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1.
PLoS One ; 15(8): e0237231, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853250

RESUMO

In this study, we examined the effect of differing gap lengths on regeneration of transected recurrent laryngeal nerves using silicon tubes containing type I collagen gel and the ability of this regeneration to result in restoration of vocal fold movements in rats. We simulated nerve gaps in Sprague-Dawley rats by transecting the left recurrent laryngeal nerves and bridged the nerve stumps using silicon tubes containing type 1 collagen gel. Three experimental groups, in which the gap lengths between the stumps were 1, 3, or 5 mm, were compared with a control group in which the nerve was transected but was not bridged. After surgery, we observed vocal fold movements over time with a laryngoscope. At week 15, we assessed the extent of nerve regeneration in the tube, histologically and electrophysiologically. We also assessed the degree of atrophy of the thyroarytenoid muscle (T/U ratio). Restoration of vocal fold movements was observed in 9 rats in the 1-mm group, in 6 rats in the 3-mm group, and in 3 rats in the 5-mm group. However, in most rats, restoration was temporary, with only one rat demonstrating continued vocal fold movements at week 15. In electromyograph, evoked potentials were observed in rats in the 1-mm and 3-mm groups. Regenerated tissue in the tube was thickest in the 1-mm group, followed by the 3-mm and 5-mm groups. The regenerated tissue showed the presence of myelinated and unmyelinated nerve fibers. In assessment of thyroarytenoid muscle atrophy, the T/U ratio was highest in the 1-mm group, followed by the 3-mm and 5-mm groups. We successfully regenerated the nerves and produced a rat model of recurrent laryngeal nerve regeneration that demonstrated temporary recovery of vocal fold movements. This rat model could be useful for assessing novel treatments developing in the future.


Assuntos
Colágeno/uso terapêutico , Regeneração Nervosa , Traumatismos do Nervo Laríngeo Recorrente/terapia , Nervo Laríngeo Recorrente/fisiopatologia , Animais , Materiais Biocompatíveis/química , Colágeno/administração & dosagem , Modelos Animais de Doenças , Géis/administração & dosagem , Géis/uso terapêutico , Masculino , Regeneração Nervosa/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Nervo Laríngeo Recorrente/fisiologia , Traumatismos do Nervo Laríngeo Recorrente/fisiopatologia , Silício/química
2.
Int J Nanomedicine ; 15: 4171-4189, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32606671

RESUMO

Background: Angiogenic and osteogenic activities are two major problems with biomedical titanium (Ti) and other orthopedic implants used to repair large bone defects. Purpose: The aim of this study is to prepare hydroxyapatite (HA) coatings on the surface of Ti by using electrochemical deposition (ED), and to evaluate the effects of nanotopography and silicon (Si) doping on the angiogenic and osteogenic activities of the coating in vitro. Materials and Methods: HA coating and Si-doped HA (HS) coatings with varying nanotopographies were fabricated using two ED modes, ie, the pulsive current (PC) and cyclic voltammetry (CV) methods. The coatings were characterized through scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectrometer (XPS), and atomic force microscopy (AFM), and their in vitro bioactivity and protein adsorption were assessed. Using MC3T3-E1 pre-osteoblasts and HUVECs as cell models, the osteogenic and angiogenic capabilities of the coatings were evaluated through in vitro cellular experiments. Results: By controlling Si content in ~0.8 wt.%, the coatings resulting from the PC mode (HA-PC and HS-PC) and CV mode (HA-CV and HS-CV) had nanosheet and nanorod topographies, respectively. At lower crystallinity, higher ionic dissolution, smaller contact angle, higher surface roughness, and more negative zeta potential, the HS and PC samples exhibited quicker apatite deposition and higher BSA adsorption capacity. The in vitro cell study showed that Si doping was more favorable for enhancing the viability of the MC3T3-E1 cells, but nanosheet coating increased the area for cell spreading. Of the four coatings, HS-PC with Si doping and nanosheet topography exhibited the best effect in terms of up-regulating the expressions of the osteogenic genes (ALP, Col-I, OSX, OPN and OCN) in the MC3T3-E1 cells. Moreover, all leach liquors of the surface-coated Ti disks promoted the growth of the HUVECs, and the HS samples played a more significant role in promoting cell migration and tube formation than the HA samples. Of the four leach liquors, only the two HS samples up-regulated NO content and expressions of the angiogenesis-related genes (VEGF, bFGF and eNOS) in the HUVECs, and the HS-PC yielded a better effect. Conclusion: The results show that Si doping while regulating the topography of the coating can help enhance the bone regeneration and vascularization of HA-coated Ti implants.


