Polyethyleneimine-Sulfur Quantum Dot Composites for Dual-Channel Detection of Tetracycline by Colorimetric and Fluorescence Sensing

Abstract

The residue of tetracycline from food and environment poses a potential threat to public health. Developing a more convenient portable optical detection system has become more demanding than fluorescence detection. This study describes a sensor of sulfur quantum dots (SQDs) with a positively charged passivator for tetracycline in the concentrations from 0.20 to 100 μM and a limit of detection of 0.15 μM (3σ/k). A new optical sensing device was also designed with a smartphone as the detector for sensing the color change from blue to yellow-green upon the addition of tetracycline. In the presence of Eu3+, the detectable color change is extended to red. The verification of the sensing device was applied to the real detection of lake water and milk, with a standard recovery from 93.1 to 109%. This emissive excitation-independent SQD first ensures a sensitive and accurate analysis at very low concentrations and also demonstrates evident color changes upon interaction with tetracycline. The application of this method has provided great convenience for practical detection.

Chiral Sensing of Tryptophan Enantiomers Based on the Enzyme Mimics of β-Cyclodextrin-Modified Sulfur Quantum Dots

“…The transmission electron microscopy (TEM) image (Figure 2a) shows that CD-SQDs have an almost spherical structure and good water dispersion, and the mean particle diameter of CD-SQDs was 3.6 ± 0.11 nm (Figure 2b), which agrees well with the previous studies. 18,19 The surface elemental composition and valence state of CD-SQDs were investigated by XPS, and the survey spectrum is shown in Figure 2c. (2p 2/3 ) and SO 3 2− (2p 1/2 ), respectively.…”

“…Thanks to the great optical properties, water-soluble sulfur quantum dots (SQDs) have been extensively studied since 2014 . As pure-element and environmentally benign metal-free nanoparticles, SQDs have tunable photoluminescence properties, good dispersion, and high photostability, which have been applied for tetracycline detection . Polyethylene glycol-400 (PEG-400)-functionalized SQDs have been prepared by an assembly fission method and demonstrated great potential for photoluminescence and electrochemical luminescence .…”

“…17 As pure-element and environmentally benign metalfree nanoparticles, SQDs have tunable photoluminescence properties, good dispersion, and high photostability, which have been applied for tetracycline detection. 18 pared by an assembly fission method and demonstrated great potential for photoluminescence and electrochemical luminescence. 19 The modification of the surface state of SQDs by changing the passivator/dispersant could effectively change the photophysical and chemical properties of SQDs.…”

CdTe/Silica Nanospheres in a Lateral Flow Immunoassay for Prostate-Specific Antigen

“…Fluorescent labeling is actively important for fluorescent immunoassay strips. , The preparation principle of UQSN is illustrated in Scheme a. Under high temperature and an alkaline environment, QDs grow continuously, while at the same time, the −Si–O- bonds on the surface of DMSN would break, resulting in the release of orthosilicic acid.…”

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“…Polyethyleneimine (PEI) using as a passivator for the synthesis of SQDs, found good water solubility and stablility with a quantum yield of 5 %. 4.0 g of NaOH, 5 mL of PEI and 4.0 g of sublimed sulfur powder dissolved in 50 mL DI water and heated at 75 ºC for 120 h 37 .…”