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1.
Molecules ; 26(5)2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33804444

RESUMO

Co-continuous blend systems of polycarbonate (PC), poly(styrene-co-acrylonitrile) (SAN), commercial non-functionalized multi-walled carbon nanotubes (MWCNTs) or various types of commercial and laboratory functionalized single-walled carbon nanotubes (SWCNTs), and a reactive component (RC, N-phenylmaleimide styrene maleic anhydride copolymer) were melt compounded in one step in a microcompounder. The blend system is immiscible, while the RC is miscible with SAN and contains maleic anhydride groups that have the potential to reactively couple with functional groups on the surface of the nanotubes. The influence of the RC on the localization of MWCNTs and SWCNTs (0.5 wt.%) was investigated by transmission electron microscopy (TEM) and energy-filtered TEM. In PC/SAN blends without RC, MWCNTs are localized in the PC component. In contrast, in PC/SAN-RC, the MWCNTs localize in the SAN-RC component, depending on the RC concentration. By adjusting the MWCNT/RC ratio, the localization of the MWCNTs can be tuned. The SWCNTs behave differently compared to the MWCNTs in PC/SAN-RC blends and their localization occurs either only in the PC or in both blend components, depending on the type of the SWCNTs. CNT defect concentration and surface functionalities seem to be responsible for the localization differences.


Assuntos
Resinas Acrílicas/química , Materiais Biocompatíveis/química , Nanotubos de Carbono/química , Cimento de Policarboxilato/química , Polímeros/química , Poliestirenos/química , Propriedades de Superfície
2.
Food Chem ; 354: 129578, 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-33756331

RESUMO

A microfluidic colorimetric biosensor was developed using thiolated polystyrene microspheres (SH-PSs) for aggregating of gold nanoparticles (AuNPs), a novel hose-based microvalve for controlling the flow direction, and a smartphone imaging APP for monitoring colorimetric signals. Aptamer-PS-cysteamine conjugates were used as detection probes and reacted with Salmonella in samples. Complementary DNA - magnetic nanoparticle (cDNA - MNP) conjugates were used as capture probes, reacted with the free aptamer-PS-cysteamine conjugates. AuNPs were aggregated on the surface of Salmonella-aptamer-PS-cysteamine conjugates, resulting in a visible color change in the detection chamber, which indicating different concentrations of Salmonella. The limit of detection was low to 6.0 × 101 cfu/mL. The microfluidic biosensor exhibited a good specificity. It was evaluated by analyzing salad samples spiked with Salmonella. The recoveries ranged from 91.68% to 113.76%, which indicated its potential application in real samples.


Assuntos
Técnicas Biossensoriais/instrumentação , Colorimetria/instrumentação , Dispositivos Lab-On-A-Chip , Poliestirenos/química , Salmonella/isolamento & purificação , Smartphone , Verduras/microbiologia , Ouro/química , Limite de Detecção , Nanopartículas Metálicas , Microesferas
3.
J Chromatogr A ; 1642: 462010, 2021 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-33652368

RESUMO

Evaluation of the chromatographic properties of covalently bonded hyperbranched stationary phase based on poly(styrene-divinylbenzene) (PS-DVB) and containing zwitterionic fragments in the structure of functional layer was conducted in suppressed ion chromatography (IC), reversed phase high performance liquid chromatography (RP HPLC), and hydrophilic interaction liquid chromatography (HILIC) modes. Besides the possibility of resolving 20 inorganic anions and organic acids using KOH eluent in suppressed IC, prepared resin provided the separation of alkylbenzenes in RP HPLC, water-soluble vitamins, amino acids, and sugars in HILIC mode. Trends in the retention of hydrophobic and polar analytes on the prepared stationary phase indicated the dominating effect of analyte nature on the retention mechanism and proved satisfactory hydrophilization of PS-DVB surface with hyperbranched functional layer for retaining polar compounds. The obtained results revealed good prospects of using hydrophobic PS-DVB substrate for preparing stationary phases for mixed-mode chromatography.


