White-light emissive upconversion nanoparticles for visual and colorimetric determination of the pesticide thiram
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The authors describe the use of white-light emitting upconversion nanoparticles (WL-UCNPs) for visual detection of the pesticide thiram. The method is demonstrated to undergo a better discernable color change upon target binding. The WL-UCNPs are modified with the lead(II)-dithizone complex which acts as the energy acceptor and recognition unit. This leads to quenching of the blue (475 nm) and green (545 nm) emissions of the WL-UCNPs, while the red emission (650 nm) remains unaffected. Upon addition of thiram, the quenched emissions are recovered, with a linear signal increase in the range from 2 nM to 20 nM of thiram and a limit of detection of 0.26 nM. The nanoprobe was further integrated into a test paper for visual detection. The concentration-dependent color change that varies from red to cyan and bluish violet and then to white can be visually distinguished.
KeywordsUpconversional nanoprobe Lead-dithizone complex Energy transfer Test paper Color-differentiation
The work was supported by National Natural Science Foundation of China (31671011), and grants from the Ministry of Education of Singapore (MOE2016-T3-1-004, R-397-000-270-114).
Compliance with ethical standards
The authors declare that they have no competing interests.