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1.
Water Sci Technol ; 82(5): 877-886, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031067

RESUMO

Water pollution from antibiotics has attracted a lot of attention for its serious threat to human health. In this study, a magnetic adsorbent (zinc ferrite/activated carbon (ZnFe2O4/AC) was synthesized via microwave method to effectively remove gemifioxacin mesylate (GEM) and moxifloxacin hydrochloride (MOX). Based on the porosity of AC and the magnetism of ZnFe2O4, the resulting ZnFe2O4/AC has high adsorption capacities and can be easily separated from the solid-liquid system via a magnetic field. The largest adsorption capacities for GEM and MOX can reach up to 433.4 mg g-1 and 388.8 mg g-1, respectively, higher than those of reported adsorbents such as MIL-101 and MOF-808. Fastest adsorptions of GEM and MOX were found at 5 min, and solution pH and coexisting salts do not have a significant influence on the adsorption process. The adsorption mechanism analysis indicates that electrostatic interaction and H-bond interaction contribute to the effective adsorption.


Assuntos
Carvão Vegetal , Poluentes Químicos da Água , Adsorção , Antibacterianos , Magnetismo
2.
Nat Commun ; 11(1): 4714, 2020 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-32948754

RESUMO

The application of forces and torques on the single molecule level has transformed our understanding of the dynamic properties of biomolecules, but rare intermediates have remained difficult to characterize due to limited throughput. Here, we describe a method that provides a 100-fold improvement in the throughput of force spectroscopy measurements with topological control, which enables routine imaging of 50,000 single molecules and a 100 million reaction cycles in parallel. This improvement enables detection of rare events in the life cycle of the cell. As a demonstration, we characterize the supercoiling dynamics and drug-induced DNA break intermediates of topoisomerases. To rapidly quantify distinct classes of dynamic behaviors and rare events, we developed a software platform with an automated feature classification pipeline. The method and software can be readily adapted for studies of a broad range of complex, multistep enzymatic pathways in which rare intermediates have escaped classification due to limited throughput.


Assuntos
DNA/química , Fenômenos Magnéticos , Magnetismo/métodos , Nanotecnologia , Análise Espectral/métodos , Ciprofloxacino/farmacologia , DNA/efeitos dos fármacos , Quebras de DNA/efeitos dos fármacos , Conformação de Ácido Nucleico , Pinças Ópticas , Fenômenos Físicos , Software
3.
Chemosphere ; 258: 127276, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947657

RESUMO

It is crucial for water environment security to remove its p-arsanilic acid (p-ASA) efficiently. Namely, removing p-arsanilic acid from aqueous media through magnetic separation, has become a novel method of removing toxic pollutants from water. Batch adsorption experiments demonstrated a higher adsorption of lignin-based magnetic activated carbon (201.64 mg g-1) toward p-ASA. In addition, LMAC nanoparticles exhibited typical magnetism (35.63 emu g-1 of saturation magnetization) and could be easily separated from the aqueous solution. Meanwhile, the endothermic adsorption of p-ASA over LMAC could spontaneously proceed and be well described by the pseudo-first-order and pseudo-second-order model as well as the intra-particle diffusion model. Moreover, the mechanisms during p-ASA adsorption over LMAC included the electrostatic attraction, surface complexation, π-π stacking and hydrogen bonding interaction. Importantly, lignin-based magnetic activated carbon has high absorbability and preferable reusability in real water samples. Consequently, this paper provides insights into preparation of the lignin-based magnetic activated carbon may be potential adsorbents for the remediation of organoarsenic compounds.


Assuntos
Ácido Arsanílico/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Carvão Vegetal , Cinética , Lignina , Fenômenos Magnéticos , Magnetismo , Imãs , Água , Poluentes Químicos da Água/análise
4.
Bone Joint J ; 102-B(10): 1375-1383, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32993330

