[Determination of 35 prohibited pesticide residues in Saussurea costus by modified QuEChERS method based on multi-walled carbon nanotubes coupled with gas chromatography-tandem mass spectrometry].

Saussurea costus, a perennial herb belonging to the Asteraceae family, is a vital ingredient in traditional Chinese medicine. Increased demands for the herb have led to its widespread cultivation in China, but the corresponding increase in pesticide use has raised concerns about pesticide residues. Such residues would affect the safety and global market potential of Saussurea costus. Thus, a simple method is crucial to detect pesticide residues. The QuEChERS technique, in combination with gas chromatography-tandem mass spectrometry (GC-MS/MS), is commonly used for residue detection. However, traditional adsorbents may be unable to purify complex herbal mixtures well, affecting accuracy and instrument performance. Choosing suitable purification materials for Saussurea costus samples with complex matrices is of significant importance. This study focused on the detection of 35 prohibited pesticides in Saussurea costus. A rapid detection method was established by combining the QuEChERS technique with GC-MS/MS and utilizing a combination of multiwalled carbon nanotubes (MWCNTs), octadecylsilane-bonded silica gel (C18), and anhydrous magnesium sulfate (MgSO4) as the purification adsorbent. The samples were extracted with acetonitrile, purified by an improved QuEChERS process, subjected to GC-MS/MS analysis in multiple reaction monitoring (MRM) mode, and quantified using the internal standard method. The purification effects of four materials (C18, MWCNTs, N-propyl ethylenediamine (PSA), and graphitized carbon black (GCB)) and their optimal dosages were investigated by considering the matrix characteristics of the samples. An orthogonal experimental design was employed to optimize the ratio of adsorbent combinations, and the optimal adsorbent combination was determined to be 450 mg of MgSO4, 400 mg of C18, and 50 mg of MWCNTs. Matrix effect (ME) evaluation of the S. costus matrix showed that 31 target compounds strongly exhibited matrix-enhancement effects. Thus, matrix-matched calibration was employed in this study. Methodological investigation revealed that the standard curves for the 35 pesticides exhibited good linearity, with correlation coefficients (r2) greater than 0.9970. The average recoveries at three spiked levels ranged from 69.6% to 126.9%, and the relative standard deviations (RSDs) for parallel groups were all less than 10%. The limits of detection (LODs) and quantification (LOQs) ranged from 0.2 to 5.4 µg/kg and from 0.6 to 18.1 µg/kg, respectively. The developed method was used to screen and detect 35 pesticide residues in 20 batches of S. costus samples, and the target compounds were detected in six batches. The proposed method is simple, sensitive, and accurate. Thus, it is suitable for the rapid screening and detection of the 35 pesticide residues in S. costus and provides technical support for the cultivation, production, and quality control of the herb.

Curcumin coating: a novel solution to mitigate inherent carbon nanotube toxicity.

Multi-walled Carbon Nanotubes (MWCNTs) are inert structures with high aspect ratios that are widely used as vehicles for targeted drug delivery in cancer and many other diseases. They are largely non-toxic in nature however, when cells are exposed to these nanotubes for prolonged durations or at high concentrations, they show certain adverse effects. These include cytotoxicity, inflammation, generation of oxidative stress, and genotoxicity among others. To combat such adverse effects, various moieties can be attached to the surface of these nanotubes. Curcumin is a known anti-inflammatory, antioxidant and cytoprotective compound derived from a medicinal plant called Curcuma longa. In this study, we have synthesized and characterized Curcumin coated-lysine functionalized MWCNTs and further evaluated the cytoprotective, anti-inflammatory, antioxidant and antiapoptotic effect of Curcumin coating on the surface of MWCNTs. The results show a significant decrease in the level of inflammatory molecules like IL-6, IL-8, IL-1ß, TNFα and NFκB in cells exposed to Curcumin-coated MWCNTs as compared to the uncoated ones at both transcript and protein levels. Further, compared to the uncoated samples, there is a reduction in ROS production and upregulation of antioxidant enzyme-Catalase in the cells treated with Curcumin-coated MWCNTs. Curcumin coating also helped in recovery of mitochondrial membrane potential in the cells exposed to MWCNTs. Lastly, cells exposed to Curcumin-coated MWCNTs showed reduced cell death as compared to the ones exposed to uncoated MWCNTs. Our findings suggest that coating of Curcumin on the surface of MWCNTs reduces its ability to cause inflammation, oxidative stress, and cell death.

