[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.

[Determination of 14 perfluoroalkyl substances in Chinese mitten crab by multi-plug filtration cleanup coupled with ultra-performance liquid chromatography-tandem mass spectrometry].

Perfluoroalkyl substances (PFASs) have become a new food-safety problem. Dietary intake is a major pathway of human exposure to PFASs. Chinese mitten crab (Eriocheir sinensis) is a high-end aquaculture product popular among consumers in China. Conventional extraction methods for PFASs are cumbersome and time consuming, and result in incomplete purification; thus, this technique does not meet the requirements for PFAS detection. Herein, an analytical strategy was established for the rapid detection of 14 PFASs in Chinese mitten crab based on multi-plug filtration cleanup (m-PFC) and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The carbon-chain length of the 14 PFASs analyzed in this study ranged from 4 to 14, and they are perfluorobutanoic acid (PFBA), perfluoro-n-pentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), perfluorotetradecanoic acid (PFTeDA), perfluoro-1-butane sulfonic acid (PFBS), perfluoro-1-hexane sulfonic acid (PFHxS), perfluoro-1-octane sulfonic acid (PFOS), and perfluoro-1-decanesulfonate (PFDS). The m-PFC column was prepared using carboxy-based multiwalled carbon nanotubes, and used to reduce the interference of sample impurities. The samples were extracted with 5 mL of 0.1% formic acid aqueous solution, 15 mL of acetonitrile and extraction salt (2 g Na2SO4 and 2 g NaCl). The supernatant (10 mL) was purified using the m-PFC column, concentrated to near dryness under nitrogen, and then redissolved in 1 mL of methanol. Finally, the sample solution was filtered through a 0.22 µm polypropylene syringe filter for UPLC-MS/MS analysis. The target analytes were separated using a Shimadzu Shim-pack G1ST-C18 chromatographic column (100 mm×2.1 mm, 2 µm) using methanol (A) and 5 mmol/L ammonium acetate aqueous solution (B) as the mobile phases via gradient elution. The linear gradient program were as follows: 0-0.5 min, 10%A-35%A; 0.5-3 min, 35%A-60%A; 3-5 min, 60%A-100%A; 5-6.5 min, 100%A; 6.5-7 min, 100%A-10%A. The target analytes were analyzed using negative electrospray ionization in multiple-reaction monitoring mode, and quantitative analysis was performed using the internal standard method. In this study, we optimized the mobile-phase system as well as the extraction solvent, time, volume, and salt. The 14 PFASs exhibited good peak shapes and sensitivities when the 5 mmol/L ammonium acetate solution-methanol system was used as the mobile phase. Compared with acetonitrile or methanol alone, the extraction efficiencies of the 14 PFASs were significantly improved when 5 mL of 0.1% formic acid aqueous solution was added, followed by 15 mL of acetonitrile. The extraction efficiencies of the 14 PFASs did not differ significantly when the extraction time was within 3-15 min. The extraction salt (MgSO4, Na2SO4, NaCl, (NH4)2SO4, and Na2SO4+NaCl) significantly affected the extraction efficiencies of the 14 PFASs. The highest extraction efficiencies of the 14 PFASs, which ranged from 47.9% to 121.9%, were obtained when Na2SO4+NaCl was used as the extraction salt. Under the optimal experimental conditions, good linearities (R2=0.998-0.999) were obtained for seven PFASs (PFBS, PFHxA, PFHpA, PFHxS, PFDA, PFDoDA, PFTeDA) at 0.10-100 µg/L, and seven PFASs (PFBA, PFPeA, PFOA, PFOS, PFNA, PFUnDA, PFDS) at 0.50-100 µg/L. The average spiked recoveries for the 14 PFASs in Chinese mitten crabs at three levels ranged from 73.1% to 120%, with relative standard deviations (RSDs) in the range of 1.68%-19.5%(n=6). The limits of detection (LODs) and quantification (LOQs) of the 14 PFASs were in the range of 0.03-0.15 and 0.10-0.50 µg/kg, respectively. The developed method was applied to the analysis of crab samples collected from three farms in Shanghai, and PFASs with total concentrations of 3.52-37.77 µg/kg were detected in all samples. The detection frequencies for PFDA, PFUnDA, PFDoDA, PFTeDA, and PFOS were 100%. PFDA, PFUnDA, PFOS, and PFDoDA were the most abundant congeners, accounting for 31.2%, 30.6%, 15.0%, and 10.9%, respectively, of the 14 PFASs detected. The proposed method is simple, efficient, accurate, and suitable for the rapid analysis of 14 PFASs in Chinese mitten crabs.

