RESUMEN
In this work, a new surface plasmon resonance (SPR) sensor based on sulphur-doped titanium dioxide (S-TiO2) nanostructures and molecularly imprinted polymer (MIP) was presented for thiram (THI) determination in milk samples. Firstly, the S-TiO2 nanomaterial with a high product yield was prepared by using a facile sol-gel hydrolysis technique with a high product yield. After that, UV polymerization was carried out for the preparation of the THI-imprinted SPR chip based on S-TiO2 using a mixture including ethylene glycol dimethacrylate (EGDMA) as the cross-linker, N,N'-azobisisobutyronitrile (AIBN) as the initiator, and methacryloylamidoglutamicacid (MAGA) as the monomer. The reliability of the sensor preparation procedure has been successfully proven by characterization studies of the prepared nanomaterials and SPR chip surfaces through spectroscopic, microscopic, and electrochemical methods. As a result, the prepared SPR sensor showed linearity in the range of 1.0 × 10-9-1.0 × 10-7 M with a detection limit (LOD) of 3.3 × 10-10 M in the real samples, and a sensor technique for THI determination with high sensitivity, repeatability, and selectivity can be included in the literature.
Asunto(s)
Leche , Polímeros Impresos Molecularmente , Azufre , Resonancia por Plasmón de Superficie , Tiram , Titanio , Titanio/química , Leche/química , Azufre/química , Polímeros Impresos Molecularmente/química , Animales , Tiram/análisis , Límite de Detección , Impresión Molecular , Polímeros/químicaRESUMEN
A gold nanogap substrate was used to measure the thiram and carbaryl residues in various fruit juices using surface-enhanced Raman scattering (SERS). The gold nanogap substrates can detect carbaryl and thiram with limits of detection of 0.13 ppb (0.13 µgkg-1) and 0.22 ppb (0.22 µgkg-1). Raw SERS data were first preprocessed to reduce noise and undesirable effects and, were later used for model creation, implementing classification, and regression analysis techniques. The partial least-squares regression models achieved the highest prediction correlation coefficient (R2) of 0.99 and the lowest root mean square of prediction value below 0.62 ppb for both pesticide-infected juice samples. Furthermore, to differentiate between juice samples contaminated by both pesticides and control (pesticide-free), logistic-regression classification models were produced and achieved the highest classification accuracies of 100% and 99% for contaminated juice containing thiram and 100% accurate results for contaminated juice containing carbaryl. This indicates that the gold nanogap surface has significant potential for achieving high sensitivity in detecting trace contaminants in food samples.
Asunto(s)
Carbaril , Contaminación de Alimentos , Jugos de Frutas y Vegetales , Oro , Residuos de Plaguicidas , Espectrometría Raman , Tiram , Residuos de Plaguicidas/análisis , Espectrometría Raman/métodos , Carbaril/análisis , Jugos de Frutas y Vegetales/análisis , Tiram/análisis , Contaminación de Alimentos/análisis , Oro/química , Quimiometría , Nanopartículas del Metal/química , Límite de Detección , Frutas/químicaRESUMEN
Over the last few decades, there is increasing worldwide concern over human health risks associated with extensive use of pesticides in agriculture. Developing excellent SERS substrate materials to achieve highly sensitive detection of pesticide residues in the food is very necessary owing to their serious threat to human health through food chains. Self-assembled metallic nanoparticles have been demonstrated to be excellent SERS substrate materials. Hence, alkanethiols-protected gold nanoparticles have been successfully prepared for forming larger-scale two-dimensional monolayer films. These films can be disassembled into a fluid state and re-assembled back to crystallized structure by controlling surface pressure. Further investigations reveal that their self-assembled structures are mainly dependent on the diameter of gold nanoparticles and ligand length. These results suggest that the size ratio of nanoparticle diameter/ligand length within the range of 4.45-2.35 facilitates the formation of highly ordered 2D arrays. Furthermore, these arrays present excellent Surface-Enhanced Raman Scattering performances in the detection of trace thiram, which can cause environmental toxicity to the soil, water, animals and result in severe damage to human health. Therefore, the current study provides an effective way for preparing monodispersed hydrophobic gold nanoparticles and forming highly ordered 2D close-packed SERS substrate materials via self-assembly to detect pesticide residues in food. We believe that, our research provides not only advanced SERS substrate materials for excellent detection performance of thiram in food, but also novel fundamental understandings of self-assembly, manipulation of nanoparticle interactions, and controllable synthesis.
