PVA/Stevia/MIL-88A@AuNPs composite nanofibers as a novel sorbent for simultaneous extraction of eight agricultural pesticides in food and vegetable samples followed by HPLC-UV analysis

An ultra-sensitive photoelectrochemical biosensing platform based on the AgVO3/BiOI heterojunction for an enzyme activity inhibition reaction

An ultra-sensitive photoelectrochemical sensing platform for profenofos detection based on the inhibition of catalase activity was prepared in this work. First, the novel functional nanocomposite material AgVO3/BiOI was prepared by a hot solvent method and successive ion layer adsorption reaction. Then, chitosan was employed as a dispersion medium to disperse and immobilize the catalase. Under visible light irradiation, the prepared CAT/CS/AgVO3/BiOI/ITO nanocomposite electrode generates a stable low photocurrent in hydrogen peroxide solution. When this electrode is immersed in a phosphate buffer solution containing profenofos, the activity of the catalase is inhibited, resulting in an increase in the photocurrent. Under the optimized experimental conditions, the profenofos concentration and increase in photocurrent are linearly related in the concentration range of 1 × 10-10 to 5.0 × 10-8 mol L-1, and the limit of detection is 1.0 × 10-11 mol L-1. This biosensor shows good selectivity for detecting profenofos in fruits and vegetables, and the determination results of profenofos are satisfactory.

Imidazolium-decorated Bis-cyanostilbene Macrocycle: An Effect Fluorescence Sensor for Pesticide Starane

Fluorescence sensors for complicated molecules such as pesticides were paid much attention lately due to the merits of simple operation, high sensitivity and selectivity, and in-situ detection. In this work, a novel fluorescent sensor for pesticide starane was prepared based on imidazolium-decorated bis-cyanostilbene macrocycle (IBM). IBM exhibited the obvious "turn-on" fluorescence change from dark blue-green to bright blue after sensing starane with the high sensing selectivity among 28 kinds of guests. The detecting limitation was as low as 0.011 μM, which was the lowest one in literatures. The sensing mechanism was confirmed as that starane was located in cavity of IBM based on the molecular interaction of multiple hydrogen bonds, π-π stacking and hydrophobic interaction. The application experiments suggested that starane was examined well on test paper with good selectivity and was quantitatively detected in water samples, implying the good real-time and in-situ application potential for IBM on sensing starane in real environment and daily life.

The preparation, resources, applications, and future trends of nanofibers in active food packaging: a review

Active packaging is a novel strategy for maintaining the shelf life of products and ensuring their safety, freshness, and integrity that has emerged with the consumer demand for safer, healthier, and higher quality food. Nanofibers have received a lot of attention for the application in active food packaging due to their high specific surface area, high porosity, and high loading capacity of active substances. Three common methods (electrospinning, solution blow spinning, and centrifugal spinning) for the preparation of nanofibers in active food packaging and their influencing parameters are presented, and advantages and disadvantages between these methods are compared. The main natural and synthetic polymeric substrate materials for the nanofiber preparation are discussed; and the application of nanofibers in active packaging is elaborated. The current limitations and future trends are also discussed. There have been many studies on the preparation of nanofibers using substrate materials from different sources for active food packaging. However, most of these studies are still in the laboratory research stage. Solving the issues of preparation efficiency and cost of nanofibers is the key to their application in commercial food packaging.

A novel sorbent based on electrospun for electrically-assisted solid phase microextraction of six non-steroid anti-inflammatory drugs, followed by quantitation with HPLC-UV in human plasma samples

BACKGROUND

Although NSAIDs possess notable therapeutic and pharmaceutical qualities, it's essential to acknowledge that excessive doses can result in toxicity within the human body. Moreover, the importance lies in identifying and measuring their trace amounts. Due to their existence within intricate matrices, the creation of novel electrospun nanofibers as sorbents for electrically-assisted solidphase microextraction (EA-SPME) becomes vital. This innovation caters to the requirement for the effective pre-treatment of NSAID samples, providing a strategic approach to managing the complexities associated with trace quantities found in various matrices.