Assuntos
Cromatografia/métodos , Poliestirenos/química , Aminoácidos/isolamento & purificação , Cromatografia de Fase Reversa , Interações Hidrofóbicas e Hidrofílicas , Açúcares/isolamento & purificação , Vitaminas/isolamento & purificação
4.
J Chromatogr A ; 1642: 462000, 2021 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-33684874

RESUMO

The anti-citrillinated protein antibody (ACPA) plays an important role in early diagnosis of rheumatoid arthritis (RA), and is usually detected by using cyclic citrullinated peptide (CCP) as antigen. The ACPA against CCP test is usually performed utilizing enzyme-linked immunosorbent assay (ELISA), but the ELISA is expensive and time-consuming. Here, latex particle-enhanced turbidimetric immunoassay (LTIA) based on CCP-immobilized latex bead was proposed for fast measurements of ACPA of RA patients. CCP-immobilized latex bead was fabricated through three methods, including direct coupling, overall coupling and layer by layer coupling. According to the optimized experiments, layer-by-layer coupling was the best method with advantages of time-saving, simple operation and good repeatability. In addition, a spacer arm of appropriate length between latex beads and CCP could avoid stereoscopic obstacles and make ACPA closer to CCP. The CCP-immobilized latex bead based on layer by layer coupling (CCP-LB-LLC) was used for assembling the homemade kit, which was applied in fast measurements of ACPA through LTIA. The homemade kit possessed a low limit of detection (0.2 U/mL) and an acceptable the batch-to-batch reproducibility. In addition, the homemade kit can be stored at 4 °C for at least one month. When used to detect 20 clinical samples, the results of homemade kit were consistent with commercial ELISA. Furthermore, LTIA based on the homemade kit was simpler and cheaper than ELISA. These results demonstrated that the homemade kit could be useful for diagnosis of RA patients.


Assuntos
Autoanticorpos/análise , Citrulinação/imunologia , Imunoturbidimetria/métodos , Látex/química , Microesferas , Peptídeos Cíclicos/química , Animais , Artrite Reumatoide/diagnóstico , Artrite Reumatoide/imunologia , Autoanticorpos/imunologia , Bovinos , Humanos , Nefelometria e Turbidimetria , Tamanho da Partícula , Polissorbatos/química , Poliestirenos/química , Reprodutibilidade dos Testes , Soroalbumina Bovina/química , Eletricidade Estática , Fatores de Tempo
5.
Ecotoxicol Environ Saf ; 214: 112115, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33691242

RESUMO

Nanoplastics (NPs) are becoming an emerging pollutant of global concern. A potential risk of NPs is that they can serve as carriers and synergistically function with other contaminants to cause diseases. A variety of diseases such as Alzheimer's disease are related to the generation of amyloid fibrils, and insulin is typically used as a model to study the fibrillation process. In this study, we examined the fibrillation of insulin promoted by polystyrene nanoplastics (PSNPs) alone and synergistically with organic contaminants (denoted as X, X = pyrene, bisphenol A, 2,2',4,4'-tetrabromodiphenyl ether, 4,4'-dihydroxydiphenylmethane, or 4-nonylphenol) having different polarities using thioflavin T fluorescence assays, dynamic light scattering, and circular dichroism spectroscopy. The presence of PSNPs and small organic contaminants decreased the lag phase time (tlag) for insulin fibrillation from 54.6 h to 35-51 h and their combination (PS-X) enhanced this process (tlag = 21-30 h). Notably, the lag phase time for insulin fibrillation with PS-nonpolar contaminants, PS-weakly polar contaminants, and PS-polar contaminants is around 20.8, 26.7, and 30.1 h, respectively, indicating the synergistic effect of PS-nonpolar contaminants or PS-weakly polar contaminants was more obvious than that of PS-polar contaminants. Moreover, molecular dynamic simulation reveal the interactions between insulin and PSs or small organic contaminants are primarily driven by van der Waals forces and hydrophobic interactions. Overall, the findings of this study underscore the potentially significant environmental impact of small organic contaminants assisting NPs in promoting insulin fibrillation.