Rationally Designed Functionalization of Single-Walled Carbon Nanotubes for Real-Time Monitoring of Cholinesterase Activity and Inhibition in Plasma.

Enzymes play a pivotal role in regulating numerous bodily functions. Thus, there is a growing need for developing sensors enabling real-time monitoring of enzymatic activity and inhibition. The activity and inhibition of cholinesterase (CHE) enzymes in blood plasma are fluorometrically monitored using near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) as probes, strategically functionalized with myristoylcholine (MC)- the substrate of CHE. A significant decrease in the fluorescence intensity of MC-suspended SWCNTs upon interaction with CHE is observed, attributed to the hydrolysis of the MC corona phase of the SWCNTs by CHE. Complementary measurements for quantifying choline, the product of MC hydrolysis, reveal a correlation between the fluorescence intensity decrease and the amount of released choline, rendering the SWCNTs optical sensors with real-time feedback in the NIR biologically transparent spectral range. Moreover, when synthetic and naturally abundant inhibitors inhibit the CHE enzymes present in blood plasma, no significant modulations of the MC-SWCNT fluorescence are observed, allowing effective detection of CHE inhibition. The rationally designed SWCNT sensors platform for monitoring of enzymatic activity and inhibition in clinically relevant samples is envisioned to not only advance the field of clinical diagnostics but also deepen further understanding of enzyme-related processes in complex biological fluids.

Recent advancement in synthesizing bio-epoxy nanocomposites using lignin, plant oils, saccharides, polyphenols, and natural rubbers: A review.

Due to environmental issues, production costs, and the low recycling capability of conventional epoxy polymers and their composites, many science groups have tried to develop a new type of epoxy polymers, which are compatible with the environment. Considering the precursors, these polymers can be produced from plant oils, saccharides, lignin, polyphenol, and natural resins. The appearance of these bio-polymers caused to introduce a new type of composites, namely bio-epoxy nanocomposites, which can be classified according to the synthesized bio-epoxy, the used nanomaterials, or both. Hence, in this work, various bio-epoxy resins, which have the proper potential for application as a matrix, are completely introduced with the synthesis viewpoint, and their characterized chemical structures are drawn. In the next steps, the bio-epoxy nanocomposites are classified based on the used nanomaterials, which are carbon nanoparticles (carbon nanotubes, graphene nanoplatelets, graphene oxide, reduced graphene oxide, etc.), nano-silica (mesoporous and spherical), cellulose (nanofibers and whiskers), nanoclay and so on. Also, the features of these bio-nanocomposites and their applications are introduced. This review study can be a proper guide for developing a new type of green nanocomposites in the near future.

Functionalized carbon nanotube-polyaniline composite coating for on-line microextraction on a screw coupled with high performance liquid chromatography to determine opium alkaloids.

A novel and efficient on-line microextraction on a screw coupled with high-performance liquid chromatography with an ultraviolet-visible detector was developed to extract and determine trace quantities of five opium alkaloids. All detections of the analytes were achieved at 210 nm. The surface of the screw grooves was electrochemically coated with the carbon nanotubes-COOH/polyaniline composite. The surface characterization was assessed by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The prepared screw was inserted into a cartridge of a guard column, and then the constructed microextraction on a screw device was placed in the loop of a six-port HPLC injection valve. The parameters affecting the extraction efficiency of the analytes were optimized using the one variable-at-a-time method. The effective parameters for the extraction efficiency of the analytes, including sample volume, extraction time, sampling flow rate, desorption solvent type, ionic strength, and pH were investigated and optimized. Under optimal conditions, the detection limits were 3-10 µg L-1, and the linear dynamic ranges were 10-2000 µg L-1 with a coefficient of determination greater than 0.9940. The inter-day and intra-day (n = 3) relative standard deviations were less than 7% and 5%, respectively. The proposed method was simple and reproducible, with an acceptable relative recovery (90-108%) for determining opium alkaloids in water and urine samples.

