Pesticide Molecules Research Articles

Comparison of pesticide adsorption efficiencies of zeolites and zeolite-carbon composites and their regeneration possibilities

The presence of pesticides in our environment is a consequence of intensive industrial and civilizational development, necessitating the search for effective and safe methods to remove them. We suggest utilizing zeolite X and a zeolite-carbon composite, obtained through the chemical transformation of fly ash, as pesticide sorbents. To increase the sorption efficiency of 2,4-dichlorophenoxyacetic acid (2,4-D), 2-methyl-4-chlorophenoxyacetic acid (MCPA), carbendazim, and simazine, we functionalized the zeolite materials with cationic (hexadecyltrimethylammonium) and nonionic (Triton X-100) surfactants. We used transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric/differential thermal analysis (TG/DTA) and point of zero charge (pHpzc) analysis to characterize the functionalized sorbent materials. Our results indicate that cationic surfactants significantly enhance the adsorption of 2,4-D and MCPA. In contrast, carbendazim and simazine exhibit maximum sorption on the unmodified zeolite-carbon composite. The sorption mechanism is intricate, with physical sorption predominating, primarily due to electrostatic interactions between the protonated binding sites of the adsorbents and the negatively charged pesticide molecules. Regeneration tests demonstrated that ethanol is the most effective in regenerating zeolite-carbon composite with adsorbed MCPA and 2,4-D, while thermal regeneration was not possible. Adsorbents with simazine and carbendazim can be regenerated using both thermal and ethanol methods, but the thermal regeneration of zeolite with adsorbed simazine is more efficient. Utilizing functionalized zeolite materials obtained from industrial waste, such as fly ash, could provide an efficient way to remove pesticides from the environment.

Ratiometric fluorescent detection of carbendazim in foods based on metallic nanoclusters self-assembled nanocomplex.

Indicator replacement assay combining with fluorescence resonance energy transfer (FRET) effect has attractive performance in sensing small molecules, however, there wasn't application in pesticide molecule sensing reported so far. In this work, we prepared a nanocomplex (NCP), AuAgNCs-CD, through self-assembly of gold nanoclusters (AuNCs), silver nanoclusters (AgNCs) and carboxymethyl-β-cyclodextrin (CM-β-CD) by one-step method. The emission of AuNCs was significantly enhance. It was found that FRET between the AuAgNCs-CD and rhodamine B (RhB) existed after AuAgNCs-CD combined with RhB. And carbendazim (CBZ) could induce anti-FRET effect through competing with RhB and binding to AuAgNCs-CD. Thus, this phenomenon was utilized to develop a ratiometric fluorescent detection of CBA. This method was applied in food sample detection and reliable results were obtained. Due to high sensitivity, rapidness and good selectivity, this ratiometric fluorescent method was expected to hold high application potential in monitoring CBZ in foods.

High-sensitivity pesticide detection on mango skins by terahertz spectroscopy with graphene oxide sensors

Regular monitoring of pesticides in agricultural farmland is essential to prevent the misuse of toxic pesticide chemicals. As crop samples are typically disintegrated to extract the pesticide residue for chromatographic analysis, non-destructive techniques for pesticide monitoring are ideal for preventing the unwanted destruction of crops. This, however, requires analytical techniques that can detect trace pesticide amounts. Here, we show that terahertz (THz) spectroscopy in attenuated total reflection mode, combined with low-cost graphene oxide (GO) plasmonic sensor, can be used for sensitive, fast, and non-destructive pesticide detection on mango skin. After the application of pesticide solution onto the mango skin, the dried pesticide residue was transferred to the GO sensor by pressing it in contact with the mango skin surface. Due to the adsorption of the pesticide molecules onto the oxygen-rich GO surface, a signal in the THz range was obtained corresponding to the pesticide’s chemical fingerprint. With this technique, pesticide surface concentrations of approximately 1 µg/cm2 on mango skins can be detected.