RESULTS

First, polyvinylalcohol/casein/tannic acid/polyaniline/titanium dioxide nanoparticles (PVA/CAS/TA/PANI/TiO2 NPs) electrospun nanofibers were prepared for EA-SPME on pewter rode and then, trace amounts of six NSAIDs (Acetaminophen, Caffeine, Naproxen, Celecoxib, Ibuprofen and mefenamic acid) were adsorbed chemically on these nanofibers. In the next step, the desorption of six NSAIDs was electrochemically done from prepared electrospun nanofibers on a pewter rod which was as working electrode at three electrodes system. Finally, these drugs were quantified from different human plasma samples with HPLC-UV. The synthesis of electrospun nanofibers was confirmed through a series of analytical techniques including field emission-scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy with elemental mapping analysis (EDX-Mapping), X-ray diffraction (XRD), and Fourier transform-infrared (FT-IR). The optimal percentage of additive compounds to PVA/CAS for electrospinning, as well as the factors influencing adsorption and desorption processes, were determined through both of Design Expert software and MATLAB programming language.

SIGNIFICANCE

Under optimum conditions, the wide linear range was 27-8000 ng mL-1 with R2≥ 0.9897, low detection limits were ranged from 8 to 27.3 ng mL-1 based on S/N = 3 and significant enrichment factors were acquired. The intra-day and inter-day RSDs% were obtained within the 4.51% - 5.68% and 4.28%-5.45%, respectively. Finally, The effectiveness of the EA-SPME-HPLC-UV method was assessed for determining NSAIDs in plasma samples, demonstrating good recoveries ranging from 90.2% to 105.2%.

Monitoring 432 potential pesticides in tomatoes produced and commercialized in Souss Massa region-Morocco, using LC-MS/MS and GC-MS/MS

In this work, we monitored 432 pesticide residues in 39 tomato samples (cherry tomato) obtained from local markets in Souss Massa region-Morocco. We used a QuEChERS combined with LC-MS/MS and GC-MS/MS, and the method was validated based on SANTE 11312/2021 guideline. The limits of quantification (LOQ) obtained for most of the pesticides analyzed are at the limit with default EU MRLs or well below other EU MRLs. Recoveries (between 70 and 120%) and RSDs (≤20%) are satisfactory for more than 95% of the analytes at spiking level of 0.01 mg/kg and more than 97% at 0.1 mg/kg. The results indicated that 22 out of 39 tomato samples are positives and the most of our samples had levels lower than the maximum residue levels (MRLs) with average concentrations between 0.011 and 0.156 mg/kg. The most found pesticides were azoxystrobin and difenoconazole in tomato (7 samples). Only buprofezin (0.095 mg/kg) was found above the EU MRLs (0.01 mg/kg). Also, banned pesticides namely benalaxyl, spirodiclofen and imidacloprid have been detected. The results of our study confirm the previous findings and gives insights on the occurrence of different pesticides in tomato samples from Souss Massa region-Morocco.

Design and development of second-generation fabric phase sorptive extraction membranes: Proof-of-concept for the extraction of organophosphorus pesticides from apple juice prior to GC-MS analysis

In this work, different sol-gel sorbent-coated second-generation fabric phase sorptive extraction (FPSE) membranes were synthesized using titania-based sol-gel precursors. The proposed membranes were tested for their efficiency to extract eleven selected organophosphorus pesticides (OPPs) from apple juice samples. Among the examined materials, sol-gel C₁₈ coated titania-based FPSE membranes showed the highest extraction efficiency. These membranes were used for the optimization and validation of an FPSE method prior to analysis by gas chromatography-mass spectrometry. The detection limits for OPPs ranged between 0.03 and 0.08 ng mL^-1. Moreover, the relative standard deviation was < 8.2% and 8.4% for intra-day and inter-day studies, respectively. The relative recoveries were 91-110% (intra-day study) and 90-106% (inter-day study) for all the target analytes, demonstrating good overall method accuracy. Moreover, the novel membranes were reusable at least 5 times. The titania-based membranes were compared to the conventional silica-based membranes and their utilization resulted in higher extraction recoveries.

