Overlapping of Second Order Scattering and Frequency Double Scattering Spectra Method and Resonance Rayleigh Scattering Method for the Determination of 6-Benzyladenine in Bean Sprout

An anti-scratch flexible SERS substrate for pesticide residue detection on the surface of fruits and vegetables

We propose an anti-scratch flexible surface-enhanced Raman scattering substrate with arrayed nanocavity microstructures fabricated by colloidal lithography. The nanocavity microstructure of the substrate can well protect the inner gold nanoparticles during wipe sampling. The prepared flexible substrate was able to detect 4-aminothiophenol (4-ATP) with a concentration down to 1 fM. Furthermore, the substrate was used to detect 6-BA residues on the surface of apples and bean sprouts through wipe sampling, which shows great potential in the field of rapid on-site detection, especially in the detection of pesticide residues on the surface of fruits and vegetables.

Developmental toxicity and alteration of gene expression in zebrafish embryo exposed to 6-benzylaminopurine

6-benzylaminopurine (6-BA) is widely used in agriculture and horticulture as plant growth regulator. Its excessive use may pose a potential risk to both environment and human health, which is causing great concern. This study was undertaken to assess the acute developmental toxicity of 6-BA to zebrafish embryos based on OECD protocols and mortality, hatching rate and malformation were investigated. Results showed that the 96 h-LC₅₀ and 96 h- EC₅₀ values were 63.29 mg/L and 41.86 mg/L, respectively. No mortality or teratogenic effects were found at concentrations lower than 10 mg/L 6-BA at concentrations higher than 50 mg/L significantly inhibited hatchability and embryo development, induced serious toxicity characterized by morphologic abnormalities (elongated pericardium, heart and yolk sac edema, spine curvature) and functional failure (slow spontaneous movement and heart rate, growth retardation, yolk sac absorption retention). Moreover, 6-BA-induced apoptosis was observed in embryos by the acridine orange staining and confirmed by the apoptotic-related genes, all of which p53 was significantly up-regulated at concentrations higher than 10 mg/L, bax at concentrations higher than 12.5 mg/L, while bcl2 was down-regulated at concentrations higher than 25 mg/L. As for genes of cardiac development, qPCR results demonstrated that nkx2.5, gata5, and amhc were significantly down-regulated at concentrations higher than 25 mg/L, vmhc and atp2a2a at concentration of 50 mg/L, in contrast, hand2 was up-regulated at concentration of 50 mg/L. Our data indicate that 6-BA induces a dose-dependent toxicity resulting in apoptosis through the involvement of p53-dependent pathways and hindering normal heart development in zebrafish embryos.

Simultaneous determination of cytokinins by high performance liquid chromatography with resonance Rayleigh scattering and mechanism discussion

A reliable, highly sensitive and highly selective method of high performance liquid chromatography associated with resonance Rayleigh scattering (HPLC-RRS) was developed to detect three cytokinins, namely, 6-benzylaminopurine (BA), kinetin (KT) and zeatin (ZT). In this work, Pd(ii) is added into the system to form ternary ion association complexes for the first time, which results in a lower limit of detection and extends the application of HPLC-RRS. The experimental conditions were optimized. In order to investigate the reaction mechanism, the ternary ion association complexes were characterized by ultraviolet-visible spectrophotometry, dynamic light scattering, scanning electron microscopy and density functional theory calculations. In a HAc-NaAc buffer solution (pH = 4.1), a ternary complex of cytokinin : Pd(ii) : EryB (1 : 1 : 2) was formed. The detection limits (S/N = 3) of BA, KT, and ZT were 0.9, 1.5 and 2.3 ng mL-1, respectively. In addition, this method was applied for the simultaneous detection of cytokinins in real samples with satisfactory results.