Smartphone-Based Electrochemical Biosensor for On-Site Nutritional Quality Assessment of Coffee Blends.

This work aimed to develop an easy-to-use smartphone-based electrochemical biosensor to quickly assess a coffee blend's total polyphenols (Phs) content at the industrial and individual levels. The device is based on a commercial carbon-based screen-printed electrode (SPE) modified with multi-walled carbon nanotubes (CNTs) and gold nanoparticles (GNPs). At the same time, the biological recognition element, Laccase from Trametes versicolor, TvLac, was immobilized on the sensor surface by using glutaraldehyde (GA) as a cross-linking agent. The platform was electrochemically characterized to ascertain the influence of the SPE surface modification on its performance. The working electrode (WE) surface morphology characterization was obtained by scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) imaging. All the measurements were carried out with a micro-potentiostat, the Sensit Smart by PalmSens, connected to a smartphone. The developed biosensor provided a sensitivity of 0.12 µA/µM, a linear response ranging from 5 to 70 µM, and a lower detection limit (LOD) of 2.99 µM. Afterward, the biosensor was tested for quantifying the total Phs content in coffee blends, evaluating the influence of both the variety and the roasting degree. The smartphone-based electrochemical biosensor's performance was validated through the Folin-Ciocâlteu standard method.

MWCNTs and ZnO-based Ce-MOF nanocomposites as enhanced sensing platform for electrochemical detection of carbendazim in Chinese traditional herbs samples.

A facile and novel Ce-MOF@MWCNTs@ZnO-modified glassy carbon electrode was prepared through drop coating and used for accurate and sensitive electrochemical detection of carbendazim. The modification of ZnO nanospheres and Ce-based metal-organic frameworks (Ce-MOFs), which possess vast surface/bulk ratio, large surface area, and excellent catalytic ability, provided more active sites for reaction. The combination of multi-walled carbon nanotubes endowed the modified electrode with excellent conductivity and greatly accelerated the electron transfer. The promotion of electrochemical response and the significant improvement of peak current indicated the outstanding electrocatalytic ability of the modified electrode. The oxidation peak current of carbendazim which was measured by DPV in a potential range from 0.5 to 1.0 V produced a good linear relationship in the concentration ranges 0.05-10.0 µM and 10.0-50.0 µM under  optimized experimental conditions. The detection limit was 13.2 nM (S/N = 3). The constructed electrode was successfully applied to the detection of carbendazim in Lithospermum and Glycyrrhiza uralensis real samples and exhibited satisfactory RSD (2.7-3.6% and 1.6-4.8%, respectively) and recovery (102-106% and 97.7-107%, respectively).

Label-Free Electrochemical Aptasensor for Sensitive Detection of Malachite Green Based on AuNPs/MWCNTs@TiO2 Nanocomposites.

This study proposes a label-free aptamer biosensor for the sensitive detection of malachite green(MG) using gold nanoparticles/multi-walled carbon nanotubes @ titanium dioxide(AuNPs/MWCNTs@TiO2). The nanocomposite provides a large surface area and good electrical conductivity, improving current transfer and acting as a platform for aptamer immobilization. The aptamer and the complementary chain(cDNA) are paired by base complementary to form the recognition element and fixed on the AuNPs by sulfhydryl group, which was modified on the cDNA. Since DNA is negatively charged, the redox probe in the electrolyte is less exposed to the electrode surface under the repulsion of the negative charge, resulting in a low-electrical signal level. When MG is present, the aptamer is detached from the cDNA and binds to MG, the DNA on the electrode surface is reduced, and the rejection of the redox probe is weakened, which leads to an enhanced electrical signal and enables the detection of MG concentration by measuring the change in the electrical signal. Under the best experimental conditions, the sensor demonstrates a good linear relationship for the detection of MG from 0.01 to 1000 ng/mL, the limit of detection (LOD)is 8.68 pg/mL. This sensor is stable, specific, and reproducible, allowing for the detection of various small-molecule pollutants by changing the aptamer, providing an effective method for detecting small-molecule pollutants.

Construction of an electrochemical sensing platform for the sensitive determination of chlorogenic acid in locally consumed bitter coffee known as Mirra.