Asunto(s)
Oro , Nanopartículas del Metal , Residuos de Plaguicidas , Espectrometría Raman , Tiram , Espectrometría Raman/métodos , Oro/química , Tiram/química , Tiram/análisis , Nanopartículas del Metal/química , Residuos de Plaguicidas/química , Residuos de Plaguicidas/análisis , Contaminación de Alimentos/análisisRESUMEN
Given the potential dangers of thiram to food safety, constructing a facile sensor is significantly critical. Herein, we presented a colorimetric sensor based on glutathioneiron 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%.
Asunto(s)
Colorimetría , Jugos de Frutas y Vegetales , Glutatión , Hierro , Tiram , Colorimetría/instrumentación , Jugos de Frutas y Vegetales/análisis , Hierro/química , Hierro/análisis , Glutatión/química , Glutatión/análisis , Tiram/análisis , Tiram/química , Contaminación de Alimentos/análisis , Plaguicidas/análisis , Plaguicidas/química , Límite de Detección , Técnicas Biosensibles/instrumentaciónRESUMEN
Owing to good flexibility, prominent mechanical properties, three-dimensional (3D) nanofibrous structure and low background interference, sustainable bacterial nanocellulose (BNC) is a highly attractive matrix material for surface-enhanced Raman scattering (SERS) sensor. Herein, a highly sensitive, flexible and scalable silver nanorod-decorated BNC (AgNRs@BNC) SERS sensor is developed by a simple vacuum-assisted filtration. The AgNRs were firmly locked in the 3D nanofibrous network of cellulose nanofibers upon vacuum drying process, resulting in the formation of 3D SERS hotspots with a depth of more than 10 µm on the sensor. With 4-aminothiophenol (4-ATP) as a target molecule, a lowest distinguishable level of 10-12 M and a high enhancement factor of 1.1 × 109 were realized by the optimal AgNRs1.5@BNC SERS sensor. Moreover, the AgNRs@BNC SERS sensor exhibits high detectable level of 10-9 M for thiram molecules by integrating with a portable Raman spectrometer. Besides, toxic thiram residues on grape surface could be directly on-site identified by the combination of AgNRs@BNC SERS sensors and a portable Raman spectrometer through a feasible press-and-peel method. The flexible AgNRs@BNC SERS sensor cooperated with portable Raman system demonstrates great potential for on-site detection of pesticide residues on irregular food surfaces.
Asunto(s)
Celulosa , Nanotubos , Residuos de Plaguicidas , Plata , Espectrometría Raman , Espectrometría Raman/métodos , Plata/química , Celulosa/química , Nanotubos/química , Residuos de Plaguicidas/análisis , Tiram/análisis , Compuestos de Anilina/química , Compuestos de Sulfhidrilo/química , Compuestos de Sulfhidrilo/análisis , Bacterias , Vitis/química , Límite de DetecciónRESUMEN
Rapid and sensitive determination of pesticide residues in fruits and vegetables is critical for human health and ecosystems. This paper used an Ag-modified CuO sphere-cavity array (CuO@Ag) electrode as a thiram SERS/electrochemical dual readout detection platform. Numerous Raman "hotspots" generated by uniformly distributed silver nanoparticles, charge transfer at the CuO@Ag interface, and the formation of Ag-thiram complexes contribute to the significant enhancement of this SERS substrate, which results in excellent SERS performance with an enhancement factor up to 1.42 × 106. When using SERS as the readout technique, the linear range of the substrate for thiram detection was 0.05-20 nM with a detection limit (LOD) of up to 0.0067 nM. Meanwhile, a correlation between the value of change in current density and thiram concentration was established due to the formation of stable complexes of thiram with Cu2+ generated at specific potentials. The linear range of electrochemical detection was 0.05-20.0 µM, and the detection limit was 0.0167 µM. The newly devised dual-readout sensor offers notable sensitivity and stability. The two signal readout methods complement each other in terms of linear range and detection limit, making it a convenient tool for assessing thiram residue levels in agro-food. At the same time, the combination of commercially available portable equipment makes on-site monitoring possible.
