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1.
Mar Pollut Bull ; 151: 110812, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32056604

RESUMO

A fluorescence probe was delicately designed for the detection of malachite green (MG) in water and fish samples. Through the electrostatic self-assembly of CdTe QDs on the surface of polystyrene (PS) microspheres, the fluorescence signal was amplified. After grafting molecularly imprinted film, the fluorescence probe of MIP@PS@CdTe was fabricated and applied to the detection of MG based on fluorescence quenching. The linear range of MG detection was 0.01-20 µmol L-1, and the detection limit was 4.7 nmol L-1 (3σ, n = 9) which was much lower than those of the previous reports. The recoveries of MG in aquaculture water and fish samples ranging from 87.6% to 105.4% illustrated that the detection by MIP@PS@CdTe probe was accurate and reliable.


Assuntos
Compostos de Cádmio , Monitoramento Ambiental/métodos , Impressão Molecular , Poliestirenos/química , Pontos Quânticos , Corantes de Rosanilina/análise , Telúrio , Animais , Microesferas , Modelos Químicos , Espectrometria de Fluorescência
2.
Chemistry ; 26(2): 379-383, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31609031

RESUMO

Peptide alcohols are clinically important compounds that are underexplored in structure-activity relationship (SAR) studies in drug discovery. One reason for this underutilization is that current syntheses are laborious and time consuming. Herein, we describe the preparation and utility of Rink, Ramage, and Sieber-chloride resins, which enables the use of a general, easy and practical method for the attachment of fluorenylmethoxycarbonyl (Fmoc)-amino alcohols to a solid support, in the synthesis of peptide alcohols. This method is the first straightforward Fmoc/tBu synthesis of peptide alcohols starting from a pre-loaded resin. The synthesized peptide alcohols can be detached from the linkers through conventional methods. Treatment with trifluoroacetic acid (TFA) (95 %) and scavengers such as triisopropylsilane and water for 2 h is sufficient to obtain a fully deprotected peptide alcohol, while treatment with 20 % hexafluoroisopropanol in dichloromethane renders a fully protected peptide alcohol that can be further modified at the C-terminus. As examples, the new resins were used in straightforward, relatively rapid syntheses of the peptide alcohols octreotide, alamethicin, and a segment of trichogin GA IV, as well as the first synthesis of stapled peptide alcohols.


Assuntos
Amino Álcoois/química , Peptídeos/química , Peptídeos/síntese química , Fenilalanina/análogos & derivados , Fenilalanina/química , Poliestirenos/química , Ácido Trifluoracético/química
3.
Chem Commun (Camb) ; 56(5): 699-702, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31829374

RESUMO

Herein, we report the synthesis of novel nanosized reduced graphene oxide@polystyrene nanospheres (rGO@PS NSs) through an electrostatic interaction method, and further their exploitation for highly sensitive label-free electrochemical immunoassay applications. These rGO@PS NSs provide a universal and promising carrier platform to develop excellent biosensors for clinical screening and diagnostic applications.


Assuntos
Biomarcadores Tumorais/análise , Grafite/química , Nanopartículas/química , Poliestirenos/química , alfa-Fetoproteínas/análise , Animais , Anticorpos Monoclonais Murinos/imunologia , Biomarcadores Tumorais/imunologia , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Imunoensaio/métodos , Limite de Detecção , Camundongos , Reprodutibilidade dos Testes , alfa-Fetoproteínas/imunologia
4.
Chemosphere ; 245: 125602, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31864042

RESUMO

As emerging contaminants of global concern, nanoplastics are significantly potential carriers of hydrophobic organic compounds in aquatic and soil environment. However, little is known about the interactions between the transports of nanoplastics and organic contaminants in porous media. In this study, the cotransport of naphthalene with polystyrene nanoplastics (PSNP) in saturated sand columns as influenced by the PSNP/naphthalene ratio and ionic strength (IS) was investigated. The presence of PSNP dramatically enhanced the mobility of naphthalene at low IS (0.5 mM), but such effect was prohibited at high IS (5 mM and 50 mM). The mobility of PSNP in the sand column was higher when it was solely exist in the pore-water than that when in the presence of naphthalene, because of the charge-shielding effect. This work showed that the coexistence of PSNP and naphthalene would influence the mobility of each other in the saturated porous media, which highly related to their concentration ratio and IS levels.