Simultaneous determination of spiropidion and its five major metabolites in sweet orange fruit and various processing by-products using ultra-high performance liquid chromatography-tandem mass spectrometry.

The present work reported the application of an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous analysis of spiropidion and its five major metabolites in sweet orange fruit and by-products throughout the whole industrial juicing process of the orange fruit. The reversed-dispersive solid phase extraction (r-DSPE) with multi-walled carbon nanotubes (MWCNTs) was employed for the extraction and purification. The established method was validated and satisfactory parameters (linearity, trueness, precision, sensitivity, matrix effect and stability) were obtained. And then, the field trial of spiropidion on sweet oranges has been conducted and the effect of commercial juicing processing on the residue of spiropidion and its metabolites was further investigated. The various processing factors (PFs) for washing, juicing, sterilization, concentrating and essential oil collecting were also determined. The final results indicated that washing processing reduced residues by 18.4%; the juicing step allowed a significant decrease of the spiropidion residue by 34.2-70.8%, with PFs value in the range of 0.290-0.658. However, high level of residual spiropidion (ranging from 4.016 to 4.205 mg/kg) was detected in orange essential oil, with PFs value of 17.157. All the above results demonstrated the efficiency of the established method in the routine control analysis of spiropidion residues in sweet orange fruits and their by-products, and will facilitate the further intensive research on its spatial distribution, transfer and degradation during the different processing procedures of the sweet orange fruits.

An Integrated Sweat Sensor for Synchronous Detection of Multiple Atherosclerosis Biomarkers.

Atherosclerosis conditions are often assessed in the clinic by measuring blood viscosity, blood flow, and blood lesion levels. In alignment with precision medicine, it is essential to develop convenient and noninvasive approaches for atherosclerosis diagnostics. Herein, an integrated electrochemical sensor was successfully demonstrated for simultaneously detecting cholesterol, transferrin, and K+ in sweat, all biomarker indicators of atherosclerosis. The sensing substrate was based on carbon quantum dots integrated within multiwalled carbon nanotubes, creating a hybrid framework with low electron transfer resistance and highly efficient electron transfer rate, yielding a highly electrochemical active platform for ultrasensitive detection of trace sweat biomarkers. To ensure specificity to corresponding targets, the sensing mechanisms were based on molecular recognition reactions of cholesterol and ß-cyclodextrin, transferrin and molecular cavities, and K+ and ion-selective permeation membrane. Moreover, the integrated nonenzymatic sensor exhibited excellent long-term stability. Furthermore, the practical utility of the sensor was successfully demonstrated by the simultaneous detection of three atherosclerosis biomarkers in sweat from volunteers who underwent predesigned daily activities. The sensor shows promise for convenient indexing of atherosclerosis conditions in a noninvasive way.

[Determination of 80 pesticide residues in milk using NH_2-MWNTs by liquid chromatography-time of flight mass spectrometry].