Assuntos
Materiais Revestidos Biocompatíveis/farmacologia , Durapatita/farmacologia , Nanopartículas/química , Osteogênese , Próteses e Implantes , Silício/química , Titânio/farmacologia , Adsorção , Animais , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Humanos , Camundongos , Nanopartículas/ultraestrutura , Nanotubos/química , Neovascularização Fisiológica/efeitos dos fármacos , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Osteogênese/genética , Soroalbumina Bovina/química , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Difração de Raios X
3.
Faraday Discuss ; 222(0): 8-9, 2020 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-32490453

RESUMO

This Faraday Discussion volume is unique in the hundred plus year history of the Faraday Discussion series, being produced at a time of unprecedented circumstances worldwide and without the preceding Faraday Discussion conference having taken place.


Assuntos
Infecções por Coronavirus/diagnóstico , Medições Luminescentes/métodos , Nanoestruturas/química , Pneumonia Viral/diagnóstico , Silício/química , Humanos , Imagem Óptica , Pandemias , Porosidade
4.
Chemosphere ; 257: 127241, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32526468

RESUMO

The role of endogenous hydrogen sulphide (H2S) in silicon-induced improvement in boron toxicity (BT) tolerance in pepper plants was studied. Two-week old seedlings were subjected to control (0.05 mM B) or 2.0 mM BT in a nutrient solution. These two treatments were combined with 2.0 mM Si. BT caused considerable reduction in biomass, chlorophyll a &b, photosystem II maximum quantum efficiency (Fv/Fm), glutathione and ascorbate in the pepper seedlings. However, it enhanced malondialdehyde (MDA) and hydrogen peroxide, electrolyte leakage, proline, H2S, and activities of catalase, superoxide dismutase, peroxidase, and L-DES. Silicon stimulated growth, proline content and activities of various antioxidant biomolecules and enzymes, leaf Ca2+, K+ and N, endogenous H2S and L-DES activity, but reduced H2O2 and MDA contents, membrane leakage and leaf B. Silicon-induced B tolerance was further enhanced by 0.2 mM NaHS, a H2S donor. A scavenger of H2S, hypotaurine (0.1 mM HT), was supplied together with Si and Si + NaHS to assess the involvement of H2S in Si-induced BT tolerance of pepper plants. Hypotaurine inverted the positive role of Si on the antioxidant defence system by reducing endogenous H2S, but NaHS supply along with Si + HT reversed the negative effects of HT, showing that H2S participated in Si-induced BT tolerance of pepper plants.


Assuntos
Boro/toxicidade , Sulfeto de Hidrogênio/química , Poluentes do Solo/toxicidade , Antioxidantes/farmacologia , Ácido Ascórbico/farmacologia , Catalase/metabolismo , Clorofila A , Glutationa/metabolismo , Peróxido de Hidrogênio/farmacologia , Malondialdeído , Estresse Oxidativo/efeitos dos fármacos , Plântula/efeitos dos fármacos , Silício/química , Sulfetos , Superóxido Dismutase/metabolismo
5.
Chemosphere ; 256: 127043, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32445999

RESUMO

Electrolytic manganese residue (EMR) is characterized by high silicon content, and thus, is an important silicon source. While considerable research has been conducted on bioleaching EMR for silicon recovery, sufficient information is not available on the impact of specific silicate mineral structures in EMR on silicon bioleaching. In the present study, the mineral composition of EMR was determined firstly, and then the leaching effect of Paenibacillus mucilaginosus on these different silicate minerals were investigated by shake flask experiments. Results showed that the silicon in EMR was mainly composed of quartz, sericite, muscovite, biotite, olivine and rhodonite; Paenibacillus mucilaginosus had a significantly different weathering and decomposition effects on different silicate minerals. Among them, sericite, muscovite and biotite with layered structure had the most obvious silicon leaching effect, followed by rhodonite with island structure, while silicon leaching from olivine with chained structure and quartz with frame structure was much more difficult. One can roughly judge the adaptability of bioleaching of silicon in EMR using Paenibacillus mucilaginosus if the main form of silicate minerals in EMR is determined.