The demand for foods with high antioxidant capacity has increased and research on food analysis continues to increase. Chlorogenic acid is a potent antioxidant molecule and can exhibit various physiological activities. This study aims to analyze Mirra coffee for the determination of chlorogenic acid using an adsorptive voltammetric method. The method is based on the strong synergistic effect between carbon nanotubes and nanoparticles of gadolinium oxide and tungsten, providing sensitive determination of chlorogenic acid. The proposed method yielded a dynamic linear range of 2.5 × 10-9 âˆ¼ 1.6 × 10-6 M with a detection limit of 1.08 × 10-9 M for chlorogenic acid. The amount of chlorogenic acid in Mirra coffee was found to be 46.1 ± 0.69 mg/L by the proposed electrochemical platform.

An ultra-sensitive uric acid second generation biosensor based on chemical immobilization of uricase on functionalized multiwall carbon nanotube grafted palm oil fiber in the presence of a ferrocene mediator.

In this work, palm oil fiber (POF) grafted functionalized multiwall carbon nanotube (FMWCNT) decorated ferrocene (Fc) has been drop coated on a platinum electrode (Pt), in which uricase (UOx) has been chemically immobilized for sensitive and selective biosensing of uric acid (UA). Through the use of EDC/NHS, a stable bioelectrode (UOx/Fc/FMWCNT-POF/Pt) was obtained and characterized by FTIR/ATRIR, XRD, Raman, EA/EDX, TGA, SEM, TEM, CV, EIS, CA, and DPV. Results from DPV showed the rapid response of the developed bioelectrode towards UA (0.185 V) with high sensitivity (41.14 µA mM-1) and good limit of detection (19 µM) in the linear range 10-1000 µM. The low value of Michaelis-Menten constant (km = 31.364 µM) shows high affinity of the UA towards the enzyme at the electrode surface. The developed biosensor demonstrates good reproducibility, repeatability, and stability with a deviation of less than 2.5%, and was successfully applied for human blood sample analysis. The CA study revealed a fast response time (2 s) of the sensor. The work has pioneered a new addition to the class of tailorable chemical species for biosensor development and proven to be a promising new tool for point of care testing (POCT) applications.

Characterizing the Interactions of Cell-Membrane-Disrupting Peptides with Lipid-Functionalized Single-Walled Carbon Nanotubes.

Lipid-functionalized single-walled carbon nanotubes (SWNTs) have garnered significant interest for their potential use in a wide range of biomedical applications. In this work, we used molecular dynamics simulations to study the equilibrium properties of SWNTs surrounded by the phosphatidylcholine (POPC) corona phase and their interactions with three cell membrane disruptor peptides: colistin, TAT peptide, and crotamine-derived peptide. Our results show that SWNTs favor asymmetrical positioning within the POPC corona, so that one side of the SWNT, covered by the thinnest part of the corona, comes in contact with charged and polar functional groups of POPC and water. We also observed that colistin and TAT insert deeply into the POPC corona, while crotamine-derived peptide only adsorbs to the corona surface. In separate simulations, we show that three examined peptides exhibit similar insertion and adsorption behaviors when interacting with POPC bilayers, confirming that peptide-induced perturbations to POPC in conjugates and bilayers are similar in nature and magnitude. Furthermore, we observed correlations between the peptide-induced structural perturbations and the near-infrared emission of the lipid-functionalized SWNTs, which suggest that the optical signal of the conjugates transduces the morphological changes in the lipid corona. Overall, our findings indicate that lipid-functionalized SWNTs could serve as simplified cell membrane model systems for prescreening of new antimicrobial compounds that disrupt cell membranes.

Covalent immobilization of tyrosinase on magnetic multi-walled carbon nanotubes for inhibitor screening.