OBJECTIVE: A method for the determination of 80 pesticide residues in milk by liquid chromatography-time-of-flight mass spectrometry(LC-QTof-MS) was developed. METHODS: The target compounds in milk were extracted with acetonitrile-methanol(9∶1, V/V) containing 1% acetic acid, and purified by aminated multi-walled carbon nanotubes(NH_2-MWNTs). The chromatographic column was Waters Acquity UPLC BEH C_(18 )(100 mm×2.1 mm, 1.7 µm). The 80 pesticides were detected by liquid chromatography-time-of-flight mass spectrometry and quantified using an external standard method by matrix matched calibration curve. RESULTS: The purification method showed a good linearity(r~2≥ 0.99) over the concentration range from 5 to 100 µg/L for the 80 pesticides in this study. The limits of detection(LODs) and quantification(LOQs) of the 80 pesticides in milk ranged from 0.01 to 0.50 µg/L and 0.03 to 1.50 µg/L, respectively. The mean recoveries of the three spiked levels ranged from 71.5% to 116.9% with the relative standard deviation ranging from 1.2% to 18.1%, indicating that the accuracy and precision of the method were good. Among the milk samples, no residues of the 80 pesticides in this study were found after screening. CONCLUSION: The method has good linearity, good sensitivity, accuracy and precision and is suitable for the simultaneous and rapid determination of 80 pesticide residues in milk.

[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.

Simultaneous determination of phthalates and bisphenols from plastic bottled water samples by dispersive solid-phase extraction with multiwalled carbon nanotubes and liquid chromatography/atmospheric pressure photoionization/high-resolution mass spectrometry.

RATIONALE: Phthalates and bisphenols were reported as endocrine disrupting chemicals and hence a potential threat to human health. Polyethylene terephthalate bottles are being used to store drinking water and the probability of migration of phthalates and bisphenols from the bottles into the water is high. The migration of analytes with respect to different storage conditions need to be studied. METHOD: A sensitive analytical method for simultaneous determination of seven phthalates and three bisphenols from packaged drinking water was developed using liquid chromatography/atmospheric pressure photoionization/high-resolution mass spectrometry. The analytes were extracted by dispersive solid-phase extraction by multiwalled carbon nanotubes. RESULTS: The developed method showed linearity from 0.5 to 5000 µg/L with the limit of detection and limit of quantification ranging from 0.5 to 1 µg/L and 1 to 2 µg/L, respectively, for phthalates and bisphenols. The inter- and intraday variations were below 10%. The recoveries were in the range of 79.5% to 112%. The migration of phthalates and bisphenols increased with storage time and temperature. Maximum migration was observed for diisobutyl phthalate of 1209.7 ng/L followed by dibutyl phthalate at 777.8 ng/L on 180 days of analysis at room temperature. Migration of bis(2-ethylhexyl) phthalate was observed to be higher at elevated temperatures, increasing from 14.9 to 514 ng/L. Similarly, migration of bisphenol-A was increased at 45°C. The results were subjected to analysis of variance (ANOVA) studies and the results showed significant variations of phthalates and bisphenols with respect to storage temperature and time. CONCLUSION: The use of atmospheric pressure photoionization facilitated simultaneous determination of phthalates and bisphenols. The migration of phthalates and bisphenols increased with increasing temperature and storage time. Maximum migration was observed for diethyl, diisobutyl, dibutyl and bis(2-ethylhexyl) phthalates. This may be attributed to the type of plastic, the processing parameters and recycling.

Carbon nanotube-passive samplers as novel tools for sampling and determining micropollutants in the aquatic environment.