Assuntos
Poluentes Ambientais/química , Insulina/química , Microplásticos/química , Nanopartículas/química , Poliestirenos/química , Compostos Benzidrílicos/química , Éteres Difenil Halogenados/química , Fenóis/química , Pirenos/química
6.
Carbohydr Polym ; 260: 117818, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712162

RESUMO

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a conducting polymer frequently used with cellulose, to develop advanced electronic materials. To understand the fundamental interactions between cellulose and PEDOT:PSS, a quartz crystal microbalance with dissipation (QCM-D) was used to study the adsorption of PEDOT:PSS onto model films of cellulose-nanofibrils (CNFs) and regenerated cellulose. The results show that PEDOT:PSS adsorbs spontaneously onto anionically charged cellulose wherein the adsorbed amount can be tuned by altering solution parameters such as pH, ionic strength and counterion to the charges on the CNF. Temperature-dependent QCM-D studies indicate that an entropy gain is the driving force for adsorption, as the adsorbed amount of PEDOT:PSS increased with increasing temperature. Colloidal probe AFM, in accordance with QCM-D results, also showed an increased adhesion between cellulose and PEDOT:PSS at low pH. AFM images show bead-like PEDOT:PSS particles on CNF surfaces, while no such organization was observed on the regenerated cellulose surfaces. This work provides insight into the interaction of PEDOT:PSS/cellulose that will aid in the design of sustainable electronic devices.


Assuntos
Celulose/química , Poliestirenos/química , Tiofenos/química , Adsorção , Concentração de Íons de Hidrogênio , Microscopia de Força Atômica , Nanofibras/química , Concentração Osmolar , Técnicas de Microbalança de Cristal de Quartzo , Propriedades de Superfície , Temperatura
7.
ACS Appl Mater Interfaces ; 13(6): 7021-7036, 2021 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-33539069

RESUMO

Implants can induce a foreign body reaction that leads to chronic inflammation and fibrosis in the surrounding tissue. Macrophages help detect the foreign material, play a role in the inflammatory response, and may promote fibrosis instead of the desired tissue regeneration around implants. Implant surface properties impact macrophage responses by changing the nature of the adsorbed protein layer, but conflicting studies highlight the complexity of this relationship. In this study, the effect of surface chemistry on macrophage behavior was investigated with poly(styrene) surfaces containing common functional groups at similar surface densities. The protein layer was characterized to identify the proteins that adsorbed on the surfaces from the medium and the proteins secreted onto the surfaces by adherent macrophages. Of the surface chemistries studied, carboxylic acid (COOH) groups promoted anti-inflammatory responses from unstimulated macrophages and did not exacerbate inflammation upon stimulation. These surfaces also enhanced the adsorption of proteins involved in integrin signaling and promoted the secretion of proteins related to angiogenesis, integrin signaling, and cytokine signaling, which have been previously associated with improved biomaterial integration. Therefore, this study suggests that surface modification with COOH groups may help improve the integration of implants in the body by enhancing anti-inflammatory macrophage responses through altered protein adsorption.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Ácidos Carboxílicos/farmacologia , Citocinas/química , Macrófagos/efeitos dos fármacos , Adsorção , Animais , Anti-Inflamatórios não Esteroides/química , Ácidos Carboxílicos/química , Bovinos , Células Cultivadas , Citocinas/genética , Humanos , Tamanho da Partícula , Poliestirenos/síntese química , Poliestirenos/química , Poliestirenos/farmacologia , Proteômica , Propriedades de Superfície , Células THP-1
8.
J Chromatogr A ; 1640: 461941, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33556685

RESUMO

The steadily rising interest in the investigation of interactions between nanomaterials and biological media has also led to an increasing interest in asymmetrical flow field-flow fractionation (AF-FFF). The biggest strength of AF-FFF is the possibility to alter the flow profiles to suit a specific separation problem. In this paper, the influence of an oscillating main flow on the separation efficiency of AF-FFF is investigated. Such oscillations can e.g. be caused by the main pump To investigate the influence of such flow conditions on the separation efficiency in AF-FFF systematically, different oscillation profiles were applied and their influence on the elution profile and the retention times was observed. It could be shown, that the separation mechanism is extremely robust and a fractionation is still possible even under unfavorable conditions.


