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1.
Sichuan Da Xue Xue Bao Yi Xue Ban ; 52(5): 754-758, 2021 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-34622588

RESUMO

Objective: To explore the effect of polystyrene (PS) and PS-polyvinylpyrrolidone (PVP) electrospun materials on the adhesion ability of Porphyromonas gingivalis( P. gingivalis), a common periodontal pathogen. Methods: PS and PS-PVP electrospun materials were prepared with stainless steel needles in high-voltage electric field. The growth and adhesion of P. gingivalis on the surface of different materials were observed with scanning electron microscope (SEM). The changes in the amount of P. gingivalis biofilm formed on the surface of different materials were measured according to viable colony forming units (CFU). The effect of surface charge of the different materials on the adhesion ability of P. gingivalis was determined through changing the charge properties on the surface of the electrospun materials. Results: SEM images showed that both PS and PS-PVP can be used to form electrospun fibers with a diameter of 0.2 µm. SEM images and CFU counts of the biofilm at 24 h and 48 h showed that there was a smaller amount of P. gingivalis biofilm on the surface of the two materials ( P<0.05). After treatment with tetrabutylammonium bromide (TBAB), the surface charge of the PS-PVP electrospun material changed from being negatively charged to being positively charged, and the amount of bacterial adhesion on the surface increased significantly in comparison to that of untreated PS and PS-PVP materials ( P<0.05). Conclusion: PS and PS-PVP electrospun materials can be used to reduce the adhesion ability of P. gingivalis on the surface of different materials, and this ability may be related to the surface charge properties of the materials.


Assuntos
Porphyromonas gingivalis , Povidona , Biofilmes , Fibras na Dieta , Poliestirenos , Povidona/farmacologia
2.
Chemosphere ; 283: 130972, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34467948

RESUMO

Synergistic effect of zinc oxide nanoparticles (ZnO-NPs) as photocatalyst and organonanoclay (ONC) as biodegradable promoter on the degradation of polystyrene (PS) film was investigated. The films were exposed to ultraviolet irradiation under ambient air at room temperature for photo-catalytic degradation and then submitted to biodegradation test in soil using respirometric procedure. Fourier-transform infrared and ultraviolet-visible spectroscopy, thermogravimetric analysis, colorimeter technique, contact angle measurement, and the carbon dioxide evolution results showed higher photo- and biodegradation efficiency of PS-ONC-ZnO nanocomposite compared to the neat PS, PS-ONC and PS-ZnO nanocomposites. Thermal stability, optical band gap, and water contact angle of photo-degraded PS-ONC-ZnO nanocomposite decreased by 11.37, 18.33 and 63.99%, respectively, while that of PS film was only 6.20, 6.44 and 5.84%, respectively. The photo-degraded PS-ONC-ZnO and PS-ZnO film indicated a biodegradation percentage value of 3.3 and 2.1%, respectively, over 16 weeks of incubation in soil. The possible degradation mechanism of nanocomposites was briefly discussed.


Assuntos
Nanocompostos , Nanopartículas , Óxido de Zinco , Poliestirenos , Espectroscopia de Infravermelho com Transformada de Fourier
3.
Sensors (Basel) ; 21(18)2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34577383

RESUMO

Ammonia gas sensors were fabricated via layer-by-layer (LbL) deposition of diazo resin (DAR) and a binary mixture of tetrakis(4-sulfophenyl)porphine (TSPP) and poly(styrene sulfonate) (PSS) onto the core of a multimode U-bent optical fiber. The penetration of light transferred into the evanescent field was enhanced by stripping the polymer cladding and coating the fiber core. The electrostatic interaction between the diazonium ion in DAR and the sulfonate residues in TSPP and PSS was converted into covalent bonds using UV irradiation. The photoreaction between the layers was confirmed by UV-vis and Fourier transform infrared spectroscopy. The sensitivity of the optical fiber sensors to ammonia was linear when exposed to ammonia gases generated from aqueous ammonia solutions at a concentration of approximately 17 parts per million (ppm). This linearity extended up to 50 ppm when the exposure time (30 s) was shortened. The response and recovery times were reduced to 30 s with a 5-cycle DAR/TSPP+PSS (as a mixture of 1 mM TSPP and 0.025 wt% PSS in water) film sensor. The limit of detection (LOD) of the optimized sensor was estimated to be 0.31 ppm for ammonia in solution, corresponding to approximately 0.03 ppm of ammonia gas. It is hypothesized that the presence of the hydrophobic moiety of PSS in the matrix suppressed the effects of humidity on the sensor response. The sensor response was stable and reproducible over seven days. The PSS-containing U-bent fiber sensor also showed superior sensitivity to ammonia when examined alongside amine and non-amine analytes.