Assuntos
Microplásticos/química , Movimento , Naftalenos/química , Poliestirenos/química , Concentração Osmolar , Porosidade , Areia , Solo
5.
Chemosphere ; 239: 124792, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526998

RESUMO

We systematically investigated the surface characteristics of polystyrene microplastic particles (PSMPs) prepared by ball milling to impart a porous surface structure and special surface characteristics, and studied the mechanism of adsorption of As(III) onto PSMPs. The sizes of the PSMPs prepared by ball milling for 2, 4, and 8 h were in the ranges of 0.1-1, 1-10, and 10-100 µm, respectively. That is, the longer the milling time is, the larger the specific surface area of the particles is. Moreover, the higher the point of zero charge is, the higher the adsorbed amount of As(III) is. The highest adsorption rate of As(III) onto PSMPs was found to be 1.12 mg g-1. After 1200 min, the adsorption reached equilibrium, and a pseudo-second-order model better fitted the As(III) adsorption kinetics. The Langmuir and Freundlich models could well describe the adsorption isotherms. Furthermore, hydrogen bonds between As(III) and PSMPs were broken at high temperatures, resulting in a decrease in As(III) adsorption onto PSMP, which indicated that the adsorption process was exothermic. Increases in the pH and concentrations of interfering nitrate and phosphate ions in the solution led to inhibited As(III) adsorption of PSMPs. The electrostatic potential of most areas of the PSMP surface was positive, and the H atom on the carboxyl group exhibited a very large positive potential (+56.6 kcal/mol), and thus attracted arsenic oxyanions. Thus, it was determined that As(III) adsorbed to the surface of PSMPs through hydrogen bonding with the carboxyl group. Electrostatic forces and non-covalent interactions are the key mechanisms affecting the adsorption of As(III) onto PSMPs. This work provides a clear theoretical basis for the behavior of the PSMP as an arsenic carrier and might aid to improve the environmental toxicity of arsenic.


Assuntos
Arsênico/química , Microplásticos/química , Poliestirenos/química , Adsorção , Ligação de Hidrogênio , Concentração de Íons de Hidrogênio , Cinética , Nitratos/química , Tamanho da Partícula , Fosfatos/química , Salinidade , Eletricidade Estática , Propriedades de Superfície , Temperatura , Poluentes Químicos da Água/química
6.
Talanta ; 206: 120252, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514822

RESUMO

A new electrochemical device based on a combination of nanomaterials such as Printex 6L Carbon and cadmium telluride quantum dots within a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate film was developed for sensitive determination of amoxicillin. The morphological, structural and electrochemical characteristics of the nanostructured material were evaluated using X-ray diffraction, confocal microscopy, transmission electron microscopy and voltammetric techniques. The synergy between these materials increased the electrochemical activity, the electron transfer rate and the electrode surface area, leading to a high magnitude of the anodic peak current for the determination of amoxicillin. The electrochemical determination of the antibiotic was carried out using square-wave voltammetry. Under the optimised experimental conditions, the proposed sensor showed high sensitivity, repeatability and stability to amoxicillin determination, with an analytical curve in the amoxicillin concentration range from 0.90 to 69 µmol L-1, and a low detection limit of 50 nmol L-1. No significant interference in the electrochemical signal of amoxicillin was observed from potential biological interferences and drugs widely used, such as uric acid, paracetamol, urea, ascorbic acid and caffeine. It was demonstrated that without any sample pre-treatment and using a simple measurement device, the sensor could be an alternative method for not only the analysis of pharmaceutical products (commercial tablets) and clinical samples (urine), but also to examine food quality (milk samples).