RESUMO

AIMS: To investigate metallosis in patients with magnetically controlled growing rods (MCGRs) and characterize the metal particle profile of the tissues surrounding the rod. METHODS: This was a prospective observational study of patients with early onset scoliosis (EOS) treated with MCGRs and undergoing rod exchange who were consecutively recruited between February 2019 and January 2020. Ten patients were recruited (mean age 12 years (SD 1.3); 2 M:8 F). The configurations of the MCGR were studied to reveal the distraction mechanisms, with crucial rod parts being the distractable piston rod and the magnetically driven rotor inside the barrel of the MCGR. Metal-on-metal contact in the form of ring-like wear marks on the piston was found on the distracted portion of the piston immediately outside the barrel opening (BO) through which the piston rod distracts. Biopsies of paraspinal muscles and control tissue samples were taken over and away from the wear marks, respectively. Spectral analyses of the rod alloy and biopsies were performed to reveal the metal constituents and concentrations. Histological analyses of the biopsies were performed with haematoxylin and eosin staining. RESULTS: Titanium (Ti), vanadium (V), and neodymium (Nd) concentrations in the biopsies taken near the wear marks were found to be significantly higher than those in the control tissue samples. Significantly increased Nd concentrations were also found in the tissues near the barrel of the MCGR. Chronic inflammation was revealed by the histological studies with fibrosis and macrophage infiltration. Black particles were present within the macrophages in the fibrotic tissues. CONCLUSION: Ti and V were generated mainly at the BO due to metal-on-metal contact, whereas the Nd from the rotor of the MCGR is likely released from the BO during distraction sessions. Phagocytotic immune cells with black particles inside raise concern regarding the long-term implications of metallosis. Cite this article: Bone Joint J 2020;102-B(10):1375-1383.


Assuntos
Reação a Corpo Estranho/etiologia , Próteses e Implantes/efeitos adversos , Escoliose/cirurgia , Biópsia , Criança , Feminino , Reação a Corpo Estranho/diagnóstico por imagem , Humanos , Magnetismo , Masculino , Neodímio/efeitos adversos , Estudos Prospectivos , Escoliose/diagnóstico por imagem , Titânio/efeitos adversos , Vanádio/efeitos adversos
5.
Chemosphere ; 260: 127681, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32758785

RESUMO

In this work, magnetic separably barium ferrite nanomaterial (BaFeO) was synthesized via citrate acid assisted sol-gel combustion method. Subsequently, X-ray diffraction (XRD), scanning electron microscopy-energy dispersion spectroscopy (SEM-EDS), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) were applied for its structural, morphological, and electromagnetic characterization. In addition, microwave (MW) absorption and thermal conversion test results indicated the BaFeO had electrothermal rather than magnetothermal conversion capacity. Meanwhile, the synthesized BaFeO showed satisfactory performance in both eliminating and mineralization of a typical triphenylmethane dye, brilliant green (BG), in MW-induced catalytic oxidation (MICO) process without extra oxidant addition. Besides, changes in element valence and content of BaFeO before and after MICO process investigated with XRD, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) showed its relatively stable properties. Furthermore, transition oxygen species involved in MICO process was deduced as lattice oxygen species. Then, the possible degradation pathway of BG was proposed as demethylation, open-loop of triphenylmethane, releasing one ring, formation of the benzene ring and the ultimate mineralization based on the degradation intermediates tentatively identified by gas chromatography mass spectrometry (GC/MS) and liquid chromatography mass spectrometry (LC/MS), respectively. Finally, ecotoxicity analysis by ecological structure activity relationships (ECOSAR) showed that both the acute and chronic toxicity of these intermediates were lower than that of parent BG. These findings are important regarding the development of efficient catalysts in MICO process for degradation of BG analogues in wastewater.


Assuntos
Compostos de Bário/química , Compostos Férricos/química , Nanoestruturas/química , Compostos de Amônio Quaternário/química , Catálise , Corantes/química , Magnetismo , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Micro-Ondas , Espectroscopia Fotoeletrônica , Águas Residuárias , Difração de Raios X
6.
J Chromatogr A ; 1626: 461379, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797854

RESUMO

Ordered porous materials are attracting enormous attention due to their uniform pore structures, particularly the magnetic photonic crystal microspheres (PCMs) which not only possess unique photonic crystal structure but also can achieve separation easily based on magnet. Here, a two-phase microfluidic self-assembly synthetic system was established simply and employed for the preparation of three dimensional PCMs (3DPCMs) by using the emulsion droplet approach. One phase (dispersed phase) was an aqueous emulsion containing Fe3O4, silica (SiO2) and polystyrene (PS) nanoparticles; another phase (continuous phase) was pure silicone oil. The droplets were formed by introducing the dispersed phase into the continuous phase through a tee valve. By heating the droplets, the water would evaporate and the nanoparticles would finally assemble into solid microspheres, which could be changed into macroporous 3DPCMs after removal of the PS nanoparticles by calcination. The contents and particle sizes of Fe3O4, SiO2 and PS nanoparticles in the dispersed phase were investigated in detail and optimized to prepare macroporous magnetic 3DPCMs with high quality. The morphologies, surface crystal structure, magnetic property, particle size distribution, specific surface area and pore size of the macroporous magnetic 3DPCMs were characterized. The expected 3DPCM displayed regular and uniform photonic crystal structure, narrow particle size distribution and strong magnetic property. The macroporous magnetic 3DPCMs grafted with vomitoxin (DON)-antibodies could be applied for selective enrichment of DON in real samples.