Asunto(s)
Cobre , Técnicas Electroquímicas , Plata , Espectrometría Raman , Tiram , Tiram/análisis , Cobre/química , Cobre/análisis , Plata/química , Espectrometría Raman/métodos , Técnicas Electroquímicas/métodos , Límite de Detección , Nanopartículas del Metal/química , Electrodos , Residuos de Plaguicidas/análisisRESUMEN
In response to the prevalent issue of thiram as a common pesticide residue on the surface of fruits and vegetables, our research team employed an acidic hydrated metal salt low co-fusion solvent to dissolve cellulose lysis slurry. Subsequently, a regenerated cellulose membrane (RCM) was successfully prepared via sol-gel method. Uniformly sized Ag nanoparticles (NPs) were deposited on RCM utilizing the continuous ion layer adsorption and reaction (SILAR) technique. The resulting Ag NPs/RCM flexible surface-enhanced Raman spectroscopy (SERS) substrates exhibited a minimum detection limit of 5 × 10-9 M for Rhodamine 6G (R6G), demonstrating good uniformity (RSD = 4.86 %) and reproducibility (RSD = 3.07 %). Moreover, the substrate displayed a remarkable sensitivity of 10-10 M toward thiram standard solution. Given its inherent flexibility, the substrate proves advantageous for the detection of three-dimensional environments such as fruit and vegetable surfaces, and its practicality has been confirmed in the detection of thiram residue on apples, tomatoes, pears, and other fruits and vegetables.
Asunto(s)
Nanopartículas del Metal , Tiram , Tiram/análisis , Verduras/química , Frutas/química , Nanopartículas del Metal/química , Reproducibilidad de los Resultados , Plata/química , Espectrometría Raman/métodos , Celulosa/análisisRESUMEN
Advances in flexible SERS substrates has made it possible to approach the ultimate goal of rapid in-situ monitoring of fruit and vegetable safety, but its vulnerability under laser ablation results in low utilization. In order to solve this problem, a 3D framework of TiO2-doped PVDF\PVP polymer was utilized to self-assemble gold-silver core-shell nanorods (Au@Ag NRs) to prepare a flexible SERS substrate with good physical stability and self-cleaning properties. This substrate showed excellent detection limit and recyclability after the detection of three pesticide residues in apple peel. The LOD of methyl-parathion (MP) was as low as 0.037 ng/cm2, with an RSD of 5.61 % for 5 cycle-detection. The recoveries of two additional pesticides thiram (TMTD) and chlorpyrifos (CPF) were 86.32 %-112.47 %. We hoped that this research will contribute to providing a recyclable and facile method for in-situ analysis of fruit and vegetable surface residues and functional manufacture of flexible SERS substrates.
Asunto(s)
Malus , Nanopartículas del Metal , Residuos de Plaguicidas , Plaguicidas , Malus/química , Espectrometría Raman/métodos , Nanopartículas del Metal/química , Plaguicidas/análisis , Residuos de Plaguicidas/análisis , Tiram/análisis , Verduras/química , Oro/químicaRESUMEN
Pesticide residues in agri-foods have risk to human health and one solution is to develop simple and accurate methods for rapid detection. We developed a SERS sensor composed of gold nanoparticles (AuNPs) and bacterial cellulose nanocrystal (BCNC) to detect thiram in fruit juice. BCNC-SO3H was used as a stabilizer to support AuNPs via electrostatic repulsion, fabricating a BCNC-AuNPs SERS substrate with uniformly distributed AuNPs. This BCNC-AuNPs SERS substrate was applied to determine thiram residues in peach juice, apple juice, and grape juice with the limits of detection of 0.036 ppm, 0.044 ppm, and 0.044 ppm, respectively. The whole test took 12 min including sample preparation and analysis. The detection limits meet the maximum residue levels of thiram in fruit juices required by China, Europe and North America, indicating that this BCNC-based substrate could serve as a satisfactory SERS sensor for pesticide residue monitoring in the food supply chain.
