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To investigate the ability of theaflavins (TF) from black tea to protect dentin collagen against enzymatic degradation via cross-linking effect under clinically relevant conditions. 10-µm-thick dentin films were microtomed from dentin slabs of human molars. Following demineralization, films or slabs were treated with TF at two concentrations (0.4% and 2%) for 30 s. A well-known collagen cross-linker grape seed proanthocyanidins (PA) was used as control. Collagen cross-linking interactions and stabilization against enzymatic degradation were investigated by Fourier transform infrared spectroscopy, weight loss, hydroxyproline release, and scanning/transmission electron microscopy. Data were analyzed by ANOVA, Tukey's and Student's T test (α = 0.05%). The results showed collagen cross-linking and stabilization efficacy was dependent on TF/PA concentrations. At 2.0%, TF and PA offered nearly full protection to collagen; at 0.4%, TF exhibited a significantly better collagen stabilization effect than PA (P < 0.05), while untreated collagen was completely digested. It's concluded that TF cross-links dentin collagen within a clinically relevant time (30 s) and offers excellent collagen protection against enzymatic degradation, with efficacy comparable to or better than PA. The study supports the potential use of TF as a novel, promising collagen cross-linker for degradation resistant, long-lasting dentin bonding in composite restorations. [ABSTRACT FROM AUTHOR]

A series of hyperbranched poly(citric polyethylene glycol) (PCPEG) materials with varied polyethylene glycol (PEG) chain lengths as plasticizers were mixed with maize starch (MS) via cooking and film‐forming. The structure, pasting property, plasticization, aging property, moisture absorption and compatibility of plasticized starches were studied by means of Fourier transform infrared spectroscopy, X‐ray diffraction, rapid viscosity analysis, tension testing, moisture absorption measurements and scanning electron microscopy. Compared with PEG and citric acid, PCPEG was more effective in promoting starch chain movement and inhibiting the retrogradation of starch film. Also, PCPEG/MS had smaller moisture content. The longer the plasticizer chain, the better were the aging resistance and moisture resistance of starch. But with an increase of PEG chain length, mechanical properties of PCPEG/MS deteriorated and the compatibility between PCPEG and MS decreased. The hyperbranched derivative of PEG with longer chain exhibited improved plasticization and compatibility with starch. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the polymerization kinetics qualitatively and quantitatively for dual-cure bulk-fill composites in comparison with light-cure bulk-fill and traditional incremental composites at two clinically relevant depths. Five commercial dental composites were evaluated, including three dual-cure bulk-fill composites (BulkEZ, HyperFIL and Injectafil), one light-cure bulk-fill composite Filtek Bulk Fill Flowable (FBF) and one traditional incremental composite Filtek Z250 (Z250) as controls. Specimens were prepared in two different depths (0.5 mm and 5 mm) for 20 s light irradiation. Self-cure was also evaluated for the three dual-cure composites. The polymerization kinetics were measured continuously in real-time for at least 10 min using a Fourier-transform infrared spectroscopy (FTIR) with an attenuated total reflectance (ATR) accessory. The experimental kinetic data were fitted using two mathematical models — a sigmoidal function and a superposition of two exponential functions characterizing the gel phase and glass phase. The degree of conversion (DC) and the rate of polymerization were calculated for all test conditions. Both experimental FTIR measurements and mathematical modeling revealed distinct depth-related polymerization kinetics for BulkEZ compared to the other two dual-cure composites. Specifically, BulkEZ exhibited moderately-paced polymerization kinetics at both depths while HyperFIL and Injectafil exhibited faster polymerization at 0.5 mm and slower polymerization at 5 mm. The bulk-fill FBF and incremental Z250 exhibited relatively fast polymerization at both depths, a characteristic for light-cure. The DC values at the two depths were not significantly different for BulkEZ, but significantly higher at 0.5 mm than at 5 mm for the other four composites (α = 0.05). Polymerization kinetics and their depth variation for dual-cure bulk-fill composites are material dependent. The distinct depth-related polymerization kinetics revealed for BulkEZ compared to other composites may affect their contraction stress and clinical performance. [ABSTRACT FROM AUTHOR]