Assuntos
Magnetismo , Microfluídica/métodos , Microesferas , Tricotecenos/análise , Anticorpos/imunologia , Cromatografia Líquida de Alta Pressão , Óxido Ferroso-Férrico/química , Contaminação de Alimentos/análise , Nanopartículas/química , Tamanho da Partícula , Poliestirenos/química , Porosidade , Dióxido de Silício/química , Espectrofotometria , Tricotecenos/imunologia
7.
J Environ Manage ; 270: 110839, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32721303

RESUMO

We aim at fabricating a ternary magnetic recyclable Bi2WO6/BiOI@Fe3O4 composite that could be applied for photodegradation of tetracycline (TC) from synthetic wastewater. To identify any changes with respect to the composite's morphology and crystal structure properties, ΧRD, FTIR, FESEM-EDS, PL and VSM analyses are carried out. The effects of Fe3O4 loading ratio on the Bi2WO6/BiOI for TC photodegradation are evaluated, while operational parameters such as pH, reaction time, TC concentration, and photocatalyst's dose are optimized. Removal mechanisms of the TC by the composite and its photodegradation pathways are elaborated. With respect to its performance, under the same optimized conditions (1 g/L of dose; 5 mg/L of TC; pH 7; 3 h of reaction time), the Bi2WO6/BiOI@5%Fe3O4 composite has the highest TC removal (97%), as compared to the Bi2WO6 (63%). After being saturated, the spent photocatalyst could be magnetically separated from solution for subsequent use. In spite of three consecutive cycles with 71% of efficiency, the spent composite still has reasonable photocatalytic activities for reuse. Overall, this suggests that the composite is a promising photocatalyst for TC removal from aqueous solutions.


Assuntos
Antibacterianos , Tetraciclina , Fenômenos Magnéticos , Magnetismo , Fotólise
8.
J Chromatogr A ; 1625: 461343, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709308

RESUMO

A simple magnetic dispersive solid-phase extraction (MDSPE) methodology based on mesoporous Fe3O4@ succinic acid nanospheres and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been developed to determine kanamycin (KNM) and neomycin (NEO) contents in Measles, Mumps, and Rubella (MMR) vaccine products. The monodispersed mesoporous Fe3O4 nanospheres with self-assembled carboxyl terminated shell have been prepared via a simple solvothermal method. These as-synthesized mesoporous Fe3O4 nanospheres showed a high magnetic saturation value (Ms = 46 emu g-1) and large specific surface area (111.12 m2 g-1) which made them potential candidates as sorbents in magnetic solid-phase extraction. The adsorption experimental data fitted well with the Freundlich-Langmuir isotherm and followed a pseudo-second-order kinetic model. Moreover influential parameters on extraction efficiency were investigated and optimized. Under optimal conditions, the limits of detection for KNM and NEO were 1.0 and 0.1 ng mL-1, respectively. Recovery assessments using real samples exhibited recoveries in the range of 96.0 ± 4.3 to 101.5 ± 7.1 %, with relative standard deviations of <10.7% (for intra- day) and <14.6% (for inter- day). The proposed method was successfully applied for different spiked and un-spiked MMR vaccine samples. The presented extraction method provides a fast, selective, robust and practical platform for the detection of KNM and NEO in MMR vaccine samples.