Assuntos
Amoxicilina/análise , Antibacterianos/análise , Pontos Quânticos/química , Amoxicilina/urina , Animais , Antibacterianos/urina , Compostos Bicíclicos Heterocíclicos com Pontes/química , Compostos de Cádmio/química , Carbono/química , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Contaminação de Alimentos/análise , Limite de Detecção , Leite/química , Polímeros/química , Poliestirenos/química , Telúrio/química
7.
Food Chem ; 309: 125618, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31767479

RESUMO

In this study, a porous organic polymer (denoted as Car-DMB) was fabricated by a simple one-step crosslinking polymerization of carbazole and p-dimethoxybenzene for the first time. Then the Car-DMB was served as adsorbent of solid phase extraction to enrich triazine herbicides from white gourd, tomato and soybean milk samples prior to their determination by high performance liquid chromatography. Under the optimal conditions, the response linearity was in the range of 0.3-100.0 ng g-1 for white gourds and tomato samples, and 0.5-100.0 ng mL-1 for soybean milk, with the coefficient of determination higher than 0.996. The detection limits were 0.1-0.2 ng g-1 for white gourd and tomato samples, and 0.15-0.3 ng mL-1 for soybean milk. The adsorption mechanism of the Car-DMB for the triazines was attributed to the strong H-bonding and weak π-π interactions. The efficient extraction for several other compounds demonstrated that Car-DMB holds great potential for diverse analysis applications.


Assuntos
Herbicidas/isolamento & purificação , Polímeros/química , Extração em Fase Sólida/métodos , Triazinas/isolamento & purificação , Verduras/química , Adsorção , Anisóis/química , Carbazóis/química , Cromatografia Líquida de Alta Pressão , Reagentes para Ligações Cruzadas/química , Teoria da Densidade Funcional , Análise de Alimentos/métodos , Herbicidas/análise , Limite de Detecção , Nanotubos de Carbono/química , Polímeros/síntese química , Poliestirenos/química , Porosidade , Extração em Fase Sólida/instrumentação , Triazinas/análise
8.
Environ Pollut ; 258: 113760, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31855670

RESUMO

Nanoplastics are inevitably released into aquatic environments due to their extensive use and the continuous fragmentation of plastics. Therefore, it is imperative to understand the aggregation behaviours that determine the transport and fate of nanoplastics in aquatic environments. In this study, the effects of various metal cations, pH, aging and extracellular polymeric substances (EPS) on the aggregation of polystyrene nanoplastics (nano-PS) in aqueous solutions were systematically evaluated based on aggregation kinetics experiments and Derjaguin-Landau-Verwey-Overbeek (DLVO) theoretical calculation. The concentration, valence and hydration ability of metal cations jointly affected the aggregation of nano-PS. The critical coagulation concentration (CCC) of nano-PS was significantly higher than the ionic strengths in aquatic environments, indicating that the aggregation rate of nano-PS is relatively low in aquatic environments. The results of the aggregation kinetics experiments were consistent with DLVO theory, which showed that the energy barrier of nano-PS was dependent on electrostatic repulsion forces and van der Waals forces, and increased with pH. Nano-PS was artificially aged by UV-H2O2, which reduced the hydrophobic nature of the particle surfaces, consequently enhancing the stability of the nanoplastics. EPS (excreted from Chlorella pyrenoidosa) decreased the aggregation rates of nano-PS due to steric effects, which was confirmed by the extend DLVO model. Our results highlight the high stability of nano-PS in aquatic environments, which could help facilitate the evaluation of their environmental impact.


Assuntos
Microplásticos/química , Nanopartículas/química , Poliestirenos/química , Chlorella , Peróxido de Hidrogênio
9.
Chemosphere ; 245: 125628, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31864060

RESUMO

Microplastics and Nitropolycyclic aromatic hydrocarbons (NPAHs) are two types of emerging pollutants that are strong potential threats to aquatic ecosystems and organisms. The adsorption of NPAHs on microplastics may explain the fate and effects of NPAHs in natural environments. In this study, the adsorption behavior of 9-Nitroanthrene (9-NAnt) on polyethylene (PE), polypropylene (PP) and polystyrene (PS) was investigated. Kinetic experiments revealed that 9-NAnt was inclined to be adsorbed onto microplastics, especially PE, which had a large adsorption amount of 734 µg g-1. A linear isothermal model better described the isothermal adsorption process for 9-NAnt, which indicated that a hydrophobic distribution may be the main adsorption mechanism in an aqueous solution. Water environment factors, such as the pH and ionic strength, had negligible effects on the adsorption for PE. In contrast, alkaline and high ionic strength conditions resulted in the inhibition of adsorption of PP and PS. In addition, the particle size of microplastics was negatively correlated with the log Kd of 9-NAnt, and the performance of transient aging treatments on microplastics reduced their affinity for 9-NAnt, due to the addition of oxygen-containing functional groups. Above all, hydrophobic and electrostatic processes were the main adsorption mechanisms between microplastics and 9-NAnt.