Highlights • Monolithic column with DES as functional group was prepared for CEC. • The process of column preparation was simple and repeatable. • Small organic compounds, small biomolecules and alkaloids can be well separated. • Electrophoretic and chromatographic mechanisms were involved in the separation. Abstract A novel monolithic column based on the copolymerization of ethylene dimethacrylate and a deep eutectic solvent (DES), which composed of chlorocholine chloride and itaconic acid, was developed for capillary electrochromatography (CEC). The structure and morphology of the obtained monolithic column was characterized by Fourier transform infrared spectra and scanning electron microscopy, which showed a porous monolithic structure with good permeability. The influence of pH value and acetonitrile content on electroosmotic flow (EOF) of DES-based monolithic column was investigated. The DES-based monolithic column was used as the separation column of CEC and exhibited excellent performance for the separation of neutral compounds, phenols, toluidines, nucleosides, nucleotide bases and alkaloids. The retention mechanism might be attributed to synergistic effect of hydrophobic interaction, hydrogen bond interaction and electronic interaction. The DES-based monolithic column showed good repeatability with relative standard deviations of migration time less than 0.80%, 2.15%, 4.26% and 3.08% for intra-day, inter-day, column-to-column and batch-to-batch, respectively. Thus, organic polymer monolithic columns with DESs as functional monomers are a promising option in chromatographic separation. [ABSTRACT FROM AUTHOR]

Photocatalytic disinfection, which is a readily reliable method in most climates, holds great promise to significantly reduce the microbial contamination in modern industry. Here we report that vanadate quantum dots-interspersed graphitic carbon nitride (vanadate QDs/g-C 3 N 4 ) can achieve efficient inactivation of Salmonella by harvesting a substantial visible light. Detailed characterization through SEM-EDS, TEM, XRD, FT-IR, and XPS confirmed the formation of the composites. Owing to the efficient reactive oxygen species (ROS) production between vanadate QDs and g-C 3 N 4 , the bactericidal efficiency of AgVO 3 QDs/g-C 3 N 4 could reach 96.4% toward Salmonella in a concentration of 0.75 mg/mL after 10 min visible-light illumination. More importantly, scavenger experiments of different reactive species proved that the photoinduced electron generated at the oxidation site of AgVO 3 /g-C 3 N 4 play a major role as oxidative species. Fluorescent-based cell live/dead test and membrane potentials were applied to demonstrate the integrity of cell membranes. Furthermore, the SEM technology, PCR and BCA protein assay were employed to verify the bacterial decomposition as well as leakage of bacterial cell contents toward Salmonella . Sterilization experiments of Staphylococcus aureus revealed that our composites have broad spectrum antimicrobial activity for both Gram-negative and Gram-positive bacteria under visible light. The results showed that the generation of high ROS could attack the bacterial cells membrane, and ultimately disrupt the cell metabolism through bacterial contents, which provided a feasible method for eliminating the microbial contaminated water. [ABSTRACT FROM AUTHOR]

A novel covalent organic framework based magnetic adsorbent was developed for magnetic solid phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs). Covalent organic framework-LZU1 (= Lan Zhou University-1) was covalently immobilized onto polyethyleneimine-functionalized magnetic nanoparticles (COF-LZU1@PEI@FeO), and the resulting material was characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. The effects of the pH value of sample solution, percentage of acetonitrile, extraction time and sampling volume on MSPE of six PAHs were investigated. The COF-LZU1@PEI@FeO displays high extraction efficiency for the PAHs such as pyrene, benzo[a]pyrene, fluoranthene, benz[a]anthracene, benzo[a]fluorathene and dibenz[a,h]anthracene. Following desorption with acetonitrile, the PAHs were quantified by HPLC. The MSPE-HPLC method shows low limit of detection (0.2-20 pg mL), wide linear range and good reproducibility (relative standard deviations <4.4% for intra-day and inter-day precision). The method was successfully applied to determine PAHs in environmental samples. Good recoveries were obtained, ranging from 90.9 to 107.8% for water samples and 85.1 to 105.0% for soil samples. [ABSTRACT FROM AUTHOR]

Graphene was prepared by a simple chemical reduction of graphite oxide in the dimethylacetamide (DMAc)/H 2 O mixture solvent. The results from Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy indicated that the reduction degree of graphene products increased with the increase in the volume ratio of DMAc and water (V DMAc /V H2O ), and kept constant when the V DMAc /V H2O ratio was equal or greater than 1. A reduction mechanism from graphite oxide to graphene was proposed. The epoxy groups and hydroxyl on the graphite oxide (GO) surface could be eliminated in the reduction process, whereas the carbonyl was converted to a hydroquinone structure. [ABSTRACT FROM AUTHOR]