Assuntos
Fracionamento por Campo e Fluxo/métodos , Reologia , Análise de Fourier , Poliestirenos/química , Padrões de Referência , Fatores de Tempo
9.
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
10.
Methods Mol Biol ; 2273: 279-296, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33604861

RESUMO

In vitro epithelial models are valuable tools for both academic and industrial laboratories to investigate tissue physiology and disease. Epithelial tissues comprise the surface epithelium, basement membrane, and underlying supporting stromal cells. There are various types of epithelial tissue and they have a diverse and intricate architecture in vivo, which cannot be successfully recapitulated using two-dimensional (2D) cell culture. Tissue engineering strategies can be applied to bioengineer the organized, multilayered, and multicellular structure of epithelial tissues in vitro. Alvetex® is a porous, polystyrene scaffold that enables fibroblasts to synthesize a complex network of endogenous, humanized extracellular matrix proteins. This creates a physiologically relevant three-dimensional (3D) subepithelial microenvironment, enriched with mechanical and chemical cues, which supports the organization and differentiation of epithelial cells. Such technology has been used to bioengineer different epithelial architectures in vitro, including the simple, columnar structure of the intestine and the stratified, squamous, and keratinized structure of skin. Epithelial tissue models provide a useful platform for fundamental and translational research, with multifaceted applications including disease modeling, drug discovery, and product development.


Assuntos
Células Epiteliais/citologia , Poliestirenos/química , Engenharia Tecidual/métodos , Tecidos Suporte/química , Células CACO-2 , Linhagem Celular , Fibroblastos/citologia , Humanos , Queratinócitos/citologia , Porosidade , Pele/citologia
11.
Ecotoxicol Environ Saf ; 212: 112018, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33550076

RESUMO

The underlying mechanisms of microRNAs (miRNAs) in regulating nanoplastic toxicity are still largely unclear in organisms. In nanopolystyrene (NPS) exposed Caenorhabditis elegans, the expression of mir-76 (a neuronal miRNA) was significantly decreased, and the mir-76 mutant was resistant to the toxicity of NPS. The aim of this study was to determine the molecular basis of mir-76 in controlling NPS toxicity in nematodes. The mir-76 mutation increased expression of glb-10 encoding a globin protein in NPS (1 µg/L) exposed nematodes. Exposure to NPS (1-100 µg/L) increased the glb-10 expression, and the glb-10(RNAi) worm was susceptible to NPS toxicity in inducing reactive oxygen species (ROS) production and in decreasing locomotion behavior. Using ROS production and locomotion behavior as endpoints, mutation of glb-10 inhibited resistance of mir-76 mutant to NPS toxicity, and neuronal overexpression of mir-76 inhibited the resistance to NPS toxicity in nematodes overexpressing neuronal glb-10 containing 3' untranslated region (3'UTR). Thus, GLB-10 functioned as a target of mir-76 in the neurons to regulate the NPS toxicity. Moreover, a signaling cascade of HRG-7-HRG-5 required for the control of heme homeostasis was identified to function downstream of neuronal GLB-10 to regulate the NPS toxicity. In this signaling cascade, the neuronal HRG-7 regulated the NPS toxicity by antagonizing function of intestinal HRG-5. Furthermore, in the intestine, HRG-5 controlled NPS toxicity by inhibiting functions of hypoxia-inducible transcriptional factor HIF-1 and transcriptional factor ELT-2. Our results highlight the crucial function of heme homeostasis related signaling in regulating the NPS toxicity in organisms.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/efeitos dos fármacos , Heme/metabolismo , Homeostase , MicroRNAs/genética , Nanoestruturas/toxicidade , Poliestirenos/toxicidade , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Intestinos/efeitos dos fármacos , Nanoestruturas/química , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Poliestirenos/química , Interferência de RNA , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais
12.
Anal Methods ; 13(7): 874-883, 2021 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-33576354

RESUMO

Using the children's toy, Shrinky-Dink©, we present an aptamer-based electrochemical (E-AB) assay that recognizes the spike protein of SARS-CoV-2 in saliva for viral infection detection. The low-cost electrodes are implementable at population scale and demonstrate detection down to 1 ag mL-1 of the S1 subunit of the spike protein.