The inhibition of tyrosinase is considered to be a common therapeutic strategy for some hyperpigmentation disorders. Screening of tyrosinase inhibitors is of great significance to the treatment of pigmentation diseases. In this study, tyrosinase was covalently immobilized on magnetic multi-walled carbon nanotubes for the first time, and the immobilized tyrosinase was applied for ligand fishing of tyrosinase inhibitors from complex medicinal plants. The immobilized tyrosinase was characterized by transmission electron microscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, and thermo-gravimetric analyzer, which indicated that tyrosinase was immobilized onto magnetic multi-walled carbon nanotubes. The immobilized tyrosinase showed better thermal stability and reusability than the free one. The ligand was fished out from Radix Paeoniae Alba and identified as 1,2,3,4,6-pentagalloylglucose by ultra-performance liquid chromatography-quadrupole time-of-flight high-resolution mass spectrometry. 1,2,3,4,6-pentagalloylglucose was found to be a tyrosinase inhibitor with similar half maximal inhibitory concentration values of 57.13 ± 0.91 µM compared to kojic acid (41.96 ± 0.78 µM). This work not only established a new method for screening tyrosinase inhibitors but also holds considerable potential for exploring the new medicinal value of medicinal plants.

[QuEChERS-liquid chromatography-tandem mass spectrometry for determination of 22 triazole pesticide residues in Chinese herbal medicines].

Eight well-known herbals in Zhejiang Province, Zhebawei, are commonly used as traditional Chinese herbal medicines owing to their rich active ingredients. However, the unavoidable use of pesticides during agricultural production has led to pesticide residue problems in these herbs. In this study, a simple, rapid, and accurate method was established to determine 22 triazole pesticide residues in Zhebawei. An improved QuEChERS method was used for sample pretreatment, and Rhizoma Atractylodis Macrocephalae was used as a representative sample. The sample was extracted with acetonitrile to eliminate some polar and nonpolar compounds, pigments, and other impurities, and the purification effects of multiwalled carbon nanotubes (MWCNTs), amino-modified multiwalled carbon nanotubes (MWCNTs-NH2), carboxylated multiwalled carbon nanotubes (MWCNTs-COOH), crosslinked polyvinylpyrrolidone (PVPP), zirconium dioxide (ZrO2), 3-(N,N-diethylamino)-propyltrimethoxysilane (PSA), octadecyl (C18), and graphitized carbon black (GCB) were compared. MWCNTs-COOH and C18 were selected as the purification adsorbents, and their dosages were systematically optimized. The combination of 10 mg of MWCNTs-COOH and 20 mg of C18 was eventually selected as the purification adsorbents. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for analysis, and box graphs were plotted to present the dispersion of each group of recoveries, thus enabling the identification of the data outliers, dispersion distribution, and data symmetry. The established method was systematically verified and showed good linearity over the concentration range of 1-200 µg/L (except for bromuconazole, epoxiconazole, and etaconazole) with correlation coefficients >0.99. The average recoveries of the 22 pesticides at spiked levels of 10, 20, 100, and 200 µg/kg were in the range of 77.0%-115% with relative standard deviations (RSDs) <9.4%. The limits of detection and quantification were 1-2.5 µg/kg and 10-20 µg/kg, respectively. The applicability of the developed method to other herbals was investigated at 100 µg/kg, and the average recoveries of the target pesticides in different matrices ranged from 76.4% to 123% with RSDs <12.2%. Finally, the method established was used to detect triazole pesticide residues in 30 actual Zhebawei samples. The results showed that triazole pesticides were present in Bulbus Fritillariae Thunbergii and Dendranthema Morifolium. Difenoconazole was detected in Bulbus Fritillariae Thunbergii at contents ranging from 41.4 µg/kg to 110 µg/kg, while difenoconazole, myclobutanil, triadimenol and propiconazole were detected in Dendranthema Morifolium at contents ranging from 16.1 µg/kg to 250 µg/kg. The established method can meet the requirements for the accurate quantitative analysis of triazole fungicides in Zhebawei.

Ligand-targeted fishing of α-glucosidase inhibitors from Tribulus terrestris L. based on chitosan-functionalized multi-walled carbon nanotubes with immobilized α-glucosidase.

