A highly sensitive bio-barcode immunoassay for multi-residue detection of organophosphate pesticides based on fluorescence antiquenching

Balancing the risks and benefits of organophosphate pesticides(OPs)on human and environmental health relies partly on their accurate measurement.A highly sensitive fluorescence anti-quenching multi-residue bio-barcode immunoassay was developed to detect OPs(triazophos,parathion,and chlorpyrifos)in apples,turnips,cabbages,and rice.Gold nanoparticles were functionalized with monoclonal antibodies against the tested OPs.DNA oligonucleotides were complementarily hybridized with an RNA fluorescent label for signal amplification.The detection signals were generated by DNA-RNA hybridization and ribonuclease H dissociation of the fluorophore.The resulting fluorescence signal enables multiplexed quantification of triazophos,parathion,and chlorpyrifos residues over the concentration range of 0.01-25,0.01-50,and 0.1-50 ng/mL with limits of detection of 0.014,0.011,and 0.126 ng/mL,respectively.The mean recovery ranged between 80.3% and 110.8% with relative standard deviations of 7.3%-17.6%,which correlate well with results obtained by liquid chromatography-tandem mass spectrometry(LC-MS/MS).The proposed bio-barcode immunoassay is stable,reproducible and reliable,and is able to detect low residual levels of multi-residue OPs in agricultural products.

Development of an analytical method for multi-residue quantification of 18 anthelmintics in various animal-based food products using liquid chromatography-tandem mass spectrometry

In this study,we developed a simple screening procedure for the determination of 18 anthelmintics(including benzimidazoles,macrocyclic lactones,salicylanilides,substituted phenols,tetrahydropyrimidines,and imidazothiazoles)in five animal-derived food matrices(chicken muscle,pork,beef,milk,and egg)using liquid chromatography-tandem mass spectrometry.Analytes were extracted using acetonitrile/1% acetic acid(milk and egg)and acetonitrile/1% acetic acid with 0.5 mL of distilled water(chicken muscle,pork,and beef),and purified using saturated n-hexane/acetonitrile.A reversed-phase analytical column and a mobile phase consisting of(A)10 mM ammonium formate in distilled water and(B)methanol were used to achieve optimal chromatographic separation.Matrix-matched standard calibration curves(R^(2)≥0.9752)were obtained for concentration equivalent to ×1/2,×1,×2,×3,×4,and×5 fold the maximum residue limit(MRL)stipulated by the Korean Ministry of Food and Drug Safety.Recoveries of 61.2e118.4%,with relative standard deviations(RSDs)of ≤19.9%(intraday and interday),were obtained for each sample at three spiking concentrations(×1/2,×1,and ×2 the MRL values).Limits of detection,limits of quantification,and matrix effects were 0.02e5.5 mg/kg,0.06e10 mg/kg,and -98.8 to 13.9%(at 20 μg/kg),respectively.In five samples of each food matrix(chicken muscle,pork,beef,milk,and egg)purchased from large retailers in Seoul that were tested,none of the target analytes were detected.It has therefore been shown that this protocol is adaptable,accurate,and precise for the quantification of anthelmintic residues in foods of animal origin.

Combined metabolic activators improve cognitive functions in Alzheimer’s disease patients:a randomised,double-blinded,placebo-controlled phase-II trial

Background Alzheimer’s disease(AD)is associated with metabolic abnormalities linked to critical elements of neurodegeneration.We recently administered combined metabolic activators(CMA)to the AD rat model and observed that CMA improves the AD-associated histological parameters in the animals.CMA promotes mitochondrial fatty acid uptake from the cytosol,facilitates fatty acid oxidation in the mitochondria,and alleviates oxidative stress.Methods Here,we designed a randomised,double-blinded,placebo-controlled phase-II clinical trial and studied the effect of CMA administration on the global metabolism of AD patients.One-dose CMA included 12.35 g L-serine(61.75%),1 g nicotinamide riboside(5%),2.55 g N-acetyl-L-cysteine(12.75%),and 3.73 g L-carnitine tartrate(18.65%).AD patients received one dose of CMA or placebo daily during the first 28 days and twice daily between day 28 and day 84.The primary endpoint was the difference in the cognitive function and daily living activity scores between the placebo and the treatment arms.The secondary aim of this study was to evaluate the safety and tolerability of CMA.A comprehensive plasma metabolome and proteome analysis was also performed to evaluate the efficacy of the CMA in AD patients.Results We showed a significant decrease of AD Assessment Scale-cognitive subscale(ADAS-Cog)score on day 84 vs day 0(P=0.00001,29%improvement)in the CMA group.Moreover,there was a significant decline(P=0.0073)in ADAS-Cog scores(improvement of cognitive functions)in the CMA compared to the placebo group in patients with higher ADAS-Cog scores.Improved cognitive functions in AD patients were supported by the relevant alterations in the hippocampal volumes and cortical thickness based on imaging analysis.Moreover,the plasma levels of proteins and metabolites associated with NAD+and glutathione metabolism were significantly improved after CMA treatment.Conclusion Our results indicate that treatment of AD patients with CMA can lead to enhanced cognitive functions and improved clinical parameters associated with phenomics,metabolomics,proteomics and imaging analysis.