Assuntos
Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Poliestirenos/química , Saliva/química , Glicoproteína da Espícula de Coronavírus/análise , Aptâmeros de Nucleotídeos/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ouro/química , Humanos , Limite de Detecção , Domínios Proteicos , Glicoproteína da Espícula de Coronavírus/química
13.
J Chromatogr A ; 1641: 461985, 2021 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-33611113

RESUMO

The effect of the polydispersity of polystyrenes on the dispersion through silicas having different morphologies (fully porous, core-shell particles and monoliths) was investigated. The heights equivalent to a theoretical plate (HETP) of those columns were measured for a small molecule (toluene) and a series of polystyrenes of different sizes in non-adsorbing conditions. The different contributions to the total HETP including polydispersity were determined experimentally. The longitudinal diffusion and the mass transfer resistance term were obtained from peak parking experiments. The eddy dispersion was obtained from models and experiments. The effect of polydispersity on the HETP values (Hpoly) can thus be calculated from the total HETP by substraction of the other contributions. The results were compared to the Knox model which surestimates the Hpoly values for porous and core-shell particles which is usually explained by an overestimation of the polydispersity index (PDI) given by the manufacturer. The PDI of two polymers (P02, Mw= 690 g.mol-1 and P03, Mw=1380 g.mol-1) was verified by liquid chromatography by separating each fraction of the polymer on the silica columns by using adsorbing conditions which are obtained with a mixture of heptane and THF. The PDI obtained are comparable to the PDI given by the manufacturer meaning that the assumptions made by Knox are not entirely valid. A direct method is proposed in this paper in order to determine Hpoly. In this method the excess of spreading as compared with a polymer with only one size corresponding to the average size is studied assuming the polymer size distribution is gaussian. The Hpoly values obtained by the direct method are comparable to the experimental values.


Assuntos
Polímeros/química , Dióxido de Silício/química , Calibragem , Cromatografia Líquida , Difusão , Peso Molecular , Tamanho da Partícula , Poliestirenos/química , Porosidade
14.
Food Chem ; 345: 128846, 2021 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-33601659

RESUMO

The objective of this study was to determine of nutritional value, in vitro cytotoxicity, and oxidative stress parameters in cells of selected insect species (Tenebrio molitor and Zophobas morio) after 30 days of Styrofoam consumption. Furthermore, part of our research is also a consumer survey on the willingness to eat insects fed with Styrofoam (EPS 80). Mealworms fed with Styrofoam were determined to have higher protein (48.66 ± 0.92%) and ash content (4.81 ± 0.22%) with reduced fat (24.05 ± 0.55%) and carbohydrate content (2.95 ± 0.15%) than insects with a conventional diet (48.66 ± 0.92, 2.82 ± 0.12, 43.74 ± 0.77, and 4.78 ± 0.18, respectively) while in the case of superworms, no significant difference in nutrient composition was observed. Moreover, Styrofoam has no influence on the health status of gut cells in examined insects. Additionally, in studied concentrations of insects extracts standardized for protein replacement of the traditional insect diet with polystyrene foam did not increase the cytotoxic properties.


Assuntos
Valor Nutritivo , Estresse Oxidativo/efeitos dos fármacos , Poliestirenos/toxicidade , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Dieta , Larva/efeitos dos fármacos , Camundongos , Poliestirenos/química , Poliestirenos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Tenebrio/efeitos dos fármacos , Tenebrio/crescimento & desenvolvimento
15.
Talanta ; 225: 122064, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33592783

RESUMO

Quantum dots (QDs) based fluorescent nanobeads are considered as promising materials for next generation point-of-care diagnosis systems. In this study, we carried out, for the first time, the synthesis of QDs nanobeads using polystyrene (PS) nanobead as the template. QDs loading on PS nanobead surface in this method can be readily achieved by the use of polyelectrolyte, avoiding the time-consuming and uncontrollable silane reagents-involved functionalization procedure that conventional synthesis of silica-based QDs nanobeads often suffer from. Notably, the application of QDs nanobeads in suspension microarray for H5N1 virus detection leads to a sensitivity lower than 25 PFU/mL. In addition, QDs nanobead was also incorporated into lateral flow assay for SARS-CoV-2 antibody detection, leading to more than one order of magnitude detection sensitivity as compared to that of commercial one based on colloid gold.