Passive sampling is an interesting and cost-effective strategy for the quantification of micropollutants in the aquatic environment. When combined especially with a sensitive analytical method such as liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS), the use of passive sampling devices (PSDs) enables long-term and reliable determination of a wide range of chemicals. In this study, carbon nanotubes (CNTs) were used as an innovative sorbent in POCIS-like samplers (Polar Organic Chemical Integrative Sampler). The developed CNTs-PSDs were calibrated by the flow-through method and the obtained sampling rates (Rs) of analytes were compared with the previously obtained Rs values using the semi-static method. Subsequently, passive samplers were placed in the Baltic Sea, the Nogat River, and the Sztumskie Pole Lake in order to sample and concentrate 28 chemical compounds belonging to the group of contaminants of emerging concern (CECs). For the first time, the effectiveness of the use of CNTs-PSDs in the field was proven by the quantification of carbamazepine, diclofenac, p-nitrophenol, bisphenol A, 3,5-dichlorophenol, 17-ß-estradiol, 17-α-ethinylestradiol and metoprolol in the tested surface waters. The obtained time-weighted average (TWA) concentrations of analytes ranged from 0.22 ± 0.12 ng/L (for metoprolol in the Nogat River) to 32.1 ± 2.4 ng/L (for bisphenol A in the Sztumskie Pole Lake). More importantly, CNTs-PSDs determined a greater amount of micropollutants than grab sampling and solid-phase extraction (SPE), which proves the advantage of passive sampling over grab sampling, especially when monitoring contaminants in the aquatic environment at low concentration levels.

[Modified QuEChERS method based on multi-walled carbon nanotubes coupled with gas chromatography-tandem mass spectrometry for the detection of 10 pyrethroid pesticide residues in tea].

A modified QuEChERS method, based on multi-walled carbon nanotubes (MWCNTs), was established for the detection of 10 pyrethroid pesticides (cyfluthrin, flucythrinate, fenpropathrin, bifenthrin, cyhalothrin, permethrin, cypermethrin, etofenprox, fenvalerate, deltamethrin) in tea, in combination with gas chromatography-tandem mass spectrometry (GC-MS/MS). The purification effects and dosages of four carbon nanomaterials, viz. single-walled carbon nanotubes (SWCNTs), MWCNTs, amino-modified MWCNTs, and graphene, were compared. An orthogonal experimental design was used to determine the optimal experimental conditions for sample pretreatment. The experimental factors governing the process were analyzed using variance. The results showed that the optimized sample pretreatment parameters were as follows. Acetonitrile was used as the extraction solvent with ultrasonic extraction for 35 min, while 60 mg MWCNTs, 200 mg PSA, and 200 mg C18, were used as purifiers. The effects of the extraction solvent and the carbon nanomaterials used on the recoveries of the 10 pyrethroid pesticides were significantly different (p<0.001), and the effect of extraction time on the recoveries was statistically different (p<0.05). The dosage of carbon nanomaterials had no significant effect on the recoveries (p>0.05). Good linearities were observed for the 10 pyrethroid pesticides in the concentration range of 0.01-2 mg/L. The limits of detection (LODs) and limits of quantification (LOQs) were in the ranges of 0.001-0.01 mg/kg and 0.005-0.04 mg/kg, respectively. The average recoveries of the pyrethroid pesticides spiked into blank samples of green tea were 91.4%-109.7%, and the relative standard deviations were 0.12%-9.80% (n=6). Furthermore, the matrix effects (MEs) of scented green tea, green tea, and black tea were evaluated. It was found that the addition of MWCNTs to the purifier can effectively reduce the matrix effect in green tea and black tea matrices. The developed method and the national standard method were used to detect the residues of the 10 pyrethroid pesticides in 120 tea samples available in the market. The results showed that cyfluthrin, deltamethrin, fenvalerate, permethrin, fenpropathrin, cypermethrin, bifenthrin and cyhalothrin were detected, and the contents obtained with the two methods were similar. Although pyrethroids were detected in most tea samples, the contents of all pesticide residues were below the maximum residue limits (MRLs). Therefore, the developed method is suitable for the rapid quantitative analysis of pesticide residues in tea.

Real-Time Emission and Exposure Measurements of Multi-walled Carbon Nanotubes during Production, Power Sawing, and Testing of Epoxy-Based Nanocomposites.