Assuntos
Dextranos/química , Canamicina/análise , Nanopartículas de Magnetita/química , Vacina contra Sarampo/análise , Caxumba/imunologia , Nanosferas/química , Neomicina/análise , Vacina contra Rubéola/análise , Espectrometria de Massas em Tandem/métodos , Adsorção , Cromatografia Líquida de Alta Pressão , Concentração de Íons de Hidrogênio , Cinética , Limite de Detecção , Magnetismo , Nanosferas/ultraestrutura , Reprodutibilidade dos Testes , Extração em Fase Sólida , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Ácido Succínico/química , Fatores de Tempo , Água/química
9.
Proc Natl Acad Sci U S A ; 117(31): 18186-18193, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32680965

RESUMO

To overcome the reversible nature of low-Reynolds-number flow, a variety of biomimetic microrobotic propulsion schemes and devices capable of rapid transport have been developed. However, these approaches have been typically optimized for a specific function or environment and do not have the flexibility that many real organisms exhibit to thrive in complex microenvironments. Here, inspired by adaptable microbes and using a combination of experiment and simulation, we demonstrate that one-dimensional colloidal chains can fold into geometrically complex morphologies, including helices, plectonemes, lassos, and coils, and translate via multiple mechanisms that can be varied with applied magnetic field. With chains of multiblock asymmetry, the propulsion mode can be switched from bulk to surface-enabled, mimicking the swimming of microorganisms such as flagella-rotating bacteria and tail-whipping sperm and the surface-enabled motion of arching and stretching inchworms and sidewinding snakes. We also demonstrate that reconfigurability enables navigation through three-dimensional and narrow channels simulating capillary blood vessels. Our results show that flexible microdevices based on simple chains can transform both shape and motility under varying magnetic fields, a capability we expect will be particularly beneficial in complex in vivo microenvironments.


Assuntos
Engenharia Química , Coloides/química , Robótica , Magnetismo
10.
Food Chem ; 332: 127427, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32619936

RESUMO

A magnetic porous organic framework (M-POF) was rationally designed and served as a sorbent for magnetic solid-phase extraction of six nitroimidazoles from chicken meat prior to their assay by high-performance liquid chromatography with diode array detection. The M-POF exhibited good magnetic responsiveness and outstanding affinity to nitroimidazoles with large adsorption capacity up to 36 mg g-1. Under optimal conditions, the developed method offered good linearity (r greater than 0.992) in the range of 1.5-100.0 ng g-1, low limits of detection (S/N = 3) of 0.5-0.8 ng g-1, low limits of quantification of 1.5-2.5 ng g-1 and high enrichment factors of 80-175 for the nitroimidazoles. The method was successfully applied to analyze nitroimidazoles in chicken meat. The recoveries were 80.2-118% with relative standard deviations lower than 12%. The adsorption mechanism was further explored and the results showed that the M-POF exhibited adsorption potential for compounds with strong polar interactions.


Assuntos
Antibacterianos/isolamento & purificação , Contaminação de Alimentos/análise , Magnetismo/métodos , Carne/análise , Estruturas Metalorgânicas/química , Nitroimidazóis/isolamento & purificação , Extração em Fase Sólida/métodos , Adsorção , Animais , Antibacterianos/análise , Bioensaio , Galinhas , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Magnetismo/instrumentação , Músculo Esquelético/química , Nitroimidazóis/análise , Porosidade , Extração em Fase Sólida/instrumentação
11.
Huan Jing Ke Xue ; 41(2): 815-822, 2020 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-32608742

RESUMO

Antibiotic resistance genes (ARGs) in municipal wastewater pose a potential threat to the environment. In this study, the change in absolute and relative abundance of ARGs, metal resistance genes (MRGs), and mobile genetic elements (MGTs) were investigated during an emergent municipal wastewater treatment by the magnetic separation process. Results indicate that all the concentrations of targeted ARGs, MRGs, and MGTs decreased significantly in the primary and secondary stirring tank. However, the absolute abundance of some ARGs and MRGs increased in the effluent, which is likely caused by the presence of ample MGTs, in the order of int1 (2.00×1010 copies·mL-1) > int2 (1.91×108 copies·mL-1) > Tn 916/1545e(5.38×108 copies·mL-1). The results obtained from network and PCA analysis showed that the removal of ARGs and MRGs were significantly associated with variations in the microbial community and common pollutants in urban wastewater, such as suspended solids, phosphorus, and COD, which are important factors for affecting the removal efficiency of antibiotic resistance genes and metal heavy resistance genes. These results show that magnetic separation can effectively reduce common pollutants in urban wastewater and might further restrict the transmission and transfer of ARGs. Moreover, it is necessary to strengthen the subsequent management of magnetic separation effluent and dehydrated sludge by disinfection technologies to lessen the risk of antimicrobial contamination.