A detailed study on the selection of borderline features for accurate mechanism description of the adsorption of different pesticide molecules under different temperature ranges

Mathematical models play a crucial role in data acquisition by boosting the capacity to interpret and group the gathered information. However, the challenge lies in choosing the most accurate model to represent data sets with very slight nuances, as it occurs in the validation of adsorption processes considering molecules with different properties but similar structural attributes. Due to these very small variations, there is a high chance of excessive adaption to specific patterns created by the distributions, statistically blindsiding the decision-making. In this work, we used statistical physics (sta-phy) modeling and thermodynamic calculations of the three different pesticides 2,4-dichlorophenoxyacetic acid (2,4-D), dicamba (DCB), and mecoprop (MCPP) on a woody based activated carbon (WBAC) to demonstrate these patterns while also unveiling the mechanisms involved. We demonstrate that the statistical criteria alone do not provide enough clarity in these cases, and we propose using the physical meaning of each estimated parameter as a way out. Thus, in this work, we prove in detail that using sta-phy models requires absolute mastering of the subjects to ensure reliable results by understanding the relationships between the adsorption parameters and the system properties instead of a simple read of the determination coefficients.

Green and efficient delivery of pesticides throughout their life cycle via cooperative solid and solution self-assembly

Addressing the economic and environmental challenges posed by non-target losses throughout the pesticide life cycle necessitates a simple, yet effective strategy. In this work, a cooperative solid and solution self-assembly material is developed for the eco-friendly and efficient delivery of pesticides, based on a precise design. In the solid state, supramolecular self-assembly of pesticide (herbicide, amitrole) and coformer molecules (nutrients, vanillic and sinapinic acids) occurs through non-covalent interactions, characterized by single-crystal structures. The solid self-assembly strategy enables enhanced stability, temperature-responsive controlled release and heightened rain erosion resistance. In the solution state, supramolecular assembly behavior is confirmed via spectroscopy and molecular simulations, improving wetting, retention, evaporation, UV resistance, and soil adsorption performances. Bioassays demonstrate a significant improvement in herbicidal lethality under simulated rainfall conditions in conjunction with enhanced cucumber germination and development, as well as reduced zebrafish toxicity, when comparing the cooperative strategy to pure amitrole. This cooperative self-assembly material in both solid and solution phases, featuring simple preparation, robust stability enhanced interfacial ability, temperature-responsive release, and excellent environmental safety, provides a promising approach for pesticide application, promoting sustainable, high-yield agriculture.

Inorganic Nanoparticles–Driven Self–Assembly of natural small molecules in water for constructing multifunctional nanocapsules against plant diseases

Directly constructing nanoparticles through the self–assembly of natural small molecules in aqueous media presents many opportunities for crop protection; however, this special strategy is hindered by the lack of simple and cost–effective preparation methods to date. Herein, we report a facile strategy for constructing multifunctional natural nanocapsules for treating plant diseases based on the special coassembly of natural small organic molecules and inorganic nanoparticles. In aqueous conditions, uniform curcumin nanocapsules (ZnO@Cur) are assembled through electrostatic interactions, coordination effects and hydration effects as mediated by trace of nanoscale zinc oxide. The nanocapsules obtained can be further modified to enhance stability by introducing a polydopamine coating (ZnO@Cur@PDA). The antibacterial activity of ZnO@Cur@PDA against plant-pathogenic bacteria was better than that of curcumin, ZnO NPs, ZnO@Cur and zinc thiazole in vitro. The nanocapsules effectively kill plant–pathogenic bacteria via tight binding to the bacterial surface, inducing reactive oxygen species accumulation and disrupting bacterial cell walls. ZnO@Cur@PDA display strong activities against rice bacterial blight with protective activity of 64.0 % and curative activity of 62.2%, which is much better than commercial drugs bismerthiazol (protective activity of 33.0 % and curative activity of 38.4%) and zinc thiazole(protective activity of 38.6 % and curative activity of 31.8%). ZnO@Cur@PDA display adequate washing resistance, and low rice plant toxicity; furthermore, they are degradable. Additionally, both the inner cavities and outer surfaces of nanocapsules bear abundant sites and spaces that can be further tuned for loading other pesticide molecules or flexible construct complex multifunctional nanoparticles. Our study should encourage further development in the coassembly of organic and inorganic materials via green processes for effective and tunable nanopesticides.

