Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.002
Filtrar
1.
J Chromatogr A ; 1648: 462192, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-33984649

RESUMO

Determination of folic acid and riboflavin in biological samples is difficult due to their high polarity, low concentration, chemical instability, and complex matrix. In this study, the polypyrrole-coated magnetic nanocomposite (Fe3O4@PPy) was synthesized innovatively with the assistance of hexadecyltrimethylammonium bromide. To evaluate the adsorption mechanism and the feasibility of synthesized Fe3O4@PPy as an adsorbent, the adsorption capacities, kinetics and thermodynamics of folic acid and riboflavin were investigated systemically. Furthermore, in light of the chemical instability of folic acid and riboflavin a method for rapid extraction and detection of them from human urine within 10 min was developed successfully by combining magnetic solid phase extraction with ultra-performance liquid chromatography (MSPE/UPLC). The adsorption parameters including sorbent amount, pH value, extraction time, desorption solvent and desorption time were studied. Under optimum conditions, the performance of the established determination method was validated with the linearly dependent coefficients (>0.9995), the limits of detection (0.02-0.05 µg/mL), the limits of quantification (0.07-0.18 µg/mL), and the recoveries (92.2-105.1%, with relative standard deviation < 3.3%). The rapid extraction and detection of folic acid and riboflavin from real urine samples were achieved subsequently. The present study suggests that the developed method exhibits a promising application in the analysis of free folic acid and riboflavin in human urine samples, which can provide a reference for the clinical drug monitoring and treatment.


Assuntos
Cromatografia Líquida/métodos , Ácido Fólico/urina , Magnetismo/métodos , Polímeros/química , Pirróis/química , Riboflavina/urina , Extração em Fase Sólida/métodos , Adsorção , Humanos , Limite de Detecção , Nanocompostos/química , Solventes/química
2.
Nat Commun ; 12(1): 3024, 2021 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-34021137

RESUMO

Manipulating and separating single label-free cells without biomarker conjugation have attracted significant interest in the field of single-cell research, but digital circuitry control and multiplexed individual storage of single label-free cells remain a challenge. Herein, by analogy with the electrical circuitry elements and electronical holes, we develop a pseudo-diamagnetophoresis (PsD) mattertronic approach in the presence of biocompatible ferrofluids for programmable manipulation and local storage of single PsD holes and label-free cells. The PsD holes conduct along linear negative micro-magnetic patterns. Further, eclipse diode patterns similar to the electrical diode can implement directional and selective switching of different PsD holes and label-free cells based on the diode geometry. Different eclipse heights and junction gaps influence the switching efficiency of PsD holes for mattertronic circuitry manipulation and separation. Moreover, single PsD holes are stored at each potential well as in an electrical storage capacitor, preventing multiple occupancies of PsD holes in the array of individual compartments due to magnetic Coulomb-like interaction. This approach may enable the development of large programmable arrays of label-free matters with high throughput, efficiency, and reliability as multiplex cell research platforms.


Assuntos
Engenharia Biomédica/métodos , Dispositivos Lab-On-A-Chip , Magnetismo/métodos , Sobrevivência Celular , Elétrons , Humanos , Nanopartículas/química , Células THP-1
3.
Int J Mol Sci ; 22(5)2021 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-33802613

RESUMO

This study demonstrates the rational fabrication of a magnetic composite nanofiber mesh that can achieve mutual synergy of hyperthermia, chemotherapy, and thermo-molecularly targeted therapy for highly potent therapeutic effects. The nanofiber is composed of biodegradable poly(ε-caprolactone) with doxorubicin, magnetic nanoparticles, and 17-allylamino-17-demethoxygeldanamycin. The nanofiber exhibits distinct hyperthermia, owing to the presence of magnetic nanoparticles upon exposure of the mesh to an alternating magnetic field, which causes heat-induced cell killing as well as enhanced chemotherapeutic efficiency of doxorubicin. The effectiveness of hyperthermia is further enhanced through the inhibition of heat shock protein activity after hyperthermia by releasing the inhibitor 17-allylamino-17-demethoxygeldanamycin. These findings represent a smart nanofiber system for potent cancer therapy and may provide a new approach for the development of localized medication delivery.


