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1.
Int J Mol Sci ; 22(12)2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34201173

RESUMO

Biofilms are the reason for a vast majority of chronic inflammation cases and most acute inflammation. The treatment of biofilms still is a complicated task due to the low efficiency of drug delivery and high resistivity of the involved bacteria to harmful factors. Here we describe a magnetically controlled nanocomposite with a stimuli-responsive release profile based on calcium carbonate and magnetite with an encapsulated antibiotic (ciprofloxacin) that can be used to solve this problem. The material magnetic properties allowed targeted delivery, accumulation, and penetration of the composite in the biofilm, as well as the rapid triggered release of the entrapped antibiotic. Under the influence of an RF magnetic field with a frequency of 210 kHz, the composite underwent a phase transition from vaterite into calcite and promoted the release of ciprofloxacin. The effectiveness of the composite was tested against formed biofilms of E. coli and S. aureus and showed a 71% reduction in E. coli biofilm biomass and an 85% reduction in S. aureus biofilms. The efficiency of the composite with entrapped ciprofloxacin was higher than for the free antibiotic in the same concentration, up to 72%. The developed composite is a promising material for the treatment of biofilm-associated inflammations.


Assuntos
Biofilmes/crescimento & desenvolvimento , Carbonatos/química , Ciprofloxacina/farmacologia , Escherichia coli/crescimento & desenvolvimento , Magnetismo , Nanocompostos/administração & dosagem , Staphylococcus aureus/crescimento & desenvolvimento , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos , Escherichia coli/efeitos dos fármacos , Nanocompostos/química , Staphylococcus aureus/efeitos dos fármacos
2.
Biosensors (Basel) ; 11(7)2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34201531

RESUMO

Quality and food safety represent a major stake and growing societal challenge in the world. Bacterial contamination of food and water resources is an element that pushes scientists to develop new means for the rapid and efficient detection and identification of these pathogens. Conventional detection tools are often bulky, laborious, expensive to buy, and, above all, require an analysis time of a few hours to several days. The interest in developing new, simple, rapid, and nonlaborious bacteriological diagnostic methods is therefore increasingly important for scientists, industry, and regulatory bodies. In this study, antibiotic-functionalized metallic nanoparticles were used to isolate and identify the foodborne bacterial strains Bacillus cereus and Shigella flexneri. With this aim, a new diagnostic tool for the rapid detection of foodborne pathogenic bacteria, gold nanoparticle-based centri-chronoamperometry, has been developed. Vancomycin was first stabilized at the surface of gold nanoparticles and then incubated with the bacteria B. cereus or S. flexneri to form the AuNP@vancomycin/bacteria complex. This complex was separated by centrifugation, then treated with hydrochloric acid and placed at the surface of a carbon microelectrode. The gold nanoparticles of the formed complex catalyzed the hydrogen reduction reaction, and the generated current was used as an analytical signal. Our results show the possibility of the simple and rapid detection of the S. flexneri and B. cereus strains at very low numbers of 3 cells/mL and 12 cells/mL, respectively. On the other hand, vancomycin-capped magnetic beads were easily synthesized and then used to separate the bacteria from the culture medium. The results show that vancomycin at the surface of these metallic nanoparticles is able to interact with the bacteria membrane and then used to separate the bacteria and to purify an inoculated medium.


Assuntos
Antibacterianos/química , Microbiologia de Alimentos , Nanopartículas Metálicas/química , Animais , Bacillus cereus , Ouro , Separação Imunomagnética , Fenômenos Magnéticos , Magnetismo
3.
Biosensors (Basel) ; 11(6)2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-34205541

RESUMO

A magnetic beads (MB)-involved amperometric immunosensor for the determination of ST2, a member of the IL1 receptor family, is reported in this work. The method utilizes a sandwich immunoassay and disposable screen-printed carbon electrodes (SPCEs). Magnetic immunoconjugates built on the surface of carboxylic acid-microsized magnetic particles (HOOC-MBs) were used to selectively capture ST2. A biotinylated secondary antibody further conjugated with a streptavidin peroxidase conjugate (Strep-HRP) was used to accomplish the sandwiching of the target protein. The immune platform exhibits great selectivity and a low limit of detection (39.6 pg mL-1) for ST2, allowing the determination of soluble ST2 (sST2) in plasma samples from healthy individuals and patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) in only 45 min once the immunoconjugates have been prepared. The good correlation of the obtained results with those provided by an ELISA kit performed using the same immunoreagents demonstrates the potential of the developed strategy for early diagnosis and/or prognosis of the fatal PDAC disease.