Engineering green MOF-based superhydrophobic sponge for efficiently synchronous removal of microplastics and pesticides from high-salinity water.

Microplastics (MPs) and pesticides are becoming an intractable environmental issue due to their wide spreading and non-degradable nature, posing serious threat to ecosystem and human health. To settle such dilemma, this work reasonably designed a superhydrophobic MOF-based coated sponge (ODSOSS/TiO2/Ni-MOF/PDA@Sponge) through the combination of an environmentally friendly in-situ supersaturated coprecipitation and polysesiloxane modification method. Among them, (I) the introduction of polydopamine (PDA) not only improves the adhesion between coatings and sponge, but also enhances the growth of MOF structure through complexation. (II) The obtained Ni-MOF shows large-area microscale anthemy structure with multilayered flaky texture, forming heterogeneously hierarchical structure with the deposited TiO2 nanoparticles, which promotes photodegradation ability of TiO2 owing to great specific surface area of Ni-MOF. (III) The high specific large area Ni-MOF supplies sufficient action sites for linkage of PDA and polysesiloxane molecules with unique nanocage-like structure, thus further greatly increasing adsorption force for various pollutants. (IV) The superhydrophobicity protect the porous channels of MOF from contamination of various absorbed pollutants, while TiO2 nanoparticles effectively photodegrade the absorbed organic pollutants, endowing the sponge superior recyclability. The superhydrophobic sponge selectively rapidly and synchronously adsorbs various MPs (maintained almost 100% after 60 cycles) and pesticides (adsorption rates 71.6%-95.1%) from high-salinity water. The large-area sponge (9cm×6cm×1cm) simultaneously removes almost 100% MPs (40mg/L), Sudan Ⅲ (10mg/L), kerosene (30mL/L), and four pesticides (10mg/L) within 1min. Particularly, four pesticides are quickly photocatalytic degraded by the coated sponge. The free radical capture trials show that hydroxyl radicals (·OH) are the main active species of pesticide degradation. Furthermore, we reveal the negative centers where pesticide molecules are most vulnerable to ·OH attack, on basis of the charge distribution and molecular electrostatic potential (MEP) analysis. The adsorption mechanisms are carefully clarified through theoretical calculation and experimental data. This work not only provide an effective superhydrophobic candidate for MPs and pesticides removal in a broad applicable scope (especially in high-salinity wastewater), but also opens a new strategy for environmental remediation.

Physisorption Behaviors of Organochlorine Pesticides on the InP3 Monolayer from Theoretical Insight.

Dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (BHC), aldrin, and chlordimeform are ubiquitous organochlorine pesticide (OCP) residues in the environment, which pose a great threat to human health and ecosystems due to their high toxicity and easy accumulation. Based on the density functional theory (DFT) calculations, a two-dimensional InP3 monolayer was selected as a sensing material to study the sensitivity detection and adsorption behaviors toward BHC, aldrin, chlordimeform, and DDT. The calculation results show that four pesticide molecules are adsorbed on the InP3 surface by physical interaction. The identified response values (69.1, -43.1%) for DDT and chlordimeform reveal the potential of the InP3 monolayer as a sensing material for the detection of these two pesticides, accompanied by the achievement of cyclic utilization by heating to 498 K. The most satisfactory result is the adsorption of BHC, owing to the admirable sensing response (62.7%) and short recovery time (1.8 s) at room temperature, which makes InP3 a promising pesticide sensor for BHC. However, the InP3 surface is unsuitable for aldrin sensing due to poor response (-1.9%). Our work gives theoretical insight into the good sensitivity and recycling of the InP3 monolayer as a new pesticide sensor to detect DDT, BHC, and chlordimeform, which further broadens the application prospect of the InP3 nanosheet into the sensitive detection of organochlorine pesticides in the ecological environment.

Universal Method Based on Layer-by-Layer Assembly for Aptamer-Based Sensors for Small-Molecule Detection.