Assuntos
Amônia , Porfirinas , Umidade , Fibras Ópticas , Poliestirenos
4.
Soft Matter ; 17(36): 8314-8321, 2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34550159

RESUMO

Styrene-maleic acid copolymers have become an advantageous detergent-free alternative for membrane protein isolation. Since their discovery, experimental membrane protein extraction and purification by keeping intact their lipid environment has become significantly easier. With the aim of identifying new applications of these interesting copolymers, their molecular binding and functioning mechanisms have recently become intense objects of study. In this work, we describe the use of styrene-maleic acid copolymers as an artificial tool to stabilize the fusion pore. We show that when these copolymers circumscribe the water channel that defines the fusion pore, they keep it from shrinking and closing. We describe how only intra-organelle copolymers have stabilizing capabilities while extra-organelle ones have negligible or even contrary effects on the fusion pore life-time.


Assuntos
Bicamadas Lipídicas , Maleatos , Organelas , Polímeros , Poliestirenos
5.
Lab Chip ; 21(19): 3686-3694, 2021 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-34518854

RESUMO

We present a novel concept for the controlled trapping and releasing of beads and cells in a PDMS microfluidic channel without obstacles present around the particle or in the channel. The trapping principle relies on a two-level microfluidic configuration: a top main PDMS channel interconnected to a buried glass microchannel using round vias. As the fluidic resistances rule the way the liquid flows inside the channels, particles located in the streamlines passing inside the buried level are immobilized by the round via with a smaller diameter, leaving the object motionless in the upper PDMS channel. The particle is maintained by the difference of pressure established across its interface and acts as an infinite fluidic resistance, virtually cancelling the subsequent buried fluidic path. The pressure is controlled at the outlet of the buried path and three modes of operation of a trap are defined: idle, trapping and releasing. The pressure conditions for each mode are defined based on the hydraulic-electrical circuit equivalence. The trapping of polystyrene beads in a compact array of 522 parallel traps controlled by a single pressure was demonstrated with a trapping efficiency of 94%. Pressure conditions necessary to safely trap cells in holes of different diameters were determined and demonstrated in an array of 25 traps, establishing the design and operation rules for the use of planar hydrodynamic traps for biological assays.


Assuntos
Hidrodinâmica , Técnicas Analíticas Microfluídicas , Eletricidade , Microfluídica , Poliestirenos
6.
Phys Rev Lett ; 127(10): 108001, 2021 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-34533362

RESUMO

Limited-valency colloidal particles can self-assemble into polymeric structures analogous to molecules. While their structural equilibrium properties have attracted wide attention, insight into their dynamics has proven challenging. Here, we investigate the polymerization dynamics of semiflexible polymers in 2D by direct observation of assembling divalent particles, bonded by critical Casimir forces. The reversible critical Casimir force creates living polymerization conditions with tunable chain dissociation, association, and bending rigidity. We find that unlike dilute polymers that show exponential size distributions in excellent agreement with Flory theory, concentrated samples exhibit arrest of rotational and translational diffusion due to a continuous isotropic-to-nematic transition in 2D, slowing down the growth kinetics. These effects are circumvented by the addition of higher-valency particles, cross linking the polymers into networks. Our results connecting polymer flexibility, polymer interactions, and the peculiar isotropic-nematic transition in 2D offer insight into the polymerization processes of synthetic two-dimensional polymers and biopolymers at membranes and interfaces.