Assuntos
Antracenos/química , Microplásticos/química , Poluentes Químicos da Água/química , Adsorção , Ecossistema , Interações Hidrofóbicas e Hidrofílicas , Cinética , Plásticos/química , Polietileno/química , Polipropilenos/química , Poliestirenos/química , Eletricidade Estática , Poluentes Químicos da Água/análise
10.
Environ Sci Pollut Res Int ; 27(7): 6861-6871, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31879867

RESUMO

Arsenic decontamination from groundwater is an urgent but still challenging task. Polystyrene-based hydrated ferric oxide (denoted as D201-HFO) nanocomposite is a new emerging current adsorbent for efficient arsenate removal in natural waters; the resulting materials can interact with arsenate, mainly driven by inner complexation and static interaction and the existing HA effects on adsorption was well investigated. Results reveals that low concentrations of HA (below 25 mg/L) coexistence led to negligible effects on As(V) removal, but high levels of HA (100 mg/L) exerted outstanding sorption competition to As(V) removal; kinetics results revealed the HA additions brought about the diffusion prolonging and capacity decline, due to the large molecule structure of HA. Column experiments further showed the slight decrease application capacity of 810 BV by HA additions, with satisfactory saturation capacity; significantly, the presence of HA also exerted negligible influences on regeneration performances. All the sorbents with or without HA could be well regenerated by binary alkaline and salt mixture.


Assuntos
Arseniatos/química , Nanopartículas/química , Poliestirenos/química , Poluentes Químicos da Água/química , Adsorção , Arseniatos/análise , Arsênico , Recuperação e Remediação Ambiental/métodos , Compostos Férricos/química , Água Subterrânea , Concentração de Íons de Hidrogênio , Poliestirenos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos
11.
J Pharm Biomed Anal ; 177: 112883, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31546136

RESUMO

The article is devoted to the application of modern sample preparation technique - microextraction by packed sorbent (MEPS) - in conjunction with non-conventional type of sorbent - hypercrosslinked polystyrene, that was investigated for the first time in this work. Their combination was used to extract phenylcarboxylic acid-type aromatic microbial metabolites from serum samples of a healthy volunteer with following derivatization and GC-MS detection. As barrel insert and needle for MEPS with hypercrosslinked polystyrene is not produced, we designed a device to imitate the commercial MEPS system with packed granular biporous hypercrosslinked polystyrene. Nine aromatic microbial metabolites, including sepsis associated phenyllactic, 4-hydroxyphenyllactic and 4-hydroxyphenylacetic acids, were extracted from serum samples (recoveries were 20-70%) and a linear dependence was revealed in the most clinically significant range of concentrations (0.5-18 µM). The results obtained demonstrate the perspective of the applying of hypercrosslinked polystyrene in commercial devices for MEPS for the future analyses of biological samples, in particular for the early diagnosis of sepsis and treatment effectiveness control.


Assuntos
Bactérias/metabolismo , Fenilacetatos/sangue , Poliestirenos/química , Sepse/diagnóstico , Microextração em Fase Sólida/métodos , Reagentes para Ligações Cruzadas/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Voluntários Saudáveis , Humanos , Limite de Detecção , Fenilacetatos/metabolismo , Sepse/sangue , Sepse/microbiologia
12.
Chem Commun (Camb) ; 56(2): 217-220, 2019 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-31803869

RESUMO

Herein, we evaluate the suitablity of polystyrenes with thiol, dithioester and trithiocarbonate end-groups for the synthesis of Al nanocrystals. Both the end-groups and molecular weight of the polymer ligands play important roles for controlling the size and shape of the Al nanocrystals. A general criterion for evaluating polymers as the ligand for the synthesis of Al nanocrystals is proposed.