Development of a fast and accurate pesticide analysis system is a challenging task, as a large amount of commonly used pesticide has negative effects on humans' health. Detection of pesticide residues is crucial for food safety management and environmental protection. Aptamers─short single-stranded oligonucleotides (RNA or DNA) selected by aptamer selection method SELEX─can selectively bind to their target pesticide molecules with high affinity. Thus, in the present study, we developed an electrochemical biosensor based on aptamers to detect the commonly used pesticide, glyphosate. Carbon fibers were used as the platform to assemble polyelectrolyte layers with the incorporated aptamers selectively binding with glyphosate molecules for electrochemical detection. The best limit of detection of 0.3 μM was achieved at open-circuit potential measurements, which is comparable to the current need in detection of glyphosate. The developed method can be implemented into existing systems for the determination of pesticides on farms to control residual concentrations of glyphosate in soil and water.

Calcium-Alginate-Chitosan Nanoparticle as a Potential Solution for Pesticide Removal, a Computational Approach.

Pesticides have a significant negative impact on the environment, non-target organisms, and human health. To address these issues, sustainable pest management practices and government regulations are necessary. However, biotechnology can provide additional solutions, such as the use of polyelectrolyte complexes to encapsulate and remove pesticides from water sources. We introduce a computational methodology to evaluate the capture capabilities of Calcium-Alginate-Chitosan (CAC) nanoparticles for a broad range of pesticides. By employing ensemble-docking and molecular dynamics simulations, we investigate the intermolecular interactions and absorption/adsorption characteristics between the CAC nanoparticles and selected pesticides. Our findings reveal that charged pesticide molecules exhibit more than double capture rates compared to neutral counterparts, owing to their stronger affinity for the CAC nanoparticles. Non-covalent interactions, such as van der Waals forces, π-π stacking, and hydrogen bonds, are identified as key factors which stabilized the capture and physisorption of pesticides. Density profile analysis confirms the localization of pesticides adsorbed onto the surface or absorbed into the polymer matrix, depending on their chemical nature. The mobility and diffusion behavior of captured compounds within the nanoparticle matrix is assessed using mean square displacement and diffusion coefficients. Compounds with high capture levels exhibit limited mobility, indicative of effective absorption and adsorption. Intermolecular interaction analysis highlights the significance of hydrogen bonds and electrostatic interactions in the pesticide-polymer association. Notably, two promising candidates, an antibiotic derived from tetracycline and a rodenticide, demonstrate a strong affinity for CAC nanoparticles. This computational methodology offers a reliable and efficient screening approach for identifying effective pesticide capture agents, contributing to the development of eco-friendly strategies for pesticide removal.

Research Progress of a Pesticide Polymer-Controlled Release System Based on Polysaccharides.

In recent years, with the development of the nanomaterials discipline, many new pesticide drug-carrying systems-such as pesticide nano-metal particles, nano-metal oxides, and other drug-carrying materials-had been developed and applied to pesticide formulations. Although these new drug-loading systems are relatively friendly to the environment, the direct exposure of many metal nanoparticles to the environment will inevitably lead to potential effects. In response to these problems, organic nanomaterials have been rapidly developed due to their high-quality biodegradation and biocompatibility. Most of these organic nanomaterials were mainly polysaccharide materials, such as chitosan, carboxymethyl chitosan, sodium alginate, β-cyclodextrin, cellulose, starch, guar gum, etc. Some of these materials could be used to carry inorganic materials to develop a temperature- or pH-sensitive pesticide drug delivery system. Herein, the pesticide drug-carrying system developed based on polysaccharide materials, such as chitosan, was referred to as the pesticide polymer drug-carrying system based on polysaccharide materials. This kind of drug-loading system could be used to protect the pesticide molecules from harsh environments, such as pH, light, temperature, etc., and was used to develop the function of a sustained release, targeted release of pesticides in the intestine of insects, and achieve the goal of precise application, reduction, and efficiency of pesticides. In this review, the recent progress in the field of polysaccharide-based polymer drug delivery systems for pesticides has been discussed, and suggestions for future development were proposed based on the current situation.