Assuntos
Benzoquinonas/farmacologia , Preparações de Ação Retardada/farmacologia , Doxorrubicina/farmacologia , Lactamas Macrocíclicas/farmacologia , Nanofibras/química , Neoplasias/tratamento farmacológico , Benzoquinonas/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Preparações de Ação Retardada/química , Doxorrubicina/química , Liberação Controlada de Fármacos , Sinergismo Farmacológico , Compostos Férricos/química , Humanos , Lactamas Macrocíclicas/química , Células MCF-7 , Magnetismo/métodos , Nanopartículas de Magnetita/química
4.
Annu Rev Biophys ; 50: 419-445, 2021 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-33646813

RESUMO

Single-molecule technologies have expanded our ability to detect biological events individually, in contrast to ensemble biophysical technologies, where the result provides averaged information. Recent developments in atomic force microscopy have not only enabled us to distinguish the heterogeneous phenomena of individual molecules, but also allowed us to view up to the resolution of a single covalent bond. Similarly, optical tweezers, due to their versatility and precision, have emerged as a potent technique to dissect a diverse range of complex biological processes, from the nanomechanics of ClpXP protease-dependent degradation to force-dependent processivity of motor proteins. Despite the advantages of optical tweezers, the time scales used in this technology were inconsistent with physiological scenarios, which led to the development of magnetic tweezers, where proteins are covalently linked with the glass surface, which in turn increases the observation window of a single biomolecule from minutes to weeks. Unlike optical tweezers, magnetic tweezers use magnetic fields to impose torque, which makes them convenient for studying DNA topology and topoisomerase functioning. Using modified magnetic tweezers, researchers were able to discover the mechanical role of chaperones, which support their substrate proteinsby pulling them during translocation and assist their native folding as a mechanical foldase. In this article, we provide a focused review of many of these new roles of single-molecule technologies, ranging from single bond breaking to complex chaperone machinery, along with the potential to design mechanomedicine, which would be a breakthrough in pharmacological interventions against many diseases.


Assuntos
Fenômenos Bioquímicos , Biofísica , DNA/química , Humanos , Magnetismo/métodos , Chaperonas Moleculares , Nanotecnologia
5.
Molecules ; 26(3)2021 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-33525515

RESUMO

Polymer templates play an essential role in the robust infiltration-based synthesis of functional multicomponent heterostructures with controlled structure, porosity, and composition. Such heterostructures are be used as hybrid organic-inorganic composites or as all-inorganic systems once the polymer templates are removed. Using iron oxide/alumina heterostructures formed by two-step infiltration of polystyrene-block-polyvinyl pyridine block copolymer with iron and aluminum precursors from the solution and vapor-phases, respectively, we show that the phase and morphology of iron oxide nanoparticles dramatically depend on the approach used to remove the polymer. We demonstrate that thermal and plasma oxidative treatments result in iron oxide nanoparticles with either solid or hollow morphologies, respectively, that lead to different magnetic properties of the resulting materials. Our study extends the boundaries of structure manipulations in multicomponent heterostructures synthesized using polymer infiltration synthesis, and hence their properties.


Assuntos
Nanopartículas/química , Nanoestruturas/química , Polímeros/química , Óxido de Alumínio/química , Compostos Férricos/química , Magnetismo/métodos , Nanotecnologia/métodos , Poliestirenos/química , Piridinas/química
6.
J Mater Chem B ; 9(5): 1259-1271, 2021 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-33410453