Assuntos
Resistência Microbiana a Medicamentos/genética , Genes Bacterianos , Magnetismo , Águas Residuárias , Purificação da Água/métodos , Antibacterianos , Metais Pesados
13.
PLoS One ; 15(6): e0231854, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32479545

RESUMO

UltraPrep is an open-source, two-step method for purification of cell-free DNA that entails extraction of total DNA followed by size-selective enrichment of the smaller fragments that are characteristic of DNA originating from fragmentation between nucleosome. The advantages of the two related protocols that are described are that they can easily accommodate a wide range of sample input volumes, they rely on simple, magnetic bead-based technology, the yields of cfDNA are directly comparable to the most popular methods for cfDNA purification, and they dramatically reduce the cost of cfDNA isolation relative to currently available commercial methods. We provide a framework for physical and molecular quality analysis of purified cfDNA and demonstrate that the cfDNA generated by UltraPrep meets or exceeds the quality metrics of the most commonly used procedure. In addition, our method removes high molecular weight genomic DNA (hmwgDNA) that can interfere with downstream assay results, thereby addressing one of the primary concerns for preanalytical collection of blood samples.


Assuntos
Ácidos Nucleicos Livres/isolamento & purificação , Extração em Fase Sólida/métodos , Ácidos Nucleicos Livres/sangue , Humanos , Biópsia Líquida , Magnetismo , Nucleossomos/genética , Dióxido de Silício/química , Extração em Fase Sólida/economia
14.
Chemosphere ; 258: 127336, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32563916

RESUMO

Modification of commercially available Douglas fir biochar (BC) by iron oxide nanoparticle precipitation from aqueous Fe2+/Fe3+ salt solutions upon NaOH treatment generated a hybrid adsorbent (MBC) that removed three common emerging aqueous contaminants, a stimulant (caffeine) and two anti-inflammatory drugs (ibuprofen and acetylsalicylic acid) through batch sorption. Fe3O4 particles (12.3 ± 7.1 nm diameter fundamental particles with aggregates 1-17 µm diameter) dispersed on the biochar surface provided magnetization and created new adsorption sites for the contaminant uptake. These smaller quasi-spherical, octahedral Fe3O4 particles as well as the spindle-like Fe2O3 particles were observed with scanning electron microscopy (SEM) images of MBC, and the composition was confirmed by X-ray powder diffraction (XRD). Adsorption features were evaluated using Langmuir and Freundlich isotherm models. The Langmuir adsorption capacities on MBC at 35 °C have increased from 24.6 ± 0.4 to 75.1 ± 1.8 mg/g for caffeine, 17.5 ± 0.4 to 39.9 ± 1.2 mg/g for ibuprofen and 106.2 ± 2.8 to 149.9 ± 4.5 mg/g for acetylsalicylic acid after Fe3O4 modification. Fast adsorption resulted in equilibrium within 5 min. MBC has potential as a low cost, green adsorbent for pharmaceutical mitigation from water with high adsorption capacities and fast kinetics. The Douglas fir biochar is a byproduct waste from a syn-gas from wood production process covering its production costs.


Assuntos
Carvão Vegetal , Compostos Férricos/química , Magnetismo , Preparações Farmacêuticas/isolamento & purificação , Águas Residuárias/química , Purificação da Água/métodos , Adsorção , Cinética , Pseudotsuga , Poluentes Químicos da Água/isolamento & purificação
15.
J Environ Manage ; 270: 110816, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32501235

RESUMO

Disinfection using chlorine has paramount importance in the treatment of either drinking water or sewage since it can kill and inhibit all waterborne pathogens, but it may result in carcinogenic substances when interacting with organic matter. An eco-friendly sol-gel process with citrate was used to prepare the nano-cubic activated nickel-zinc ferrite magnetic nanostructures (Ni0.6Zn0.4Fe2O4 and Ni0.6Zn0.2Ce0.2Fe2O4). The activated nanomagnetic samples were characterized using XRD, HR-TEM, HR-SEM, FTIR, and VSM techniques. The structural and magnetic results showed that the nano-cubes magnetic-structures exhibited higher crystalline degrees and an increase in the total magnetization, enabling spinel nano-ferrite to possess potentials for excellent industry various applications. Likewise, the VSM results reveal that Ce2O3 had a significant influence on the magnetic behavior such as the coercivity (Hc; 69.226-133.15) saturation and magnetization (Ms; 24.562-52.174). The results revealed that all Magnetic nanoparticles (MNPs) had an outstanding inhibitory effect on microbes tested. The manufactured particles showed a remarkable ability to eliminate pathogenic bacteria in real sewage samples. The results obtained endorsed that the manufactured magnetic nanoparticles (MNPs) are powerful nano-weapons with an excellent anticipated output for the deactivation of pathogenic microbes during sewage treatment, with, nickel-zinc-cerium ferrite being more effective in inhibiting microbial growth than nickel-zinc-cerium ferrite.


