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1.
Anal Chem ; 93(9): 4154-4159, 2021 03 09.
Artículo en Inglés | MEDLINE | ID: mdl-33645217

RESUMEN

Chip-scale SARS-CoV-2 testing was demonstrated using silicon nitride (Si3N4) nanoslot fluidic waveguides to detect a tagged oligonucleotide with a coronavirus DNA sequence. The slot waveguides were fabricated using complementary metal-oxide-semiconductor (CMOS) fabrication processes, including multiscale lithography and selective reactive ion etching (RIE), forming femtoliter fluidic channels. Finite difference method (FDM) simulation was used to calculate the optical field distribution of the waveguide mode when the waveguide sensor was excited by transverse electric (TE) and transverse magnetic (TM) polarized light. For the TE polarization, a strong optical field was created in the slot region and its field intensity was 14× stronger than the evanescent sensing field from the TM polarization. The nanoscale confinement of the optical sensing field significantly enhanced the light-analyte interaction and improved the optical sensitivity. The sensitivity enhancement was experimentally demonstrated by measuring the polarization-dependent fluorescence emission from the tagged oligonucleotide. The photonic chips consisting of femtoliter Si3N4 waveguides provide a low-cost and high throughput platform for real-time virus identification, which is critical for point-of-care (PoC) diagnostic applications.


Asunto(s)
/métodos , /virología , ADN Viral/análisis , Nanopartículas/química , /aislamiento & purificación , Compuestos de Silicona/química , Humanos , Óptica y Fotónica , Sistemas de Atención de Punto , Refractometría , Semiconductores , Sensibilidad y Especificidad
2.
ACS Appl Mater Interfaces ; 13(4): 5795-5802, 2021 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-33480669

RESUMEN

A novel ratiometric electrochemical (EC) sensing platform was established for sensitive immunoassay of target cytokeratin 19 fragment 21-1 (CYFRA21-1) biomarker by combining competitive immunoreaction and multisignal output. This immunosensor utilized Ag nanoparticles (NPs)-functionalized urchin-like Fe3O4@polydopamine (u-Fe3O4@PDA-Ag) as a matrix to immobilize CYFRA21-1 antigens and methylene blue (MB)-absorbed Ni3Si2O5(OH)4-Au nanotubes (NTs) to label the anti-CYFRA21-1 (Ab). During the competitive immunoreaction, square wave voltammetric (SWV) current changes of Ag NPs from u-Fe3O4@PDA-Ag indicator and MB from Ni3Si2O5(OH)4-Au/MB indicator are relevant to the dosage of CYFRA21-1-acquired Ni3Si2O5(OH)4-Au/MB/Ab. More importantly, numerous CYFRA21-1 loaded stably on u-Fe3O4@PDA-Ag exhibited strong competitive capacity toward the target-CYFRA21-1 to combine Ni3Si2O5(OH)4-Au/MB/Ab, causing sensitive changes in the ratio of two measured SWV currents. Prominently, "ΔI = ΔIMB + |ΔIAg NPs|" (ΔIMB and |ΔIAg NPs| represents the change values of the oxidation peak currents of MB and Ag NPs, respectively) could be regarded as significantly amplifying the signal response and ultimately improving the sensitivity of CYFRA21-1 detection, from which we derived a wide dynamic range from 500 fg/mL to 50 ng/mL and a low detection limit of 0.39 pg/mL (S/N = 3). This work may exert a profound impact on monitoring other biomarkers in early diagnosis of diseases.


Asunto(s)
Antígenos de Neoplasias/sangre , Óxido Ferrosoférrico/química , Oro/química , Queratina-19/sangre , Azul de Metileno/química , Nanotubos/química , Antígenos de Neoplasias/análisis , Técnicas Electroquímicas/métodos , Humanos , Inmunoensayo/métodos , Indoles/química , Queratina-19/análisis , Límite de Detección , Nanopartículas del Metal/química , Nanopartículas del Metal/ultraestructura , Nanotubos/ultraestructura , Polímeros/química , Compuestos de Silicona/química , Plata/química
3.
Molecules ; 26(3)2021 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-33499359