RESUMO

In recent years, the inputs from magnetically assisted strategies have been contributing to the development of more sensitive screening methods and precise means of diagnosis to overcome existing and emerging treatment challenges. The features of magnetic materials enabling in vivo traceability, specific targeting and space- and time-controlled delivery of nanomedicines have highlighted the resourcefulness of the magnetic toolbox for biomedical applications and theranostic strategies. The breakthroughs in magnetically assisted technologies for contact-free control of cell and tissue fate opens new perspectives to improve healing and instruct regeneration reaching a wide range of diseases and disorders. In this review, the contribution of magnetic nanoparticles (MNPs) will be explored as sophisticated and versatile nanotriggers, evidencing their unique cues to probe and control cell function. As cells detect and engage external magnetic features, these approaches will be overviewed considering molecular engineering and cell programming perspectives as well as cell and tissue targeting modalities. The therapeutic relevance of MNPs will be also emphasized as key components of nanostructured systems to control the release of nanomedicines and in the context of new therapy technologies.


Assuntos
Técnicas Biossensoriais/métodos , Fenômenos Magnéticos , Magnetismo/métodos , Humanos
7.
Int J Biol Macromol ; 172: 55-65, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33444653

RESUMO

In this content, a green approach for the ultrasound promoted in situ immobilization of Pd NPs over biodegradable chitosan/agarose modified ferrite NP (Fe3O4@CS-Agarose/Pd) is developed. The structural and physicochemical features of the material were estimated using advanced analytical techniques like FT-IR, ICP-OES, FESEM, EDS, XRD, TEM and VSM. The magnetic material was catalytically explored in the oxidation of alcohols under ultrasonic waves. Sonication had a significant role in enhancing the catalytic performance in the alcohol's oxidation as compared to conventional heating. The heterogeneous nanocatalyst was efficiently recycled up to 10 times with nominal loss in catalytic activity. Towards the biological applications, the Fe3O4@CS-Agarose/Pd nanocomposite showed high antioxidant activities against DPPH free radicals, comparable to standard butylated hydroxytoluene (BHT). In addition, it exhibited excellent cytotoxicity in terms of % cell viability against breast adenocarcinoma (MCF7), breast carcinoma (Hs 578Bst), infiltrating ductal cell carcinoma (Hs 319.T), and metastatic carcinoma (MDA-MB-453) cell lines. The best anti-breast cancer potential of the nanocomposite was observed in Hs 319.T cell line.


Assuntos
Álcoois/química , Plásticos Biodegradáveis/química , Neoplasias da Mama/tratamento farmacológico , Quitosana/química , Nanopartículas de Magnetita/administração & dosagem , Nanopartículas de Magnetita/química , Paládio/química , Sefarose/química , Antioxidantes/química , Compostos de Bifenilo/química , Catálise , Linhagem Celular Tumoral , Feminino , Compostos Férricos/química , Humanos , Magnetismo/métodos , Nanocompostos/química , Oxirredução , Picratos/química , Ondas Ultrassônicas
8.
Int J Biol Macromol ; 172: 104-113, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33444655

RESUMO

In recent days the nanomagnetic biocomposites have been evolved as sustainable green catalysts. In that context, we are prompted to design and synthesize a novel Pd NP adorned chitosan-starch dual biopolymer encapsulated core-shell type magnetic nanocomposite (Fe3O4@CS-Starch/Pd) in an eco-friendly pathway applying ultrasound irradiations. The morphological and physicochemical features of the material were determined using several advanced techniques like FT-IR, FESEM, HRTEM, EDX, atomic mapping, VSM, XRD and ICP-OES. Catalytic efficiency of the material was investigated in the ultrasound assisted classical Suzuki-Miyaura coupling towards the synthesis of diverse range of biaryl derivatives and in the catalytic reduction of 4-Nitrophenol.In both the protocols the catalyst exhibited excellent performances. Sonication had a significant role in enhancing the catalytic performances in both the reactions as compared to conventional heating. Due to super-paramagnetism, the catalyst was easily magnetically isolable and reused in 11 cycles without considerable leaching and change in reactivity.


