An "off-on" colorimetric and fluorometric assay for Cu(II) based on the use of NaYF4:Yb(III),Er(III) upconversion nanoparticles functionalized with branched polyethylenimine

作者：Shao, Hong; Xu, Dan; Ding, Yadan; Hong, Xia^*; Liu, Yichun

来源：Microchimica Acta, 2018, 185(4): 211.

DOI：10.1007/s00604-018-2740-7

• Multimode detection
• Absorption spectrum
• Upconversion quenching
• BPEI-Cu(II) complex
• Inner filter effect

The authors describe an "off-on" colorimetric and fluorometric assay for the determination of Cu(II). It is based on the use of upconversion nanoparticles (UCNPs) of type NaYF4:Yb(III),Er(III) that were functionalized with branched polyethylenimine (BPEI). A color change from colorless to blue occurs within 2 s after addition of Cu(II) to a solution of the modified UCNPs. The color change can be visually detected at Cu(II) concentrations down to 80 mu M. The upconversion fluorescence of the modified UCNPs, measured at excitation wavelength of 980 nm, is reduced due to the predominant inner filter effect caused by the formation of the BPEI-Cu(II) complex. Normalized fluorescence intensity drops linearly in the 50 nM to 10 mu M Cu(II) concentration range, and the fluorometric detection limit is 45 nM. Both the color and the fluorescence are recovered on addition of EDTA. Excellent selectivity over other metal ions and anions is achieved.

• 出版日期2018-4
• 单位东北师范大学