RESUMEN

Carbonized elastomer-based composites (CECs) possess a number of attractive features in terms of thermomechanical and electromechanical performance, durability in aggressive media and facile net-shape formability, but their relatively low ductility and strength limit their suitability for structural engineering applications. Prospective applications such as structural elements of micro-electro-mechanical systems MEMS can be envisaged since smaller principal dimensions reduce the susceptibility of components to residual stress accumulation during carbonization and to brittle fracture in general. We report the results of in situ in-SEM study of microdeformation and fracture behavior of CECs based on nitrile butadiene rubber (NBR) elastomeric matrices filled with carbon and silicon carbide. Nanostructured carbon composite materials were manufactured via compounding of elastomeric substance with carbon and SiC fillers using mixing rolling mill, vulcanization, and low-temperature carbonization. Double-edge notched tensile (DENT) specimens of vulcanized and carbonized elastomeric composites were subjected to in situ tensile testing in the chamber of the scanning electron microscope (SEM) Tescan Vega 3 using a Deben microtest 1 kN tensile stage. The series of acquired SEM images were analyzed by means of digital image correlation (DIC) using Ncorr open-source software to map the spatial distribution of strain. These maps were correlated with finite element modeling (FEM) simulations to refine the values of elastic moduli. Moreover, the elastic moduli were derived from unloading curve nanoindentation hardness measurements carried out using a NanoScan-4D tester and interpreted using the Oliver-Pharr method. Carbonization causes a significant increase of elastic moduli from 0.86 ± 0.07 GPa to 14.12 ± 1.20 GPa for the composite with graphite and carbon black fillers. Nanoindentation measurements yield somewhat lower values, namely, 0.25 ± 0.02 GPa and 9.83 ± 1.10 GPa before and after carbonization, respectively. The analysis of fractography images suggests that crack initiation, growth and propagation may occur both at the notch stress concentrator or relatively far from the notch. Possible causes of such response are discussed, namely, (1) residual stresses introduced by processing; (2) shape and size of fillers; and (3) the emanation and accumulation of gases in composites during carbonization.


Asunto(s)
Elastómeros/química , Nanocompuestos/química , Carbono/química , Compuestos Inorgánicos de Carbono/química , Simulación por Computador , Módulo de Elasticidad , Análisis de Elementos Finitos , Dureza , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Nanocompuestos/ultraestructura , Compuestos de Silicona/química , Estrés Mecánico , Resistencia a la Tracción
4.
Food Chem ; 339: 128072, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33152867

RESUMEN

The efficient magnetic adsorbent (Fe3O4@ATP) was prepared by precipitation through the dispersion of Fe3O4 nanoparticles on the natural attapulgite (ATP) and then tested as an adsorbent for aflatoxin B1 (AFB1) removal from contaminated oils. The adsorbent characterization results revealed that the Fe3O4 were incorporated into the ATP, affording the Fe3O4@ATP composite. This magnetic composite displayed a good ability to eliminate AFB1 from contaminated oils with a removal efficiency of 86.82% using a 0.3% dosage. The Fe3O4@ATP possessed paramagnetic character with a saturation magnetization of 50.86 emu/g, enabling its easy separation from the medium using an external magnet. The adsorption process followed the pseudo-second-order model and fitted the Freundlich isotherm well. Moreover, the thermodynamic studies showed that AFB1 adsorption onto Fe3O4@ATP was exothermic and spontaneous. The novelty of this study lies in the fabrication of magnetic composite adsorbents for AFB1 elimination from oils.


Asunto(s)
Aflatoxina B1/aislamiento & purificación , Arachis/química , Contaminación de Alimentos , Compuestos de Magnesio/química , Imanes/química , Aceites Vegetales/química , Compuestos de Silicona/química , Adsorción , Aflatoxina B1/química , Cinética , Termodinámica
5.
Int J Nanomedicine ; 15: 6945-6960, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33061361

RESUMEN

Background: Natural clay nanomaterials are an emerging class of biomaterial with great potential for tissue engineering and regenerative medicine applications, most notably for osteogenesis. Materials and Methods: Herein, for the first time, novel tissue engineering scaffolds were prepared by 3D bioprinter using nontoxic and bioactive natural attapulgite (ATP) nanorods as starting materials, with polyvinyl alcohol as binder, and then sintered to obtain final scaffolds. The microscopic morphology and structure of ATP particles and scaffolds were observed by transmission electron microscope and scanning electron microscope. In vitro biocompatibility and osteogenesis with osteogenic precursor cell (hBMSCs) were assayed using MTT method, Live/Dead cell staining, alizarin red staining and RT-PCR. In vivo bone regeneration was evaluated with micro-CT and histology analysis in rat cranium defect model. Results: We successfully printed a novel porous nano-ATP scaffold designed with inner channels with a dimension of 500 µm and wall structures with a thickness of 330 µm. The porosity of current 3D-printed scaffolds ranges from 75% to 82% and the longitudinal compressive strength was up to 4.32±0.52 MPa. We found firstly that nano-ATP scaffolds with excellent biocompatibility for hBMSCscould upregulate the expression of osteogenesis-related genes bmp2 and runx2 and calcium deposits in vitro. Interestingly, micro-CT and histology analysis revealed abundant newly formed bone was observed along the defect margin, even above and within the 3D bioprinted porous ATP scaffolds in a rat cranial defect model. Furthermore, histology analysis demonstrated that bone was formed directly following a process similar to membranous ossification without any intermediate cartilage formation and that many newly formed blood vessels are within the pores of 3D-printed scaffolds at four and eight weeks. Conclusion: These results suggest that the 3D-printed porous nano-ATP scaffolds are promising candidates for bone tissue engineering by osteogenesis and angiogenesis.