Assuntos
Quitosana/química , Compostos Férricos/química , Nanocompostos/química , Nanopartículas/química , Nitrofenóis/química , Paládio/química , Amido/química , Biopolímeros/química , Catálise , Química Verde/métodos , Magnetismo/métodos , Ondas Ultrassônicas
9.
Int J Biol Macromol ; 170: 768-779, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33385450

RESUMO

Modified biopolymer chitosan namely 2-hydroxy-1-naphthaldehyde chitosan (CTS-Nap) has been synthesized for the removal of toxic chromium from aqueous solutions. In an attempt to enhance the adsorption capacity of toxic chromium on the prepared modified biopolymer, magnetic Fe3O4 nanoparticles have been loaded on the modified adsorbent to form the magnetite adsorbent (Fe3O4@CTS-Nap). The adsorption mechanism of both adsorbents is explored by batch experiments, FT-IR, SEM, TEM, XRD, VSM, and EDS. The optimum adsorption is achieved at pH 1.5 for CTS-Nap and 1.0 for Fe3O4@CTS-Nap. Pseudo second order illustrated the best description for the adsorption process with correlation coefficient R2 = 0.999 and the film diffusion or chemisorption is the rate-limiting step. The equilibrium data is analyzed using five isotherm models, the experimental data agreed well with the Freundlich model with a maximum adsorption capacity of 78.12 mg g-1 and 57.14 mg g-1 for CTS-Nap and Fe3O4@CTS-Nap, respectively. However, this unexpected result revealed that the presence of magnetic nanoparticles does not always enhance the adsorption process and many other factors could control the adsorption process. Generally, these outcomes revealed that the unmagnetite modified adsorbent CTS-Nap have practical greater influence on wastewater treatment management rather than the magnetic modified chitosan Fe3O4@CTS-Nap.


Assuntos
Biopolímeros/química , Quitosana/química , Cromo/química , Nanopartículas de Magnetita/química , Adsorção , Cinética , Magnetismo/métodos , Água/química , Poluentes Químicos da Água/química , Purificação da Água/métodos
10.
Methods Mol Biol ; 2182: 51-65, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32894487

RESUMO

One of the main drawbacks in current methods for bacterium detection is their quantification at very low concentration level in complex specimens. Novel developments that are needed involve solid-phase preconcentration procedures which can be easily integrated with emerging technologies. Here, we describe the immunomagnetic separation (IMS) of Salmonella using magnetic carriers. Nano (300 nm) and micro (2.8 µm) sized magnetic particles are modified with anti-Salmonella antibody to preconcentrate the bacteria from the samples throughout an immunological reaction. The immunomagnetic separation can be easily coupled with downstream characterization and quantification methods, including classical culturing, molecular biology techniques such as PCR, immunoassays, confocal and scanning electron microscopy, and emerging technologies and rapid detection methods including biosensors, lateral flow, and microfluidic devices.


Assuntos
Separação Imunomagnética/métodos , Salmonella/isolamento & purificação , Imunoensaio/métodos , Dispositivos Lab-On-A-Chip , Limite de Detecção , Fenômenos Magnéticos , Magnetismo/métodos , Reação em Cadeia da Polimerase/métodos , Salmonella/genética
11.
Molecules ; 26(1)2020 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-33379377

RESUMO

This study developed a nano-magnetite-modified biochar material (m-biochar) using a simple and rapid in situ synthesis method via microwave treatment, and systematically investigated the removal capability and mechanism of chromium (VI) by this m-biochar from contaminated groundwater. The m-biochar was fabricated from reed residues and magnetically modified by nano-Fe3O4. The results from scanning electron microscopy (SEM) and X-ray diffraction (XRD) characterisations confirmed the successful doping of nano-Fe3O4 on the biochar with an improved porous structure. The synthesised m-biochar exhibited significantly higher maximum adsorption capacity of 9.92 mg/g compared with that (8.03 mg/g) of the pristine biochar. The adsorption kinetics followed the pseudo-second-order model and the intraparticle diffusion model, which indicated that the overall adsorption rate of Cr(VI) was governed by the processes of chemical adsorption, liquid film diffusion and intramolecular diffusion. The increasing of the pH from 3 to 11 significantly affected the Cr(VI) adsorption, where the capabilities decreased from 9.92 mg/g to 0.435 mg/g and 8.03 mg/g to 0.095 mg/g for the m-biochar and pristine biochar, respectively. Moreover, the adsorption mechanisms of Cr(VI) by m-biochar were evaluated and confirmed to include the pathways of electrostatic adsorption, reduction and complexation. This study highlighted an effective synthesis method to prepare a superior Cr(VI) adsorbent, which could contribute to the effective remediation of heavy metal contaminations in the groundwater.