Assuntos
Manganês/metabolismo , Paenibacillus/metabolismo , Silício/química , Silicatos de Alumínio , Eletrólitos , Compostos Ferrosos , Íons , Compostos de Ferro , Compostos de Magnésio , Minerais , Silicatos/química , Dióxido de Silício
6.
Proc Natl Acad Sci U S A ; 117(23): 12598-12605, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32457154

RESUMO

The mechano-bactericidal activity of nanostructured surfaces has become the focus of intensive research toward the development of a new generation of antibacterial surfaces, particularly in the current era of emerging antibiotic resistance. This work demonstrates the effects of an incremental increase of nanopillar height on nanostructure-induced bacterial cell death. We propose that the mechanical lysis of bacterial cells can be influenced by the degree of elasticity and clustering of highly ordered silicon nanopillar arrays. Herein, silicon nanopillar arrays with diameter 35 nm, periodicity 90 nm and increasing heights of 220, 360, and 420 nm were fabricated using deep UV immersion lithography. Nanoarrays of 360-nm-height pillars exhibited the highest degree of bactericidal activity toward both Gram stain-negative Pseudomonas aeruginosa and Gram stain-positive Staphylococcus aureus bacteria, inducing 95 ± 5% and 83 ± 12% cell death, respectively. At heights of 360 nm, increased nanopillar elasticity contributes to the onset of pillar deformation in response to bacterial adhesion to the surface. Theoretical analyses of pillar elasticity confirm that deflection, deformation force, and mechanical energies are more significant for the substrata possessing more flexible pillars. Increased storage and release of mechanical energy may explain the enhanced bactericidal action of these nanopillar arrays toward bacterial cells contacting the surface; however, with further increase of nanopillar height (420 nm), the forces (and tensions) can be partially compensated by irreversible interpillar adhesion that reduces their bactericidal effect. These findings can be used to inform the design of next-generation mechano-responsive surfaces with tuneable bactericidal characteristics for antimicrobial surface technologies.


Assuntos
Antibacterianos/farmacologia , Nanoestruturas/química , Estresse Mecânico , Antibacterianos/química , Aderência Bacteriana , Elasticidade , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/fisiologia , Silício/química , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/fisiologia
7.
J Chromatogr A ; 1623: 461065, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32448558

RESUMO

We report the preparation of high performance, sputtered, polydimethylsiloxane (PDMS)-coated solid phase microextraction (SPME) fibers that show negligible carry-over and phase bleed. This process involves sputtering silicon onto silica fibers and functionalizing the resulting porous nanostructures with ultrathin films of vapor-deposited PDMS. Different thicknesses of silicon (0.25, 0.8, and 1.8 µm) and PDMS (8, 16, and 36 nm) were produced and their extraction efficiencies evaluated. The deposition of PDMS was confirmed by time-of-fight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), and contact angle goniometry on model, planar silicon substrates. These fibers were investigated using direct immersion SPME coupled with gas chromatography-mass spectrometry (GC-MS) analysis of a series of polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic pollutants. The 1.8 µm thick silicon coating with 16 nm of PDMS (Si (1.8 µm)/PDMS (16 nm)) produced the best response among the combinations tested. Conditions for the extraction of PAHs with this fiber were optimized and its extraction performance was compared to that of a commercial 7 µm PDMS fiber. The linearity (1-110 µgL-1), repeatability (RSD%, n = 3) (17% ave.), and minimum detection limits (0.6-1.5 µgL-1) of the sputtered fibers were determined and found to be superior to the commercial 7 µm PDMS fiber in many respects. Carry-over and phase bleed from commercial PDMS-based SPME fibers are two of their major drawbacks, which decrease their lifetimes and usefulness. Minimal carry-over and phase bleed were observed for our sputtered PDMS-coated fibers. In particular, our fiber only shows 12% of the phase bleed of the comparable commercial fiber. In addition, it shows no carry-over for analytes with retention times greater than pyrene, and only 5% of the carry-over of the other analytes. Our fibers could be used for at least 300 injections without any significant loss of performance.