Asunto(s)
Regeneración Ósea/fisiología , Células Madre Mesenquimatosas/citología , Ingeniería de Tejidos/métodos , Andamios del Tejido/química , Animales , Huesos/fisiología , Calcio/metabolismo , Chlorocebus aethiops , Condrogénesis , Fuerza Compresiva , Regulación de la Expresión Génica , Humanos , Compuestos de Magnesio/química , Masculino , Ensayo de Materiales , Nanotubos/química , Osteogénesis/fisiología , Alcohol Polivinílico/química , Porosidad , Impresión Tridimensional , Ratas Sprague-Dawley , Compuestos de Silicona/química , Células Vero , Microtomografía por Rayos X
6.
Int J Nanomedicine ; 15: 6761-6777, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32982232

RESUMEN

Purpose: Guided bone regeneration (GBR) therapy, which is a widely used technique in clinical practice and is effective in improving the repair of alveolar bone defects or bone mass deficiency regeneration, requires the use of membrane materials with good biocompatibility, barrier function, rigidity matching the space maintenance ability, economic benefits and excellent clinical applicability. The aim of this study was to develop an electrospun attapulgite (ATT)-doped poly (lactic-co-glycolic acid) (PLGA) scaffold (PLGA/ATT scaffold) as a novel material for GBR applications. Methods and Results: Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to determine the morphology and the crystalline structure of the PLGA/ATT scaffolds, respectively. Porosity and contact-angle measurements were also carried out to further characterize the physical properties of the PLGA/ATT scaffolds. The results of in vitro studies showed that bone marrow mesenchymal stem cells (BMSCs) attached more readily to and spread better over the PLGA/ATT scaffolds than the Bio-Gide membrane. Furthermore, in the in vitro osteoinductive experiments with BMSCs, the PLGA/ATT scaffolds were found to enhance the activity of alkaline phosphatase (ALP), promote the formation of mineralized bone nodules, and up-regulate the expression of several osteogenic markers-namely, runt-related transcription factor 2, alkaline phosphatase, osteopontin, and osteocalcin-which are similar to the effects of the Bio-Gide membrane. Further, in in vivo studies, the results of sequential fluorescent labeling, micro-computed tomography, and histological analysis suggest that using the PLGA/ATT scaffolds for repairing V-shaped buccal dehiscence on a dog's tooth root improved bone regeneration, which is not only similar to the result obtained using the Bio-Gide membrane but also much better than that obtained using PLGA scaffolds and the negative control. Conclusion: To achieve satisfactory therapeutic results and to lower the cost of GBR treatment, this study provided a promising alternative material of bio-degradable membrane in clinical treatment.


Asunto(s)
Pérdida de Hueso Alveolar/terapia , Regeneración Ósea/fisiología , Compuestos de Magnesio/farmacología , Compuestos de Silicona/farmacología , Andamios del Tejido/química , Animales , Regeneración Ósea/efectos de los fármacos , Calcificación Fisiológica , Colágeno , Perros , Expresión Génica , Encía/citología , Humanos , Compuestos de Magnesio/química , Masculino , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/fisiología , Osteogénesis/efectos de los fármacos , Osteogénesis/genética , Osteogénesis/fisiología , Copolímero de Ácido Poliláctico-Ácido Poliglicólico/química , Porosidad , Ratas Sprague-Dawley , Compuestos de Silicona/química , Raíz del Diente/diagnóstico por imagen , Microtomografía por Rayos X
7.
Phys Med Biol ; 65(19): 195005, 2020 09 24.
Artículo en Inglés | MEDLINE | ID: mdl-32575086