Assuntos
Carvão Vegetal/química , Cromo/química , Óxido Ferroso-Férrico/química , Água Subterrânea/química , Poluentes Químicos da Água/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Magnetismo/métodos , Micro-Ondas , Nanopartículas
12.
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 , Ciprofloxacina/farmacologia , DNA/efeitos dos fármacos , Quebras de DNA/efeitos dos fármacos , Conformação de Ácido Nucleico , Pinças Ópticas , Fenômenos Físicos , Software
13.
J Vis Exp ; (161)2020 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-32744515

RESUMO

Magnetic nanomaterials have received great attention in different biomedical applications. Biofunctionalizing these nanomaterials with specific targeting agents is a crucial aspect to enhance their efficacy in diagnostics and treatments while minimizing the side effects. The benefit of magnetic nanomaterials compared to non-magnetic ones is their ability to respond to magnetic fields in a contact-free manner and over large distances. This allows to guide or accumulate them, while they can also be monitored. Recently, magnetic nanowires (NWs) with unique features were developed for biomedical applications. The large magnetic moment of these NWs enables a more efficient remote control of their movement by a magnetic field. This has been utilized with great success in cancer treatment, drug delivery, cell tracing, stem cell differentiation or magnetic resonance imaging. In addition, the NW fabrication by template-assisted electrochemical deposition provides a versatile method with tight control over the NW properties. Especially iron NWs and iron-iron oxide (core-shell) NWs are suitable for biomedical applications, due to their high magnetization and low toxicity. In this work, we provide a method to biofunctionalize iron/iron oxide NWs with specific antibodies directed against a specific cell surface marker that is overexpressed in a large number of cancer cells. Since the method utilizes the properties of the iron oxide surface, it is also applicable to superparamagnetic iron oxide nanoparticles. The NWs are first coated with 3-aminopropyl-tri-ethoxy-silane (APTES) acting as a linker, which the antibodies are covalently attached to. The APTES coating and the antibody biofunctionalization are proven by electron energy loss spectroscopy (EELS) and zeta potential measurements. In addition, the antigenicity of the antibodies on the NWs is tested by using immunoprecipitation and western blot. The specific targeting of the biofunctionalized NWs and their biocompatibility are studied by confocal microscopy and a cell viability assay.


Assuntos
Magnetismo/métodos , Nanoestruturas/química , Sistemas de Liberação de Medicamentos/métodos , Humanos
14.
J Chromatogr A ; 1629: 461476, 2020 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-32841771

RESUMO

Core-shell structured magnetic covalent organic frameworks (Fe3O4@COFs) were synthesized via a facile approach at room temperature using 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,5-dibromo-1,4-benzenedicarboxaldehyde (DBDA) as two building blocks for the first time. The Fe3O4@COFs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), nitrogen adsorption-desorption isotherms, and zeta potentiometric analysis. The Fe3O4@COFs had a high specific surface area (141.94 m2·g-1) and uniform pore size distribution (average 4.53 nm). They also demonstrated good magnetic response (32.49 emu·g-1) and good thermal and chemical stabilities. Furthermore, adsorption experiments were conducted to evaluate the adsorption capacities and adsorption times of Fe3O4@COFs to diphenylamine (DPA) and its analogs, including benzidine (BZ), 1-naphthylamine (1-NA), 4-phenylphenol (4-PP), and O-tolidine (O-TD). From the experimental results, the maximum adsorption capacities of DPA, 1-NA, 4-PP, BZ, and O-TD were calculated as 246.25, 95.20, 85.85, 107.20, and 123.55 mg·g-1, respectively. A duration of 20 min was sufficient for adsorption. The Fe3O4@COFs were explored as adsorbents for magnetic solid-phase extraction (MSPE) of DPA and its analogs, and the MSPE parameters, including adsorbent dosage, extraction time, pH, ionic strength, desorption solvent, desorption time, and desorption frequency were optimized. Combined with HPLC using diode-array detection, a simple, fast, and sensitive method was proposed to detect DPA and its analogs, which exhibited good linearity (r >0.9946) in the range of 0.1-100 µg·mL-1. Moreover, the low limits of detection (ranging from 0.02 to 0.08 µg·mL-1, S/N = 3), low limits of quantitation (ranging from 0.05 to 0.30 µg·mL-1, S/N = 10), good precision with low relative SDs (<5.86% for intra-day and <6.44% for inter-day) were obtained. Finally, Fe3O4@COFs were applied to the effective MSPE of DPA and its analogs in actual samples chosen from the natural environment, and good recoveries (ranging from 79.97 to 122.52%) were observed.