Assuntos
Técnicas Biossensoriais , Imunoensaio , Neoplasias/diagnóstico , Anticorpos , Carbono , Técnicas Eletroquímicas , Eletrodos , Ensaio de Imunoadsorção Enzimática , Humanos , Peróxido de Hidrogênio , Limite de Detecção , Magnetismo
4.
Sensors (Basel) ; 21(14)2021 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-34300364

RESUMO

Protective SiO2 coating deposited to iron microparticles is highly demanded both for the chemical and magnetic performance of the latter. Hydrolysis of tetraethoxysilane is the crucial method for SiO2 deposition from a solution. The capabilities of this technique have not been thoroughly studied yet. Here, two factors were tested to affect the chemical composition and the thickness of the SiO2 shell. It was found that an increase in the hydrolysis reaction time thickened the SiO2 shell from 100 to 200 nm. Moreover, a decrease in the acidity of the reaction mixture not only thickened the shell but also varied the chemical composition from SiO3.0 to SiO8.6. The thickness and composition of the dielectric layer were studied by scanning electron microscopy and energy-dispersive X-ray analysis. Microwave permeability and permittivity of the SiO2-coated iron particles mixed with a paraffin wax matrix were measured by the coaxial line technique. An increase in thickness of the silica layer decreased the real quasi-static permittivity. The changes observed were shown to agree with the Maxwell Garnett effective medium theory. The new method developed to fine-tune the chemical properties of the protective SiO2 shell may be helpful for new magnetic biosensor designs as it allows for biocompatibility adjustment.


Assuntos
Micro-Ondas , Dióxido de Silício , Ferro , Magnetismo
5.
Sensors (Basel) ; 21(12)2021 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-34204796

RESUMO

The thin film magneto-impedance sensor is useful for detecting a magnetic material nondestructively. The sensor made by single layer uniaxial amorphous thin film has a tolerance against surface normal magnetic field because of its demagnetizing force in the thickness direction. Our previous study proposed the sensitive driving circuit using 400 MHz high frequency current running through the sensor to detect the logarithmic amplifier. We also confirmed the sensitivity of the sensor within 0.3 T static normal magnetic field, which resulted in detection of 5 × 10-8 T of 5 Hz signal. This paper proposes a nondestructive inspection system for how detecting a contaminant of small tool steel chipping in aluminum casting specimen would be carried out. Three channel array sensors installed in the 30 mT static field detecting area were fabricated and experimentally showed a detection of low remanence magnetic contaminant in a bulk aluminum casing specimen.


Assuntos
Alumínio , Magnetismo , Impedância Elétrica , Campos Magnéticos
6.
Se Pu ; 39(7): 679-685, 2021 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-34227364