OBJECTIVES: The use of manufactured nanomaterials is increasing globally. Although multi-walled carbon nanotubes (CNTs) are used in a wide range of applications, only limited data are available on emissions and exposures during CNT composite production. No exposure data using portable aethalometers in the personal breathing zone (PBZ) to monitor occupational exposure to CNTs have yet been published. The aim of this study was to characterize emissions of and exposures to CNTs during CNT composite production, sawing, and shear testing. We also investigated whether real-time aethalometer measurements of equivalent black carbon (eBC) could be used as a proxy filter sampling of elemental carbon (EC). The presence of CNTs as surface contamination in the production facility was monitored since this could contribute to airborne exposure. METHODS: During CNT composite production in an industrial setting including both chemical and manufacturing laboratories, different work tasks (WTs) were studied with a combination of direct-reading instruments (aethalometer, aerodynamic particle sizer, condensation particle counter) and filter-based methods. Measurements were performed to monitor concentrations in the emission zone (EZ), PBZ, and background zone. The filter samples were analysed for EC and fibre concentration of CNTs using scanning electron microscopy (SEM). Additionally, surfaces in the facility were tape sampled for monitoring of CNT contamination, and analysed with SEM. RESULTS: Clear eBC peaks were observed in the PBZ during several WTs, most clearly during open handling of CNT powder. Power sawing emitted the highest particle number concentration in the EZ of both nanoparticles and coarse particles, but no individual airborne CNTs, agglomerates, or aggregates were detected. Airborne CNTs were identified, for example, in a filter sample collected in the PBZ of a worker during mixing of CNT epoxy. The airborne CNT particles were large agglomerates which looked like porous balls in the SEM images. Significant EC exposures were found in the inhalable fraction while all respirable fractions of EC were below detection. The highest inhalable EC concentrations were detected during the composite production. No significant correlation was found between inhalable EC and eBC, most likely due to losses of large EC containing particles in the sampling lines and inside the eBC monitor. In total, 39 tape samples were collected. Surface contamination of CNTs was detected on eight surfaces in the chemical and manufacturing laboratories, mainly in the near-field zone. Elongated CNT-like features were detected in the sawdust after sawing of CNT composite. CONCLUSIONS: Characterization of a workplace producing CNT composite showed that open handling of the CNT powder during weighing and mixing of CNT powder material generated the highest particle emissions and exposures. The portable direct-reading aethalometer provided time-resolved eBC exposure data with complementary information to time-integrated EC filter samples by linking peak exposures to specific WTs. Based on the results it was not possible to conclude that eBC is a good proxy of EC. Surface contamination of CNTs was detected on several surfaces in the near-field zone in the facility. This contamination could potentially be resuspended into the workplace air, and may cause secondary inhalation exposure.

Simultaneous detection of ten kinds of insecticide residues in honey and pollen using UPLC-MS/MS with graphene and carbon nanotubes as adsorption and purification materials.

An analytical method of simultaneous detection of ten insecticide residues in honey and pollen was established. The samples were purified with QuEChERS approach using new adsorbents and analyzed with UPLC-MS/MS. The results showed that both of graphene and carbon nanotubes were highly efficient adsorbents for the dSPE clean up to eliminate coextractives in the samples, and graphene was superior to carbon nanotubes for the detection of pesticide residues in honey and pollen samples. The proposed method was used to detect pesticide residues in 25 honey samples and 30 pollen samples which were randomly collected from more than ten provinces in China. All honey samples contain 1-27 µg/kg of chlorpyrifos residues. Only 4% of the honey samples were detected containing acetamiprid and imidacloprid, while the other seven pesticides were not detected. Chlorpyrifos residues were found in all pollen samples (5-66 µg/kg), among which twenty percent exceeded the maximum residue limits (MRLs, 50 µg/kg, European Commission Regulation). Most of the pollen samples containing pesticide concentrations higher than MRLs were collected from rape, followed by lotus, camellia, and rose. Besides, 36.7% and 33.3% of the pollen samples had imidacloprid and flupyradifurone higher than 5 µg/kg. A total of 26.7% pollen samples were detected containing bifenthrin, while none of the other six pesticides were detected in pollen samples.