Assuntos
Difenilamina/análogos & derivados , Difenilamina/isolamento & purificação , Fenômenos Magnéticos , Estruturas Metalorgânicas/química , Extração em Fase Sólida/métodos , Adsorção , Compostos Férricos/química , Concentração de Íons de Hidrogênio , Lagos/química , Limite de Detecção , Magnetismo/métodos , Estruturas Metalorgânicas/ultraestrutura , Concentração Osmolar , Reprodutibilidade dos Testes , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo , Água/química , Difração de Raios X
15.
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
16.
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
17.
Sci Rep ; 10(1): 5981, 2020 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-32249793

RESUMO

Magnetic compression anastomosis (MCA) has been appreciated as an innovative alternative to manual suturing in vascular reconstruction. However, magnetic devices have limitations in their applications. The present study aimed to introduce a newly developed magnetic device for end-to-end vascular anastomosis. Twenty male New Zealand rabbits were randomly assigned to receive end-to-end postcaval vein anastomosis using either a newly designed MCA device (Group MCA) or continuous-interrupted suturing (Group CIS). The anastomotic patency was evaluated by Doppler or venography immediately, 1 week, and 12 weeks after surgery. Anastomotic quality was evaluated gross and microscopic histological study 12 weeks after surgery. The procedure was successfully performed and all animals survived until sacrifice. The duration of surgery and anastomosis time in Group MCA were significantly shorter compared to Group CIS (all p < 0.001), and the incidence of anastomotic patency and postoperative morbidity were comparable between the two groups (all p > 0.05). Hematoxylin-eosin staining showed that anastomotic intima from Group MCA was much smoother with more regularly arranged endothelial cells than from compared to the Group CIS. A novel MCA device was successfully applied in rabbit vascular anastomosis. We demonstrated the reliability and effectiveness of this newly developed MCA in this study.


Assuntos
Anastomose Cirúrgica/métodos , Grau de Desobstrução Vascular/fisiologia , Veias/cirurgia , Animais , Magnetismo/métodos , Modelos Animais , Coelhos
18.
J Food Sci ; 85(4): 1098-1104, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32147835

RESUMO

Newly developed magnetic carbon particles prepared from coffee grounds were used as the sorbent for the magnetic solid-phase extraction of eight phthalic acid esters (PAEs) from plastic bottled water prior to their analysis by GC-MS. The method, which uses coffee-ground particles coated with iron oxide, was validated, and exhibited linearities for the eight PAEs, with coefficients of determination above 0.998 in the 0.005 to 0.1 mg/L concentration range. Limits of detection and limits of quantification of 0.00003 to 0.002 mg/L and 0.0001 to 0.005 mg/L, respectively, were achieved, with recoveries (%) ranging between 77% and 120%, and relative standard deviations for intra- and interday precisions below 16.3% at three fortification levels. No PAE residues were detected when the developed and validated method was applied to 10 real plastic bottled water samples. Taken together, the developed magnetic solid-phase extraction method is a useful tool for monitoring phthalate esters in aqueous samples. PRACTICAL APPLICATION: The development of a new, inexpensive, and efficient magnetic sorption material derived from spent coffee grounds, and its ability to determine phthalate esters in aqueous solutions was described by GC-MS/MS. The developed magnetic solid-phase extraction method is a useful tool for monitoring phthalate esters in aqueous samples.