RESUMO

The novel coronavirus disease 2019 (COVID-19) outbreak has brought to light unprecedented challenges to global public health security. Researchers have devoted their efforts to in-depth research on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to bring the epidemic under control as rapidly as possible. Among the many areas of burgeoning SARS-CoV-2 related research, various analytical technologies have been applied to the advancement of virus detection, and development of vaccines and innovative therapies. Separation technologies with the merits of simple operation, high separation efficiency, and high selectivity, have become widely used and are key to progress in life science, medicine, pharmaceutical discovery and development, and other fields. Separation technologies have played an irreplaceable role in the isolation, detection, diagnosis, treatment, and prevention of this novel coronavirus. In this review, an overview of the relevant literature is presented from ISI Web of Science spanning Jan. 1st, 2020-Dec. 31, 2020, using "SARS-CoV-2" or "COVID-19" as keywords. The top 20 research directions are summarized, based on papers published in high impact international journals (e. g. Nature, Science, and Cell). Incorporating the impact of published papers, this review summarizes the primary separation technologies applied in these coronavirus studies, and discusses contributions of the following six technologies: affinity chromatography and size exclusion chromatography, liquid chromatography, magnetic bead separation technology, centrifugal technology, micro/nano-separation technology, and electrophoresis. First, affinity chromatography and size exclusion chromatography are discussed, which are the most frequently used protein purification techniques in Nature, Science, and Cell. The SARS-CoV-2 related proteins purified by affinity chromatography and size exclusion chromatography are summarized, and their applications in coronavirus transmission, infection mechanisms, and drug screening are introduced. Subsequently, high performance liquid chromatography (HPLC) is introduced, which is mainly employed for assessing the purity of candidate drugs. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) incorporates the strengths of HPLC and MS, offering both high separation efficiency and structural analysis capabilities with extended applications. LC-MS/MS has been applied to characterization of the binding of SARS-CoV-2 related proteins to potential inhibitors, and to metabolic analyses of candidate drugs. In SARS-CoV-2 nucleic acid tests, magnetic bead separation technology plays a crucial role in the separation of novel coronaviruses. In combination with other analytical techniques, magnetic bead separation technology can be applied to cytological analyses and immunological detection by functionalization of bead surfaces. Centrifugal technology is undoubtedly the most basic separation technology. It has been employed in almost all SARS-CoV-2 related researches. By controlling centrifugation speed, centrifugal technology can rapidly isolate virus particles or cultured cells from complex samples. Micro-nano separation technologies, such as microfluidics, offer advantages including small size, low sample consumption, rapid diffusion, and large surface area. In general, microfluidic technologies are often used in combination with other technologies to realize highly sensitive detection of SARS-CoV-2 related proteins. Finally, the applications of electrophoresis are introduced, which commonly engages in the analysis of polymerase chain reaction (PCR) products. In novel coronavirus studies, the application of electrophoresis has been relatively limited but has potential with further development to contribute significantly to future research. In conclusion, this review summarizes the contributions of six primary separation technologies to novel coronavirus studies, including epidemic detection and prevention, analyzes the main problems facing coronavirus detection efforts, and discusses the role of separation technologies in addressing these problems, with the aim of providing references for broader application of separation technologies.


Assuntos
COVID-19/diagnóstico , Epidemias/prevenção & controle , SARS-CoV-2/isolamento & purificação , Tecnologia/tendências , COVID-19/epidemiologia , Centrifugação , Cromatografia Líquida , Humanos , Magnetismo , Espectrometria de Massas em Tandem
7.
Langmuir ; 37(28): 8498-8507, 2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-34231364

RESUMO

Controlled transport of surface-functionalized magnetic beads in a liquid medium is a central requirement for the handling of captured biomolecular targets in microfluidic lab-on-chip biosensors. Here, the influence of the physiological liquid medium on the transport characteristics of functionalized magnetic particles and on the functionality of the coupled protein is studied. These aspects are theoretically modeled and experimentally investigated for prototype superparamagnetic beads, surface-functionalized with green fluorescent protein immersed in buffer solution with different concentrations of a surfactant. The model reports on the tunability of the steady-state particle substrate separation distance to prevent their surface sticking via the choice of surfactant concentration. Experimental and theoretical average velocities are discussed for a ratchet-like particle motion induced by a dynamic external field superposed on a static locally varying magnetic field landscape. The developed model and experiment may serve as a basis for quantitative forecasts on the functionality of magnetic particle transport-based lab-on-chip devices.