α-Glucosidase inhibitors in natural products are one of the promising drugs for the treatment of type 2 diabetes. However, due to the complexity of the matrix, it is challenging to comprehensibly clarify the specific pharmacodynamic substances. In this study, a novel high-throughput inhibitor screening strategy was established based on covalent binding of α-glucosidase on chitosan-functionalized multi-walled carbon nanotubes coupled with high-resolution mass spectrometry. The synthesized MWCNTs@CS@GA@α-Glu was characterized by TEM, SEM, FTIR, Raman, and TG. Performance studies showed that the microreactor exhibited stronger thermostability and pH tolerance than that of the free one while maintaining its inherent catalytic activity. Feasibility study applying a model mixture of known α-glucosidase ligand and non-ligands indicated the selectivity and specificity of the system. By integrating ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-QTOF-MS) with ion mobility mass spectrometry (IMS), 15 ligands were obtained and tentatively identified from Tribulus terrestris L., including 8 steroidal saponins, 4 flavonoids, and 3 alkaloids. These inhibitors were further validated by in vivo experiments and molecular docking simulation.

Synthesis and Structural Studies of New Selenium Derivatives Based on Covalent Functionalization of MWCNTs.

Modifying the surface of nanomaterials, such as carbon nanotubes, by introducing heteroatoms or larger functional groups into the structure causes a change in chemical properties-manifested in the increase in reactivity as well as a change in conductivity. This paper presents the new selenium derivatives obtained by a covalent functionalization of brominated multi-walled carbon nanotubes (MWCNTs). The synthesis was carried out in mild conditions (3 days at room temperature), and was additionally assisted with ultrasound. After a two-stage purification, the obtained products were identified and characterized by the following methods: scanning and transmission electron microscopy imaging (SEM and TEM), energy dispersive X-ray microanalysis (EDX), X-ray photoelectron spectroscopy (XPS), Raman and nuclear magnetic resonance (NMR), and X-ray diffraction (XRD). In the selenium derivatives of carbon nanotubes, the content of selenium and phosphorus reached 14 and 4.2 wt%, respectively.

Automatic Multi-Plug Filtration Cleanup Tip-Filtration with Ultra-Performance Liquid Chromatography/Tandem Mass Spectrometry Detection For 22 Pesticide Residues in Typical Vegetables.

An automatic multi-plug filtration cleanup (m-PFC) tip-filtration method was developed to reduce the manual operation workload in sample preparation. In this work, m-PFC was based on multi-walled carbon nanotubes mixed with primary secondary amines and anhydrous magnesium sulfate (MgSO4) in a packed column for analysis of pesticide residues followed by ultra-performance liquid chromatography coupled with tandem mass spectrometry. Method validation was performed on 22 pesticide residues in carrot, spinach and leek, at spiked levels of 5, 10 and 50 µg/kg, respectively. The average recoveries were between 70.1 and 119.5% with associated relative standard deviations <20% (n = 6) indicating satisfactory accuracy and repeatability. Matrix-matched calibration curves were performed with the correlation coefficients (R2) higher than 0.9903 within a linearity range of 5-100 ng/mL. The limits of quantification were 5 µg/kg for all the pesticides in carrot, spinach and leek matrices. The developed method was successfully used to determine pesticide residues in market samples.

Synergistic Function between Phosphorus-Containing Flame Retardant and Multi-Walled Carbon Nanotubes towards Fire Safe Polystyrene Composites with Enhanced Electromagnetic Interference Shielding.

As a universal polymer material, polystyrene (PS) is widely applied in electrical devices and construction. Thus, it is necessary to improve the flame retardancy and electromagnetic shielding properties of PS material. In this work, PS/silicon-wrapped ammonium polyphosphate/Inorganic acid-treated multi-walled carbon nanotubes composites (PS/SiAPP/aMWCNT, abbreviated as PAC) were prepared via methods of filtration-induced assembly and hot-pressing. Morphology and structure characterization demonstrated that SiAPP and aMWCNT had good dispersion in PS and excellent compatibility with the PS matrix. Thermogravimetric analysis revealed that the addition of aMWCNT to PS improved its thermal stability and carbon-forming characteristics. The peak heat release rate, the peak carbon monoxide production rate, and the peak smoke production rate of the PAC10 composite decreased by 53.7%, 41.9%, and 45.5%, respectively, while its electromagnetic shielding effectiveness reached 12 dB. These enhancements were attributed to the reason that SiAPP and aMWCNT synergistically catalyzed the char generation and SiAPP produced free radical scavengers and numbers of incombustible gases, which could decrease the oxygen concentration and retard the combustion reaction. Therefore, the assembled PS/SiAPP/aMWCNT system provides a new pathway to improve the flame retardant and electromagnetic shielding properties of PS.