Assuntos
Nanopartículas/química , Poliestirenos/química , Alumínio/química , Cristalização , Teoria da Densidade Funcional , Ligantes , Modelos Químicos , Peso Molecular , Tamanho da Partícula , Compostos de Sulfidrila/química
13.
Molecules ; 24(24)2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-31861051

RESUMO

Functional polymeric materials composed solely of lignin preparations appeared only very recently. A gradual paradigm shift spanning 56 years has revealed how lignin-lignin blends can upgrade the performance of 100 wt% lignin-based plastics. The view, first espoused in 1960, that lignin macromolecules are crosslinked reduces the plausibility of creating functional polymeric materials that are composed only of lignin preparations. Lignin-based materials would be much weaker mechanically if interstices remain in significant numbers between adjoining macromolecular structures that consist of rigid crosslinked chains. In 1982, random-coil features in the hydrodynamic character of kraft lignin (KL) components were evident from ultracentrifugal sedimentation equilibrium studies of their SEC behavior. In 1997, it was recognized that the macromolecular species in plastics with 85 wt% levels of KL are associated complexes rather than individual components. Finally, in 2016, the first polymeric material composed entirely of ball-milled softwood lignin (BML) was found to support a tensile strength above polyethylene. Except in its molecular weight, the BML was similar in structure to the native biopolymer. It was composed of associated lignin complexes, each with aromatic rings arranged in two domains. The inner domain maintains structural integrity largely through noncovalent interactions between cofacially-offset aromatic rings; the peripheral domain contains a higher proportion of edge-on aromatic-ring arrangements. Interdigitation between peripheral domains in adjoining complexes creates material continuity during casting. By interacting at low concentrations with the peripheral domains, non-lignin blend components can improve the tensile strengths of BML-based plastics to values well beyond those seen in polystyrene. The KL-based plastics are weaker because the peripheral domains of adjoining complexes are less capable of interdigitation than those of BML. Blending with 5 wt% 1,8-dinitroanthraquinone results in a tensile strength above that of polyethylene. Analogous effects can be achieved with 10 wt% maple γ-valerolactone (GVL) lignin which, with a structure close to the native biopolymer, imparts some native character to the peripheral domains of the KL complexes. Comparable enhancements in the behavior of BML complexes upon blending with 10 wt% ball-milled corn-stover lignin (BMCSL) result in lignin-only polymeric materials with tensile strengths well beyond polystyrene.


Assuntos
Lignina/química , Polietileno/química , Polímeros/química , Poliestirenos/química , Resistência à Tração , Fenômenos Químicos , Microscopia de Força Atômica , Modelos Moleculares , Estrutura Molecular , Peso Molecular , Plásticos/química , Madeira/química
14.
Environ Pollut ; 255(Pt 2): 113300, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31610513

RESUMO

Microplastics (MPs) can disintegrate into smaller sized microplastics and even nanoplastics (NPs). The toxicity of nanoplastics and microplastics on freshwater organisms have been well explored recently, however, very little is known about the potential impacts of NPs on freshwater biofilms, which are essential for primary production and nutrient cycling in aquatic ecosystems. In this study, we studied the acute effects (3 h of exposure) of polystyrene beads (PS, with diameter range from 100 nm to 9 µm) on five biological endpoints targeting community and ecosystem-level processes in biofilms: chlorophyll a, photosynthetic yield, and three extracellular enzyme activities. The results showed that the large size PS beads (500 nm, 1 µm, and 9 µm) exhibited negligible effects on the determined biological endpoints in biofilms within the range of concentrations (5-100 mg/L) in this study. However, high concentration of PS beads (100 nm, 100 mg/L) significantly decreased the content of chlorophyll a, and the functional enzyme activities of ß-glucosidase and leucine aminopeptidase, suggesting negative effects on the carbon and nitrogen cycling of freshwater biofilms. Moreover, the influences of PS NPs (100 nm) on biofilms strongly depended on the surface modification of PS particles, with the positively charged PS NPs (amide-modified) exhibiting the highest toxicity to biofilms. The excess generation of reactive oxygen species (ROS) in this study indicated oxidative stress induced by PS NPs, which might lead to the observed nano-toxic effects on biofilms. In response, the antioxidant activity of biofilm was enhanced as indicated by the increased total antioxidant capacity (T-AOC). Overall, our findings highlight nanoplastics have potential to disrupt the basic ecological functions of biofilms in aquatic environments.