Assuntos
Dimetilpolisiloxanos/química , Silício/química , Microextração em Fase Sólida/métodos , Cromatografia Gasosa-Espectrometria de Massas , Limite de Detecção , Espectroscopia Fotoeletrônica , Hidrocarbonetos Policíclicos Aromáticos/análise , Temperatura , Fatores de Tempo , Água/química , Poluentes Químicos da Água/análise
8.
J Vis Exp ; (159)2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32421002

RESUMO

Because of their unique properties, including an ultrathin thickness (3-4 nm), ultrahigh resistivity, fluidity and self-assembly ability, lipid bilayers can be readily functionalized and have been used in various applications such as bio-sensors and bio-devices. In this study, we introduced a planar organic molecule: copper (II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (CuPc) to dope lipid membranes. The CuPc/lipid hybrid membrane forms at the water/air interface by self-assembly. In this membrane, the hydrophobic CuPc molecules are located between the hydrophobic tails of lipid molecules, forming a lipid/CuPc/lipid sandwich structure. Interestingly, an air-stable hybrid lipid bilayer can be readily formed by transferring the hybrid membrane onto a Si substrate. We report a straightforward method for incorporating nanomaterials into a lipid bilayer system, which represents a new methodology for the fabrication of biosensors and biodevices.


Assuntos
Ar , Interações Hidrofóbicas e Hidrofílicas , Bicamadas Lipídicas/química , Compostos Orgânicos/química , Água/química , Cobre/química , Indóis/química , Silício/química , Espectrometria por Raios X
9.
PLoS One ; 15(4): e0230954, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32267854

RESUMO

Alternative management practices are needed to minimize the need for chemical fertilizer use in non-leguminous cropping systems. The use of biological agents that can fix atmospheric N has shown potential to improve nutrient availability in grass crops. This research was developed to investigate if inoculation with Azospirillum brasilense in combination with silicon (Si) can enhance N use efficiency (NUE) in maize. The study was set up in a Rhodic Hapludox under a no-till system, in a completely randomized block design with four replicates. Treatments were tested in a full factorial design and included: i) five side dress N rates (0 to 200 kg ha-1); ii) two liming sources (Ca and Mg silicate and dolomitic limestone); and iii) with and without seed inoculation with A. brasilense. Inoculation with A. brasilense was found to increase grain yield by 15% when N was omitted and up to 10% when N was applied. Inoculation also increased N accumulation in plant tissue. Inoculation and limestone application were found to increase leaf chlorophyll index, number of grains per ear, harvest index, and NUE. Inoculation increased harvest index and NUE by 9.5 and 19.3%, respectively, compared with non-inoculated plots. Silicon application increased leaf chlorophyll index and N-leaf concentration. The combination of Si and inoculation provided greater Si-shoot accumulation. This study showed positive improvements in maize growth production parameters as a result of inoculation, but the potential benefits of Si use were less evident. Further research should be conducted under growing conditions that provide some level of biotic or abiotic stress to study the true potential of Si application.


Assuntos
Azospirillum brasilense/fisiologia , Nitrogênio/química , Silício/química , Solo/química , Zea mays/crescimento & desenvolvimento , Produtos Agrícolas/química , Fertilizantes , Folhas de Planta/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Estresse Fisiológico/fisiologia
10.
Food Chem ; 324: 126893, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32344336

RESUMO

An Au patch electrode Ag-SnO2/SiO2/Si MIS capacitive sensor equipped with a microcontroller was designed and developed to sense low concentration (ppb to ppm regime) of volatiles (NH3, TMA, ethanol, and H2S) generated from chicken meat spoilage at room temperature. The quality threshold or the acceptance limit for consumption of chicken meat samples stored at 4 °C, 15 °C and 25 °C using our proposed technique was found to be 105 h, 48 h, and 17 h respectively, highly correlated with TVB-N, TVC, pH and sensory evaluation analysis. When these well established standard methods (TVB-N, TVC and pH analysis) take many hours to complete the analysis involving many complicated steps, our fabricated sensor takes 55 sec to deliver sensing response reflecting the meat spoilage status. The sensor calibrated with our compact technique promises portable and inexpensive onsite rapid and accurate quality assessment of meat spoilage at room temperature.