Assuntos
Técnicas Biossensoriais , Tensoativos , Campos Magnéticos , Magnetismo , Microfluídica
8.
Mater Sci Eng C Mater Biol Appl ; 126: 112117, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34082934

RESUMO

Controlled pulmonary drug delivery systems employing non-spherical particles as drug carriers attract considerable attention nowadays. Such anisotropic morphologies may travel deeper into the lung airways, thus enabling the efficient accumulation of therapeutic compounds at the point of interest and subsequently their sustained release. This study focuses on the fabrication of electrospun superparamagnetic polymer-based biodegradable microrods consisting of poly(l-lactide) (PLLA), polyethylene oxide (PEO) and oleic acid-coated magnetite nanoparticles (OA·Fe3O4). The production of magnetite-free (0% wt. OA·Fe3O4) and magnetite-loaded (50% and 70% wt. Fe3O4) microrods was realized upon subjecting the as-prepared electrospun fibers to UV irradiation, followed by sonication. Moreover, drug-loaded microrods were fabricated incorporating methyl 4-hydroxybenzoate (MHB) as a model pharmaceutical compound and the drug release profile from both, the drug-loaded membranes and the corresponding microrods was investigated in aqueous media. In addition, the magnetic properties of the produced materials were exploited for remote induction of hyperthermia under AC magnetic field, while the possibility to reduce transport losses and enhance the targeted delivery to lower airways by manipulation of the airborne microrods by DC magnetic field was also demonstrated.


Assuntos
Calefação , Nanopartículas de Magnetita , Sistemas de Liberação de Medicamentos , Pulmão , Fenômenos Magnéticos , Magnetismo
9.
Chemosphere ; 276: 130241, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34088101

RESUMO

At present, environmental contamination has become an emerging issue among researchers. These facts are due to the adverse impacts of an alarming number of recalcitrant contaminants that can affect both humans and animals. There is an urgent need to develop eco-friendly approaches to mitigate the effects of toxic pollutants from the environment. Magnetically responsive composite-based sorbents are very interesting and popular materials for pollutant abatement owing to the high specific surface area, superior adsorption capacity, and magnetic properties, which make their easy separation from sample solution/media. In this review article, we discuss various synthesis approaches, key physicochemical properties, and applications of magnetic composites for pollutant removal. Current gaps for coping with contamination are identified, and a comprehensive outlook in pollutant treatment using magnetic composites is outlined. This study unveils new horizons to researches for better understanding the properties of magnetically-composite-based sorbents and their application in environmental remediation.


Assuntos
Poluentes Ambientais , Recuperação e Remediação Ambiental , Adsorção , Animais , Humanos , Magnetismo
10.
Sensors (Basel) ; 21(9)2021 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-34063644

RESUMO

Capsule endoscopy is a well-established diagnostic tool for the gastrointestinal tract. However, the reliable tracking of capsule endoscopes needs further investigation. Recently, the static magnetic differential method for the localization of capsule endoscopes has shown promising results. This method was experimentally validated by investigating the difference in the measured values of the geomagnetic flux density of a representative sensor pair. In the measurements, it was revealed that misalignment of the sensors and ferromagnetic material near the sensor pair had the most significant impact on the differential approach. Besides, a systematical simulation-based study was conducted. Herein, the position and alignment of all sensors of the localization system were randomly varied. Furthermore, root-mean-squared noise was added to the sensor measurements, and the influence of nearby ferromagnetic material was evaluated. Subsequently, non-idealities were applied simultaneously on the proposed localization system, and the entire system was rotated. The proposed method was significantly better than state-of-the-art geomagnetic compensation methods for the localization of capsule endoscopes with mean position and orientation errors of approximately 2 mm and 1°, respectively.


Assuntos
Cápsulas Endoscópicas , Endoscopia por Cápsula , Trato Gastrointestinal , Magnetismo
11.
Sensors (Basel) ; 21(11)2021 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-34067478

RESUMO

Multilayered [FeNi (100 nm)/Cu (3 nm)]5/Cu (500 nm)/[Cu (3 nm)/[FeNi (100 nm)]5 structures were used as sensitive elements of the magnetoimpedance (MI) sensor prototype for model experiments of the detection of magnetic particles in blood vessel. Non-ferromagnetic cylindrical polymer rod with a small magnetic inclusion was used as a sample mimicking thrombus in a blood vessel. The polymer rod was made of epoxy resin with an inclusion of an epoxy composite containing 30% weight fraction of commercial magnetite microparticles. The position of the magnetic inclusion mimicking thrombus in the blood vessel was detected by the measurements of the stray magnetic fields of microparticles using MI element. Changes of the MI ratio in the presence of composite can be characterized by the shift and the decrease of the maximum value of the MI. We were able to detect the position of the magnetic composite sample mimicking thrombus in blood vessels. Comsol modeling was successfully used for the analysis of the obtained experimental results and the understanding of the origin the MI sensitivity in proposed configuration. We describe possible applications of studied configuration of MI detection for biomedical applications in the field of thrombus state evaluation and therapy.