• A blended low-carbon cementitious materials containing high-volume mine solid waste activated ultra-fine IOT is designed. • IOT2 has higher pozzolanic activity and better dense filling effect. • IOT2 can consume more portlandite produced from cement hydration to form more rigid hydration products. • The increase of later compressive strength owes to the synergistic action of the improvement of hydrates and filler effect. Iron ore tailings (IOT) are a type of mining solid waste and cause many environmental and safety problems. The aim of this paper was to investigate the effect of high-volume ultra-fine IOT on the mechanical properties and hydration mechanism of cementitious materials. To obtain ultra-fine particles, IOT was processed via grinding in water, and the particle characteristics were characterized using a laser particle-size analyzer, scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and inductively coupled plasma (ICP). The influence of the IOT particle size (D50 = 47.63 μm, 4.32 μm, 1.09 μm), substitution percentage (30 %, 40 %, 50 %), and hydration age (1 d, 7 d, 28 d) on the compressive strength of mortar specimens were also studied. The results show that ultra-fine treatment enhances the hydration activity of IOT particles and has a positive effect on the mechanical properties of cementitious materials. The addition of IOT increases the setting time and reduces the hydration heat at early hydration stage; however, the ultra-fine treatment can minimize this problem and meet the requirements of practical engineering applications. Compared with raw IOT, the ultra-fine IOT exhibits more remarkable filling effect and hydration activity. They can consume a large amount of portlandite, which is produced by cement hydration to form densified calcium silicate hydrate gel and accelerate the development of strength. This study provides a design method and experimental data support for the preparation of a kind of low-carbon cementitious materials. [ABSTRACT FROM AUTHOR]

The wheat straw carboxymethylcellulose (WSC), a typical natural polymer, was modified by functional poly(acrylic acid) (PAA) with in situ polymerization, which afforded natural and synthetic polymer composite (WSC/PAA). The polymer (WSC/PAA) was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis techniques. WSC/PAA was used as polymer adsorbent for removing Pb(II) ions in wastewater. The removal rate of 99.8% was obtained when the experimental conditions were chosen as follows: initial Pb(II) ion concentration; 600 mg/L, WSC/PAA concentration; 0.1 g/100 mL, pH; 5.0, contact time; 60 minutes at 20°C. Adsorption dynamics were consistent with pseudo-second-order kinetic model and the isotherm model can meet the Langmuir isotherm. [ABSTRACT FROM AUTHOR]

The Fourier transform infrared (FTIR) imaging technique was used in a transmission model for the evaluation of twelve oral hyperkeratosis (HK), eleven oral epithelial dysplasia (OED), and eleven oral squamous cell carcinoma (OSCC) biopsy samples in the fingerprint region of 1800–950 cm−1. A series of 100 µm × 100 µm FTIR imaging areas were defined in each sample section in reference to the hematoxylin and eosin staining image of an adjacent section of the same sample. After outlier removal, signal preprocessing, and cluster analysis, a representative spectrum was generated for only the epithelial tissue in each area. Two representative spectra were selected from each sample to reflect intra-sample heterogeneity, which resulted in a total of 68 representative spectra from 34 samples for further analysis. Exploratory analyses using Principal component analysis and hierarchical cluster analysis showed good separation between the HK and OSCC spectra and overlaps of OED spectra with either HK or OSCC spectra. Three machine learning discriminant models based on partial least squares discriminant analysis (PLSDA), support vector machines discriminant analysis (SVMDA), and extreme gradient boosting discriminant analysis (XGBDA) were trained using 46 representative spectra from 12 HK and 11 OSCC samples. The PLSDA model achieved 100% sensitivity and 100% specificity, while both SVM and XGBDA models generated 95% sensitivity and 96% specificity, respectively. The PLSDA discriminant model was further used to classify the 11 OED samples into HK-grade (6), OSCC-grade (4), or borderline case (1) based on their FTIR spectral similarity to either HK or OSCC cases, providing a potential risk stratification strategy for the precancerous OED samples. The results of the current study support the application of the FTIR-machine learning technique in early oral cancer detection. [ABSTRACT FROM AUTHOR]

