A convenient method for determination of malathion based on the resonance Rayleigh scattering enhancement

Sensitive and label-free chemiluminescence detection of malathion using exonuclease-assisted dual signal amplification and G-quadruplex/hemin DNAzyme

Malathion is one of the most commonly used organophosphorus pesticides that can cause serious harm to the ecological environment and human health. Herein, we demonstrated a label-free chemiluminescent aptasensor for the sensitive detection of malathion based on exonuclease-assisted dual signal amplification and G-quadruplex/hemin DNAzyme. Upon the addition of malathion, the aptamer probe specifically bound to the target to form a complex malathion-S3, leaving a duplex S1-S2. The complex malathion-S3 was digested by exonuclease I and the target was released. The released target was recycled to perform exonuclease I-assisted signal amplification. Furthermore, after treatment with exonuclease III, the duplex S1-S2 was converted into the secondary target ST. The secondary target ST interacted with the hairpin H1 to form a complex H1-ST, which was further digested by exonuclease III and released the secondary target. The released secondary target was recycled to perform exonuclease III-assisted signal amplification. After complete amplification, large numbers of G-quadruplex/hemin DNAzymes were generated. Under the optimal experimental conditions, the prepared aptasensor showed an excellent linear response to malathion with a detection limit of 0.47 pM. The relative standard deviations were in the range of 4.2-6.9%. Moreover, the aptasensor was successfully applied to detect malathion in spiked food and traditional Chinese medicine samples.

The triple-wavelength overlapping resonance Rayleigh scattering method and the fluorescence quenching method for the determination of chitooligosaccharides using trisodium-8-hydroxypyrene-1,3,6-trisulfonate as a probe

In this assay, the triple-wavelength overlapping resonance Rayleigh scattering (TWO-RRS) method and the fluorescence quenching method for the quantitative detection of chitooligosaccharides (COS) were developed. In the weakly Britton-Robinson buffer solution, COS interacted with Trisodium-8-hydroxypyrene-1,3,6-trisulfonate (HPTS) to form an ion-association complex of HPTS-COS, which increased the RRS intensities at 321 nm, 430 nm and 511 nm and decreased the fluorescence intensities of the system at 512 nm. And the changes in the intensities of both methods were related to the changes in the concentration of COS. Moreover, for the TWO-RRS method, OP-10 made the RRS intensities increased stronger, finally, the three peaks' total was linear to the concentration of COS in the range of 1.00-8.00 μg/mL and the limit of detection (LOD) was 0.247 μg/mL, and for the fluorescence quenching method, the linear range was 0.50-3.50 μg/mL with the LOD of 0.108 μg/mL. Based on these, two new and fast spectral methods with high sensitivity and simplicity for the determination of trace COS had been established. The generation mechanism of the TWO-RRS and the fluorescence quenching was studied. At the same time, the two methods were applied to the determination of COS in health products with satisfactory results.

A novel spectral method for determination of trace malathion using EryB as light scattering probe by resonance Rayleigh scattering technique

A convenient and sensitive spectrophotometric methods was proposed for determination of Malathion (Mala) using Erythrosin B (EryB) as a probe through the Resonance Rayleigh scattering (RRS) technique. The interaction between EryB, Pd²⁺and malathion in the system was investigated by fluorescence, RRS and UV-Vis spectroscopy. Under the optimum conditions, the RRS intensity of EryB, Pd²⁺ and malathion was weak when exist in alone or any two kinds, however, the RRS intensity of the EryB-Pd²⁺-Mala system had an obvious enhancement due to Pd²⁺ could interact with the hydrolysis products of Mala and EryB each other form a new complexes. At the same time, the fluorescence intensity of EryB was decreased significantly in the presence of Pd²⁺, and the fluorescence intensity of EryB-Pd²⁺ system further decreased when Mala added, interestingly. So it was further proved that there was a forming complex in EryB-Pd²⁺-Mala system. Under the optimal conditions, the RRS enhanced intensity of the system was linearly proportional to the Mala's concentration in the range of 0.012-0.8 μg/mL, and the LOD was 1.7 ng/mL, with the correlation coefficient was R² = 0.9960. So, a new method for determination of Mala was established and this method has been demonstrated in real sample with satisfactory results.