Assuntos
Nanopartículas , Nanoestruturas , Fenômenos Magnéticos , Magnetismo , Esgotos
16.
Environ Sci Pollut Res Int ; 27(29): 37011-37021, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32577974

RESUMO

A large number of iron ore tailings (IOTs) are produced in steel industry, posing threat to the environment during its storage and disposal. To effectively reutilize Fe in IOTs, we propose a comprehensive utilization scheme: (1) most Fe in IOTs is extracted by concentrated hydrochloric acid to form FeCl3 flocculants; (2) after separation from the FeCl3 flocculants, a small amount of Fe is absorbed on the residue solids, which is further washed out to synthesize micron Fe3O4 as magnetic seeds. Results show that the as-synthetic FeCl3 flocculants meet the product standard for FeCl3 flocculants in China (GB/T 4482-2018) after a series of treatments including rotary evaporation, neutralization, and dilution and have comparable performance with commercial polyaluminum chloride (PAC) and polyaluminum ferric chloride (PAFC). Moreover, the addition of synthetic superparamagnetic Fe3O4 (as magnetic seeds) doubled the flocculation rate compared with as-synthetic FeCl3 flocculants alone. Finally, the reutilization of Fe in IOTs can create a direct economic value of ¥ 1.27/kg IOTs, and produce 745 g high-silicon residues for further reutilization, which indicates that our comprehensive utilization scheme is of great application potential.


Assuntos
Ferro , Magnetismo , China , Floculação , Fenômenos Magnéticos
17.
Biosens Bioelectron ; 165: 112356, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32510339

RESUMO

Circle-to-circle amplification (C2CA) is a specific and precise cascade nucleic acid amplification method consisting of more than one round of padlock probe ligation and rolling circle amplification (RCA). Although C2CA provides a high amplification efficiency with a negligible increase of false-positive risk, it contains several step-by-step operation processes. We herein demonstrate a homogeneous and isothermal nucleic acid quantification strategy based on C2CA and optomagnetic analysis of magnetic nanoparticle (MNP) assembly. The proposed homogeneous circle-to-circle amplification eliminates the need for additional monomerization and ligation steps after the first round of RCA, and combines two amplification rounds in a one-pot reaction. The second round of RCA produces amplicon coils that anneal to detection probes grafted onto MNPs, resulting in MNP assembly that can be detected in real-time using an optomagnetic sensor. The proposed methodology was applied for the detection of a synthetic complementary DNA of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2, also known as 2019-nCoV) RdRp (RNA-dependent RNA polymerase) coding sequence, achieving a detection limit of 0.4 fM with a dynamic detection range of 3 orders of magnitude and a total assay time of ca. 100 min. A mathematical model was set up and validated to predict the assay performance. Moreover, the proposed method was specific to distinguish SARS-CoV and SARS-CoV-2 sequences with high similarity.


Assuntos
Betacoronavirus/isolamento & purificação , Técnicas Biossensoriais/instrumentação , Infecções por Coronavirus/diagnóstico , DNA Complementar/análise , Técnicas de Amplificação de Ácido Nucleico/instrumentação , Pneumonia Viral/diagnóstico , Técnicas Biossensoriais/métodos , Desenho de Equipamento , Estudos de Viabilidade , Humanos , Limite de Detecção , Magnetismo/instrumentação , Magnetismo/métodos , Nanopartículas de Magnetita/química , Técnicas de Amplificação de Ácido Nucleico/métodos , Pandemias
18.
Br J Radiol ; 93(1111): 20200113, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32496816