Assuntos
Organismos Aquáticos/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Nanopartículas/toxicidade , Poliestirenos/toxicidade , Poluentes Químicos da Água/toxicidade , Organismos Aquáticos/metabolismo , Clorofila A/metabolismo , Ecossistema , Água Doce/química , Nanopartículas/química , Estresse Oxidativo/efeitos dos fármacos , Tamanho da Partícula , Poliestirenos/química , Propriedades de Superfície , Poluentes Químicos da Água/química
15.
Mar Pollut Bull ; 145: 260-269, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590785

RESUMO

The sorption of polybrominated diphenyl ethers (PBDEs) onto polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyamide (PA) microplastics was analyzed using different kinetic and isotherm models, and under various environmental conditions, including temperature, pH, salinity and dissolved organic matter (DOM). The sorption capacity was in the order of PS > PA > PP > PE, due to the different crystallinity, specific surface area, and surface structure. PS demonstrated the equilibrium sorption capacity, namely, 6.41 ng/g BDE-47, 12.83 ng/g BDE-99, and 14.42 ng/g BDE-153. The second-order kinetic model described the sorption kinetics of PBDEs, and surface sorption was the main mechanism. The sorption of PBDEs by microplastics was a multilayer and physical process. Low temperatures reduced BDE-47 sorption on microplastics, and sorption was a spontaneous and endothermic process. The sorption of BDE-47 was not significantly influenced by pH and salinity. However, DOM exerted a negative effect on the sorption of BDE-47.


Assuntos
Éteres Difenil Halogenados/química , Plásticos/química , Poluentes Químicos da Água/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Bifenil Polibromatos/química , Polietileno/química , Poliestirenos/química , Salinidade , Temperatura
16.
Mar Pollut Bull ; 145: 536-546, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590821

RESUMO

Microplastic particles (<5 mm), which are an emerging threat, are commonly found in marine ecosystems worldwide. This study investigated the effect of different types of coastal land use on microplastic frequency and distribution on the coastline of Bandar Abbas city; this study used a large sample compared to that used in other studies conducted in this region. The average number of microplastics was determined as 3252 ±â€¯2766 microplastics/m2 (±SD). ATR FT-IR spectroscopy showed that the dominant microplastic particles are expanded polystyrene, polyethylene terephthalate, polypropylene, and polyethylene. Statistical analysis showed a significant difference in microplastic contamination levels between the urban and nonuse beaches. This shows that heavily urbanized areas and human activities have significant effects on the dispersion and frequency of microplastics in the coastal areas of Bandar Abbas. Periodical coast-based cleanup and studies on microplastic pollution and their fluxes by comprehensive sampling are mostly recommended for the Persian Gulf coastline.


Assuntos
/análise , Poluentes Químicos da Água/análise , Monitoramento Ambiental/métodos , Oceano Índico , Irã (Geográfico) , Polietileno/análise , Polietileno/química , Polipropilenos/análise , Polipropilenos/química , Poliestirenos/análise , Poliestirenos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Urbanização , Poluentes Químicos da Água/química
17.
Mar Pollut Bull ; 145: 547-554, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590822

RESUMO

Microplastics are becoming a global concern due to their potential to accumulate pollutants in aquatic environments. In this paper, sulfamethazine (SMT) sorption onto six types of microplastics, including polyamide (PA), polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC) was investigated by experimental and molecular dynamics simulation methods. The experimental results indicated that SMX sorption reached equilibrium within 16 h. The kinetics of SMT sorption by PA, PVC, PE, and PP could be fitted by pseudo first-order model, while SMT sorption by PA and PET could be described by pseudo second-order model. The partition coefficient Kd values were 38.7, 23.5, 21.0, 22.6, 18.6 and 15.1 L·kg-1 for PA, PE, PS, PET, PVC and PP, respectively. SMT sorption onto microplastics decreased when pH and salinity increased. The molecular dynamics simulation results indicated that the main mechanisms involved in sorption are electrostatic and Van der Waals interaction.