RESUMEN

Gadolinium aluminum gallium garnet (GAGG) is a promising scintillator crystal for positron emission tomography (PET) detectors owing to its advantages of energy resolution, light yield, and absence of intrinsic radiation. However, a large portion of the incident photons undergoes Compton scattering within GAGG crystal because of its low stopping power compared to that of lutetium-based crystals such as Lu2SiO5 (LSO). Inter-detector scattering (IDS) and inter-crystal scattering (ICS) result in loss of sensitivity and image quality of PET, respectively. We performed a Monte Carlo simulation study to evaluate IDS recovery in our currently developing brain-dedicated PET, and extended the idea to ICS recovery. We also compared the impact of the recoveries on LSO- and GAGG-based PET scanners. We measured the sensitivity and spatial resolution of the brain PET, and analyzed the image quality using a lesion phantom, a hot-rod phantom, and a 2D Hoffman phantom with applying IDS or ICS recovery. IDS recovery increased the PET sensitivity and improved the noise level of the reconstructed images. ICS recovery enhanced the spatial resolution and the contrast of the images was improved. As the occurrence rates of IDS and ICS were higher in GAGG than in LSO, the overall impact of IDS or ICS recovery was significant in GAGG. In conclusion, we showed that the proportional method would be suitable for IDS and ICS recoveries of PET, and emphasized the importance of ICS and IDS recoveries for PET using crystals with low stopping power.


Asunto(s)
Encéfalo/diagnóstico por imagen , Gadolinio/química , Galio/química , Lutecio/química , Fantasmas de Imagen , Tomografía de Emisión de Positrones/métodos , Compuestos de Silicona/química , Diseño de Equipo , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Método de Montecarlo , Fotones , Conteo por Cintilación/instrumentación
8.
Artículo en Inglés | MEDLINE | ID: mdl-32326056

RESUMEN

The effects of sepiolite, montmorillonite, and attapulgite on the removal and immobilization of Cr(VI) in water and soil were studied. X-ray diffraction (XRD) characterizations showed that the purities of these three mineral materials decreased in the following order: montmorillonite > attapulgite > sepiolite, and that their surface molecular bond types were similar. The adsorption potential of Cr(VI) in aqueous solutions of the three mineral materials was in the following order: sepiolite > attapulgite > montmorillonite. The adsorption mechanism for attapulgite was consistent with the Freundlich isotherm adsorption model, whereas that for montmorillonite was more consistent with the Langmuir model. Sepiolite had a good fitting effect for both isothermal adsorption models. For montmorillonite and attapulgite, a lower pH corresponded to a higher removal of Cr(VI). For sepiolite, however, the removal efficiency of Cr(VI) from an aqueous solution was the lowest at a pH of approximately 5.0. The results of the soil toxicity characteristic leaching procedure showed that, following the addition of 15% sepiolite, attapulgite, or montmorillonite to the contaminated soil, Cr(VI) concentrations in the leachates decreased by 16.8%, 18.9%, and 15.9%, respectively, and the total Cr concentrations in the leachates were reduced by 21.2%, 29.2%, and 17.6%. Of the three mineral materials, attapulgite demonstrated the highest Cr(VI) immobilization efficiency in soil. This study emphasizes the effect of attapulgite on the immobilization of Cr(VI) in soil and aqueous solutions, thus providing a theoretical basis for the potential application of natural mineral material remediation of Cr(VI)-contaminated aqueous solutions and soils.


Asunto(s)
Bentonita/química , Cromo/análisis , Compuestos de Magnesio/química , Silicatos de Magnesio/química , Compuestos de Silicona/química , Contaminantes del Suelo/análisis , Contaminantes Químicos del Agua/análisis , Adsorción , Restauración y Remediación Ambiental , Suelo , Agua
9.
J Vis Exp ; (156)2020 02 16.
Artículo en Inglés | MEDLINE | ID: mdl-32116307

RESUMEN

Heteroarylation introduces heteroaryl fragments to organic molecules. Despite the numerous available reactions reported for arylation via transition metal catalysis, the literature on direct heteroarylation is scarce. The presence of heteroatoms such as nitrogen, sulfur and oxygen often make heteroarylation a challenging research field due to catalyst poisoning, product decomposition and the rest. This protocol details a highly efficient direct α-C(sp3) heteroarylation of ketones under microwave irradiation. Key factors for successful heteroarylation include the use of XPhos Palladacycle Gen. 4 Catalyst, excess base to suppress side reactions and the high temperature and pressure achieved in a sealed reaction vial under microwave irradiation. The heteroarylation compounds prepared by this method were fully characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), carbon nuclear magnetic resonance spectroscopy (13C NMR) and high-resolution mass spectrometry (HRMS). This methodology has several advantages over literature precedents including broad substrate scope, rapid reaction time, greener procedure and operational simplicity by eliminating the preparation of intermediates such as silyl enol ether. Possible applications for this protocol include, but are not limited to, diversity-oriented synthesis for the discovery of biologically active small molecules, domino synthesis for the preparation of natural products and ligand development for new transition metal catalytic systems.