Serum peptidome: diagnostic window into pathogenic processes following occupational exposure to carbon nanomaterials.

BACKGROUND: Growing industrial use of carbon nanotubes and nanofibers (CNT/F) warrants consideration of human health outcomes. CNT/F produces pulmonary, cardiovascular, and other toxic effects in animals along with a significant release of bioactive peptides into the circulation, the augmented serum peptidome. While epidemiology among CNT/F workers reports on few acute symptoms, there remains concern over sub-clinical CNT/F effects that may prime for chronic disease, necessitating sensitive health outcome diagnostic markers for longitudinal follow-up. METHODS: Here, the serum peptidome was assessed for its biomarker potential in detecting sub-symptomatic pathobiology among CNT/F workers using label-free data-independent mass spectrometry. Studies employed a stratified design between High (> 0.5 µg/m3) and Low (< 0.1 µg/m3) inhalable CNT/F exposures in the industrial setting. Peptide biomarker model building and refinement employed linear regression and partial least squared discriminant analyses. Top-ranked peptides were then sequence identified and evaluated for pathological-relevance. RESULTS: In total, 41 peptides were found to be highly discriminatory after model building with a strong linear correlation to personal CNT/F exposure. The top-five peptide model offered ideal prediction with high accuracy (Q2 = 0.99916). Unsupervised validation affirmed 43.5% of the serum peptidomic variance was attributable to CNT/F exposure. Peptide sequence identification reveals a predominant association with vascular pathology. ARHGAP21, ADAM15 and PLPP3 peptides suggest heightened cardiovasculature permeability and F13A1, FBN1 and VWDE peptides infer a pro-thrombotic state among High CNT/F workers. CONCLUSIONS: The serum peptidome affords a diagnostic window into sub-symptomatic pathology among CNT/F exposed workers for longitudinal monitoring of systemic health risks.

Photoluminescent Nanoparticles for Chemical and Biological Analysis and Imaging.

Research related to the development and application of luminescent nanoparticles (LNPs) for chemical and biological analysis and imaging is flourishing. Novel materials and new applications continue to be reported after two decades of research. This review provides a comprehensive and heuristic overview of this field. It is targeted to both newcomers and experts who are interested in a critical assessment of LNP materials, their properties, strengths and weaknesses, and prospective applications. Numerous LNP materials are cataloged by fundamental descriptions of their chemical identities and physical morphology, quantitative photoluminescence (PL) properties, PL mechanisms, and surface chemistry. These materials include various semiconductor quantum dots, carbon nanotubes, graphene derivatives, carbon dots, nanodiamonds, luminescent metal nanoclusters, lanthanide-doped upconversion nanoparticles and downshifting nanoparticles, triplet-triplet annihilation nanoparticles, persistent-luminescence nanoparticles, conjugated polymer nanoparticles and semiconducting polymer dots, multi-nanoparticle assemblies, and doped and labeled nanoparticles, including but not limited to those based on polymers and silica. As an exercise in the critical assessment of LNP properties, these materials are ranked by several application-related functional criteria. Additional sections highlight recent examples of advances in chemical and biological analysis, point-of-care diagnostics, and cellular, tissue, and in vivo imaging and theranostics. These examples are drawn from the recent literature and organized by both LNP material and the particular properties that are leveraged to an advantage. Finally, a perspective on what comes next for the field is offered.

Evaluation of 1-dimensional nanomaterials release during electrospinning and thermogravimetric analysis.