Asunto(s)
Nanopartículas del Metal , Tiram , Humanos , Tiram/análisis , Jugos de Frutas y Vegetales/análisis , Celulosa/análisis , Oro/química , Nanopartículas del Metal/química , Frutas/química , Espectrometría Raman/métodosRESUMEN
BACKGROUND: Surface-enhanced Raman spectroscopy (SERS) has been extensively used in biomedical and food safety detection due to its advantages of label-free, in situ and fingerprint spectrum. However, it is challenging to develop an excellent SERS substrate that possesses all three of these characteristics including sensitivity, repeatability and stability. RESULTS: In this work, a specific sodium alginate hydrogel flexible SERS substrate encapsulated gold-silver core-shell nanoparticles (Au@Ag NPs) was developed to address the aforementioned issue. The Au@Ag NPs with SERS "hot spot" structure were evenly dispersed in the hydrogel, which achieved the direct and high efficiency detection of the pesticide residues from complex sample matrix. Taking thiram as objective, this SERS substrates exhibit high sensitivity (detection limit of approximately 1 × 10-10 mol/L), excellent stability (maintain above 78.35 % of SERS activity after 7 weeks) and outstanding repeatability (RSD in one substrate as low as 3.56 %). Furthermore, the flexible hydrogel SERS substrates can be used to analyze a variety of small molecules in real samples (juices, vegetables and fruits), without the need for a laborious pretreatment process. SIGNIFICANCE: In light of the aforementioned benefits, the functional flexible hydrogel SERS substrates present a reliable platform for the accurate and on-site measurement of chemical contaminants from complex samples.
Asunto(s)
Nanoestructuras , Residuos de Plaguicidas , Residuos de Plaguicidas/análisis , Hidrogeles , Tiram/análisis , Espectrometría Raman/métodosRESUMEN
Fast detection of contaminants of emerging concern (CECs) in water resources is of great environmental interest. Ideally, sustainable materials should be used in water quality monitoring technologies implemented for such purposes. In this regard, the application of bio-based materials aimed at the fabrication of analytical platforms has become of great importance. This research merges both endeavors by exploring the application of chitosan-coated paper, decorated with silver nanoparticles (AgNPs), on surface-enhanced Raman scattering (SERS) spectroscopy studies of two distinct types of CECs dissolved in aqueous samples: an antibiotic (ciprofloxacin) and a pesticide (thiram). Our results indicate the superior SERS performance of biocoated substrates compared to their non-coated paper counterparts. The detection limits achieved for thiram and ciprofloxacin using the biocoated substrates were 0.024 ppm and 7.7 ppm, respectively. The efficient detection of both analytes is interpreted in terms of the role of the biopolymer in promoting AgNPs assemblies that result in local regions of enhanced SERS activity. Taking advantage of these observations, we use confocal Raman microscopy to obtain Raman images of the substrates using ciprofloxacin and thiram as molecular probes. We also demonstrate that these biobased substrates can be promising for on-site analysis when used in conjunction with portable Raman instruments.
