Selective Fluorescence Turn-On and Ratiometric Detection of Organophosphate Using Dual-Emitting Mn-Doped ZnS Nanocrystal Probe

Abstract

Semiconductor nanocrystals (NCs) possess unique photoluminescent properties which can be used to design fluorescence probes for chemo/biosensing applications. Several have recently emerged that offer excellent turn-on or ratiometric fluorescence chemosensory protocols by sophisticated procedures, but it has been challenging to realize all of these advantages in a single construct. Herein, we develop an intrinsic dual-emitting Mn-doped ZnS nanocrystal-based probe that achieves this goal with turn-on and ratiometric fluorescence response for the determination of organophosphate (diethylphosphorothioate, DEP). The probe relies on the modification of dopamine dithiocarbamate on the surface of NCs and the modulation of dual emission through a photoinduced electron transfer process, which makes use of red fluorescence of Mn(2+) ions doped in the NCs as specific recognition for the target analyte and blue defect emission of the NCs as stable internal reference. In presence of DEP, the red emission of the probe is thus enhanced by switching off the electron transfer pathway, while the blue emission is almost unchanged. With the addition of different amounts DEP, the two emission intensity ratios gradually vary and display color changes from dark-blue to purple to red. Thus, this method generates turn-on and ratiometric fluorescence signals for quantitative and visual detection of the analyte. Significantly, the dual-emitting probe has been used to fabricate paper-based test strips for visual detection of DEP residues, which validate the method for its rapid, on-site, and visual identification.

L-cysteine capped ZnS:Mn quantum dots for room-temperature detection of dopamine with high sensitivity and selectivity

“…Since urine is mainly composed of amino acids, glucose and anions/cations, our recovery results further confirm that these co-existing biomolecules do not significantly interfere with the DA detection in diluted urine samples. Using this approach, similar results were reported to detect AA, vanillin, cyanide ions and organophosphate in urine, food, tap/ground and lake water, respectively (Bian et al, 2013;Duran et al, 2015;Shamsipur et al, 2014;Zhang et al, 2014). Finally, our findings reveal the potential applicability and accuracy of our ZnS:Mn phosphorescent probes to detect DA in biological fluids with high sensitivity and selectivity.…”

A molecular imprinting-based turn-on Ratiometric fluorescence sensor for highly selective and sensitive detection of 2,4-dichlorophenoxyacetic acid (2,4-D)

“…However, either turn off or turn on fluorescence intensity as a sole responsive signal, the signal is easily interfered by various experimental factors, such as the change in fluorescence intensity and instrumental conditions. Excitingly, ratiometric measurements have the advantages to eliminate these environmental effects and give more precise measurement owing to their self-referencing capability by calculation of two emission intensity ratio instead of the absolute intensity of one peak (Liu et al, 2013;Wang et al, 2016;Zhang et al, 2014). In general, two individual materials with different fluorescence emission wavelengths can be used to build ratiometric sensors (Xu and Lu, 2015).…”

Molecular imprinting ratiometric fluorescence sensor for highly selective and sensitive detection of phycocyanin

“…Owing to the improved sensitivity, ratiometric fluorescence technique has attracted increasing attention for trace level analysis. For example, Wang's group proposed several ratiometric probes for the visual observation of fluorescence color changes induced by analytes without the need of elaborate equipment (Yao et al, 2013;Zhang et al, 2014;Zhu et al, 2014). Zhang's group developed a nanohybrid ratiometric fluorescence sensor for selective detection of mercuric ions.…”