Optical sensing of 3-phenoxybenzoic acid as a pyrethroid pesticides exposure marker by surface imprinting polymer capped on manganese-doped zinc sulfide quantum dots

The present communication deals with the synthesis of luminescent Mn-doped ZnS quantum dots (QDs) anchored to surface imprinted polymer for the optical sensing of 3-phenoxy benzoic acid (3-PBA) in urine samples. The combination of sensing and surface functionalization not only improves the selectivity of the method, but also increases the optosensing ability of the material for non-phosphorescent substances. The developed material was utilized for the selective and sensitive detection of 3-PBA in urine samples. The proposed method shows good linearity with a regression coefficient (R2) of 0.98. The limit of detection was found to be 0.117 μM. The method has an acceptable precision and accuracy which are found to be less than 8% and 80–90% respectively at three different concentrations. The quenching constant of quantum dot-molecular imprinted polymer was found to be 3.4 times higher to that of the quantum dot-non imprinted polymer (QD-NIP) as calculated by Stern–Volmer equation. The sensing method developed has shown immense utility to detect 3-PBA in complex biological samples like urine

Gas Chromatography- Mass Spectrometry Based Metabolomic Approach for Optimization and Toxicity Evaluation of Earthworm Sub-Lethal Responses to Carbofuran

<div><p>Despite recent advances in understanding mechanism of toxicity, the development of biomarkers (biochemicals that vary significantly with exposure to chemicals) for pesticides and environmental contaminants exposure is still a challenging task. Carbofuran is one of the most commonly used pesticides in agriculture and said to be most toxic carbamate pesticide. It is necessary to identify the biochemicals that can vary significantly after carbofuran exposure on earthworms which will help to assess the soil ecotoxicity. Initially, we have optimized the extraction conditions which are suitable for high-throughput gas chromatography mass spectrometry (GC-MS) based metabolomics for the tissue of earthworm, <i>Metaphire posthuma</i>. Upon evaluation of five different extraction solvent systems, 80% methanol was found to have good extraction efficiency based on the yields of metabolites, multivariate analysis, total number of peaks and reproducibility of metabolites. Later the toxicity evaluation was performed to characterize the tissue specific metabolomic perturbation of earthworm, <i>Metaphire posthuma</i> after exposure to carbofuran at three different concentration levels (0.15, 0.3 and 0.6 mg/kg of soil). Seventeen metabolites, contributing to the best classification performance of highest dose dependent carbofuran exposed earthworms from healthy controls were identified. This study suggests that GC-MS based metabolomic approach was precise and sensitive to measure the earthworm responses to carbofuran exposure in soil, and can be used as a promising tool for environmental eco-toxicological studies.</p></div

Earthworm metabolite responses to carbofuran exposure 1) control group 2) concentration of 0.15 mg kg⁻¹ exposed group 3) concentration of 0.3 mg kg⁻¹ exposed group 4) concentration of 0.6 mg kg⁻¹ exposed group.

<p>Earthworm metabolite responses to carbofuran exposure 1) control group 2) concentration of 0.15 mg kg⁻¹ exposed group 3) concentration of 0.3 mg kg⁻¹ exposed group 4) concentration of 0.6 mg kg⁻¹ exposed group.</p

Clustered heat map of intracellular metabolites extracted using A) MCW B) AMW C) Pure MeOH D) MIPW E) 80% MeOH.

<p>Clustered heat map of intracellular metabolites extracted using A) MCW B) AMW C) Pure MeOH D) MIPW E) 80% MeOH.</p

Principle component analysis (PCA) A) scores and B) loadings plots for 1.control earthworms and earthworms exposed to soil spiked with 2. Concentration of 0.1 mg/Kg, 3. Concentration of 0.3 mg/Kg, and 4. Concentration of 0.6 mg/Kg of carbofuran.

<p>Principle component analysis (PCA) A) scores and B) loadings plots for 1.control earthworms and earthworms exposed to soil spiked with 2. Concentration of 0.1 mg/Kg, 3. Concentration of 0.3 mg/Kg, and 4. Concentration of 0.6 mg/Kg of carbofuran.</p

Compounds structurally identified from earthworm, <i>Metaphire.posthuma</i> by GC-MS.

<p>Rt  =  retention time, Idn  =  identification, A  =  These compounds are confirmed by authentic standards, B  =  These compounds are identified by NIST library Mass Spectral fragmentation pattern.</p

PCA of optimization of extraction solvent system for global metabolite profiling of earthworm <i>Metaphire posthuma</i> A) scores plot, explaining the extraction efficiency of different solvent systems 1. 80% MeOH, 2. Pure MeOH, 3. MIPW, 4. MCW, 5. AMW. B) Loadings plot.

<p>PCA of optimization of extraction solvent system for global metabolite profiling of earthworm <i>Metaphire posthuma</i> A) scores plot, explaining the extraction efficiency of different solvent systems 1. 80% MeOH, 2. Pure MeOH, 3. MIPW, 4. MCW, 5. AMW. B) Loadings plot.</p

Predictive accuracy of the model discriminating carbofuran exposed and healthy control earthworms summarised using ROC curve analysis.

<p>Area under the curve = 0.99.</p

Key putatively identified metabolic perturbations from GC MS based metabolomic analyses of earthworms after exposed to carbofuran.

<p>Key putatively identified metabolic perturbations from GC MS based metabolomic analyses of earthworms after exposed to carbofuran.</p