Thiram Pesticide Research Articles

A novel self-powered SERS platform PVDF-HFP/BZT-BCT@PDA/Ag based on piezoelectricity for sensitive detection of food contaminants

Electrically modulated surface-enhanced Raman scattering (E-SERS) enhances Raman signals by adjusting the plasmon resonance of noble metal nanostructures with an electric field. However, traditional E-SERS substrates require complex electrochemical setups, limiting portability. Piezoelectric materials, which generate surface charges under external forces, present a promising alternative. This study develops a novel self-powered E-SERS substrate by embedding piezoelectric material 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) in polyvinylidene difluoride-hexafluoropropylene (PVDF-HFP) matrix combined with silver nanoparticles. Experiments with nanogenerator piezoelectricity reveal that pressing the substrate with a finger generates current and voltage, providing an electric field for SERS enhancement. Gradual addition of weights on the substrate significantly boosts Raman signals of molecules like p-aminothiophenol (PATP), crystal violet (CV), thiram, and methyl bromide (MB). The synergy of piezoelectric effect and localized plasmon resonance achieves high sensitivity, reproducibility, and detection limits down to 10−9 M, with an enhancement factor of 109. Moreover, the sensor effectively detects trace MB veterinary drug residues in fish meat and thiram pesticide residues on apple skin, introducing a new self-powered E-SERS platform for sensitive food contaminant detection.

Flexible paper-based Ag dendritic SERS chips for rapid in situ detection of thiram residues on pear skin.

Surface-enhanced Raman scattering (SERS) is a powerful, highly efficient analytical technique capable of providing label-free, non-invasive, rapid, and ultrasensitive molecular detection down to the single-molecule level. Despite its advantages, SERS remains largely confined to laboratory settings due to the complexities of substrate fabrication and challenges in analyzing real-world samples. Developing flexible SERS substrates that achieve both high fabrication efficiency and high sensing performance, while being practical for field applications, is critical for advancing SERS toward broader, real-world use. In this study, we present a novel paper-based Ag dendritic SERS chip, fabricated via a simple chemical reduction process that directly forms Ag dendritic nanostructures on cellulose fibers. This chip substrate demonstrates exceptional sensitivity for the detection of thiram pesticide, with a detection limit as low as 7.76 × 10-11 M. The chip substrate also exhibits outstanding reliability, with reproducibility and repeatability both less than 5%. Furthermore, the flexible nature of the paper substrate enables it to conform to curved surfaces and be in direct contact with analytes, exemplified by its ability to adhere to and retrieve thiram from pear skin using a novel "paste-and-peel-off" technique. The substrate shows remarkable performance for thiram detection on pear skin, with sharp recovery rates ranging from 90% to 105%. With its facile fabrication, excellent sensitivity, high reliability, and practical applicability in non-invasive sampling, the paper-based Ag dendritic SERS substrate offers significant potential as an advanced substrate to bring SERS out of the laboratory and closer to real-world applications.

Dual hot-spot SERS test strip for picomole level analysis of thiram

The misuse and improper disposal of thiram pesticide present significant health and environmental risks, emphasizing the need for highly sensitive detection methods, particularly in food safety. In this study, we introduce a novel approach for thiram detection using surface-enhanced Raman scattering (SERS) test strips with dual hot-spots. Thiram prevents Ag+ from acting as specific bridging molecules in a SERS hotspots model. Initially, the aggregation of 4-aminothiophenol (4-ABT) functionalized silver nanoparticles (AgNPs@4-ABT) can be efficiently triggered by Ag+ ions, simultaneously enhancing the SERS signal of 4-ABT. However, the introduction of thiram inhibits the aggregation of Ag NPs@4-ABT, leading to a reduction in the SERS signal. Based on this principle, we have developed a SERS analysis method for detecting thiram in solution. To address the reliance on initial signal intensity, we translocated the detection system onto cotton fabric. This adjustment not only amplifies the initial signal through the physical aggregation of nanoparticles, creating secondary hotspots, but also improves portability and reduces resource consumption. Compared to the single hotspot solution model, our dual hotspot configuration significantly enhances sensitivity due to the stronger initial signal, achieving an impressive broad linear detection range from 5 × 10−5 to 5 × 10−11 M. This range substantially outperforms the linear range of Ag NPs@4-ABT alone, which spans from 5 × 10−5 to 10−8 M. The SERS test strips exhibit a detection limit as low as 2.56 × 10−12 M, enabling picomolar level analysis. This innovative dual hotspot SERS approach provides a powerful tool for sensitive and practical detection of thiram in safety-critical applications.