Asunto(s)
Cetonas/síntesis química , Metales/química , Microondas , Elementos de Transición/química , Compuestos Inorgánicos de Carbono/química , Espectroscopía de Resonancia Magnética con Carbono-13 , Catálisis , Cromatografía , Cetonas/química , Paladio/química , Espectroscopía de Protones por Resonancia Magnética , Compuestos de Silicona/química , Temperatura
10.
Int J Mol Sci ; 21(3)2020 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-32024227

RESUMEN

We report a highly compliant process for patterning nanoparticle arrays on micro- and nanomechanical devices. The distinctive step involves the single layer self-assembled nanoparticles on top of released nanomechanical devices. We demonstrate the process by fabricating sizable arrays of nanomechanical devices on silicon-on-insulator substrates, acting as nanomechanical torque magnetometers. Later, the nanoparticles were self-assembled in geometrical shapes on top of the devices by a unique combination of top-down and bottom-up methods. The self-assembled array of nanoparticles successfully showed a magnetic torque signal by magnetic actuation of the magnetometer. This patterning process can be generalized for any shape and for a wide range of nanoparticles on the nanomechanical resonators.


Asunto(s)
Nanopartículas de Magnetita/química , Magnetometría/instrumentación , Magnetometría/métodos , Nanotecnología/métodos , Compuestos de Silicona/química , Torque , Nanotecnología/instrumentación , Semiconductores
11.
Food Chem ; 317: 126425, 2020 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-32106006

RESUMEN

Herein, we developed a novel magnetic solid phase extraction method based on attapulgite-modified magnetic metal-organic frameworks (ATP@Fe3O4@ZIF-8), and this method could be used for the determination of benzoylureas when it was coupled with high-performance liquid chromatography. The established method was validated in terms of linearity (2.5-500 µg L-1, with correlation coefficient (R2) > 0.9994), accuracy (with satisfactory recovery of 88.29-95.99%) and precision (with relative standard deviation (RSD) of less than 8%). In addition, the enrichment factors (EF) ranged from 63.6 to 72.2. Limit of detection (LOD) and limit of quantitation (LOQ) were 0.7-3.2 µg L-1 and 2.3-10.7 µg L-1, respectively. Moreover, there was hardly any noticeable loss of the extraction efficiency when this extraction method undergoes five cycles. Finally, this method was successfully used for the determination of six benzoylureas in different tea infusions and the determined relative recoveries ranged from 78.8 to 114.3%.


Asunto(s)
Cromatografía Líquida de Alta Presión , Insecticidas/análisis , Estructuras Metalorgánicas/química , Extracción en Fase Sólida/métodos , Adsorción , Benzamidas/análisis , Concentración de Iones de Hidrógeno , Límite de Detección , Compuestos de Magnesio/química , Magnetismo , Nanocompuestos/química , Concentración Osmolar , Compuestos de Silicona/química , Té/química , Contaminantes Químicos del Agua/análisis
12.
J Vis Exp ; (155)2020 01 11.
Artículo en Inglés | MEDLINE | ID: mdl-31984969

RESUMEN

The para-substituted di-tert-butylfluorosilylbenzene structural motif known as the silicon-fluoride acceptor (SiFA) is a useful tag in the radiochemist's toolkit for incorporating radioactive [18F]fluoride into tracers for use in positron emission tomography. In comparison to conventional radiolabeling strategies, isotopic exchange of fluorine-19 from SiFA with [18F]fluoride is carried out at room temperature and requires minimal reaction participants. The formation of by-products is thus negligible, and purification is greatly simplified. However, while the precursor molecule used for labeling and the final radiolabeled product are isotopically discrete, they are chemically identical and are thus inseparable during purification procedures. The SiFA tag is also susceptible to degradation under the basic conditions arising from the processing and drying of [18F]fluoride. The '4 drop method', wherein only the first 4 drops of eluted [18F]fluoride are used from the solid-phase extraction, reduces the amount of base in the reaction, facilitates lower molar amounts of precursor, and reduces degradation.