Assuntos
Coloides/química , Modelos Químicos , Cinética , Metacrilatos/química , Compostos de Organossilício/química , Polimerização , Poliestirenos/química
7.
Ecotoxicol Environ Saf ; 225: 112732, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34478982

RESUMO

The aim of this study was to identify Gα proteins mediating function of neuronal G protein-coupled receptors (GPCRs) in controlling the response to polystyrene nanoparticles (PS-NPs). Caenorhabditis elegans was used as an animal model, and both gene expression and functional analysis were performed to identify the Gα proteins in controlling PS-NPs toxicity. In nematodes, exposure to PS-NPs (1-100 µg/L) significantly altered transcriptional expressions of some neuronal Gα genes, including gpa-5, gpa-10, gpa-11, gpa-15 gsa-1, egl-30, and goa-1. Among these 7 Gα genes, only neuronal RNAi knockdown of gsa-1, gpa-10, and goa-1 affected toxicity of PS-NPs in inducing ROS production and in decreasing locomotion behavior. Some neuronal GPCRs (such as GTR-1, DCAR-1, DOP-2, NPR-8, NPR-12, NPR-9, and DAF-37) functioned upstream of GOA-1, some neuronal GPCRs (such as DCAR-1, DOP-2, NPR-9, NPR-8, and DAF-37) functioned upstream of GSA-1, and some neuronal GPCRs (such as DOP-2, NPR-8, DAF-37, and DCAR-1) functioned upstream of GPA-10 to regulate the toxicity of PS-NPs. Moreover, GOA-1 acted upstream of MPK-1/ERK MAPK, JNK-1/JNK MAPK, DBL-1/TGF-ß, and DAF-7/ TGF-ß, GSA-1 functioned upstream of MPK-1/ERK MAPK, JNK-1/JNK MAPK, and DBL-1/TGF-ß, and GPA-10 functioned upstream of GLB-1/Globin and DBL-1/TGF-ß to control the PS-NPs toxicity. Therefore, neuronal Gα proteins of GOA-1, GSA-1, and GPA-10 functioned to transduce signals of multiple GPCRs to different downstream signaling pathways during the control of PS-NPs toxicity in nematodes. Our results provide clues for understanding the important function of GPCRs-Gα signaling cascade in the neurons in controlling response to nanoplastics in organisms.


Assuntos
Proteínas de Caenorhabditis elegans , Nanopartículas , Animais , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Nanopartículas/toxicidade , Neurônios , Poliestirenos , Receptores Acoplados a Proteínas G
8.
Nanoscale ; 13(32): 13758-13763, 2021 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-34477650

RESUMO

Here, we report how the nature of the hydrophobic core affects the molecular interactions of DNA block copolymer assemblies. Three different amphiphilic DNA block copolymers, DNA-b-polystyrene (DNA-b-PS), DNA-b-poly(2-vinylpyridine) (DNA-b-P2VP), and DNA-b-poly(methyl acrylate) (DNA-b-PMA) were synthesized and assembled into spherical micelles composed of a hydrophobic polymer core and DNA corona. Interestingly, DNA block copolymer micelles having different hydrophobic cores exhibited markedly different molecular and biological interactions. DNA-b-PS exhibited higher melting temperature, sharper melting transition, higher stability to nuclease-catalyzed DNA degradation, and higher cellular uptake efficiency compared to DNA-b-P2VP and DNA-b-PMA. The investigation of the self-assembly behavior revealed a much higher aggregation number and DNA density for DNA-b-PS micelles, which explains the superior properties of DNA-b-PS. These results demonstrate that the type of the hydrophobic core polymer, which has been largely overlooked, has a profound impact on the molecular and biological interactions of the DNA shell.