Feasibility of biomass-based flexible and transparent AuNPs-acetylcellulose membrane for multifarious surface-enhanced Raman spectroscopy detection

BackgroundLignocellulosic biomass-based derivatives coupled with surface-enhanced Raman spectroscopy (SERS) technology have emerged as an appealing and indispensable tool in food safety and environmental monitoring for rapidly detecting trace contaminants like pesticide residues. The membrane material, serving as a substrate, ensures both sampling flexibility and test accuracy by directing the diffusion-adsorption process of the molecules. However, the existing membrane substrates, critical for the practical application of SERS, suffer from issues such as costly, intricate fabrication procedures, or restricted detection capabilities. ResultsHerein, we present a flexible, transparent, and biodegradable cellulose acetate membrane with gold nanoparticles (AuNPs) uniformly embedded, fabricated using a simple scraping method. This membrane achieved a limit of detection (LOD) of thiram pesticide in water at 10−8 g mL−1. The unique optical transparency of the substrates allowed for in-situ detection on surfaces, with an LOD of thiram reaching 30 ng cm−2. SignificanceFurthermore, SERS substrates made from corn stover-derived cellulose acetate enable the detection of various contaminants, highlighting their cost-effectiveness and eco-friendliness because of the abundance and low environmental impact of the raw materials.

Reuseable Fe3O4@PEI-DTC-Au@Ag magnetic nanocomposites: A versatile and sensitive SERS substrate for food safety assessment

A novel recyclable SERS substrate with magnetic manipulation capability and surface-enhanced Raman scattering (SERS) effect based on Fe3O4@PEI-DTC-Au@Ag (FPDAA) core-shell nanocomposites has been successfully prepared by engineered hydrothermal deposition and seed deposition techniques. The uniformity and SERS efficacy of these substrates, incorporating various Au@Ag core-shell nanocomposites with differing Ag shell thicknesses, were evaluated using 4-aminothiophenol (4-ATP) molecules. The optimal SERS substrate, Fe3O4@PEI-DTC-Au@Ag-3 (FPDAA-3), exhibited an enhancement factor (EF) of up to 1.121×106. This remarkable performance can be attributed to the synergistic effect between the magnetic plasmon of the Fe3O4 nanoparticles (NPs) core and the surface plasmonic resonance properties of Au@Ag core-shell nanocomposites, which create abundant interparticle hotspots within the FPDAA nanocomposites. Furthermore, the FPDAA-3 nanocomposite was employed as a SERS substrate for rapid thiram detection, achieving a minimum detectable concentration of 1×10−9 M. Notably, the relative standard deviation of SERS measurements from 50 randomly selected points was found to be less than 12.13 %, and the SERS spectra intensity showed minimal variation after 5 cycling tests, underscoring the excellent uniformity and recyclability of the FPDAA-3 substrate. The highly reusable and reliable FPDAA-3 nanocomposites enable direct on-site detection of thiram pesticide residues on fruit skins, thereby offering significant implications for food safety assessment and spectroscopic identification.

Glutathione‑iron hybrid nanozyme-based colorimetric sensor for specific and stable detection of thiram pesticide on fruit juices

Given the potential dangers of thiram to food safety, constructing a facile sensor is significantly critical. Herein, we presented a colorimetric sensor based on glutathione‑iron hybrid (GSH-Fe) nanozyme for specific and stable detection of thiram. The GSH-Fe nanozyme exhibits good peroxidase-mimicking activity with comparable Michaelis constant (Km = 0.551 mM) to the natural enzyme. Thiram pesticides can specifically limit the catalytic activity of GSH-Fe nanozyme via surface passivation, causing the change of colorimetric signal. It is worth mentioning that the platform was used to prepare a portable hydrogel kit for rapid qualitative monitoring of thiram. Coupling with an image-processing algorithm, the colorimetric image of the hydrogel reactor is converted into the data information for accurate quantification of thiram with a detection limit of 0.3 μg mL−1. The sensing system has good selectivity and high stability, with recovery rates in fruit juice samples ranging from 92.4% to 106.9%.

Titanium carbide MXene/silver nanostars composite as SERS substrate for thiram pesticide detection

Two-dimensional transition metal carbonitrides, Ti3C2Tx MXene nanosheets, have drawn much attention due to their unique optical properties. These materials have huge potential to be employed as surface-enhanced Raman scattering (SERS) substrates. Herein, to combine the benefits of metal nanoparticles and MXene as SERS substrates, we prepared composite SERS films with different volume ratios composed of Ti3C2Tx MXene with silver nanostars (AgNs) as a promising SERS substrate for detection of pesticides. These SERS films were prepared via a drop-casting technique. The SERS activities of the MXene/AgNs composites were evaluated through detection of the thiram pesticide. MXene/AgNs exhibited the highest SERS intensity compared to MXene or AgNs substrate alone. Sampling from 20 different areas and samples of the substrate gave very consistent SERS signals. The MXene/AgNs substrate shows good stability for 1 month when stored in a small transparent container with silica gel. The MXene/AgNs SERS substrate exhibits excellent sensitivity able to detect thiram concentrations as low as 10−8 M which also having low a relative standard deviation (RSD) value for reproducibility and stability over a significant period.