RESUMO

MRI developed during the last half-century from a very basic concept to an indispensable non-ionising medical imaging technique that has found broad application in diagnostics, therapy control and far beyond. Due to its excellent soft-tissue contrast and the huge variety of accessible tissue- and physiological-parameters, MRI is often preferred to other existing modalities. In the course of its development, MRI underwent many substantial transformations. From the beginning, starting as a proof of concept, much effort was expended to develop the appropriate basic scanning technology and methodology, and to establish the many clinical contrasts (e.g., T1, T2, flow, diffusion, water/fat, etc.) that MRI is famous for today. Beyond that, additional prominent innovations to the field have been parallel imaging and compressed sensing, leading to significant scanning time reductions, and the move towards higher static magnetic field strengths, which led to increased sensitivity and improved image quality. Improvements in workflow and the use of artificial intelligence are among many current trends seen in this field, paving the way for a broad use of MRI. The 125th anniversary of the BJR is a good point to reflect on all these changes and developments and to offer some slightly speculative ideas as to what the future may bring.


Assuntos
Invenções/tendências , Imagem por Ressonância Magnética/tendências , Inteligência Artificial/tendências , Meios de Contraste , Aprendizado Profundo/tendências , Humanos , Imagem por Ressonância Magnética/instrumentação , Imagem por Ressonância Magnética/métodos , Magnetismo , Fluxo de Trabalho
19.
J Chromatogr A ; 1624: 461229, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32540071

RESUMO

This work describes a sensitive and rapid analytical method for trace determination of polycyclic aromatic hydrocarbons (PAHs) in cosmetic samples. The proposed method is based on stir bar sorptive-dispersive microextraction (SBSDME). A magnetic composite made of CoFe2O4 magnetic nanoparticles embedded into reduced graphene oxide sheets is used as sorbent phase. After the extraction, the target analytes are desorbed in toluene and then analyzed by gas chromatography-mass spectrometry (GC-MS). The main parameters involved in the extraction procedure (i.e., composite amount, extraction time and desorption time) were evaluated and optimized to provide the best extraction efficiency. The method was successfully validated under the selected conditions, showing a linear range of at least up to 125 ng mL-1, instrumental and method limits of detection from 0.02 to 2.50 ng mL-1 and from 0.15 to 24.22 ng g-1, respectively, and relative standard deviations (RSD) below 10 % for all the target analytes. Standard addition combined with internal standard calibration was employed for quantification. The proposed method was successfully applied to the analysis of ten PAHs in four cosmetic products of different matrix. Several analytes between 14 and 464 ng g-1 were found, some of them prohibited in cosmetic products. This work expands the analytical potential of SBSDME technique to other analytes and to the use of new sorbent phases, showing the great versatility of this approach depending on the characteristics of the analytes.


Assuntos
Cosméticos/análise , Cromatografia Gasosa-Espectrometria de Massas , Grafite/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Microextração em Fase Sólida/métodos , Cobalto/química , Compostos Férricos/química , Limite de Detecção , Magnetismo , Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação
20.
Environ Sci Pollut Res Int ; 27(27): 34311-34321, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32542569

RESUMO

This study investigates the impact of an engineered magnetic nanoparticle (MNP) on a crop plant. For this purpose, a sonochemical synthetic approach was utilized in order to dope magnetic elements (Co and Nd) into technologically important iron oxide NPs. After being characterized by using TEM, SEM, and XRD instruments, the MNPs were hydroponically applied to barley plants with varying doses (from 125 to 1000 mg/L) both in germination (4 days) and early growing stages (3 weeks). Physiological responses, as well as expression of photosystem marker genes, were assessed. Compared to the untreated control, MNP treatment enhanced germination rate (~ 31%), tissue growth (8% in roots, 16% in shoots), biomass (~ 21%), and chlorophyll (a, b) (~ 20%), and carotenoids (~ 22%) pigments. In general, plants showed the highest growth enhancement at 125 or 250 mg/L treatment. However, higher doses diminished the growth indices. Compared to the control, the catalase activity was significantly reduced in the leaves (~ 33%, p < 0.005) but stimulated in the roots (~ 46%, p < 0.005). All tested photosystem marker genes (BCA, psbA, and psaA) were overexpressed in MNP-treated leaves than non-treated control. Moreover, the gene expressions were found to be proportionally increased with increasing MNP doses, indicating a positive correlation between MNPs and the photosynthetic machinery, which could contribute to the enhancement of plant growth.


Assuntos
Nanopartículas de Magnetita , Nanopartículas , Clorofila , Hordeum , Magnetismo , Folhas de Planta , Raízes de Plantas
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