Assuntos
Micelas , Polímeros , DNA , Interações Hidrofóbicas e Hidrofílicas , Poliestirenos
9.
Nanoscale ; 13(31): 13519-13528, 2021 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-34477756

RESUMO

Membrane proteins are of fundamental importance to cellular processes and nano-encapsulation strategies that preserve their native lipid bilayer environment are particularly attractive for studying and exploiting these proteins. Poly(styrene-co-maleic acid) (SMA) and related polymers poly(styrene-co-(N-(3-N',N'-dimethylaminopropyl)maleimide)) (SMI) and poly(diisobutylene-alt-maleic acid) (DIBMA) have revolutionised the study of membrane proteins by spontaneously solubilising membrane proteins direct from cell membranes within nanoscale discs of native bilayer called SMA lipid particles (SMALPs), SMILPs and DIBMALPs respectively. This systematic study shows for the first time, that conformational changes of the encapsulated protein are dictated by the solubilising polymer. The photoactivation pathway of rhodopsin (Rho), a G-protein-coupled receptor (GPCR), comprises structurally-defined intermediates with characteristic absorbance spectra that revealed conformational restrictions with styrene-containing SMA and SMI, so that photoactivation proceeded only as far as metarhodopsin-I, absorbing at 478 nm, in a SMALP or SMILP. In contrast, full attainment of metarhodopsin-II, absorbing at 382 nm, was observed in a DIBMALP. Consequently, different intermediate states of Rho could be generated readily by simply employing different SMA-like polymers. Dynamic light-scattering and analytical ultracentrifugation revealed differences in size and thermostability between SMALP, SMILP and DIBMALP. Moreover, encapsulated Rho exhibited different stability in a SMALP, SMILP or DIBMALP. Overall, we establish that SMA, SMI and DIBMA constitute a 'toolkit' of solubilising polymers, so that selection of the appropriate solubilising polymer provides a spectrum of useful attributes for studying membrane proteins.


Assuntos
Proteínas de Membrana , Polímeros , Bicamadas Lipídicas , Maleatos , Poliestirenos , Rodopsina , Estireno
10.
J Hazard Mater ; 416: 125847, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492800

RESUMO

Microplastics (MPs) and antibiotic resistance genes (ARGs) are two classes of emerging and prevalent contaminants in terrestrial environments. To date, effects of MPs on the occurrence of ARGs in terrestrial invertebrates remain uncertain. Here we exposed earthworms to a soil amended with polystyrene MPs at two environmentally relevant concentrations to elucidate the occurrence and mechanisms of ARGs in earthworms impacted by MPs with different sizes. Nano-size and 10 mg/kg of 100 µm MPs slightly affected the occurrence of ARGs in earthworms. Highest abundance of ARGs was found in the presence of 10 mg/kg of 10 µm MPs, whereas 100 mg/kg of 10 µm MPs significantly changed the profile of ARGs. Metagenomics sequencing and toxicity tests indicated that MPs caused toxicity and influenced the abundance of microbial community in earthworms, resulting in the changes of ARGs. Results of proteomics and metabolomics demonstrated that 100 mg/kg of 10 µm MPs changed the microenvironment of earthworm gut, built a new homeostatic process, and thus increased the abundance of key bacterial that carried a variety of ARGs. This study highlights the size-dependent toxic effects of MPs and their impacts on the transfer of ARGs in terrestrial environments.


Assuntos
Microplásticos , Oligoquetos , Animais , Antibacterianos/farmacologia , Resistência Microbiana a Medicamentos , Genes Bacterianos , Oligoquetos/genética , Plásticos , Poliestirenos , Solo
11.
J Hazard Mater ; 416: 125879, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492819

RESUMO

In this study, we synthesized polystyrene coated persulfate polyacrylonitrile beads (PC-PSPANBs) to control persulfate (PS) release for targeted PAHs' degradation in a batch reactor. Initially, the persulfate release rate (ksr = 20.553 h-1) from PSPANBs was fast, but coating the PSPANBs with polystyrene controlled PS release rate (ksr= 2.841 h-1), nearly ten times slower than without coating. When Fe(II) activated PC-PSPANBs applied for 12 h degradation of acenaphthene (ACE), 2-methlynaphthalene (2-MN) and dibenzofuran (DBF), the optimum percent removal efficiencies (% R.Es) were as ACE (82.12%) > DBF (68.57%) > 2-MN (58.80%) and the optimum degradation rate constants (kobs) were found as ACE (11.348 h-1) > 2-MN (3.441 h-1) > DBF (1.101 h-1). The effect of SO42- and Cl- on ACE degradation showed that % R.E and kobs were enhanced with increasing anionic concentrations. The maximum % R.E was achieved for SO42- (76.24%) > Cl- (65.51%), but the highest kobs was in case of Cl- (1.536 h-1) > SO42- (0.510 h-1). The effectiveness of PS release longevity was also found because net degradations of ACE and DBF after first spiking were 12 mg L-1 and 16 mg L-1, while after second spiking were 18 mg L-1 and 10 mg L-1, respectively.