Silver-nanoparticle-coated Fe3O4/chitosan core–shell microspheres for rapid and ultrasensitive detection of thiram using surface magnetic solid-phase extraction–surface-enhanced Raman scattering (SMSPE-SERS)

We report a surface magnetic solid-phase extraction–surface-enhanced Raman scattering (SMSPE-SERS) method based on silver-nanoparticle-coated Fe3O4/chitosan (Fe3O4/CS@Ag) microspheres as the substrate, and this method integrates all steps from sample pretreatment to detection. Fe3O4/CS was synthesized by a one-step solvothermal method in which chitosan (CS) was used as a surface modifier and adsorbent. Fe3O4/CS@Ag microspheres exhibit both adsorption ability and SERS activity. Therefore, we used the SMSPE-SERS method to detect pesticide residues on fruit peel. The procedures of capturing, separating and enriching pesticides, as well as detection, are all integrated. In addition, the SERS substrate allows label-free detection of thiram pesticide in both fruit peel and apple juice. Owing to the uniform distribution of Ag NPs and the adsorption ability of CS, the thiram-detection sensitivity was sufficiently high to detect the lowest concentration of 1.2 ng/cm2, which was significantly lower than the maximum thiram residue limit (7 μg/cm2) in fruits. The method was comparable to high-performance liquid chromatography with recovery ranging from 86.60 to 109.69 %.

Honeycomb-like Ag Nanocavity Array for SERS Observations Using Plasmon-Mediated Chemical Reactions.

Organized two-dimensional polystyrene bead arrays perform ion etching, and protruding nanostructures are created on polystyrene beads due to the shadow effects from the ring beads, leading to nucleus selection and growth in Au nanostructure deposition. Ag nanostructures are prepared via plasmon-mediated chemical reactions (PMCRs), leading to the Ag nanocavity geometry of the honeycomb pattern when the etching time and Ag growth time are tuned. Due to the strong electromagnetic coupling, the Ag honeycomb-shaped nanocavity array works as the SERS substrate with high sensitivity and good repeatability, which is used to detect thiram pesticide residues with a concentration down to 10-9 M.

Inner filter effect-based upconversion nanosensor for rapid detection of thiram pesticides using upconversion nanoparticles and dithizone–cadmium complexes

Herein, we propose a method for detecting thiram based on the fluorescence inner filter effect using upconversion nanoparticles and dithizone–cadmium complexes (DZ-Cd2+). The ultraviolet absorption of DZ-Cd2+ was in the range of 480–600 nm under alkaline conditions, resulting in fluorescence quenching of the nanoparticles at 540 nm. Thiram had a stronger coordination effect with Cd2+ than dithizone; thus, more thiram–cadmium complex (T-Cd2+) formed when thiram was added, leading to fluorescence recovery at 540 nm. The standard thiram curve was found to have a detection limit of 6.75 ng/mL in the linear range of 0.01–1000 µg/mL. In addition, high-performance liquid chromatography results for detecting thiram in apple samples revealed good application performance. The results demonstrate that the developed method has great potential to detect thiram residues in food.

Flexible, high-performance and facile PVA/cellulose/Ag SERS chips for in-situ and rapid detection of thiram pesticide in apple juice

Flexible surface-enhanced Raman scattering (SERS) sensors have gained significant attention for their practical applications in detecting chemical and biological molecules. However, the fabrication of flexible SERS chips is often complex and requires advanced techniques. In this study, we present a simple and rapid method to design a flexible SERS chip based on polyvinyl alcohol (PVA), cellulose, and silver nanoparticles (AgNPs) using mechanical stirring and drying methods. Benefiting from the abundant hydroxide groups on cellulose, AgNPs easily adhere and distribute evenly on the cellulose surface. The combination of PVA and cellulose forms a bendable film-like SERS chip. This chip allows convenient immersion in liquid analyte samples. We demonstrate its effectiveness by using it to detect the thiram pesticide in apple juice using the “dip and dry” method, achieving an outstanding detection limit of 1.01 × 10−8 M. The Raman signals on the SERS chips exhibit high repeatability and reproducibility, with relative standard deviation values below 10%. These findings show that the flexible PVA/cellulose/Ag SERS chips is a strong candidate for real-world analysis.