Polyvinyl alcohol/citric acid/β-cyclodextrin/CuONP composite nanofibers as an effective and green absorbent for the simultaneous extraction of three antidepressant drugs in biological fluids prior to GC-FID analysis

Composite nanofibers, namely, polyvinyl alcohol (PVA), citric acid (CA), β-cyclodextrin (β-CD), and copper oxide nanoparticles (PVA/CA/β-cyclodextrin/CuO NPs), were developed as a novel, green, and efficient adsorbent in the pipette tip-micro-solid-phase extraction method (PT-µSPE), for the simultaneous extraction of three antidepressants drugs namely imipramine (IMP), citalopram (CIT), and clozapine (CLZ) in biological fluids before quantification by gas chromatography (GC-FID). Based on the obtained results from field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD), the successful synthesis of composite nanofibers was approved. Due to the presence of β-cyclodextrins and CuO NPs rich of functional groups on their surface, the nanofibers have high extraction efficiency. Under the optimal conditions, the linear range for imipramine, citalopram, and clozapine was 0.1 to 1000.0 ng mL^-1 with a determination coefficient ≥ 0.99. The limits of detection (LODs) were in the range 0.03 to 0.15 ng mL^-1. The relative standard deviation was 4.8 to 8.7% (within-day, n = 4) and 5.1 to 9.2% (between-day, n = 3) for 3 consecutive days. In addition, excellent clean-up was achieved which is a great advantage over other sample preparation methods. Finally, the ability of the developed method to extract the target analytes from the biological samples was evaluated.

Electrospun composite nanofibers modified with silver nanoparticles for extraction of trace heavy metals from water and rice samples: An highly efficient and reproducible sorbent

Herein, a composite of polyacrylonitrile (PAN)/agar/silver nanoparticles (AgNPs) electrospun nanofibers was fabricated and applied as an efficient sorbent for thin-film micro-extraction (TFME) of five metal ions followed by inductively coupled plasma optical emission spectroscopy (ICP-OES). Incorporating agar into the nanofibers followed by in situ photo-reductive reaction under UV-lamp resulted in highly uniform dispersion of AgNPs in the nanofibers. Under the optimized conditions, agreeable linearity was acquired in the range of 0.5-250.0 ng mL^-1 (R² ≥ 0.9985). The LODs (based on S/N = 3) were attained in the range of 0.2 to 0.5 ng mL^-1. The relative standard deviations (RSDs) were between 4.5% and 5.6% (intra-day, n = 5) and 5.3%-5.9% (inter-day, n = 3) for three sequential days. The developed method was investigated with water and rice samples, and recoveries (93.9-98.0%) indicated that the PAN/agar/AgNPs could be a promising film for the adsorption of heavy metal ions in varied samples.

High-Speed Centrifugal Spinning Polymer Slip Mechanism and PEO/PVA Composite Fiber Preparation

Composite nanofibers with excellent physical and chemical properties are widely used in new energy, biomedical, environmental, electronic, and other fields. Their preparation methods have been investigated extensively by many experts. High-speed centrifugal spinning is a novel method used to fabricate composite nanofibers. The slip mechanism of polymer solution flows is an important factor affecting the morphology and quality of composite nanofibers prepared by high-speed centrifugal spinning. As the polymer solution flows, the liquid wall slip occurs inside the nozzle, followed by liquid-liquid interface slip and gas-liquid interface slip. The factors affecting polymer slip were investigated by developing a mathematical model in the nozzle. This suggests that the magnitude of the velocity is an important factor that affects polymer slip and determines fiber quality and morphology. Under the same rotational speed, the smaller the nozzle diameter, the greater the concentration of velocity distribution and the smaller the diameter of the produced composite nanofibers. Finally, PEO/PVA composite nanofibers were prepared using high-speed centrifugal spinning equipment at 900-5000 rpm and nozzle diameters of 0.2 mm, 0.4 mm, 0.6 mm, and 0.8 mm. The morphology and quality of the collected PEO/PVA composite nanofibers were analyzed using scanning electron microscopy (SEM) and TG experiments. Then, the optimal parameters for the preparation of PEO/PVA composite nanofibers by high-speed centrifugal spinning were obtained by combining the external environmental factors in the preparation process. Theoretical evaluation and experimental data were provided for the centrifugal composite spinning slip mechanism and for the preparation of composite nanofibers.

