tellurium and 4-nitrophenol

A dual-response ratiometric fluorescence imprinted sensor based on visible/near-infrared emission was established for ultrasensitive, selective and visual detection 4-nitrophenol (4-NP). The molecularly imprinted polymer was incorporated in the ratiometric sensing system consisting of visible emission carbon dots@zeolitic imidazolate framework-8 (CDs@ZIF-8) and near-infrared emission cadmium telluride (CdTe) quantum dots. The CDs@ZIF-8 enhanced the emission of CDs and the fluorescence sensing performance. Compared to short wavelength of fluorophore, the near-infrared emission CdTe is less interference caused by auto-fluorescence of sample. The ratiometric fluorescence imprinted sensor exhibited dual response for 4-NP at 420 nm and 703 nm and a wide concentration response range. Moreover, a good linear response was existed in the two concentration ranges of 0.1 pM-3.0 pM and 0.05 μM-30 μM with the detection limit of 0.08 pM and 0.05 μΜ, respectively. Significantly, the fluorescence color changes can be observed from purple to pink to red with the naked eye. The fluorescence quenching mechanism of the ratimetric fluorescence imprinted sensor was discussed in detail. The ratiometric fluorescence imprinted sensor was used to detect 4-NP in various real samples with satisfactory recoveries of 97.5-106.3%, which provided an interesting avenue for the rapid detection of pollutant with high sensitivity, high selectivity and visualization in real environment.

Topics: Biosensing Techniques; Cadmium Compounds; Limit of Detection; Metal-Organic Frameworks; Molecular Imprinting; Nitrophenols; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Topics: Alkaline Phosphatase; Cadmium Compounds; Energy Transfer; Fluorescence; Fluorescent Dyes; Humans; Limit of Detection; Nitrophenols; Organophosphorus Compounds; Quantum Dots; Spectrometry, Fluorescence; Sulfides; Tellurium

A sensitive fluorescence probing strategy for parathion-methyl (PM) detection was developed based on electron transfer (ET) between p-nitrophenol (the hydrolysate of PM) and CdTe quantum dots (QDs) in cetyltrimethylammonium bromide (CTAB). PM was hydrolyzed by organophosphorus hydrolase (OPH) to form p-nitrophenol. P-nitrophenol is a typically electron-deficient compound due to the strong electron-withdrawing effect of the nitro groups. The positive charge of CTAB which make it assemble with electronegative mercaptopropionic acid-capped QDs, could be used as an absorbent for p-nitrophenol due to the strong hydrophobic interaction between the long alkyl chain of CTAB and aromatic ring of p-nitrophenol. Thus, the fluorescence intensity of CdTe QDs/CTAB probe could be quenched by p-nitrophenol due to the ET mechanism. The fluorescence intensity of the QD/CTAB system was proportional to PM concentration in the range of 25-3000 ng mL(-1), with a detection limit of 18 ng mL(-1). Furthermore, the proposed method was simple in design and fast in operation, and has been successfully used for PM detection in environmental and agricultural samples with satisfactory recovery.

Topics: Cadmium Compounds; Cetrimonium; Cetrimonium Compounds; Fluorescent Dyes; Limit of Detection; Methyl Parathion; Nitrophenols; Oryza; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water