Assuntos
Gases/análise , Ouro/química , Carne/análise , Semicondutores , Amônia/análise , Animais , Galinhas , Eletrodos , Qualidade dos Alimentos , Sulfeto de Hidrogênio/análise , Concentração de Íons de Hidrogênio , Silício/química , Dióxido de Silício/química , Prata/química , Temperatura , Compostos de Estanho/química
11.
Proc Natl Acad Sci U S A ; 117(17): 9173-9179, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32303653

RESUMO

We present a platform for parallel production of standalone, untethered electronic sensors that are truly microscopic, i.e., smaller than the resolution of the naked eye. This platform heterogeneously integrates silicon electronics and inorganic microlight emitting diodes (LEDs) into a 100-µm-scale package that is powered by and communicates with light. The devices are fabricated, packaged, and released in parallel using photolithographic techniques, resulting in ∼10,000 individual sensors per square inch. To illustrate their use, we show proof-of-concept measurements recording voltage, temperature, pressure, and conductivity in a variety of environments.


Assuntos
Eletrônica/instrumentação , Desenho de Equipamento/métodos , Condutividade Elétrica , Fontes de Energia Elétrica , Dispositivos Ópticos/tendências , Silício/química
12.
Chemosphere ; 251: 126347, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32169700

RESUMO

Currently, exploring effective measures to reduce multiple toxic metals accumulation in rice grains is an urgent issue to be tackled. Pot experiments were thus conducted to explore the effects and mechanisms of foliar spraying with composite sols of silicon (Si) and selenium (Se) during tillering to booting stage on diminishing cadmium (Cd) and lead (Pb) translocation to rice grains and affiliated physiological and biochemical responses in rice seedlings grown in Cd + Pb-polluted soils (positive control). Results showed that Cd and Pb contents in leaves or grains were distinctly below the positive control by the sols. Compared to the positive control, transcriptions of Cd transporter-related genes including OsLCT1, OsCCX2, OsHMA2 and OsPCR1 genes in leaves, and OsLCT1, OsCCX2, TaCNR2 and OSPCR1 in peduncles were downregulated by the increasing sols. Meanwhile, Se-binding protein 1 was evidently upregulated, together to retard Cd and Pb translocation to rice grains. The sols not only upregulated transcriptions of Lhcb1, RbcL, and OsBTF3 genes and production of psbA, Lhcb1 and RbcL proteins, but also increased the chlorophylls contents and RuBP carboxylase activities in the leaves, improving photosynthesis. The sols restrained ROS production from NADPH oxidases, but activated glutathione peroxidase, alleviating oxidative stress and damage. Additionally, Se was significantly enriched and was existed as selenomethionine in the rice grains. However, Pb transporter-related genes remain to be specified. Thus, the composite sols have potential to reduce Cd and Pb accumulation, mitigate oxidative damage, and promote photosynthesis and organic Se enrichment in rice plants under Cd and Pb combined pollution.