Assuntos
Técnicas Biossensoriais , Óxido Ferroso-Férrico , Campos Magnéticos , Magnetismo
12.
ACS Sens ; 6(6): 2191-2201, 2021 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-34124887

RESUMO

In clinical practice, a variety of diagnostic applications require the identification of target cells. Density has been used as a physical marker to distinguish cell populations since metabolic activities could alter the cell densities. Magnetic levitation offers great promise for separating cells at the single cell level within heterogeneous populations with respect to cell densities. Traditional magnetic levitation platforms need bulky and precise optical microscopes to visualize levitated cells. Moreover, the evaluation process of cell densities is cumbersome, which also requires trained personnel for operation. In this work, we introduce a device (HologLev) as a fusion of the magnetic levitation principle and lensless digital inline holographic microscopy (LDIHM). LDIHM provides ease of use by getting rid of bulky and expensive optics. By placing an imaging sensor just beneath the microcapillary channel without any lenses, recorded holograms are processed for determining cell densities through a fully automated digital image processing scheme. The device costs less than $100 and has a compact design that can fit into a pocket. We perform viability tests on the device by levitating three different cell lines (MDA-MB-231, U937, D1 ORL UVA) and comparing them against their dead correspondents. We also tested the differentiation of mouse osteoblastic (7F2) cells by monitoring characteristic variations in their density. Last, the response of MDA-MB-231 cancer cells to a chemotherapy drug was demonstrated in our platform. HologLev provides cost-effective, label-free, fully automated cell analysis in a compact design that could be highly desirable for laboratory and point-of-care testing applications.


Assuntos
Holografia , Microscopia , Animais , Processamento de Imagem Assistida por Computador , Fenômenos Magnéticos , Magnetismo , Camundongos
13.
J Pediatr Orthop ; 41(6): 356-361, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34096549

RESUMO

BACKGROUND: Lengthening of long bones by distraction osteogenesis is now possible using intramedullary lengthening nails. Constraints of bone size, medullary canal obstruction, and the presence of an open physis are contraindications in skeletally immature patients. We present a technique describing the "off-label" use of a magnetic lengthening nail placed extramedullary and in retrograde manner, for lengthening of the femur in skeletally immature patients. METHODS: A retrospective review of 5 skeletally immature patients with significant length discrepancy of the femur are presented along with a description of the surgical technique. Data collected included age, sex, date of surgery, diagnosis, presence of associated deformities, the magnitude of length discrepancy, the amount of length gained, the amount of time to achieve full weight-bearing, the time to hardware removal, and any complications. RESULTS: There were 5 patients (3 females). The mean age was 7.2±2.7 years (4 to 10 y). The mean limb length discrepancy was 6.5±3.7 cm (3.5 to 11 cm). A mean length of 3.46±0.4 cm (3.1 to 4 cm) was achieved which represents 12.9±1.8% (10.32 to 13.47%) of the bone length. The time taken to achieve full weight-bearing ambulation was 89.2±19.3 days (60 to 109 d) or 12.7 weeks. All hardware was removed 247.6±215.6 days (99 to 628 d) after surgery. Patients were followed up for a mean duration of 19.2 months (11 to 30 mo). No supplemental fixation was required and no complications were noted. Acute deformity correction was also performed at the time of surgery in 2 patients who had distal femur valgus deformity. CONCLUSIONS: Retrograde extramedullary lengthening of the femur is an option that should be considered for limb length equalization in skeletally immature patients. It avoids the inconvenience of external fixation and can be used to simultaneously correct deformities of the distal femur. Although the total amount of length gained is modest, we believe it is a promising limb lengthening technique that merits further investigation. LEVEL OF EVIDENCE: Level III.