Asunto(s)
Quitosano , Nanopartículas del Metal , Tiram/análisis , Plata/química , Espectrometría Raman/métodos , Ciprofloxacina , Nanopartículas del Metal/químicaRESUMEN
Pesticide residue detection in food has become increasingly important. Herein, surface-enhanced Raman scattering (SERS) coupled with an intelligent algorithm was developed for the rapid and sensitive detection of pesticide residues in tea. By employing octahedral Cu2O templates, Au-Ag octahedral hollow cages (Au-Ag OHCs) were developed, which improved the surface plasma effect via rough edges and hollow inner structure, amplifying the Raman signals of pesticide molecules. Afterward, convolutional neural network (CNN), partial least squares (PLS), and extreme learning machine (ELM) algorithms were applied for the quantitative prediction of thiram and pymetrozine. CNN algorithms performed optimally for thiram and pymetrozine, with correlation values of 0.995 and 0.977 and detection limits (LOD) of 0.286 and 29 ppb, respectively. Accordingly, no significant difference (P greater than 0.05) was observed between the developed approach and HPLC in detecting tea samples. Hence, the proposed Au-Ag OHCs-based SERS technique could be utilized for quantifying thiram and pymetrozine in tea.
Asunto(s)
Aprendizaje Profundo , Nanopartículas del Metal , Residuos de Plaguicidas , Tiram/análisis , Residuos de Plaguicidas/análisis , Espectrometría Raman/métodos , Algoritmos , Redes Neurales de la Computación , Té , Nanopartículas del Metal/química , Oro/químicaRESUMEN
We developed a novel fabrication of flexible surface-enhanced Raman scattering (SERS) substrate to perform selective and sensitive determination of thiram residue in fruits and juices. Au nanostars (Au NSs) with multi-branching structure were self-assembled on aminated Polydimethylsiloxane (PDMS) slides by electrostatic interaction. By measuring the Thiram's characteristic peak intensity at 1371 cm-1, the SERS method could distinguish Thiram from other pesticide residues. A good linear relationship between the peak intensity at 1371 cm-1 and thiram's concentration was established at the range from 0.01 ppm to 100 ppm and the Limit of detection is 0.0048 ppm. We directly used this SERS substrate to detect Thiram in apple juice. By standard addition method, recoveries varied in the range of 97.05% to 106.00% and the RSD were from 3.26% to 9.35%. The SERS substrate exhibited a good sensitivity, stability and selectively for the detection of Thiram in food samples, which can be spread as a common method for the detection of pesticides in food samples.
Asunto(s)
Malus , Nanopartículas del Metal , Plaguicidas , Tiram/análisis , Malus/química , Plaguicidas/análisis , Frutas/química , Dimetilpolisiloxanos , Espectrometría Raman/métodos , Nanopartículas del Metal/química , Oro/químicaRESUMEN
In recent years, growing food safety and quality concerns have emerged and created an urgent need for the development of rapid and reliable food control technologies. This study proposes a novel surface-enhanced Raman spectroscopy (SERS) substrate printing technology that utilizes commercial filter paper functionalized by silver nanoparticles. We modified the Automatic TLC Sampler using a two-dimensional (2D) printer. The modification allows for various sampling modes which can be applied to 2D printing. The shape and size of nano silver on the substrate were determined, and the substrate sensitivity, uniformity, and stability were evaluated. As demonstrated by the experimental outcomes, the proposed technology is highly sensitive and reproducible, that is, the limit of quantitation was 10-5 mg/kg, and the spot-to-spot and block-to-block Raman intensity variations were below 4.2%. We also successfully applied the technology to pears and apples for thiram recognition, yielding outstanding detectability down to 2.5 × 10-6 and 3.9 × 10-7 mg/mL (equal to 2.5 × 10-3 and 3.9 × 10-4 mg/kg), respectively. These were well below the maximum residue limit (7 mg/kg). More importantly, the linear relationships between thiram levels and the SERS intensity allow for sensitive monitoring of minute variations in agricultural insecticide residues. This proposed detection method can realize in situ detection with a strong signal fingerprint.