Asunto(s)
Fluoruros/química , Radioisótopos de Flúor/química , Tomografía de Emisión de Positrones , Radiofármacos/química , Compuestos de Silicona/química , Animales , Aniones , Línea Celular Tumoral , Cromatografía Líquida de Alta Presión , Humanos , Ligandos , Ratones , Extracción en Fase Sólida , Ensayos Antitumor por Modelo de Xenoinjerto
13.
Biosens Bioelectron ; 153: 112047, 2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-31999559

RESUMEN

The rising cost of global healthcare provision and new approaches to managing disease are driving the development of low-cost biosensing modalities, such as label-free photonic methods based on dielectric resonances. Here, we use the combined sensing and imaging capability of a guided mode resonance (GMR) sensor to detect multiple biomarkers (troponin, procalcitonin and C-Reactive Protein) in parallel in undiluted urine samples. A key requirement of such a biosensor is the simple and direct functionalization with suitable antibodies to ensure the disease-specific detection of protein biomarkers. Here, antibodies were immobilized using a succinimidyl-[(N-maleimidopropionamido)-hexaethyleneglycol] ester (SM(PEG)6) spacer. The polyethylene glycol (PEG) chemistry enables low detection limits of 10 pg mL-1 or better for all protein biomarkers, while minimizing non-specific binding compared to more commonly used strategies such as (3-Aminopropyl)triethoxysilane (APTES) or dextran. Our approach supports the vision of a simple yet highly sensitive diagnostic platform that could be used for pre-screening patients for a wide range of diseases at point-of-care, thereby relieving the pressure on overstretched healthcare services.


Asunto(s)
Anticuerpos Inmovilizados/orina , Biomarcadores/orina , Nanoestructuras/química , Resonancia por Plasmón de Superficie/métodos , Humanos , Inmunoensayo , Límite de Detección , Sistemas de Atención de Punto , Polietilenglicoles/química , Propilaminas/química , Tecnicas de Microbalanza del Cristal de Cuarzo , Sensibilidad y Especificidad , Silanos/química , Compuestos de Silicona/química , Propiedades de Superficie
14.
Talanta ; 209: 120501, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-31892087

RESUMEN

In the present study, we have developed a capacitance electrochemical biosensor based on silicon nitride substrate (Si3N4/SiO2/Si[P]/Al) for Tumour Necrosis Factor Alpha (TNF-α) cytokines detection. Micro-contact printing, Fluorescence microscopy characterization and contact angle measurement (CAM) were carried out during the bio-functionalization of the biosensor surface. Mott-Schottky analyses were applied for TNF-α detection within the range of 1 pg/mL to 30 pg/mL in which the immunosensor has exhibited a good linearity, a sensitivity of 4 mV.pM-1 and 4.4 mV.pM-1 in PBS and artificial saliva (AS) respectively. While the LOD was found at 0.38 pg/mL and 1 pg/mL in PBS and AS respectively. The developed immunosensor has also demonstrated a high and good selectivity for TNF-α detection in human AS when compared to other interferences like Cortisol and Interleukin-10. The performances of the developed biosensor are very promising for biomedical application to predict the first sign of inflammation.


Asunto(s)
Técnicas Biosensibles/métodos , Técnicas Electroquímicas/métodos , Saliva Artificial/química , Compuestos de Silicona/química , Transductores , Factor de Necrosis Tumoral alfa/análisis , Anticuerpos Inmovilizados/inmunología , Anticuerpos Monoclonales/inmunología , Capacidad Eléctrica , Técnicas Electroquímicas/instrumentación , Electrodos , Colorantes Fluorescentes/química , Humanos , Inmunoensayo/métodos , Límite de Detección , Rodaminas/química , Dióxido de Silicio/química , Factor de Necrosis Tumoral alfa/inmunología
15.
Artículo en Inglés | MEDLINE | ID: mdl-31940746

RESUMEN

In this paper, attapulgite purified by acid heat was employed, and millimeter polyethersulfone-modified attapulgite hybrid microspheres were prepared. The effects of mixed bisphenol A (BPA) and sulfamethoxazole (SMX) solution on the modified attapulgite doping ratio, initial solution pH, adsorbent dosage, contaminant concentration, and temperature were studied. The experimental results showed that BPA and SMX compete in the adsorption process, and the hybrid microspheres preferentially select the BPA molecules (anionic endocrine disruptors) compared to the SMX. The adsorption process in the mixed solution conforms to the quasi-secondary-order kinetic model. The adsorption of BPA and SMX by hybrid microspheres is more consistent with the extended Langmuir adsorption thermodynamic model, and the adsorption of BPA + SMX is more in line with the Langmuir adsorption thermodynamic model. At 25 °C, the maximum adsorption capacity of hybrid microspheres for BPA and SMX was 102.04 and 12.80 µmol·g-1, respectively, and the maximum adsorption of BPA + SMX was 112.36 µmol·g-1. After five regenerations, the removal effect of the hybrid microspheres on the endocrine disruptors remained above 95%.