Colorimetric recognition of 6-benzylaminopurine in environmental samples by using thioglycolic acid functionalized silver nanoparticles

A simple and selective colorimetric sensor thioglycolic acid capped silver nanoparticles (TGA-AgNPs) was developed for the detection of 6-benzylaminopurine (6-BAP). The synthesized TGA-AgNPs were characterized by UV-vis spectroscopy, dynamic light scattering (DLS), and transmission electron microscopic (TEM) techniques. The TGA-AgNPs as a sensor for binding 6-BAP through hydrogen-bonding and π-π bonding that causes large conjugate clusters, resulting in a color change from yellow to reddish orange. The surface plasmon resonance (SPR) band of TGA-AgNPs at 397nm is red-shifted to 510nm, which confirms that 6-BAP induces the aggregation of TGA-AgNPs. Under the optimized conditions, a linear relationship between the absorption ratio (A510nm/A397nm) and 6-BAP concentration was found in the range of 4-26μM. The detection limit of 6-BAP was 0.2μM, which is lower than the other analytical techniques. Moreover, the proposed sensor was successfully applied for the detection of 6-BAP in environmental samples with good recoveries. The proposed assay provides a simple and cost-effective method for the analysis of 6-BAP in vegetable and water samples.

Determination of thorium (IV) using isophthalaldehyde-tetrapyrrole as probe by resonance light scattering, second-order scattering and frequency-doubling scattering spectra

The coordination reaction of thorium (IV) with a ditopic bidentate ligand to form supramolecular polymer was studied by resonance light scattering (RLS) spectra, second-order scattering (SOS) spectra and frequency-doubling scattering (FDS) spectra, respectively. The ditopic bidentate ligand is isophthalaldehyde-tetrapyrrole (IPTP). It was synthesized through a condensation reaction of isophthalaldehyde with pyrrole. The formation of supramolecular polymer results in remarkable intensity enhancements of the three light scattering signals. The maximum scattering wavelengths of RLS, FDS and SOS were 290, 568 and 340nm, respectively. The reaction was used to establish new light scattering methods for the determination of thorium (IV) by using IPTP as probe. Under optimum conditions, the intensity enhancements of RLS, SOS and FDS were directly proportional to the concentration of thorium (IV) in the ranges of 0.01 to 1.2μgmL^-1, 0.05 to 1.2μgmL^-1 and 0.05 to 1.2μgmL^-1, respectively. The detection limits were 0.003μgmL^-1, 0.012μgmL^-1 and 0.021μgmL^-1, respectively. The methods were suitable for analyzing thorium (IV) in actual samples. The results show acceptable recoveries and precision compared with a reference method.

Enzyme-catalyzed Michael addition for the synthesis of warfarin and its determination via fluorescence quenching of l-tryptophan

A sensitive fluorescence sensor for warfarin was proposed via quenching the fluorescence of l-tryptophan due to the interaction between warfarin and l-tryptophan. Warfarin, as one of the most effective anticoagulants, was designed and synthesized via lipase from porcine pancreas (PPL) as a biocatalyst to catalyze the Michael addition of 4-hydroxycoumarin to α, β-unsaturated enones in organic medium in the presence of water. Furthermore, the spectrofluorometry was used to detect the concentration of warfarin with a linear range and detection limit (3σ/k) of 0.04-12.0μmolL^-1 (R²=0.994) and 0.01μmolL^-1, respectively. Herein, this was the first application of bio-catalytic synthesis and fluorescence for the determination of warfarin. The proposed method was applied to determine warfarin of the drug in tablets with satisfactory results.

Facile colorimetric detection of 6-benzylaminopurine based on p-aminobenzenethiol functionalized silver nanoparticles

A simple colorimetric assay has been developed to detect 6-benzylaminopurine (6-BA) in a complex environment by using the novel probe p-aminobenzenethiol functionalized silver nanoparticles (ABT-AgNPs).

A novel method for detecting allura red based on triple-wavelength overlapping resonance Rayleigh scattering

A simple, sensitive and selective assay was established to detect trace allura red with ethyl violet in drinks, based on triple-wavelength overlapping resonance Rayleigh scattering.