Assuntos
Pinos Ortopédicos , Fêmur/cirurgia , Desigualdade de Membros Inferiores/cirurgia , Osteogênese por Distração/métodos , Criança , Pré-Escolar , Feminino , Fêmur/anormalidades , Humanos , Magnetismo , Masculino , Osteogênese por Distração/instrumentação , Estudos Retrospectivos , Resultado do Tratamento , Caminhada , Suporte de Carga
14.
Molecules ; 26(9)2021 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-34065150

RESUMO

Bioanalysis is the scientific field of the quantitative determination of xenobiotics (e.g., drugs and their metabolites) and biotics (e.g., macromolecules) in biological matrices. The most common samples in bioanalysis include blood (i.e., serum, plasma and whole blood) and urine. However, the analysis of alternative biosamples, such as hair and nails are gaining more and more attention. The main limitations for the determination of small organic compounds in biological samples is their low concentration in these matrices, in combination with the sample complexity. Therefore, a sample preparation/analyte preconcentration step is typically required. Currently, the development of novel microextraction and miniaturized extraction techniques, as well as novel adsorbents for the analysis of biosamples, in compliance with the requirements of Green Analytical Chemistry, is in the forefront of research in analytical chemistry. Graphene oxide (GO) is undoubtedly a powerful adsorbent for sample preparation that has been successfully coupled with a plethora of green extraction techniques. GO is composed of carbon atoms in a sp2 single-atom layer of a hybrid connection, and it exhibits high surface area, as well as good mechanical and thermal stability. In this review, we aim to discuss the applications of GO and functionalized GO derivatives in microextraction and miniaturized extraction techniques for the determination of small organic molecules in biological samples.


Assuntos
Grafite/química , Química Verde , Compostos Orgânicos/química , Extração em Fase Sólida/métodos , Adsorção , Carbono/química , Humanos , Magnetismo , Polímeros Molecularmente Impressos , Nanomedicina , Nanoestruturas , Reprodutibilidade dos Testes , Propriedades de Superfície
15.
Molecules ; 26(11)2021 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-34070428

RESUMO

Magnetic MXene composite Fe3O4@Ti3C2 was successfully prepared and employed as 17α-ethinylestradiol (EE2) adsorbent from water solution. The response surface methodology was employed to investigate the interactive effects of adsorption parameters (adsorption time, pH of the solution, initial concentration, and the adsorbent dose) and optimize these parameters for obtaining maximum adsorption efficiency of EE2. The significance of independent variables and their interactions were tested by the analysis of variance (ANOVA) and t-test statistics. Optimization of the process variables for maximum adsorption of EE2 by Fe3O4@Ti3C2 was performed using the quadratic model. The model predicted maximum adsorption of 97.08% under the optimum conditions of the independent variables (adsorption time 6.7 h, pH of the solution 6.4, initial EE2 concentration 0.98 mg L-1, and the adsorbent dose 88.9 mg L-1) was very close to the experimental value (95.34%). pH showed the highest level of significance with the percent contribution (63.86%) as compared to other factors. The interactive influences of pH and initial concentration on EE2 adsorption efficiency were significant (p < 0.05). The goodness of fit of the model was checked by the coefficient of determination (R2) between the experimental and predicted values of the response variable. The response surface methodology successfully reflects the impact of various factors and optimized the process variables for EE2 adsorption. The kinetic adsorption data for EE2 fitted well with a pseudo-second-order model, while the equilibrium data followed Langmuir isotherms. Thermodynamic analysis indicated that the adsorption was a spontaneous and endothermic process. Therefore, Fe3O4@Ti3C2 composite present the outstanding capacity to be employed in the remediation of EE2 contaminated wastewaters.