Polyhydroxybutyrate-starch/carbon nanotube electrospun nanocomposite: A highly potential scaffold for bone tissue engineering applications.

Blend nanofibers composed of synthetic and natural polymers with carbon nanomaterial, have a great potential for bone tissue engineering. In this study, the electrospun nanocomposite scaffolds based on polyhydroxybutyrate(PHB)-Starch-multiwalled carbon nanotubes (MWCNTs) were fabricated with different concentrations of MWCNTs including 0.5, 0.75 and 1 wt%. The synthesized scaffolds were characterized in terms of morphology, porosity, thermal and mechanical properties, biodegradation, bioactivity, and cell behavior. The effect of the developed structures on MG63 cells was determined by real-time PCR quantification of collagen type I, osteocalcin, osteopontin and osteonectin genes. Our results showed that the scaffold containing 1 wt% MWCNTs presented the lowest fiber diameter (124 ± 44 nm) with a porosity percentage above 80 % and the highest tensile strength (24.37 ± 0.22 MPa). The addition of MWCNTs has a positive effect on surface roughness and hydrophilicity. The formation of calcium phosphate sediments on the surface of the scaffolds after immersion in SBF is observed by SEM and verified by EDS and XRD analysis.MG63 cells were well cultured on the scaffold containing MWCNTs and presented more cell viability, ALP secretion, calcium deposition and gene expression compared to the scaffolds without MWCNTs. The PHB-starch-1wt.%MWCNTs scaffold can be considerable for studies of supplemental bone tissue engineering applications.

Simultaneous Determination of 108 Pesticide Residues in Three Traditional Chinese Medicines Using a Modified QuEChERS Mixed Sample Preparation Method and HPLC-MS/MS.

A rapid, efficient, simple, and high-throughput method for the simultaneous determination of 108 pesticide residues in three traditional Chinese medicines (TCMs) was established, comprising an improved QuEChERS method in combination with HPLC-MS/MS based on mixed samples. A quantity of 10 mL of acetonitrile was used as extraction solvent, and 10 mg of amino-modified multi-walled carbon nanotubes (MWCNTs-NH2) and 150 mg of anhydrous magnesium sulfate (MgSO4) were selected as sorbents for dispersive solid phase extraction. The performance of the method was verified according to the analytical quality control standards of SANTE/11813/2017 guidelines. With good linearity (R2 > 0.9984) in the range of 2−200 µg/L for all pesticides in the selected matrices, and good accuracy, precision, and high sensitivity, the recoveries were in the range of 70−120% for more than 95% of the pesticides, with a relative standard deviation (RSD) of less than 16.82% for all. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.01−3.87 µg/kg and 0.07−12.90 µg/kg, respectively, for Fritillaria thunbergii Miq (F. thunbergii), Chrysanthemum Morifolium Ramat (C. morifolium), and Dendrobium officinale Kimura et Migo (D. officinale). The method was successfully applied to 60 batches of actual samples from different regions.

Monolithic robust hybrid sponge with enhanced light adsorption and ultrafast photothermal heating rate for rapid oil cleaning.

It remains a significant challenge to develop a photothermal adsorbent with a heating response as fast as a joule-heating adsorbent and simultaneously possessing excellent mechanical stability and reusability for rapid oil cleaning. Here, we report a novel monolithic design to fabricate a photothermal hybrid sponge for rapid oil cleaning by integrating graphite interlayer compounds as photothermal units into the three-dimensional photothermal network of carbon nanotubes. This unique monolithic design enabled the hybrid sponge to present excellent photothermal performance: firstly, the superhydrophobic hybrid sponge has low thermal resistance resulting from the defectless surface; secondly, the photothermal units were weaved in the photothermal network, preventing detachment in the cycling and providing ultrafast photothermal heating rate. The hybrid sponge rises to 81 °C in merely 25 s under irradiation (1 Sun), superior to most photothermal oil adsorbents reported so far. This study provides a new structural design for constructing photothermal adsorbents with a fast-heating response for rapid crude oil cleaning.