Ultrasensitive Pesticide Detection and Specific Recognition in Microenvironment-Modulated Fluorescent Micro-/Mesoporous Polyaminals.

Two new carbazole-based monomers 6,6'-(9-n-butyl-9H-carbazole-3,6-diyl)bis(1,3,5-triazine-2,4-diamine) and 6,6'-(9H-carbazole-3,6-diyl)bis(1,3,5-triazine-2,4-diamine) are synthesized and employed to polymerize with formamide and N,N-dimethylformamide, respectively, to afford thee fluorescent micro-/mesoporous polyaminals with physicochemical microenvironment modulated by -NH2, -NH-, -N(CH3)2, and n-butyl groups. Their chemosensing properties for five pesticides trifluralin (TFR), triflumizole, imidacloprid, lambda-cyhalothrin, and cyfluthrin are studied. Surprisingly, the polymers exhibit exceptionally high recognition for TFR, and the fluorescent quenching coefficients measured in water reach 4.1 × 106 M-1, being 2 orders of magnitude higher than those of other porous polymers reported in the literature. The limit of detection (0.7 ppb) for TFR can compete with that of the electrochemical method. The fluorescence response at an extremely low concentration of 3 × 10-8 M and selective recognition for TFR are confirmed by the visual observation using the portable polymer plates. Additionally, the different water mediums including varied acid-basic conditions and the presence of heavy metal ions have nearly no effect on the detection sensitivity. The ultrasensitive recognizable response for TFR is explained in terms of the photoinduced electron transfer, inner filter effect, improved hydrophilicity of polymer skeleton and porous trapping effect, and the dimensions and geometric configurations of pesticide molecules.

Thermo-acoustic approach for pesticide-plasma protein binding in colloidal system: An impact of membrane mimic structures on molecular interactions in biological systems

Recently, use of agrochemicals, most importantly pesticides has experienced an enormous upsurge as a consequence of continuously increasing demand of enhanced crop production. Various toxins in the environment interact with bio-molecules and causes serious ailments in human beings. Different physicochemical, computational and spectroscopic methods have been used to study binding of toxins with bio-molecules. In present study, thermo-acoustic method was aimed to employ for studying binding of organophosphate pesticides with plasma protein in absence and presence of colloidal solutions of ionic surfactants. Role of different binding sites in protein molecules, nature of pesticide molecules and forces involved in pesticide-plasma protein binding were investigated. Volumetric and acoustic parameters such as apparent (Vϕ) and partial molar volume (Voϕ), expansibility factor (Eoϕ), Hepler’s constant, compressibility factor (Kϕ) and intermolecular free length (Lf) were calculated using density and sound velocity data at different temperatures (293.15–313.15)K. Positive values of Vϕ increased with increasing pesticide concentration in aqueous plasma protein solutions which were indicative of strong associative molecular interactions in solutions. Obtained results of this study about pesticides-protein binding will be helpful for medical and pharmaceutical researchers.

ReS2 Nanoflowers-Assisted Confined Growth of Gold Nanoparticles for Ultrasensitive and Reliable SERS Sensing.

ReS2, as a new member of transition metal dichalcogenides (TMDCs), has emerged as a promising substrate for semiconductor surface-enhanced Raman spectroscopy (SERS) due to its unique optoelectronic properties. Nevertheless, the sensitivity of the ReS2 SERS substrate poses a significant challenge to its widespread application in trace detection. In this work, we present a reliable approach for constructing a novel ReS2/AuNPs SERS composite substrate, enabling ultrasensitive detection of trace amounts of organic pesticides. We demonstrate that the porous structures of ReS2 nanoflowers can effectively confine the growth of AuNPs. By precisely controlling the size and distribution of AuNPs, numerous efficient and densely packed "hot spots" were created on the surface of ReS2 nanoflowers. As a result of the synergistic enhancement of the chemical and electromagnetic mechanisms, the ReS2/AuNPs SERS substrate demonstrates high sensitivity, good reproducibility, and superior stability in detecting typical organic dyes such as rhodamine 6G and crystalline violet. The ReS2/AuNPs SERS substrate shows an ultralow detection limit of 10-10 M and a linear detection of organic pesticide molecules within 10-6-10-10 M, which is significantly lower than the EU Environmental Protection Agency regulation standards. The strategy of constructing ReS2/AuNPs composites would contribute to the development of highly sensitive and reliable SERS sensing platforms for food safety monitoring.