Abstract: Highly hydrophobic surface property of membranes is very important for membrane contactor application that is normally used for CO2 capture. This study explores a simple and inexpensive approach for hydrophobic modification of imide group contained polymeric membranes. Poly(amide–imide) (PAI) hollow fiber membrane with controlled pore structure as porous substrate was fabricated by dry-jet wet spinning process, followed by a wet-chemical hydrophobic modification using octadecylamine. The modification mechanism was confirmed by ATR-FTIR, and the effect of different modification times on the modified membrane properties was investigated. Experiments reveal that the modification changed the membrane morphology and structure, resulted in surface pore opening and thinning down of the membrane skin layer. As a compromise between the membrane hydrophobicity and mechanical strength, 10–30min were considered as appropriate modification times for the PAI membranes. The treated membranes showed much higher hydrophobicity with an improvement in contact angle of around 30°. The liquid entry pressure (LEPw) also increased dramatically from 7psi to 63psi after 30min modification due to the enhanced membrane hydrophobicity. The treated membranes were tested in the membrane contactor for CO2 absorption. It was observed the CO2 flux increased with the liquid velocity and modification time. A stable long-term performance of CO2 absorption by a 2M sodium taurinate aqueous solution for 15days of operation was attained. Moreover, poly(etherimide) (PEI) hollow fiber membranes were successfully modified by octadecylamine, which demonstrated the effectiveness and versatility of the modification method on imide-contained polymeric membranes. [Copyright &y& Elsevier]

The water contents of nominally anhydrous clinopyroxene (cpx), orthopyroxene (opx) and olivine (ol) in peridotite xenoliths hosted by Cenozoic basalts from Yingfengling, Zhangchouchun, Fujitian and Lindi, South China, were measured by Micro-FTIR. All cpx and opx grains contained a certain amount of water, which was indicated by the presence of hydroxyls in the crystal structure. The water contents (HO, ppm) of cpx and opx from peridotite xenoliths of the study areas were 293-981, 183-752, 73-586 and 51-423 ppm, and 82-471, 74-571, 53-170 and 9-135 ppm, respectively. No prominent OH absorption bands were detected for any ol grains, indicating that the water contents were below the detection limit (approximately 2 ppm). The entire rock contents recalculated according to mineral volume proportions were 49-163, 48-168, 21-111 and 8-40 ppm, respectively. Combined with previously reported data describing the water contents of peridotite xenoliths worldwide, the results presented here suggest that water distribution in the continental lithospheric mantle is spatially heterogeneous at a global scale. The lithospheric mantle of South China is much richer in water than that of the North China Craton, and is close to that typical of off-craton localities, such as the Basin and Range Province, and Massif Central. [ABSTRACT FROM AUTHOR]

Oral cancer is one of the most common cancers worldwide. Despite easy access to the oral cavity and significant advances in treatment, the morbidity and mortality rates for oral cancer patients are still very high, mainly due to late-stage diagnosis when treatment is less successful. Oral cancer has also been found to be the most expensive cancer to treat in the United States. Early diagnosis of oral cancer can significantly improve patient survival rate and reduce medical costs. There is an urgent unmet need for an accurate and sensitive molecular-based diagnostic tool for early oral cancer detection. Fourier transform infrared spectroscopy has gained increasing attention in cancer research due to its ability to elucidate qualitative and quantitative information of biochemical content and molecular-level structural changes in complex biological systems. The diagnosis of a disease is based on biochemical changes underlying the disease pathology rather than morphological changes of the tissue. It is a versatile method that can work with tissues, cells, or body fluids. In this review article, we aim to summarize the studies of infrared spectroscopy in oral cancer research and detection. It provides early evidence to support the potential application of infrared spectroscopy as a diagnostic tool for oral potentially malignant and malignant lesions. The challenges and opportunities in clinical translation are also discussed. [ABSTRACT FROM AUTHOR]

Restoration of the lubrication functions of articular cartilage is an effective treatment to alleviate the progression of osteoarthritis (OA). Herein, we fabricated chitosan- block -poly(sulfobetaine methacrylate) (CS-b-pSBMA) copolymer via a free radical polymerization of sulfobetaine methacrylate onto activated chitosan segment, structurally mimicking the lubricating biomolecules on cartilage. The successful copolymerization of CS-b-pSBMA was verified by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and 1H nuclear magnetic resonance. Friction test confirmed that the CS-b-pSBMA copolymer could achieve an excellent lubrication effect on artificial joint materials such as Ti6Al4V alloy with a coefficient of friction as low as 0.008, and on OA-simulated cartilage, better than the conventional lubricant hyaluronic acid, and the adsorption effect of lubricant on cartilage surface was proved by a fluorescence labeling experiment. In addition, CS-b-pSBMA lubricant possessed an outstanding stability, which can withstand enzymatic degradation and even a long-term storage up to 4 weeks. In vitro studies showed that CS-b-pSBMA lubricant had a favorable antibacterial activity and good biocompatibility. In vivo studies confirmed that the CS-b-pSBMA lubricant was stable and could alleviate the degradation process of cartilage in OA mice. This biomimetic lubricant is a promising articular joint lubricant for the treatment of OA and cartilage restoration. [Display omitted] [ABSTRACT FROM AUTHOR]