Effect of pH on the optimization of cysteine‐functionalized gold core‐silver shell nanoparticles for surface‐enhanced Raman scattering‐based pesticide detection on apple peels

AbstractBackgroundThe rapid detection and efficient properties of surface‐enhanced Raman scattering (SERS) have been widely exploited in food safety.PurposeIn this study, the SERS impact of cysteine‐functionalized gold core‐silver shell bimetallic nanoparticle (Au@Ag@CysNPs) substrates with different pH treatments on pesticide compounds was examined.ResultsThe pH‐dependent SERS impact of Au@Ag@CysNPs on detecting pesticide compounds exhibited different enhancements over the pH range of 2–11 and exited the highest enhancement at a pH of 5 for thiabendazole and thiram pesticides. The prepared Au@Ag@CysNPs were further utilized in SERS‐based rapid detection of pesticides on apple peels by directly dropping Au@Ag@CysNPs on the surface of the samples, where the target molecules could be identified without elution or extraction. These findings revealed that this Au@Ag@CysNPs substrate exhibited excellent SERS performances for pesticide compounds and good stability. With additional optimization, detection limits of 0.1 ng/cm2 for thiabendazole and thiram on apple peels were obtained.

Spectrophotometric detection of thiram pesticide in vegetables, fruits, soil and water samples using silane-modified silver nanoparticles

Spectrophotometric detection of thiram pesticide in vegetables, fruits, soil and water samples using silane-modified silver nanoparticles

Label-free detection of Thiram pesticide on flexible SERS-active substrate

Thiram (tetramethyl thiuram disulfide) is a fungicide and is used for crop protection. It has several health-related issues when we consume this for a long period. Food and drug administration (FDA) warns higher than 30 μM (7 ppm) limit. Hence, the monitoring of the Thiram pesticide in foods and vegetables is of utmost importance. Conventional techniques such as GC–MS, HPLC and LC-MS available for quantification of pesticides are very costly, time-consuming and require sophisticated laboratory with highly skilled manpower. This work aims to design and develop an efficient label-free SERS (Surface Enhanced Raman Spectroscopy) active substrate which can detect a very low-level concentration of pesticides with low cost and simple process. SERS is a surface-sensitive technique that provides the enhanced form of Raman signals. Gold nanoparticles are used for SERS-active substrate preparation which has been synthesized by the chemical reduction method. Thiram pesticide with concentration as low as 1 nM is detected with the SERS substrate developed in this work. This makes rapid and on-site detection of pesticides feasible in future.

Versatile and high performance in-paper flexible SERS chips for simple and in-situ detection of methylene blue in river water and thiram on apple skin

In-paper flexible SERS chips were simply prepared by immersing pieces of filter paper into colloidal silver nanoparticle (e-AgNP) solution for 24 h and drying naturally at room temperature. Characteristic properties of cellulose fibers allowed the paper-based chips to be available for two sample collecting approaches. Being hydrophilic but insoluble in water, the chips were convenient to be dipped into aqueous media to collect soluble target analytes. Besides, they could “stick” on wet surfaces and bend along them to grab analytes. Hence, they were employed for in-situ detection of methylene blue dye in river water using “dip and dry” method and thiram pesticide on apple skin using “paste and peel off” procedure, resulting in detection limit of 10−10 M with excellent recovery rates of 93–104% and 86–93%, respectively. Therefore, the e-AgNPs-based in-paper SERS chips have served as a versatile tool for a large range of samples. More importantly, simple procedures of SERS chip preparation and sample collecting do not require the use of any complex equipment or expert operators. It can bring SERS techniques a step closer to real applications.

Facile fabrication of flexible AuNPs@CDA SERS substrate for enrichment and detection of thiram pesticide in water

Pesticide residues in water is one of the most serious problems in developing countries. Surface enhanced Raman spectroscopy (SERS) is widely used in the detection and monitoring of pesticide and other trace compounds because of its low limits of detection (LODs). However, different SERS substrate synthesis methods have different economic benefits and environmental impacts. In this paper, a flexible AuNPs@CDA SERS substrate was fabricated by the gold nanoparticles (AuNPs) and the biomass-based cellulose diacetate (CDA), which had stable test performance and considerable LODs. The substrates were economically viable and environment friendly. The characterization analysis of the substrate allows us to flexibly select different test methods (drop-test or enrichment-test) as coping strategy in different situation. The results showed that the LODs of thiram pesticide in water by enrichment-test could reach 10−7 g/mL, and had a good linear relationship in the concentration range of 10−7-10−6 g/mL. This strategy can realize the rapid and effective detection and monitoring of thiram pesticide in water.