Assuntos
Cloretos , Poluentes Químicos da Água , Oxirredução , Poliestirenos , Sulfatos , Poluentes Químicos da Água/análise
12.
J Hazard Mater ; 416: 125918, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492850

RESUMO

Polystyrene nanoplastics (PS-NPs) are known to impair the function of the digestive system, intestinal flora, immune system, and nervous system of marine organisms. We tested whether PS-NPs influence viral infection of orange-spotted grouper (Epinephelus coioides). We found that grouper spleen (GS) cells took up PS-NPs at exposure concentrations of 5, 50, and 500 µg/mL and experienced cytotoxicity at 50 and 500 µg/mL concentrations. At 12 h after exposure to 50 µg/mL of PS-NPs, the replication of Singapore grouper iridovirus (SGIV) and red-spotted grouper nervous necrosis virus (RGNNV) increased in GS cells after their invasion. Juvenile fish exposed to 300 and 3000 µg/L of PS-NPs for 7 d showed PS-NPs uptake to the spleen and vacuole formation in brain tissue. Moreover, PS-NPs exposure accelerated SGIV replication in the spleen and RGNNV replication in the brain. PS-NP exposure also decreased the expression of toll-like receptor genes and interferon-related genes before and after virus invasion in vitro and in vivo, thus reducing the resistance of cells and tissues to viral replication. This is the first report that PS-NPs have toxic effects on GS cells and spleen and brain tissues, and it provides new insights into assessing the impact of PS-NPs on marine fish.


Assuntos
Bass , Infecções por Vírus de DNA , Doenças dos Peixes , Animais , Bass/metabolismo , Encéfalo/metabolismo , Proteínas de Peixes/genética , Regulação da Expressão Gênica , Microplásticos , Filogenia , Poliestirenos , Baço/metabolismo , Replicação Viral
13.
J Hazard Mater ; 416: 125923, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492855

RESUMO

The hyper-cross-linked polymers (HCPs) based on the polystyrene was synthesized during the Friedel-Craft reaction in various situations. The HCPs synthesis were carried out in various operating conditions including reaction time in the range of 3-23 h, the ratio of cross-linker to monomer in range of 1-5 at temperature of 80 â„ƒ. In addition, the cadmium adsorption process was carried out at a temperature in the range of 25-85 â„ƒ and initial cadmium concentration in the range of 10-100 mg/L. The response surface methodology (RSM) has been applied for optimizing the process using synthesis and adsorption parameters. The optimized synthesis conditions were obtained 3.32, 11.26 h, 80 â„ƒ, in ratio, synthesis time, and temperature, respectively. Also, the optimized adsorption conditions were obtained 80 mg/L and 35 â„ƒ, initial cadmium ion concentration, and temperature, respectively. The surface area and thermal stability were obtained at 853.89 m2/g and 450 â„ƒ, respectively. The maximum adsorption capacity and removal efficiency had been obtained 950 mg/g and 92% at a temperature of 20 â„ƒ, after 80 min, respectively. The maximum adsorption capacity and removal efficiency were observed in the initial concentration of 120 mg/L and 10 mg/L, respectively. The adsorption process behavior was surveyed using isotherm, kinetic and thermodynamic models. The isotherm results showed that the adsorption of cadmium by HCPs is multi-layer and heterogeneous. The thermodynamic parameters showed that the process is exothermic and spontaneous. Finally, the kinetic results showed that the process occurred physically and slowly as the temperature raised.