Assuntos
Cádmio/toxicidade , Chumbo/toxicidade , Oryza/fisiologia , Poluentes do Solo/toxicidade , Antioxidantes/metabolismo , Cádmio/análise , Clorofila/metabolismo , Poluição Ambiental , Chumbo/análise , Oryza/química , Estresse Oxidativo/efeitos dos fármacos , Fotossíntese , Folhas de Planta/metabolismo , Plântula/efeitos dos fármacos , Selênio/química , Selênio/metabolismo , Silício/química , Silício/metabolismo , Solo/química , Poluentes do Solo/análise
13.
Nature ; 579(7798): 205-209, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32161384

RESUMO

Nuclear spins are highly coherent quantum objects. In large ensembles, their control and detection via magnetic resonance is widely exploited, for example, in chemistry, medicine, materials science and mining. Nuclear spins also featured in early proposals for solid-state quantum computers1 and demonstrations of quantum search2 and factoring3 algorithms. Scaling up such concepts requires controlling individual nuclei, which can be detected when coupled to an electron4-6. However, the need to address the nuclei via oscillating magnetic fields complicates their integration in multi-spin nanoscale devices, because the field cannot be localized or screened. Control via electric fields would resolve this problem, but previous methods7-9 relied on transducing electric signals into magnetic fields via the electron-nuclear hyperfine interaction, which severely affects nuclear coherence. Here we demonstrate the coherent quantum control of a single 123Sb (spin-7/2) nucleus using localized electric fields produced within a silicon nanoelectronic device. The method exploits an idea proposed in 196110 but not previously realized experimentally with a single nucleus. Our results are quantitatively supported by a microscopic theoretical model that reveals how the purely electrical modulation of the nuclear electric quadrupole interaction results in coherent nuclear spin transitions that are uniquely addressable owing to lattice strain. The spin dephasing time, 0.1 seconds, is orders of magnitude longer than those obtained by methods that require a coupled electron spin to achieve electrical driving. These results show that high-spin quadrupolar nuclei could be deployed as chaotic models, strain sensors and hybrid spin-mechanical quantum systems using all-electrical controls. Integrating electrically controllable nuclei with quantum dots11,12 could pave the way to scalable, nuclear- and electron-spin-based quantum computers in silicon that operate without the need for oscillating magnetic fields.


Assuntos
Modelos Teóricos , Silício/química , Fenômenos Eletromagnéticos , Elétrons , Pontos Quânticos/química
14.
J Vis Exp ; (157)2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-32176215

RESUMO

Desalination through direct contact membrane distillation (DCMD) exploits water-repellent membranes to robustly separate counterflowing streams of hot and salty seawater from cold and pure water, thus allowing only pure water vapor to pass through. To achieve this feat, commercial DCMD membranes are derived from or coated with water-repellent perfluorocarbons such as polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF). However, the use of perfluorocarbons is limiting due to their high cost, non-biodegradability, and vulnerability to harsh operational conditions. Unveiled here is a new class of membranes referred to as gas-entrapping membranes (GEMs) that can robustly entrap air upon immersion in water. GEMs achieve this function by their microstructure rather than their chemical make-up. This work demonstrates a proof-of-concept for GEMs using intrinsically wetting SiO2/Si/SiO2 wafers as the model system; the contact angle of water on SiO2 is θo ≈ 40°. Silica-GEMs had 300 µm-long cylindrical pores whose diameters at the (2 µm-long) inlet and outlet regions were significantly smaller; this geometrically discontinuous structure, with 90° turns at the inlets and outlets, is known as the "reentrant microtexture". The microfabrication protocol for silica-GEMs entails designing, photolithography, chrome sputtering, and isotropic and anisotropic etching. Despite the water loving nature of silica, water does not intrude silica-GEMs on submersion. In fact, they robustly entrap air underwater and keep it intact even after six weeks (>106 seconds). On the other hand, silica membranes with simple cylindrical pores spontaneously imbibe water (< 1 s). These findings highlight the potential of the GEMs architecture for separation processes. While the choice of SiO2/Si/SiO2 wafers for GEMs is limited to demonstrating the proof-of-concept, it is expected that the protocols and concepts presented here will advance the rational design of scalable GEMs using inexpensive common materials for desalination and beyond.