Asunto(s)
Adsorción , Compuestos de Bencidrilo/química , Disruptores Endocrinos/química , Contaminantes Ambientales/química , Compuestos de Magnesio/química , Fenoles/química , Polímeros/química , Compuestos de Silicona/química , Sulfametoxazol/química , Sulfonas/química , Cinética , Microesferas , Termodinámica
16.
Sensors (Basel) ; 20(2)2020 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-31940833

RESUMEN

A convenient electrochemical sensing pathway was investigated for neurotransmitter detection based on newly synthesized silole derivatives and laccase/horseradish-peroxidase-modified platinum (Pt)/gold (Au) electrodes. The miniature neurotransmitter's biosensors were designed and constructed via the immobilization of laccase in an electroactive layer of the Pt electrode coated with poly(2,6-bis(3,4-ethylenedioxythiophene)-4-methyl-4-octyl-dithienosilole) and laccase for serotonin (5-HT) detection, and a Au electrode modified with the electroconducting polymer poly(2,6-bis(selenophen-2-yl)-4-methyl-4-octyl-dithienosilole), along with horseradish peroxidase (HRP), for dopamine (DA) monitoring. These sensing arrangements utilized the catalytic oxidation of neurotransmitters to reactive quinone derivatives (the oxidation process was provided in the enzymes' presence). Under the optimized conditions, the analytical performance demonstrated a convenient degree of sensitivity: 0.0369 and 0.0256 µA mM-1 cm-2, selectivity in a broad linear range (0.1-200) × 10-6 M) with detection limits of ≈48 and ≈73 nM (for the serotonin and dopamine biosensors, respectively). Moreover, the method was successfully applied for neurotransmitter determination in the presence of interfering compounds (ascorbic acid, L-cysteine, and uric acid).


Asunto(s)
Peroxidasa de Rábano Silvestre/metabolismo , Lacasa/metabolismo , Neurotransmisores/análisis , Técnicas Biosensibles , Catálisis , Dopamina/orina , Técnicas Electroquímicas , Electrodos , Enzimas Inmovilizadas/metabolismo , Oro/química , Concentración de Iones de Hidrógeno , Límite de Detección , Microscopía de Fuerza Atómica , Oxidación-Reducción , Platino (Metal)/química , Polímeros/química , Serotonina/orina , Compuestos de Silicona/química
17.
Analyst ; 145(5): 1657-1666, 2020 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-31922169

RESUMEN

Resistive pulse sensing with nanopores is expected to enable identification and analysis of nanoscale objects in ionic solutions. However, there is currently no remarkable method to characterize the three-dimensional shape of charged biomolecules or nanoparticles with low-cost and high-throughput. Here we demonstrate the sensing capability of solid-state nanopores for shape characterization of single nanoparticles by monitoring the ionic current blockades during their electrophoretic translocation through nanopores. By using nanopores that are a bit larger than the particles, shape characterization of both spherical and cubic silver nanoparticles is successfully realized due to their rapid rotation with respect to the pore axis, which is further validated by our all-atom molecular dynamics simulations. The single-molecule approach based on nanopores will allow people to measure the dimension and to characterize the shape of single nanoparticles or proteins simultaneously in real time, which is significant for its potential application in investigation of structural biology and proteomics in the near future.


Asunto(s)
Nanopartículas del Metal/análisis , Nanoporos , Nanopartículas del Metal/química , Simulación de Dinámica Molecular , Compuestos de Silicona/química , Plata/química
18.
J Agric Food Chem ; 68(6): 1536-1545, 2020 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-31961689

RESUMEN

In this work, an electrical-driven release and migration glyphosate (EDRMG) was fabricated using a nanocomposite made up of attapulgite (ATP), glyphosate (Gly), and calcium alginate (CA). Therein, ATP-CA acted as a nanonetwork-structured carrier to efficiently load plenty of Gly to form porous ATP-Gly-CA hydrogel spheres (actually EDRMG-0.5) via a cross-linking reaction. The pores in EDRMG-0.5 hydrogel spheres were enlarged under an electric field because of the Coulomb force of the anionic CA polymer, and the release of negatively charged Gly from the spheres could be driven by the electric field force. Thus, EDRMG-0.5 exhibited a great electroresponsively controlled-release property, which was confirmed by a pot experiment. Importantly, the EDRMG-0.5 hydrogel spheres had fine biocompatibility on fish and mice, displaying good biosafety. This work provides a low cost and promising approach to control Gly release, deliver Gly precisely, and improve utilization efficiency, which might have a high application value.