Application of electrospun composite nanofibers as an efficient sorbent for extraction of pesticides from food samples

Herein, the composite of polylactic acid (PLA)/ Iron-based metal-organic framework (r-MIL-88A)/ Cellulose electrospun nanofibers was fabricated; and then, applied as a novel sorbent for thin-film micro-extraction (TFME) of four selected pesticides followed by GC-FID analysis. From the evaluation of scanning electron microscopy, Fourier transform infrared spectroscopy energy dispersive X-ray spectroscopy and X-ray diffraction, the successful fabrication of composite nanaofibers was approved. The presence of r-MIL-88A/Cellulose with large surface area and plenty of OH-functional groups results in improving PLA extraction efficiency. The effect of various main parameters on extraction efficiency was evaluated. The LODs (based on S/N = 3) were in the range of 1.0 to 1.5 ng mL^-1. Intra-day and inter-day relative standard deviations (RSDs) were in the range of 4.8% - 5.6% and 5.2%-6.4%, respectively. In addition, the fiber to fiber relative standard deviations were observed in the range of 5.2%-12.3%. By using the optimized factors, acceptable linearity ranges were obtained in the range of 3.0-1900.0 ng mL^-1 for metribuzin and ethofumasate, and 5.0-2000.0 for atrazine and ametryn (R² = 0.9913-0.9967). The developed method was investigated in fruit juice, vegetables, milk and honey samples, and recoveries (79.3-95.6%) indicate that the PLA/r-MIL-88A/Cellulose can be a prominent composite film for the extraction of the target analytes in various samples.

Nanomaterials-Based Electrochemiluminescence Biosensors for Food Analysis: Recent Developments and Future Directions

Developing robust and sensitive food safety detection methods is important for human health. Electrochemiluminescence (ECL) is a powerful analytical technique for complete separation of input source (electricity) and output signal (light), thereby significantly reducing background ECL signal. ECL biosensors have attracted considerable attention owing to their high sensitivity and wide dynamic range in food safety detection. In this review, we introduce the principles of ECL biosensors and common ECL luminophores, as well as the latest applications of ECL biosensors in food analysis. Further, novel nanomaterial assembly strategies have been progressively incorporated into the design of ECL biosensors, and by demonstrating some representative works, we summarize the development status of ECL biosensors in detection of mycotoxins, heavy metal ions, antibiotics, pesticide residues, foodborne pathogens, and other illegal additives. Finally, the current challenges faced by ECL biosensors are outlined and the future directions for advancing ECL research are presented.

Rapid Detection of Malathion, Phoxim and Thiram on Orange Surfaces Using Ag Nanoparticle Modified PDMS as Surface-Enhanced Raman Spectroscopy Substrate

Malathion, phoxim, and thiram are organophosphates and organosulfur pesticides widely used in agricultural products. The residues of these pesticides present a direct threat to human health. Rapid and on-site detection is critical for minimizing such risks. In this work, a simple approach was introduced using a flexible surface-enhanced Raman spectroscopy (SERS) substrate. The prepared Ag nanoparticles-polydimethylsiloxane (AgNPs-PDMS) substrate showed high SERS activity, good precision (relative standard deviation = 5.33%), and stability (30 days) after optimization. For target pesticides, the linear relationship between characteristic SERS bands and concentrations were achieved in the range of 10~1000, 100~5000, and 50~5000 μg L-1 with LODs down to 3.62, 41.46, and 15.69 μg L-1 for thiram, malathion, and phoxim, respectively. Moreover, SERS spectra of mixed samples indicated that three pesticides can be identified simultaneously, with recovery rates between 96.5 ± 3.3% and 118.9 ± 2.4%, thus providing an ideal platform for detecting more than one target. Pesticide residues on orange surfaces can be simply determined through swabbing with the flexible substrate before acquiring the SERS signal. This study demonstrated that the prepared substrate can be used for the rapid detection of pesticides on real samples. Overall, this method greatly simplified the pre-treatment procedure, thus serving as a promising analytical tool for rapid and nondestructive screening of malathion, phoxim, and thiram on various agricultural products.