Face-to-Face Assembly of Ag Nanoplates on Filter Papers for Pesticide Detection by Surface-Enhanced Raman Spectroscopy

Surface-enhanced Raman spectroscopy (SERS) technology has been regarded as a most efficient and sensitive strategy for the detection of pollutants at ultra-low concentrations. Fabrication of SERS substrates is of key importance in obtaining the homogeneous and sensitive SERS signals. Cellulose filter papers loaded with plasmonic metal NPs are well known as cost-effective and efficient paper-based SERS substrates. In this manuscript, face-to-face assembly of silver nanoplates via solvent-evaporation strategies on the cellulose filter papers has been developed for the SERS substrates. Furthermore, these developed paper-based SERS substrates are utilized for the ultra-sensitive detection of the rhodamine 6G dye and thiram pesticides. Our theoretical studies reveal the creation of high density hotspots, with a huge localized and enhanced electromagnetic field, near the corners of the assembled structures, which justifies the ultrasensitive SERS signal in the fabricated paper-based SERS platform. This work provides an excellent paper-based SERS substrate for practical applications, and one which can also be beneficial to human health and environmental safety.

Dendrimer stabilized nanoalloys for inkjet printing of surface-enhanced Raman scattering substrates

Research on paper substrates prepared by inkjet deposition of metal nanoparticles for sensing applications has become a hot topic in recent years; however, the design of such substrates based on the deposition of alloy nanoparticles remains less explored. Herein, we report for the first time the inkjet printing of dendrimer-stabilized colloidal metal nanoalloys for the preparation of paper substrates for surface-enhanced Raman scattering (SERS) spectroscopy. To this end, nanoassemblies containing variable molar ratios of Au:Ag were prepared in the presence of poly(amidoamine) dendrimer (PAMAM), resulting in plasmonic properties that depend on the chemical composition of the final materials. The dendrimer-stabilized Au:Ag:PAMAM colloids exhibit high colloidal stability, making them suitable for the preparation of inks for long-term use in inkjet printing of paper substrates. Moreover, the pre-treatment of paper with a polystyrene (PS) aqueous emulsion resulted in hydrophobic substrates with improved SERS sensitivity, as illustrated in the analytical detection of tetramethylthiuram disulfide (thiram pesticide) dissolved in aqueous solutions. We suggest that the interactions established between the two polymers (PAMAM and PS) in an interface region over the cellulosic fibres, resulted in more exposed metallic surfaces for the adsorption of the analyte molecules. The resulting hydrophobic substrates show long-term plasmonic stability with high SERS signal retention for at least ninety days.

Synergetic effect of silver nanoparticles and thiram on lipid bilayers

The excessive concentration of nanomaterials and pesticides in industrial products, food, and in the environment can be a risk to human health. Exposure to these materials can occur through inhalation, dermal contact, or oral ingestion, which depends directly on the type of products we are exposed to. Extensive studies about the individual action of these compounds have been described. However, the effect of these mixtures (nanoparticles and pesticides, for instance) requires more investigation. Here, we evaluated by phase-contrast microscopy the individual and mixture effects of silver nanoparticles (AgNp) and thiram pesticide on mimetic systems of the lipid bilayer structure of the plasma membrane using DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) giant unilamellar vesicles (GUVs). Besides, the effect of thiram pesticide on DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) multilamellar vesicles containing AgNp (encapsulated) was also evaluated by surface-enhanced Raman scattering (SERS). The results showed a synergetic effect of the AgNp and thiram mixture, which lead to a loss of phase contrast intensity and rupture of the lipid bilayers. The synergetic effect was ascribed to the strong interaction AgNp-thiram through Ag-S bond formation.

Cover Image, Volume 139, Issue 6

The cover image created by Hossein Tavanai and his colleagues shows an SEM image of thiram pesticide incorporated polycaprolactone micro & nanofibers produced by electrospinning. Thiram loading efficiency as well as its release from the microfibers were compared with those of nanofibers which were also electrospun. The amount of thiram pesticide loaded in micro and nanofibers was measured to be in the range of 42.5–150 mg·g−1 and 26.4–163.4 mg·g−1, respectively. Microfibers showed a higher release rate with lower amounts of the loaded thiram. Nanofibrous matrices showed an opposite trend. Thiram was held by the polycaprolactone matrix physically and could not reorganize itself as crystals in the fibrous matrix. A wide range of release conditions (time, amount and rate) can be engineered. DOI: 10.1002/app.51641