Asunto(s)
Sistemas de Liberación de Medicamentos/métodos , Glicina/análogos & derivados , Herbicidas/química , Nanogeles/química , Alginatos/química , Animales , Portadores de Fármacos/química , Composición de Medicamentos , Sistemas de Liberación de Medicamentos/economía , Sistemas de Liberación de Medicamentos/instrumentación , Electricidad , Peces , Glicina/química , Hidrogeles/química , Compuestos de Magnesio/química , Ratones , Compuestos de Silicona/química
19.
Geobiology ; 18(2): 225-236, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-31788917

RESUMEN

Bacillus subtilis endospore-mediated forsterite dissolution experiments were performed to assess the effects of cell surface reactivity on Mg isotope fractionation during chemical weathering. Endospores present a unique opportunity to study the isolated impact of cell surface reactivity because they exhibit extremely low metabolic activity. In abiotic control assays, 24 Mg was preferentially released into solution during forsterite dissolution, producing an isotopically light liquid phase (δ26 Mg = -0.39 ± 0.06 to -0.26 ± 0.09‰) relative to the initial mineral composition (δ26 Mg = -0.24 ± 0.03‰). The presence of endospores did not have an apparent effect on Mg isotope fractionation associated with the release of Mg from the solid into the aqueous phase. However, the endospore surfaces preferentially adsorbed 24 Mg from the dissolution products, which resulted in relatively heavy aqueous Mg isotope compositions. These aqueous Mg isotope compositions increased proportional to the fraction of dissolved Mg that was adsorbed, with the highest measured δ26 Mg (-0.08 ± 0.07‰) corresponding to the highest degree of adsorption (~76%). The Mg isotope composition of the adsorbed fraction was correspondingly light, at an average δ26 Mg of -0.49‰. Secondary mineral precipitation and Mg adsorption onto secondary minerals had a minimal effect on Mg isotopes at these experimental conditions. Results demonstrate the isolated effects of cell surface reactivity on Mg isotope fractionation separate from other common biological processes, such as metabolism and organic acid production. With further study, Mg isotopes could be used to elucidate the role of the biosphere on Mg cycling in the environment.


Asunto(s)
Compuestos de Silicona/química , Isótopos , Magnesio , Compuestos de Silicona/clasificación , Solubilidad
20.
Nanotechnology ; 31(11): 115503, 2020 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-31751958

RESUMEN

Microcantilever-based sensor platform has attracted a lot of attention over the time in detection of a variety of molecules due to their miniaturized dimensions. Sensitivity enhancement is an important aspect of such sensors, especially when used for point-of-care diagnostic purpose. However, the major concern while operating these sensors in deflection mode is their sensitivity which mainly relies on selective chemical modification protocols employed on these sensor surfaces. One of the ways of getting better sensitivity is through asymmetric (one side) biofunctionalization of the sensor surface. In the presented work here, we have demonstrated a novel approach of asymmetric biofunctionalization of proteins in overall sensitivity enhancement of piezoresistive silicon nitride-oxide microcantilever sensor platform inside a flow chamber. Herein, using our developed surface chemistry, asymmetrically biofunctionalized microcantilevers first exhibited a greater electrical response in terms of piezoresistance change than their symmetric counterpart in the detection of human immunoglobulins (HIgGs) protein. Finally, these microcantilevers were employed to exhibit the enhanced sensitivity towards the detection of a crucial cardiac marker protein, i.e. Troponin-I (cTnI) down to 250 ng ml-1 using asymmetric biofunctionalization process. This study shows that the developed asymmetric biofunctionalization methodology may be used as a general protocol to detect other important biomarkers of clinical applications with improved sensitivity.


Asunto(s)
Técnicas Biosensibles/métodos , Troponina I/análisis , Anticuerpos Inmovilizados/química , Anticuerpos Inmovilizados/inmunología , Conductividad Eléctrica , Humanos , Límite de Detección , Nanoestructuras/química , Óxidos/química , Compuestos de Silicona/química , Troponina I/inmunología
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