Assuntos
Técnicas Biossensoriais/métodos , Influenza Humana/diagnóstico , Microesferas , Nanoestruturas/química , Poliestirenos/química , Pontos Quânticos , Anticorpos Antivirais/imunologia , Corantes Fluorescentes/química , Humanos , Virus da Influenza A Subtipo H5N1/fisiologia , Influenza Humana/virologia , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Nanoestruturas/ultraestrutura , /fisiologia , Sensibilidade e Especificidade , Dióxido de Silício/química
16.
J Chromatogr A ; 1637: 461840, 2021 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-33412293

RESUMO

The investigation and subsequent understanding of the interactions of nanomaterials with components of their surrounding media is important to be able to evaluate both potential use cases as well as potential risks for human health and for the environment. To investigate such interactions, asymmetrical flow field-flow fractionation (AF4) is an interesting analytical tool. This statement grounds on the fact that interactions of the analyte with the membrane and with components of the eluent are crucial for the retention behavior of the analyte within the field-flow fractionation (FFF) channel. Therefore, the investigation of the retention behavior provides an insight in the nature of the interactions between analyte, membrane and eluent. Within this publication, the influence of the composition of the eluent on the retention behavior of aqueous dispersions of two model analytes is investigated. Eluents with different types of salts and surfactants and eluents with different salt concentrations were prepared and the influence of the composition of these eluents on the retention behavior of polystyrene and polyorganosiloxane particles was compared. Three main trends were observed: Elution times increase with increasing electrolyte concentration; when comparing different electrolyte anions, the retention time increases the more kosmotropic the anion is; when comparing different electrolyte cations, the retention order depends on the surfactant. Additional dynamic light scattering (DLS) measurements were conducted to verify that the differences in retention times are not caused by actual differences in particle size. Instead, the differences in elution time can be correlated with the concentration and with the chao-/kosmotropicity of the added electrolyte ions. Therefore, AF4 proves to be sensitive to subtile changes of interaction forces on the level of Coulomb and van der Waals forces. The experimentally gathered elution times were used to develop a model describing the retention behavior, based on an enhanced version of the standard AF4 model: By introducing particle-medium-membrane interactions in the standard AF4 model via the respective Hamaker constants, the calculation of retention times was possible. The congruence of the calculated with the experimental retention times confirmed the validity of the simulation.


Assuntos
Fracionamento por Campo e Fluxo , Nanopartículas/química , Simulação por Computador , Difusão Dinâmica da Luz , Humanos , Concentração Osmolar , Tamanho da Partícula , Poliestirenos/química , Siloxanas/química , Eletricidade Estática , Fatores de Tempo , Água
17.
Nat Commun ; 12(1): 507, 2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33479231

RESUMO

There is great interest in exploiting van der Waals gaps in layered materials as nanofluidic channels. Graphene oxide (GO) nanosheets are known to spontaneously assemble into stacked planar membranes with transport properties that are highly selective to molecular structure. Use of conventional GO membranes in liquid-phase applications is often limited by low flux values, due to intersheet nanochannel alignment perpendicular to the desired Z-directional transport, which leads to circuitous fluid pathways that are orders of magnitude longer than the membrane thickness. Here we demonstrate an approach that uses compressive instability in Zr-doped GO thin films to create wrinkle patterns that rotate nanosheets to high angles. Capturing this structure in polymer matrices and thin sectioning produce fully dense membranes with arrays of near-vertically aligned nanochannels. These robust nanofluidic devices offer pronounced reduction in fluid path-length, while retaining the high selectivity for water over non-polar molecules characteristic of GO interlayer nanochannels.