Ovomucin is hypothesized to be responsible for the gel-like nature of egg white. However, few investigations have revealed the rheological property and conformational alterations of ovomucin from eggs with different interior quality. In this study, ovomucin was isolated from eggs with different Haugh unit (HU) values, ranging from 80 to 30 as a result of storage. The viscoelasticity and structural characteristics of ovomucin were analyzed using rheology, DLS, fluorescence, CD and FTIR spectroscopy. Rheological data revealed a significant decrease in the viscosity and elastic modulus (G′) of ovomucin gel with decreasing HU value. The same trend was observed in the ovomucin content. The particle size distribution results showed the smaller average particle size and wider distribution range of the ovomucin from low HU eggs. When the HU decreased from 80 to 64, the blue shift and disappearance in infrared absorption peaks at 800-1200 cm−1 confirmed the dissociation of glycosidic bond in ovomucin. Infrared and CD spectroscopic results demonstrated that the ovomucin undergoes a transition from intermolecular β-sheet and α-helix structure to random coil structure when HU decreased from 80 to 64, and the stretched protein re-forms an ordered secondary structure such as β-turn when HU further decreased from 53 to 30. There was an intermediate form in the secondary structure of ovomucin from eggs with HU between 64 and 53, indicating that the conformational transition of ovomucin does not fit the simple two-state mechanism. Zeta potential and hydrophobicity measurements further confirmed the existence of intermediate state. Image 10241 • Rheological and structural properties of ovomucin isolated from different HU eggs are studied. • High HU egg-derived ovomucin has better elasticity. • Ovomucin from low HU eggs has smaller particle size and wider distribution range. • Ovomucin prepared from different HU eggs shows different secondary structures. • There is an intermediate form in the structure of ovomucin during storage. [ABSTRACT FROM AUTHOR]

OFL detection based on β-CD/Sm 2 O 3 NPs/LIG electrochemical sensor. [Display omitted] • Sm 2 O 3 nanoparticles and β-CD were firstly used to modified graphene electrode. • The synergistic effect of two modification compositions promoted OFL detection. • DFT calculation confirmed the enhanced adsorption energy and electron transfer. • The developed sensor obtained a very low detection limit of 0.005 μM for OFL. We developed a new electrochemical sensor that detects ofloxacin (OFL) in water by depositing β-cyclodextrin (β-CD) and samarium oxide nanoparticles (Sm 2 O 3 NPs) onto a laser-induced graphene (LIG) electrode. Scanning electron microscopy, Transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, contact angle measurements, and electrochemical impedance spectroscopy were used to characterize β-CD/Sm 2 O 3 NPs/LIG electrodes. Our results showed that the improved electrochemical activity is due to the excellent electrocatalytic performance of Sm 2 O 3 NPs, improving electron transfer efficiency. The deposition of β-CD improves electrode hydrophilicity and increases the adsorption capacity of OFL on the electrode surface. The synergistic effect of two modification compositions can promote OFL detection. The enhanced adsorption energy and improved electron transfer characteristics were also confirmed by density functional theory calculations. Under optimal detection conditions, the sensor achieves a wide linear range (0.01 ∼ 1.0 μmol/L and 1.0 ∼ 120 μmol/L) and a low detection limit (0.005 μmol/L) with good anti-interference ability and stability. This sensor has also been successfully applied to the detection of OFL in tap water and lake water. These results show that the developed sensor is a promising step towards rapid in situ detection of OFL in water environments. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a ‘green” method has been discovered by utilizing the amino functional poly(ethylene oxide) (PEO) and epoxy functional PEO with low molecular weights to synthesis cross-linked membranes for enhancing H2 purification and CO2 capture performance by retarding the crystallinity of semi-crystalline polymer of PEO. The cross-linking reaction can happen simply by mixing two materials without using any solvent. The reaction has been characterized by Fourier transform infrared-attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), solid-state 13C nuclear magnetic resonance (NMR) and the gel content test. Furthermore, X-ray diffraction (XRD) and differential scanning calorimeter (DSC) confirm the amorphous structure of cross-linked PEO membranes, which should benefit the gas transport. The gas transport properties and the plasticizing phenomenon of CO2 have been examined in detail. Interestingly, the investigation on CO2 plasticization phenomenon reveals that the cross-linked PEO membrane should be plasticized immediately after the pressure load. The pressure dependence of CO2 permeability in the pressure range from 0.25 atm to 30 atm can be separated into two stages based on the permeability increment although the CO2 permeability continuously increases with the loading pressure. The gas transport results illustrate that CO2 has much larger permeability than that of any tested gas (including H2, N2 and CH4) attributing to the CO2-philic characteristic of ethylene oxide (EO) groups in the cross-linked PEO membrane. The good permeability and selectivity make the developed PEO membrane promising for H2 purification and CO2 capture applications. [Copyright &y& Elsevier]