Assuntos
Coffea/química , Água Potável/análise , Ésteres/isolamento & purificação , Magnetismo/métodos , Ácidos Ftálicos/isolamento & purificação , Plásticos/isolamento & purificação , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Carbono/química , Ésteres/química , Cromatografia Gasosa-Espectrometria de Massas , Limite de Detecção , Magnetismo/instrumentação , Ácidos Ftálicos/análise , Plásticos/química , Sementes/química , Extração em Fase Sólida/instrumentação , Poluentes Químicos da Água/química
19.
Phys Rev Lett ; 124(5): 058101, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-32083903

RESUMO

We report that trivalent cobalt hexammine cations decrease the persistence length, stretching modulus, helical density, and size of plectonemes formed under torque of DNA but increase those of RNA. Divalent magnesium cations, however, decrease the persistence lengths, contour lengths, and sizes of plectonemes while increasing the helical densities of both DNA and RNA. The experimental results are explained by different binding modes of the cations on DNA and RNA in our all-atom molecular dynamics simulations. The significant variations of the helical densities and structures of DNA and RNA duplexes induced by high-valent cations may affect interactions of the duplexes with proteins.


Assuntos
DNA/química , RNA de Cadeia Dupla/química , Cátions/química , Cobalto/química , Elasticidade , Magnésio/química , Magnetismo/instrumentação , Magnetismo/métodos , Modelos Químicos , Modelos Moleculares , Simulação de Dinâmica Molecular , Pinças Ópticas , RNA/química
20.
J Robot Surg ; 14(5): 753-758, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32036495

RESUMO

The purpose of this study was to describe technical considerations and first outcomes from a single-port robotic-assisted sacrocolpopexy (RSC) using the da Vinci SP platform (Intuitive Surgical, Sunnyvale, CA) and the Levita™ Magnetic Surgical System (San Mateo, CA, USA), a novel magnetic retraction system. Three females with pelvic organ prolapse elected to undergo RSC using the da Vinci SP platform. The supraumbilical incision length was 25 mm through which SP trocar was placed. A 12-mm assistant port was placed in the right upper quadrant. The external magnet was attached to the left side of the bed and used for bowel and bladder retraction. We then proceeded by duplicating the steps of our approach for a RSC performed using a multi-port robotic platform with necessary modifications given the SP approach. Intra-operative outcomes and peri-operative outcomes were collected and reported. The patients were women of 64, 66 and 73 years of age with BMI of 22, 25, and 34, respectively, and POP-Q stage III and IV prolapse. The RSC was performed between 198 and 247 min, estimated blood loss was 10-50 cc, and there were no complications. All patients were discharged home on post-operative day 1. All patients were doing well 1 month out with resolution of bulge symptoms. To our knowledge, this represents the first case series of robotic, magnetic-assisted sacrocolpopexies using the da Vinci SP platform and the Levita™ Magnetic Surgical System. It appears to be a safe and feasible approach, but long-term comparative studies will be necessary to assess functional outcomes.


Assuntos
Procedimentos Cirúrgicos em Ginecologia/instrumentação , Procedimentos Cirúrgicos em Ginecologia/métodos , Laparoscopia/instrumentação , Laparoscopia/métodos , Magnetismo/instrumentação , Magnetismo/métodos , Prolapso de Órgão Pélvico/cirurgia , Procedimentos Cirúrgicos Robóticos/instrumentação , Procedimentos Cirúrgicos Robóticos/métodos , Idoso , Perda Sanguínea Cirúrgica/estatística & dados numéricos , Feminino , Humanos , Pessoa de Meia-Idade , Duração da Cirurgia , Resultado do Tratamento
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...