Assuntos
Grafite/química , Membranas Artificiais , Técnicas Analíticas Microfluídicas/métodos , Nanoestruturas/química , Nanotecnologia/métodos , Técnicas Analíticas Microfluídicas/instrumentação , Nanotecnologia/instrumentação , Poliestirenos/química , Reprodutibilidade dos Testes , Temperatura , Água/química
18.
Nat Commun ; 12(1): 573, 2021 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-33495475

RESUMO

The biological identity of nanoparticles (NPs) is established by their interactions with a wide range of biomolecules around their surfaces after exposure to biological media. Understanding the true nature of the biomolecular corona (BC) in its native state is, therefore, essential for its safe and efficient application in clinical settings. The fundamental challenge is to visualize the biomolecules within the corona and their relationship/association to the surface of the NPs. Using a synergistic application of cryo-electron microscopy, cryo-electron tomography, and three-dimensional reconstruction, we revealed the unique morphological details of the biomolecules and their distribution/association with the surface of polystyrene NPs at a nanoscale resolution. The analysis of the BC at a single NP level and its variability among NPs in the same sample, and the discovery of the presence of nonspecific biomolecules in plasma residues, enable more precise characterization of NPs, improving predictions of their safety and efficacies.


Assuntos
Microscopia Crioeletrônica/métodos , Tomografia com Microscopia Eletrônica/métodos , Nanopartículas/química , Nanopartículas/ultraestrutura , Plasma/química , Poliestirenos/química , Simulação por Computador , Humanos , Imageamento Tridimensional/métodos , Microscopia Eletrônica de Transmissão/métodos , Coroa de Proteína/química , Reprodutibilidade dos Testes
19.
ACS Sens ; 6(3): 976-984, 2021 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-33496572

RESUMO

The outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) threatens global medical systems and economies and rules our daily living life. Controlling the outbreak of SARS-CoV-2 has become one of the most important and urgent strategies throughout the whole world. As of October 2020, there have not yet been any medicines or therapies to be effective against SARS-CoV-2. Thus, rapid and sensitive diagnostics is the most important measures to control the outbreak of SARS-CoV-2. Homogeneous biosensing based on magnetic nanoparticles (MNPs) is one of the most promising approaches for rapid and highly sensitive detection of biomolecules. This paper proposes an approach for rapid and sensitive detection of SARS-CoV-2 with functionalized MNPs via the measurement of their magnetic response in an ac magnetic field. For proof of concept, mimic SARS-CoV-2 consisting of spike proteins and polystyrene beads are used for experiments. Experimental results demonstrate that the proposed approach allows the rapid detection of mimic SARS-CoV-2 with a limit of detection of 0.084 nM (5.9 fmole). The proposed approach has great potential for designing a low-cost and point-of-care device for rapid and sensitive diagnostics of SARS-CoV-2.


Assuntos
Anticorpos Monoclonais/química , Nanopartículas de Magnetita/química , Glicoproteína da Espícula de Coronavírus/química , Anticorpos Monoclonais/imunologia , Técnicas Biossensoriais , Fenômenos Magnéticos , Poliestirenos/química , Glicoproteína da Espícula de Coronavírus/imunologia
20.
ACS Appl Mater Interfaces ; 13(4): 5660-5667, 2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33467850

RESUMO

Conformal integration of an epidermal device with the skin, as well as sweat and air permeability, are crucial to reduce stress on biological tissues. Nanofiber-based porous mesh structures (breathable devices) are commonly utilized to prevent skin problems. Noble metals are normally deposited on nanomesh substrates to form breathable electrodes. However, these are expensive and require high-vacuum processes involving time-consuming multistep procedures. Organic materials are suitable alternatives that can be simply processed in solution. We report a simple, cost-effective, mechanically biocompatible, and breathable organic epidermal electrode for biometric devices. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is sprayed on a nanofiber-mesh structure, treated using only heat and water to enhance its biocompatibility and conductivity, and used as the electrode. The treatment is accomplished using an autoclave, simultaneously reducing the electrical resistance and sterilizing the electrode for practical use. This research can lead to affordable and biocompatible epidermal electrodes with improved suitability for various biomedical applications.


Assuntos
Materiais Biocompatíveis/química , Epiderme/fisiologia , Nanofibras/química , Poliestirenos/química , Tiofenos/química , Dispositivos Eletrônicos Vestíveis , Biometria/instrumentação , Elasticidade , Condutividade Elétrica , Eletrodos , Humanos , Teste de Materiais
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