• Type II pyrethroids specifically adsorb to magnetic molecularly imprinted polymers. • Simulations were employed to screen optimum synthesis conditions. • Imprinted polymer showed good adsorption properties via characterization. • Polymer can act as adsorbent for magnetic solid-phase extraction. • Polymer can be combined with GC–MS to analyze type II pyrethroids in human plasma. Type II pyrethroids has been reported to possess significant toxicity. The analysis of type II pyrethroid residues in biological samples for clinical monitoring and toxicological studies will be favorable. However, due to the interference caused by complex matrix and the trace amount of the pyrethroids, the analysis remains difficult. This study details an efficient method employing magnetic molecularly imprinted polymers as a magnetic solid-phase extraction adsorbent coupled with gas chromatography-mass spectrometry for the detection of type II pyrethroids in human plasma. Molecular simulations were used to screen a suitable monomer and ratio of monomer to template molecule. A series of functional nanoparticles were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy and vibrating sample magnetometer to verify the coating of functional groups. Then, a binding experiment was employed to evaluate the adsorption properties. According to the results of isotherm study, the adsorption sites and capacity of MMIPs are much better than MNIPs, while the maximum adsorption capacity of magnetic molecular imprinted polymers is 27.115 mg g−1. The solid phase extraction conditions were investigated, including eluent type, amount of eluent, extraction time and magnetic molecular imprinted polymers amount. The chromatographic separation of type II pyrethroids in human plasma was carried out by Gas Chromatography-Mass Spectrometry; Linearity was assessed using curves prepared with pyrethroids concentrations of 0.2, 1, 2, 5, 10, 25, 50 ng mL−1; the coefficients of determination were more than 0.990, and the recoveries are within the range of 90.0 and 100.1%. The limits of detection of four pyrethroid pesticides were between 0.005 and 0.032 ng mL−1; The relative standard deviation of magnetic molecular imprinted polymers were 2.74–4.07%. It was confirmed that the current analytical approach can be applied for the selective determination of type II pyrethroids in human plasma samples or other complex matrices. [ABSTRACT FROM AUTHOR]

• It was the first time that the synthesized sheet-like polypyrrole nanowires were used as solid phase Extraction materials. • Molecular dynamics analyses were used to simulate the adsorption mechanism. • The van der Waals force was considered as an important driving force for the adsorption of pyrethroids and polypyrrole nanowires. • The method could be a concise and efficient detection method for trace pyrethroid pesticides analysis in complex biological samples. The synthesized sheet-like polypyrrole (ppy) nanowires were used as solid phase extraction materials, followed by gas chromatography-mass spectrometry (GC–MS) for the detection of traces residues of pyrethroid pesticides in human plasma. A multiresidue method was developed and verified for the determination of trace pyrethroid residues (transfluthrin, allethrin, resmethrin, fenpropathrin, etofenprox, fenvalerate) in human plasma. In this study, using the cationic surfactant cetyltrimethylammonium bromide (CTAB) as a soft template, ppy nanowires with regular morphology were prepared by oxidative polymerization. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and other techniques were employed for characterization. Molecular dynamics analyses were used to simulate the adsorption mechanism of each pyrethroid and ppy nanowires. Based on density analysis, molecular recognition analysis, and binding energy, the van der Waals force was considered as an important driving force for the adsorption of pyrethroids and ppy nanowires. The limits of detection (LOD) of six pyrethroids were 0.008–0051 ng mL−1, and the limits of quantification (LOQ) were 0.028–0.162 ng mL−1. The relative standard deviations of ppy nanowires were 2.12–5.09%, and the recoveries of six pyrethroids ranged from 76.9 to 110.4%. The enrichment factors were within the range of 47.09–51.30. The experimental results showed that the method could be an efficient detection method for trace residue analysis of pyrethroid pesticides in complex biological samples. It would be advantageous for clinical monitoring and toxicological studies of pyrethroids. [ABSTRACT FROM AUTHOR]