The growing research interests with engineered nanomaterials in academic laboratories and manufacturing facilities pose potential safety risks to students and workers. New nanoparticle substances, compositions, and processing approaches are developed regularly, creating new health risks which may not have been addressed previously. Accordingly, the Institute of Occupational Medicine conducted field studies at Texas A&M University (TAMU) to characterize possible particle emissions during processing and fabrication of carbon nanotubes, copper nanowires, and polymeric fibers. The nature of the monitoring work carried out at TAMU was to investigate the potential release of 1D nanomaterials to air from activities associated with synthesis, handling, thermal gravimetric analysis, and electrospinning processes, and evaluate the effectiveness of the utilized control measures. The potential nanoparticle release to air from each activity was investigated using a combination of particle detection instrumentations, coupled with standard filter-based sampling techniques. The analyses indicated that a measurable quantity of free carbon nanosphere aggregates was detected during these activities; however, no free MWCNTs or nanowires were detected. Scanning electron microscopy identified the presence of carbon nanospheres aggregates on the filters. While the control measures used at TAMU are effective in containing the nanomaterial release during processing, poor handling and occupational hygiene practices can increase the risk of employee exposure to the nanomaterials.

Novel methods to extract and quantify sensors based on single wall carbon nanotube fluorescence from animal tissue and hydrogel-based platforms.

Sensors that can quickly and accurately diagnose and monitor human health are currently at the forefront of medical research. Single walled carbon nanotube (SWNT) based optical biosensors are a growing area of research due to the high spatiotemporal resolution of their near infrared fluorescence leading to high tissue transparency and unparalleled sensitivity to analytes of interest. Unfortunately, due to the functionalization requirements of SWNT-based sensors, there are concerns surrounding accumulation and persistence when applied in vivo. In this study, we developed protocols to extract and quantify SWNT from complex solutions and show an 89% sensor retention by hydrogel platforms when implanted in vivo. Animal tissues of interest were also extracted and probed for SWNT content showing no accumulation (0.03 mg l-1 SWNT detection limit). The methods developed in this paper demonstrated one avenue for applying SWNT sensors in vivo without concern for accumulation.

Proteomic fingerprinting of protein corona formed on PEGylated multi-walled carbon nanotubes.

In Nanomedicine, carbon-based nanomaterials, like Carbon Nanotubes (CNT), are considered potential candidates as drug delivery systems. In vivo adsorption of physiological proteins onto carbon nanotubes, through noncovalent interactions, forms a protein corona or bio corona, able to influence biological properties and biocompatibility of CNT. This study aimed to explore the composition of protein corona formed onto PEGylated Multi-Walled Carbon Nanotubes (MWCNT-PEG5k), after their incubation in human plasma. Plasma proteins were sequentially eluted in different conditions by using both native and denaturant buffers, useful to characterize soft and hard corona. Proteomic methods and mass spectrometry analysis have identified proteins in soft corona, involved in the regulation of immune response and in the CNT transport, and biomolecules in hard corona with a role in the maintenance of host homeostasis. These promising results have demonstrated the potential of PEGylated Multi-Walled Carbon Nanotubes as future candidates for drug delivery.

Cellular senescence as a response to multiwalled carbon nanotube (MWCNT) exposure in human mesothelial cells.

Cellular senescence is a stable cell cycle arrest induced by diverse triggers, including replicative exhaustion, DNA damaging agents, oncogene activation, oxidative stress, and chromatin disruption. With important roles in aging and tumor suppression, cellular senescence has been implicated also in tumor promotion. Here we show that certain multiwalled carbon nanotubes (MWCNTs), as fiber-like nanomaterials, can trigger cellular senescence in primary human mesothelial cells. Using in vitro approaches, we found manifestation of several markers of cellular senescence, especially after exposure to a long and straight MWCNT. These included inhibition of cell division, senescence-associated heterochromatin foci, senescence-associated distension of satellites, LMNB1 depletion, γH2A.X nuclear panstaining, and enlarged cells exhibiting senescence-associated ß-galactosidase activity. Furthermore, genome-wide transcriptome analysis revealed many differentially expressed genes, among which were genes encoding for a senescence-associated secretory phenotype. Our results clearly demonstrate the potential of long and straight MWCNTs to induce premature cellular senescence. This finding may find relevance in risk assessment of workplace safety, and in evaluating MWCNT's use in medicine such as drug carrier, due to exposure effects that might prompt onset of age-related diseases, or even carcinogenesis.

