,Yongfeng Mu,Shuling Zhang,Guibin Wang
The synthesis of a nanocomposite gel polymer electrolytes (NGPEs) using Li + -functionalized SPEEK (SPEEK(Li)) nanofiber membrane as a matrix, cross-linked PVA as a gelled agent and LiClO 4 as an electrolytic salt for electric double layer capacitors (EDLCs) were reported in this work. Compared with conventional PVA based gel electrolyte, the “SO 3 − Li + ” functional groups and the pores structure of the SPEEK(Li) nanofiber membrane improves the ionic conductivity as well as mechanical stability , which made the prepared NGPEs exhibited a high ionic conductivity of 8.9 × 10 −3 S cm −1 at ambient temperature and a large voltage stability window range from 0 to 2.0 V. The fabricated symmetric EDLCs showed a specific capacitance of 146.96 F g −1 at a current density of 0.5 A g −1 , with a maximum energy density of 18.26 W h kg −1 . Meanwhile, the EDLCs showed outstanding cyclical stability of 98% specific capacitance retention after 3000 cycles GCD testing, all of these results indicated that the NGPEs should be appropriate to EDLCs and next-generation energy storage systems .
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