Degradation Pathway Estimation of Pesticide Molecule by Molecular Modeling

Degradation Pathway Estimation of Pesticide Molecule by Molecular Modeling

Spatial and seasonal distribution of pesticides in the waters of Azagny area (Grand Lahou, Cote d'Ivoire).

This study provides comprehensive data on the seasonal variation and distribution of pesticides in the waters bordering Azagny National Park (ANP). Forty-six (46) samples of water from the Azagny area were analyzed using high-performance liquid chromatography (HPLC) coupled with a UV/visible detector to assess the level of thirty-one pesticide molecules divided into six families. These include triazines, phenylureas, organophosphates, carbamates, chloroacetanilides, dicarboximides, and crimidine, which are regularly used in this area. The respective average concentrations of pesticides are 54.54µg//L, 20.93µg/L, 18.24µg/L, 3.06µg/L, and 16.52µg/L in the Bandama, Azagny Canal, ANP, mangroves, and estuarine environment. The analyses also showed that herbicides were the most abundant pesticides in the three waters, Bandama, Azagny Canal, and Azagny Park, with levels of 100%, 63%, and 59%, respectively, followed by insecticides with a levels of 0%, 37%, and 41%, respectively. However, rodenticides (76%) were more frequently detected than herbicides (24% in the mangroves). Regarding seasonal variation, high levels of pesticides were detected in the Bandama River, the Azagny Canal, and the mangroves during the dry season, while multiple pesticide residues were detected during the rainy season. The waters bordering Azagny National Park (ANP) are contaminated with pesticide residues (triazines, phenylureas, organophosphates, carbamates, and chloroacetanilides). As a result, policymakers should implement measures to regularly monitor pesticide levels in plantations surrounding the Azagny region's waters in order to better preserve biodiversity.

Interaction between Six Waxy Components in Summer Black Grapes (Vitis vinifera) and Mancozeb and Its Effect on the Residue of Mancozeb.

Mancozeb, an antifungal typically used for the growth of fruits, has the characteristic of non-internal absorption, and has a risk of binding to the waxy components of fruits. This work investigated the interaction of pesticide molecules with the waxy layer on the grape surface and their effects on pesticide residues in grapes. The study observed significant changes in the compositions of the waxy layer on the grape surface after soaking in a mancozeb standard solution. The six substances-oleanolic acid, ursolic acid, lupeol, octacosanol, hexacosanal, and γ-sitosterol-with discernible content differences were chosen for molecular docking. Docking results were further visualized by an independent gradient model based on Hirshfeld partition (IGMH). Hydrogen bonds and van der Waals forces were found between mancozeb and the six waxy components. Moreover, the negative matrix effects caused by the presence or absence of wax for the determination of mancozeb were different through the QuEChERS-HPLC-MS method. Compared with the residue of mancozeb in grapes (5.97 mg/kg), the deposition of mancozeb in grapes after dewaxing was significantly lower (1.12 mg/kg), which further supports that mancozeb may interact with the wax layer compositions. This work not only provides insights into the study of the interaction between pesticides and small molecules but also provides theoretical guidelines for the investigation of the removal of pesticide residues on the surface of fruits.

Wrinkle-bioinspired silver nanowire surface enhanced Raman scattering sensors for pesticide molecule detection.