Electrochemical determination of artemisinin based on signal inhibition for the reduction of hemin.

A novel electrochemical sensor was constructed for the determination of artemisinin (ART) based on the inhibition of redox for hemin caused by ART. As far as we know, this strategy for ART determination may be proposed for the first time. In this work, untreated multi-walled carbon nanotubes were cast on the glassy carbon electrode (GCE) as conductive carrier. We prepared a bimetallic organic framework named FeGd-MOF and combined it with hemin by a simple physical mixed method. Then, we fabricated the working electrode by layer-by-layer modification and immobilization. The sensor measured by the differential pulse voltammetry (DPV) technique had calibration curves for the determination of ART, which was 0.3-350 µM with the correlation coefficient R2 = 0.9998. Furthermore, the obtained linear range could be practically used in real sample analysis such as dried leaves of Artemisia apiacea. Under the optimized condition, the electrochemical sensor exhibited high sensitivity, good stability, and excellent anti-interference performance. The limit of detection (LOD) for this sensor was 0.17 µM (signal to noise ratio, S/N = 3), which was much lower than that for some other reported electrochemical sensors. The recovery rates were in the range of 99.54-104.34% in real samples, indicating that the sensor had good repetition and high accuracy. Graphical abstract.

Primary culture macrophages from fish as potential experimental model in toxicity studies with multiwalled carbon nanotubes

Multiwalled carbon nanotube (MWCNT) has been broadly used in several sectors of society. This material when exposed to the environment might reach the aquatic animals and cause toxic effects. Here, it was evaluated the MWCNTs toxicity in melanomacrophages primary culture that was submitted to 1 µ gm L-1 MWCNTs for 24 hours. After exposition to MWCNT, 48 and 59% liver and spleen melanomacrophages were healthy, respectively. The control group presented 85% viability. Phagocytosis activity of melanomacrophages was observed by presence of black inclusions in cytoplasm. The findings indicate MWCNT was cytotoxic to melanomacrophages, where its release and effect into aquatic environment must be more studied. Finally, the melanomacrophages present large potential as experimental model for evaluation of carbon-based nanomaterial toxicity.

Protective immunity of largemouth bass immunized with immersed DNA vaccine against largemouth bass ulcerative syndrome virus.

To reduce the largemouth bass ulcer syndrome (LBUSV) aquatic economic losses, it must take effective preventive measures and coping strategies should be urgently investigated. In this research, the effects of a functionalized single-walled carbon nanotubes (SWCNTs) applied as a delivery vehicle for DNA vaccine administration in largemouth bass (Micropterus Salmoides) against LBUSV were studied. Our results showed that SWCNTs loaded with DNA vaccine induced a better protection to largemouth bass against LBUSV. We found more than 10 times increase in serum antibody levels, enzyme activities and immune-related genes (IL-6, IL-8, IFN-γ, IgM and TNF-α) expression, in the SWCNTs-pcDNA-MCP immunized groups compared with PBS group and the pure SWCNTs group. The survival rates for control group (PBS), pure SWCNTs groups (40 mg L-1), four pcDNA-MCP groups (5 mg L-1, 10 mg L-1, 20 mg L-1 and 40 mg L-1) and four SWCNTs-pcDNA-MCP groups (5 mg L-1, 10 mg L-1, 20 mg L-1 and 40 mg L-1) were 0%, 0%, 0%, 2.77%, 11.11%, 19.44%, 27.78%, 38.89%, 52.78% and 61.11%, respectively. Our results demonstrate that the SWCNTs-DNA vaccine can be used as a new method against LBUSV showing protection following challenge with LBUSV.