Assuntos
Etinilestradiol/química , Magnetismo , Termodinâmica , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Etinilestradiol/isolamento & purificação , Cinética , Nanopartículas Metálicas/química , Águas Residuárias/química , Difração de Raios X
16.
J Chromatogr A ; 1651: 462301, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34107399

RESUMO

In this work, a core-shell structured magnetic covalent organic framework named as M-TpDAB was constructed with 3,3'-diaminobenzidine (DAB) and 1,3,5-triformylphloroglucinol (Tp) as building units. M-TpDAB was characterized by infrared spectroscopy, nitrogen adsorption-desorption isotherms, powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Using the M-TpDAB as adsorbent, a simple and highly effective method was proposed for preconcentrating phenylurea herbicides before high performance liquid-phase chromatography analysis. In the optimized conditions, a good linearity was achieved within the range of 0.15-100 ng mL-1 for water sample, 1.0-100.0 ng mL-1 for tea drink samples. The limits of detection for the analytes were 0.05-0.15 ng mL-1 for water sample and 0.30-0.50 ng mL-1 for drink samples. Satisfactory recoveries of spiked target compounds were in the range of 84.6%-105% for water sample and 80.3%-102% for tea drink samples. Finally, the M-TpDAB based method was successfully used to determine phenylurea herbicides in tea drinks and water samples, demonstrating a good alternative for analyzing trace level of phenylurea herbicides in water samples.


Assuntos
Herbicidas/isolamento & purificação , Estruturas Metalorgânicas/química , Compostos de Fenilureia/isolamento & purificação , Extração em Fase Sólida/métodos , Água/química , Adsorção , Cromatografia Líquida de Alta Pressão , Água Potável/química , Herbicidas/análise , Fenômenos Magnéticos , Magnetismo/métodos , Compostos de Fenilureia/análise , Difração de Raios X
17.
Nat Commun ; 12(1): 3840, 2021 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-34158498

RESUMO

Histopathological level imaging in a non-invasive manner is important for clinical diagnosis, which has been a tremendous challenge for current imaging modalities. Recent development of ultra-high-field (UHF) magnetic resonance imaging (MRI) represents a large step toward this goal. Nevertheless, there is a lack of proper contrast agents that can provide superior imaging sensitivity at UHF for disease detection, because conventional contrast agents generally induce T2 decaying effects that are too strong and thus limit the imaging performance. Herein, by rationally engineering the size, spin alignment, and magnetic moment of the nanoparticles, we develop an UHF MRI-tailored ultra-sensitive antiferromagnetic nanoparticle probe (AFNP), which possesses exceptionally small magnetisation to minimize T2 decaying effect. Under the applied magnetic field of 9 T with mice dedicated hardware, the nanoprobe exhibits the ultralow r2/r1 value (~1.93), enabling the sensitive detection of microscopic primary tumours (<0.60 mm) and micrometastases (down to 0.20 mm) in mice. The sensitivity and accuracy of AFNP-enhanced UHF MRI are comparable to those of the histopathological examination, enabling the development of non-invasive visualization of previously undetectable biological entities critical to medical diagnosis and therapy.


Assuntos
Meios de Contraste/química , Imageamento por Ressonância Magnética/métodos , Magnetismo , Nanopartículas/química , Neoplasias/diagnóstico por imagem , Animais , Linhagem Celular Tumoral , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Microscopia Eletrônica de Transmissão , Nanopartículas/ultraestrutura , Neoplasias/patologia , Células RAW 264.7 , Ratos Wistar , Transplante Heterólogo
18.
Biosensors (Basel) ; 11(6)2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-34071179

RESUMO

This work explores several issues of importance for the development of a diagnostic method based on circle-to-circle amplification (C2CA) and oligonucleotide-functionalized magnetic nanoparticles. Firstly, the performance of the detection method was evaluated in terms of sensitivity and speed. Synthetic target sequences for Newcastle disease virus and Salmonella were used as model sequences. The sensitivity of the C2CA assay resulted in detection of 1 amol of starting DNA target with a total amplification time of 40 min for both target sequences. Secondly, the functionalization of the nanoparticles was evaluated in terms of robustness and stability. The functionalization was shown to be very robust, and the stability test showed that 92% of the oligos were still attached on the particle surface after three months of storage at 4 °C. Altogether, the results obtained in this study provide a strong foundation for the development of a quick and sensitive diagnostic assay.