Asunto(s)
Malus , Nanopartículas del Metal , Residuos de Plaguicidas , Pyrus , Residuos de Plaguicidas/análisis , Malus/química , Tiram/análisis , Tiram/química , Nanopartículas del Metal/química , Plata , Espectrometría Raman/métodosRESUMEN
Surface-enhanced Raman spectroscopy (SERS)-based biosensors have attracted much attention for their label-free detection, ultrahigh sensitivity, and unique molecular fingerprinting. In this study, a wafer-scale, ultrasensitive, highly uniform, paper-based, portable SERS detection platform featuring abundant and dense gold nanopearls with narrow gap distances, are prepared and deposited directly onto ultralow-surface-energy fluorosilane-modified cellulose fibers through simple thermal evaporation by delicately manipulating the atom diffusion behavior. The as-designed paper-based SERS substrate exhibits an extremely high Raman enhancement factor (3.9 × 1011 ), detectability at sub-femtomolar concentrations (single-molecule level) and great signal reproductivity (relative standard deviation: 3.97%), even when operated with a portable 785-nm Raman spectrometer. This system is used for fingerprinting identification of 12 diverse analytes, including clinical medicines (cefazolin, chloramphenicol, levetiracetam, nicotine), pesticides (thiram, paraquat, carbaryl, chlorpyrifos), environmental carcinogens (benzo[a]pyrene, benzo[g,h,i]perylene), and illegal drugs (methamphetamine, mephedrone). The lowest detection concentrations reach the sub-ppb level, highlighted by a low of 16.2 ppq for nicotine. This system appears suitable for clinical applications in, for example, i) therapeutic drug monitoring for individualized medication adjustment and ii) ultra-early diagnosis for pesticide intoxication. Accordingly, such scalable, portable and ultrasensitive fibrous SERS substrates open up new opportunities for practical on-site detection in biofluid analysis, point-of-care diagnostics and precision medicine.
Asunto(s)
Nanopartículas del Metal , Plaguicidas , Oro/química , Nicotina , Plaguicidas/análisis , Espectrometría Raman/métodos , Tiram/análisis , Nanopartículas del Metal/químicaRESUMEN
Pesticide residues are a global threat to human health, and conventional sensors fail to simultaneously detect pesticide residues on the surface and inside agricultural products. In this work, we present a new microneedle (MN) patch-based surface-enhanced Raman spectroscopy (SERS) sensor. The needles and the basement of MNs can simultaneously detect pesticide residues on the surface and inside agricultural products. The Ag nanoparticles and sodium hyaluronate/poly(vinyl alcohol) (HA/PVA) hydrogel used in this MN patch-based sensor efficiently amplify the Raman signals of the pesticide residues. In addition, the HA/PVA hydrogel can effectively and quickly collect the residues, allowing this sensor to detect pesticide residues more conveniently. Furthermore, the stepped structure of the MNs increases the sensor's surface area. Experimental results show that the sensor can detect thiram and thiabendazole (TBZ) pesticide residues with detection limits of 10-7 and 10-8 M, respectively. The detection process is minimally invasive and not harmful to agricultural products. The application of this MN patch-based SERS sensor can be extended to the safety and health monitoring of other plants and animals.
Asunto(s)
Nanopartículas del Metal , Residuos de Plaguicidas , Animales , Humanos , Residuos de Plaguicidas/análisis , Espectrometría Raman/métodos , Nanopartículas del Metal/química , Plata/química , Tiram/análisisRESUMEN
Exploring the behavior of pesticide residues in fruits is important for effectively applying pesticides and minimizing the risk of pesticide exposure to humans. However, most studies do not consider in situ visual analysis of residues and migration patterns in fresh fruit samples. We investigated the migration patterns of thiram, propamocarb, imidacloprid and pyraclostrobin in fresh bananas based on ambient mass spectrometry imaging, metabolome and transcriptome analysis. The systemic pesticides entered via lateral penetration and vertical migration over time, which began to internally migrate to the inner core after 6 h. The non-systemic pesticide thiram did not enter the interior of the bananas, and remained only in the peel. The transportation rate of the pesticides increased with the decrease of water-octanol partition coefficient and the relative molecular mass. Moreover, the pesticide migrated fast with the increase of banana ripeness. The pesticides significantly enhanced pyruvate kinase, NADP-dependent malic enzyme, and malate synthase activities in the banana peels through carbohydrate metabolism. The banana pulp was also protected against the external toxicity of pesticides by the ascorbate-glutathione cycle. These results can provide guidelines for the appropriate application of pesticides and their safety evaluation.