Assuntos
Gases/química , Membranas Artificiais , Dióxido de Silício/química , Silício/química , Purificação da Água , Água/química , Ar , Destilação , Porosidade , Impressão , Água do Mar , Silanos/química
15.
J Chromatogr A ; 1618: 460938, 2020 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-32081486

RESUMO

This work presents and evaluates an algorithmic approach to deconvolving the elution profiles of chemical components of vapor mixtures that have been sampled and desorbed from a novel preconcentrator based on highly ordered silicon nanowire arrays. The arrays provide a medium for both preconcentration and partial chromatographic resolution, which is then further leveraged with multichannel detection. Here, mixtures of nitro aromatic vapors are sampled and then thermally desorbed from the device, at which point they are detected by a conventional mass selective detector. The overlapping elution profiles observed from the array are sequentially extracted using a chemometric analysis approach based on evolving factor analysis and multivariate curve resolution by alternating least squares, enabling qualitative and quantitative analysis of individual components without target analyte libraries or complete chromatographic separation. This work examines the analytical capabilities conferred to multichannel detection by silicon nanowire array pre-concentration and partial separation and discusses the technique's limitations, illustrated by both experimental and simulated data.


Assuntos
Cromatografia , Nanofios , Silício/química , Algoritmos , Gases/química , Análise dos Mínimos Quadrados , Espectrometria de Massas , Temperatura
16.
J Vis Exp ; (155)2020 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-32009634

RESUMO

With advances in electronics and fabrication technology, intracortical microelectrodes have undergone substantial improvements enabling the production of sophisticated microelectrodes with greater resolution and expanded capabilities. The progress in fabrication technology has supported the development of biomimetic electrodes, which aim to seamlessly integrate into the brain parenchyma, reduce the neuroinflammatory response observed after electrode insertion and improve the quality and longevity of electrophysiological recordings. Here we describe a protocol to employ a biomimetic approach recently classified as nano-architecture. The use of focused ion beam lithography (FIB) was utilized in this protocol to etch specific nano-architecture features into the surface of non-functional and functional single shank intracortical microelectrodes. Etching nano-architectures into the electrode surface indicated possible improvements of biocompatibility and functionality of the implanted device. One of the benefits of using FIB is the ability to etch on manufactured devices, as opposed to during the fabrication of the device, facilitating boundless possibilities to modify numerous medical devices post-manufacturing. The protocol presented herein can be optimized for various material types, nano-architecture features, and types of devices. Augmenting the surface of implanted medical devices can improve the device performance and integration into the tissue.


Assuntos
Nanopartículas/química , Impressão , Animais , Automação , Biomarcadores/metabolismo , Encéfalo/patologia , Contagem de Células , Eletrodos Implantados , Fenômenos Eletrofisiológicos , Inflamação/patologia , Íons , Microeletrodos , Neurônios/patologia , Ratos , Silício/química
17.
Molecules ; 25(2)2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31936773

RESUMO

Unique eleven-membered rings containing silicon, germanium, and tin were synthesized in good yields by the reactions of the corresponding 1,2-bis((2-bromothiophen-3-yl)methoxy)benzenes with (C6H5)2ECl2 where E = Sn, Ge, Si. The Sn and Ge congeners were crystallized, but the conformers that these rings crystallized in, were quite different. As confirmed by Density Functional Theory (DFT) calculations, (C28H22O2S2Sn) assumes a unique crystal structure that leaves more room around the tetrel atom as compared to the crystal structure of the corresponding Ge compound. In the latter, the central cavity is quite open, whereas in the former, one of the methylene groups can fold inwards. Another consequence is the influence on the planes of the aromatic rings flanking the heterocycle. In the Ge case, the benzene ring is folded away from the central cavity, whereas in the Sn case, it is almost parallel to the imaginary axis through the center of the ring. Thermal analysis investigations (TGA and DSC methods) of these eleven-membered rings suggested the loss of a phenyl group in the first decomposition step. The decomposition temperature decreased from the Si containing heterocycle to Ge and was lowest for the Sn containing heterocycle.


Assuntos
Germânio/química , Compostos Heterocíclicos/química , Compostos Heterocíclicos/síntese química , Modelos Moleculares , Silício/química , Estanho/química , Cristalografia por Raios X
18.
Chem Commun (Camb) ; 56(16): 2455-2458, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31996872

RESUMO

A group of asymmetric Si-rhodamine scaffolds was designed for protease-activated NIR probes. Dual pH-inertia for both spirocyclized fluorescent probes and fluorescent products of zwitterions form over a wide range of pH (4.0-11.0). Leucine aminopeptidase (LAP) and γ-glutamyl transpeptidase (GGT) were monitored by fluorescent imaging in vivo.