Assuntos
Técnicas Biossensoriais , Nanopartículas de Magnetita , DNA , Magnetismo , Técnicas de Amplificação de Ácido Nucleico
19.
Int J Hyperthermia ; 38(1): 846-861, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34074196

RESUMO

Purpose: Bearing partially or fully metallic passive implants represents an exclusion criterion for patients undergoing a magnetic hyperthermia procedure, but there are no specific studies backing this restrictive decision. This work assesses how the secondary magnetic field generated at the surface of two common types of prostheses affects the safety and efficiency of magnetic hyperthermia treatments of localized tumors. The paper also proposes the combination of a multi-criteria decision analysis and a graphical representation of calculated data as an initial screening during the preclinical risk assessment for each patient.Materials and methods: Heating of a hip joint and a dental implant during the treatment of prostate, colorectal and head and neck tumors have been assessed considering different external field conditions and exposure times. The Maxwell equations including the secondary field produced by metallic prostheses have been solved numerically in a discretized computable human model. The heat exchange problem has been solved through a modified version of the Pennes' bioheat equation assuming a temperature dependency of blood perfusion and metabolic heat, i.e. thermorregulation. The degree of risk has been assessed using a risk index with parameters coming from custom graphs plotting the specific absorption rate (SAR) vs temperature increase, and coefficients derived from a multi-criteria decision analysis performed following the MACBETH approach.Results: The comparison of two common biomaterials for passive implants - Ti6Al4V and CoCrMo - shows that both specific absorption rate (SAR) and local temperature increase are found to be higher for the hip prosthesis made by Ti6Al4V despite its lower electrical and thermal conductivity. By tracking the time evolution of temperature upon field application, it has been established that there is a 30 s delay between the time point for which the thermal equilibrium is reached at prostheses and tissues. Likewise, damage may appear in those tissues adjacent to the prostheses at initial stages of treatment, since recommended thermal thresholds are soon surpassed for higher field intensities. However, it has also been found that under some operational conditions the typical safety rule of staying below or attain a maximum temperature increase or SAR value is met.Conclusion: The current exclusion criterion for implant-bearing patients in magnetic hyperthermia should be revised, since it may be too restrictive for a range of the typical field conditions used. Systematic in silico treatment planning using the proposed methodology after a well-focused diagnostic procedure can aid the clinical staff to find the appropriate limits for a safe treatment window.


Assuntos
Calefação , Hipertermia Induzida , Simulação por Computador , Humanos , Hipertermia , Campos Magnéticos , Magnetismo , Masculino
20.
Molecules ; 26(9)2021 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-34063259

RESUMO

In this study, we combine magnetic solid phase extraction (MSPE), with the screen-printed carbon electrode (SPCE) modified by a molecular imprinted polymer (MIP) for sensitive and selective extraction and electrochemical determination of Rhodamine B in food samples. A magnetic solid phase extraction (MSPE) was carried out using magnetic poly(styrene-co-divinylbenzene) (PS-DVB) and magnetic nanoparticles (MNPs) synthetized on the surface of multiwalled carbon nanotubes (MWCNTs). An MIP was prepared on the surface of MWCNTs in the presence of titanium oxide nanoparticles (TiO2NPs) modifying the SPCE for the rapid electrochemical detection of Rhodamine B. The MIPs synthesis was optimized by varying the activated titanium oxide (TiO2) and multiwalled carbon nanotubes (MWCNTs) amounts. The MSPE and electrochemical detection conditions were optimized as well. The present method exhibited good selectivity, high sensitivity, and good reproducibility towards the determination of Rhodamine B, making it a suitable method for the determination of Rhodamine B in food samples.


Assuntos
Análise de Alimentos/métodos , Nanotubos de Carbono/química , Polímeros/química , Rodaminas/análise , Adsorção , Técnicas Eletroquímicas , Eletrodos , Concentração de Íons de Hidrogênio , Limite de Detecção , Magnetismo , Microscopia Eletrônica de Varredura , Impressão Molecular , Polímeros Molecularmente Impressos , Poliestirenos/química , Reprodutibilidade dos Testes , Espalhamento de Radiação , Sensibilidade e Especificidade , Extração em Fase Sólida/métodos , Análise Espectral Raman , Titânio/química
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