Assuntos
/química , Sulfametazina/química , Poluentes Químicos da Água/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Simulação de Dinâmica Molecular , Polietileno/química , Polietilenotereftalatos , Polipropilenos/química , Poliestirenos/química , Cloreto de Polivinila/química , Eletricidade Estática
18.
Environ Pollut ; 255(Pt 2): 113302, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31597113

RESUMO

The intentional production and degradation of plastic debris may result in the formation of nanoplastics. Currently, the scarce information on the environmental behaviors of nanoplastics hinders accurate assessment of their potential risks. Herein, the aggregation kinetics of different surface-modified polystyrene nanoparticles in monovalent and divalent electrolytes was investigated to shed some light on the fate of nanoplastics in the aquatic environment. Three monodisperse nanoparticles including unmodified nanoparticles (PS-Bare), carboxylated nanoparticles (PS-COOH) and amino modified nanoparticles (PS-NH2), as well as one polydisperse nanoparticles that formed by laser ablation of polystyrene films (PS-Laser) were used as models to understand the effects of surface groups and morphology. Results showed that aggregation kinetics of negatively charged PS-Bare and PS-COOH obeyed the DLVO theory in NaCl and CaCl2 solutions. The presence of Suwannee river natural organic matters (SRNOM) suppressed the aggregation of PS-Bare and PS-COOH in monovalent electrolytes by steric hindrance. However, in divalent electrolytes, their stability was enhanced at low concentrations of SRNOM (below 5 mg C L-1), while became worse at high concentrations of SRNOM (above 5 mg C L-1) due to the interparticle bridging effect caused by Ca2+ and carboxyl groups of SRNOM. The cation bridging effect was also observed for PS-laser in the presence of high concentrations of divalent electrolytes and SRNOM. The adsorption of SRNOM could neutralize or even reverse surface charges of positively charged PS-NH2 at high concentrations, thus enhanced or inhibited the aggregation of PS-NH2. No synergistic effect of Ca2+ and SRNOM was observed on the aggregation of PS-NH2, probably due to the steric repulsion imparted by the surface modification. Our results highlight that surface charge and surface modification significantly influence aggregation behaviors of nanoplastics in aquatic systems.


Assuntos
Eletrólitos/química , Nanopartículas/química , Poliestirenos/química , Adsorção , Cátions , Concentração de Íons de Hidrogênio , Cinética , Modelos Químicos , Plásticos , Rios , Cloreto de Sódio
19.
Anal Sci ; 35(10): 1123-1127, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31597872

RESUMO

Measurement of single molecule interaction is performed by various micromanipulation techniques. However, a complex operation is required to perform the measurement, so the measurement throughput is low and a large amount of time is required for statistical analysis. In this paper, we propose a method for measuring intermolecular interactions that applies a tensile force to the intermolecular bond by using centrifugal force and can easily measure binding force. The binding force of an antigen-antibody reaction system was measured by the use of the proposed method as a proof of concept. The measured binding forces were distributed in the range of 19 - 133 pN. The values obtained by use of the proposed method were consistent with the conventional method. This result is promising for applications that require further development, such as the development of a biosensor as a novel measuring technique that is based on the intermolecular interaction measurement.


Assuntos
Centrifugação/instrumentação , Dispositivos Lab-On-A-Chip , Resistência à Tração , Anticorpos Imobilizados/química , Anticorpos Imobilizados/imunologia , Microscopia de Força Atômica , Microesferas , Poliestirenos/química
20.
Bull Environ Contam Toxicol ; 103(6): 766-769, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31587083

RESUMO

The ingestion of microplastics by marine species has been at least partially attributed to plastics emitting a dimethyl sulfide signature when exposed to marine conditions. Dimethyl sulfide, a member of the volatile organic sulfur compounds group, is an infochemical that many species rely on to locate and identify prey while foraging. Microplastic ingestion is also observed in freshwater systems; however, this study shows that the same dimethyl sulfide signature is not obtained by three common types of plastic (high-density polyethylene, low-density polyethylene, and polystyrene) in freshwater systems, suggesting that there may be an alternate mechanism driving plastic ingestion by freshwater species.


Assuntos
Água Doce/química , Sulfetos/química , Animais , Monitoramento Ambiental , Modelos Químicos , Polietileno/química , Poliestirenos/química , Sulfetos/análise , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química
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