Assuntos
Corantes Fluorescentes/química , Imagem Óptica , Peptídeo Hidrolases/análise , Rodaminas/química , Silício/química , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/metabolismo , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Raios Infravermelhos , Estrutura Molecular , Peptídeo Hidrolases/metabolismo , Rodaminas/metabolismo , Silício/metabolismo , Espectrometria de Fluorescência
19.
Talanta ; 209: 120552, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31892096

RESUMO

Currently, the nanocomposites based on silicon nanoparticles (SiNPs) are usually limited to a single therapeutic modality, and the design of the SiNPs nanohybrids with multi-modal synergistic therapeutic functions is still worth being explored to achieve more effective treatment. Herein, we used mesoporous silica nanoparticle (MSN) as a nanoplatform, SiNPs and the photosensitizer 5,10,15,20-tetrakis (1-methyl 4-pyridinio) porphyrin tetra (p-toluenesulfonate) (TMPyP) were first embedded in the MSN and was further modified with folic acid (FA) to obtain the mesoporous silica nanocomposite (MSN@SiNPs@TMPyP-FA) for targeted two-photon-excited fluorescence imaging-guided photodynamic therapy (PDT) and chemotherapy. The embedded TMPyP could generate singlet oxygen to perform PDT under light irradiation, meanwhile the anticancer drugs doxorubicin (DOX) could be loaded for chemotherapy. Moreover, due to the two-photon excited fluorescence of SiNPs, the nanocomposite successfully achieved targeted two-photon fluorescence cellular imaging at the near-infrared (NIR) laser excitation, which could effectively avoid the interference of biological auto-fluorescence. And in vitro cytotoxicity assays revealed that the synergistic therapy combining PDT and chemotherapy exhibited high therapeutic efficacy for cancer cells.


Assuntos
Antineoplásicos/administração & dosagem , Doxorrubicina/administração & dosagem , Neoplasias/tratamento farmacológico , Fármacos Fotossensibilizantes/administração & dosagem , Porfirinas/administração & dosagem , Dióxido de Silício/química , Células A549 , Antineoplásicos/farmacologia , Doxorrubicina/farmacologia , Sistemas de Liberação de Medicamentos , Humanos , Células MCF-7 , Nanopartículas/química , Neoplasias/diagnóstico por imagem , Imagem Óptica , Fotoquimioterapia , Fármacos Fotossensibilizantes/farmacologia , Porfirinas/farmacologia , Silício/química , Nanomedicina Teranóstica
20.
Talanta ; 210: 120636, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31987169

RESUMO

Cobalt ions (Co2+) are among heavy metals ions which cause pollution in environment because of their toxicity and improper degradation. In this work, a new fluorescent approach based on silicon nanoparticles (Si NPs) was designed for Co2+ detection. The fluorescent Si NPs were prepared by mixing 3-aminopropyl trimethoxysilane (APTES) and basic fuchsin, and under the excitation of 400 nm, they emitted green fluorescence at 515 nm. The prepared Si NPs were highly soluble in water, stable to salt and pH, and their fluorescence emission was extremely constant, with the quantum yield of 2.28%. The detailed mechanism studies showed that Co2+ effectively quenched the fluorescence of Si NPs by forming static complex. After optimizing the reaction parameters, a good linear relationship for Co2+ was observed from 0.2 to 60 µM, and the limit of detection was 0.14 µM that is lower than the guideline announced by Department of Environmental Protection for drinking water (1.7 µM). The preparation method of Si NPs was cheap, rapid and simple, and the fluorescent approach was applied to determine Co2+ in Yellow river water, drinking water, and industrial wastewater. Moreover, the Si NPs has good response to exogenous Co2+ in HepG2 cell imaging.


Assuntos
Cobalto/análise , Fluorescência , Nanopartículas/química , Imagem Óptica , Silício/química , Poluentes Químicos da Água/análise , Células Hep G2 , Humanos , Estrutura Molecular
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