Asunto(s)
Musa , Residuos de Plaguicidas , Plaguicidas , Humanos , Residuos de Plaguicidas/análisis , Musa/química , Tiram/análisis , Plaguicidas/análisis , Frutas/química , Metaboloma , Espectrometría de Masas en Tándem/métodosRESUMEN
A flexible nanocomposite composed of bacterial cellulose (BC) and gold nanoparticles (AuNPs) was developed as a SERS substrate to determine thiram on apple surface by two collection methods namely "paste-and-peel" and "wiping". Enhancement factor of this SERS substrate for sensing thiram residues was determined to be 2.8 × 105. Compared to the benchtop Raman spectrometer, portable Raman spectroscopic device showed a lower sensitivity towards thiram residues with limit of detection at 0.98 ppm, satisfying maximum residue level of thiram on apple required by both Europe and America. A good linear correlation of SERS peak intensity at 1368 cm-1 and different concentrations of thiram (1-50 ppm) revealed a coefficient up to 0.99. This flexible BC-based SERS substrate has a great analytical performance in sensitivity, reproducibility and stability, and is suitable for rapid detection (<8 min) and quantitative analysis of pesticides on food surface.
Asunto(s)
Malus , Nanopartículas del Metal , Tiram/análisis , Malus/química , Oro/química , Celulosa , Reproducibilidad de los Resultados , Nanopartículas del Metal/química , Espectrometría Raman/métodosRESUMEN
Conventional surface-enhanced Raman scattering (SERS) molecular detection are based on hard and brittle substrate, which are not suitable for in-situ detection of analytes adsorbed on nonplanar surfaces. Here, we report a simple biomimetic synthesis method to fabricate lotus leaf mastoid structured AgNPs micro/nanoarrays as reliable SERS substrate. By ideal replicating mastoid structure of lotus leaf into a flexible and transparent PDMS film, followed by depositing plasmonic AgNPs, a powerful chemical sensor with high sensitivity and multiplex detecting capability is demonstrated. The employ of periodic mastoid structure array endows the sensor with high signal repeatability (RSD â¼ 8.6 %), solving the general repeatability problem of SERS substrates. In addition, the detailed designed flexible and transparent PDMS substrate is capable of identifying trace analytes on curved surfaces with excellent durability. In the proof-of-concept experiment, a limit of detection (LOD) of (10-5 M to 10-7 M) was achieved on a portable Raman device for three common pesticides residues (thiram, fonofos and triadophos) on dendrobium leaves and stem according to the molecular fingerprint, indicating its excellent in-situ detection capability. Further, the multiplex detection ability of the Ag/PDMS film is also demonstrated by analyzing the mixture of four typical analytes. Benefiting from its high signal uniformity, this flexible Ag/PDMS substrate also showed good quantitative detection capabilities.
Asunto(s)
Lotus , Residuos de Plaguicidas , Residuos de Plaguicidas/análisis , Tiram/análisis , Espectrometría Raman/métodosRESUMEN
Dithiocarbamate Fungicides (DTFs) are widely analyzed and studied mainly due to the fact that they play an important role in the cultivation of fruits and vegetables. This manuscript aims to display the results of a bibliometric analysis based on the Web of Science© database, performed in the DTF and food research area. A total of 374 publications were examined. The most scientific production was concentrated between 2012 and 2021, showing a decrease of 32% over the last two years. The Journal of Agricultural and Food Chemistry, India, and Sardar Vallabhbhai National Institute of Technology were the most productive journal, country, and institution, respectively. Reference Publication Year Spectroscopy index showed a decrease of 95% in the last last years studied. Finally, current and future trends should focus on keywords such as individual DTF (Mancozeb, Thiram and Maneb), metabolites (Ethylenethiourea, Propilenthiourea) and a change in the analysis methodology: HPLC versus traditional GC.