Assuntos
Cádmio , Poluentes Químicos da Água , Adsorção , Cádmio/análise , Concentração de Íons de Hidrogênio , Íons , Cinética , Polímeros , Poliestirenos , Temperatura , Termodinâmica , Poluentes Químicos da Água/análise
14.
J Hazard Mater ; 416: 125969, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492880

RESUMO

In the present study the effects of sublethal concentrations of polystyrene microplastics (PS-MPs) on zebrafish were evaluated at multiple levels, related to fish activity and oxidative stress, metabolic changes and contraction parameters in the heart tissue. Zebrafish were fed for 21 days food enriched with PS-MPs (particle sizes 3-12 µm) and a battery of stress indices like DNA damage, lipid peroxidation, autophagy, ubiquitin levels, caspases activation, metabolite adjustments, frequency and force of ventricular contraction were measured in fish heart, parallel to fish swimming velocity. In particular, exposure to PS-MPs caused significant decrease in heart function and swimming competence, while enhanced levels of oxidative stress indices and metabolic adjustments were observed in the heart of challenged species. Among stress indices, DNA damage was more vulnerable to the effect of PS-MPs. Our results provide evidence on the multiplicity of the PS-MPs effects on cellular function, physiology and metabolic pathways and heart rate of adult fish and subsequent effects on fish activity and fish fitness thus enlightening MPs characterization as a potent environmental pollutant.


Assuntos
Microplásticos , Poluentes Químicos da Água , Animais , Estresse Oxidativo , Plásticos , Poliestirenos/metabolismo , Poliestirenos/toxicidade , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/metabolismo
15.
J Hazard Mater ; 416: 126222, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492977

RESUMO

Plastic biodegradation by mealworm is regarded as an emerging strategy for plastic disposal. In this study, the polystyrene (PS) and low density polyethylene (LDPE) degradation efficiency by yellow mealworms (Tenebrio molitor larvae) supplemented with bran and the effects of plastics on the gut core microbiome were explored to construct a circular and continuous reactor for plastic biodegradation in the future. The gut microbiome was also investigated with dietary shift to explore the relationship between specific diets and gut microbes. The bran plus plastic (7:1 ratio, w/w) co-diet contributed to the mealworm survival and growth. The formation of -CË­O-/-C-O- groups in the plastic-fed mealworms frass represented the oxidation process of plastic biodegradation in the mealworm gut. The changes in molecular weights (Mw, Mn and Mz) of residual PS and LDPE in mealworms frass compared with that of PS and PE feedstock confirmed the plastic depolymerization and biodegradation. Lactobacillus and Mucispirillum were significantly associated with PE + bran diet compared to bran diet and PE diet, representing the response of mealworm gut microbiome to the bran and plastic mixture was distinguished from either bran or plastics alone. The gut microbiome changed substantially with the diet shift, indicating that microbial community assembly was a stochastic process and diverse plastic-degrading bacteria might occur in the mealworm gut.


Assuntos
Microbioma Gastrointestinal , Tenebrio , Animais , Dieta , Polietileno , Poliestirenos
16.
J Hazard Mater ; 416: 126239, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492990

RESUMO

Polystyrene (PS), a major plastic waste, is difficult to biodegrade due to its unique chemical structure that comprises phenyl moieties attached to long linear alkanes. In this study, we investigated the biodegradation of PS by mesophilic bacterial cultures obtained from various soils in common environments. Two new strains, Pseudomonas lini JNU01 and Acinetobacter johnsonii JNU01, were specifically enriched in non-carbonaceous nutrient medium, with PS as the only source of carbon. Their growth after culturing in basal media increased more than 3-fold in the presence of PS. Fourier transform infrared spectroscopy analysis, used to confirm the formation of hydroxyl groups and potentially additional chemical bond groups, showed an increase in the amount of oxidized PS samples. Moreover, field emission scanning electron microcopy analysis confirmed PS biodegradation by biofilms of the screened microbes. Water contact angle measurement additionally offered insights into the increased hydrophilic characteristics of PS films. Bioinformatics and transcriptional analysis of A. johnsonii JNU01 revealed alkane-1-monooxygenase (AlkB) to be involved in PS biodegradation, which was confirmed by the hydroxylation of PS using recombinant AlkB. These results provide significant insights into the discovery of novel functions of Pseudomonas sp. and Acinetobacter sp., as well as their potential as PS decomposers.