We demonstrate wrinkle-bioinspired flexible SERS sensor covered by silver nanowire (AgNWs) network for the detection of pesticide molecules. Compared with the silver film deposition substrates, the wrinkle-bioinspired AgNWs SERS substrates show stronger SERS effect, which were attributed to the electromagnetic field enhancement posed by the relatively high density "hot spots" of AgNWs. In order to investigate the adsorption performance of wrinkle-bioinspired flexible sensors, we measured the corresponding contact angles of AgNWs on the substrate surfaces before and after plasma treatment and found that the AgNWs treated with plasma are more hydrophilic than that without plasma treatment. Additionally, the wrinkle-bioinspired SERS sensors show different SERS activities under different tensile strain, and the 10-6 mol/L concentration of Rhodamine dye (R6G) molecules can be detected by portable Raman spectra, reducing greatly detection cost. The surface plasmon resonance of AgNWs is induced by adjusting the deformation of AgNWs substrate, enhancing the SERS signal. This reliability of wrinkle-bioinspired SERS sensors is further verified by in situ detection of pesticide molecules.

A cucurbit[8]uril-based supramolecular polymer constructed via outer surface interactions: Use as a sensor, in cellular imaging and beyond

In recent years, most of the constructions on cucurbit[n]uril-based supramolecular polymers have been based on host–guest chemistry, however, this limits the choice of host and guest. Herein, we present a newly designed supramolecular polymer, namely Q[8]@PEG-HPTS formed by utilizing outer surface Q[8] interactions. In aqueous solution, the supramolecular polymer Q[8]@PEG-HPTS was obtained quickly and simply by mixing Q[8] with PEG-HPTS, where after, a variety of characterization techniques were employed to confirm the structure of the Q[8]@PEG-HPTS. The ability of this system to selectively recognize metal ions as well as pesticide molecules was also investigated; selectivity was observed for Fe3+ and paraquat. The biocompatibility and excellent fluorescence properties associated with the constituents of the supramolecular polymer allowed for the imaging of HeLa cells. This system could image and trace the nucleus through the cytoplasm, indicating that it could enter and internalize HeLa cells. Finally, by continuously adjusting the ratio between Q[8] and PEG-HPTS, a Q[8]@PEG-HPTS hydrogel was obtained. This hydrogel exhibited a stimulated temperature response, and opens up further possibilities for exploring the applications of such supramolecular polymers.

Building of mid-infrared spectral signature of pesticides using functionally-enhanced derivative spectroscopy (FEDS)

Pesticides are synthetic substances widely used in several processes related to agriculture-based food production. Their monitoring is important to evaluate their impact on environment, ensure the food quality, and for the developing of new methods and strategies that help to understand their dynamics from the moment they are released until their end disposal. In this way, the use of mid-infrared spectroscopy (mid-IR spectroscopy) and chemometric methods have been widely explored. However, the strong overlap of spectral signals in complex analytical matrices is recognized as the main limitation of reflectance-based methods for monitoring of this kind of pollutant. In this work, the use of MID-IR spectroscopy by attenuated total reflectance (ATR), in conjunction with functionally-enhanced derivative spectroscopy (FEDS), is proposed as non-destructive technique for fast and simple monitoring of pesticides. Thus, high-resolution dynamic spectral signature (HDSS) for six pesticides commonly used in tropical crops were used as model substances; as analytical matrix was used the peel of banana (e.g., Musa paradisiaca). In addition, concentration effect was evaluated to mimic real conditions. Data recording was obtained by mid-IR spectroscopy (from 4000 to 600 cm−1) and HDSS were evaluated by Pearson’s correlation coefficient and spectral similarity FEDS index between the spectra and the reference signals. Based on these correlation parameters, some selection criteria are proposed to estimate the spectral zones where the pesticide signature persists even at relative low concentrations. For the six pesticides, the spectral region considered coincide with those bands of high polarity bonds in the pesticide molecules. Additionally, a good linear prediction models that correlate the relative absorbance intensity and the peak area of the mid signal with the pesticide concentration level are obtained in the spectral ranges of interest. The model performance is defined by Pearson’s coefficients rf greater than 0.97, residual prediction deviation RPDs (root mean square errors - RMSEs) greater (lower) than 5 (3), and limits of detection (LODs) lower than 1 g/kg. Furthermore, this methodology and results are successfully employed to detect Chlorpyrifos residues in banana peel.