Assuntos
Poliestirenos , Solo , Acinetobacter , Bactérias , Biodegradação Ambiental , Pseudomonas
17.
ACS Appl Mater Interfaces ; 13(33): 39042-39054, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34375073

RESUMO

In developing a cluster-nanocarrier design, as a magnetic resonance imaging contrast agent, we have investigated the enhanced relaxivity of a manganese and iron-oxo cluster grafted within a porous polystyrene nanobead with increased relaxivity due to a higher surface area. The synthesis of the cluster-nanocarrier for the cluster Mn8Fe4O12(O2CC6H4CH═CH2)16(H2O)4, cross-linked with polystyrene (the nanocarrier), under miniemulsion conditions is described. By including a branched hydrophobe, iso-octane, the resulting nanobeads are porous and ∼70 nm in diameter. The increased surface area of the nanobeads compared to nonporous nanobeads leads to an enhancement in relaxivity; r1 increases from 3.8 to 5.2 ± 0.1 mM-1 s-1, and r2 increases from 11.9 to 50.1 ± 4.8 mM-1 s-1, at 9.4 teslas, strengthening the potential for T1 and T2 imaging. Several metrics were used to assess stability, and the porosity produced no reduction in metal stability. Synchrotron X-ray fluorescence microscopy was used to demonstrate that the nanobeads remain intact in vivo. In depth, physicochemical characteristics were determined, including extensive pharmacokinetics, in vivo imaging, and systemic biodistribution analysis.


Assuntos
Materiais Biocompatíveis/química , Meios de Contraste/química , Ferro/química , Manganês/química , Nanopartículas/química , Compostos Organometálicos/química , Poliestirenos/química , Animais , Materiais Biocompatíveis/farmacocinética , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular , Sobrevivência Celular/efeitos dos fármacos , Meios de Contraste/farmacocinética , Reagentes para Ligações Cruzadas/química , Humanos , Imageamento por Ressonância Magnética , Camundongos Endogâmicos BALB C , Imagem Multimodal , Porosidade , Espectrometria por Raios X , Distribuição Tecidual
18.
Water Res ; 203: 117509, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34388497

RESUMO

Nanoplastics are an emerging contaminant in aquatic environments. However, analytical methods for the separation, concentration, and identification of nanoplastics, which are essential to assess nanoplastic presence in the environment, are lacking. Here, we developed a new and easy-to-use method to separate and enrich nanoplastics in field water samples with ultracentrifugation. River water was spiked with polystyrene fragments (< 1000 nm) at an environmentally relevant concentration (108-109 particles/L). The polystyrene fragments were successfully separated and enriched by a factor of nearly 50 times with a high recovery rate (87.1%) after undergoing our process. Particles were then characterized using UV-vis spectroscopy, scanning electron microscopy (SEM), and enhanced darkfield microscopy with a hyperspectral imaging (HSI) spectrometer. These techniques are non-destructive and allow the assessment of plastic concentration, morphology, and polymer type. Our method can potentially be applied to other water samples to supply clean, enriched nanoplastic samples that can facilitate their identification in environmental samples.


Assuntos
Microplásticos , Plásticos , Poliestirenos , Ultracentrifugação , Água
19.
Environ Pollut ; 287: 117626, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34426372

RESUMO

In this study, Gymnodinium aeruginosum was exposed to polystyrene (PS) and polymethyl methacrylate (PMMA) of three particle sizes (0.1 µm, 1.0 µm and 100 µm) and two concentrations (10 mg/L and 75 mg/L) for 96 h. The density of algae cells, the endpoints that reactive oxygen species (ROS), total protein (TP), malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT), scanning and transmission electron microscopy (SEM and TEM) were used to explore the toxicity mechanism to the microalgae. At a concentration of 75 mg/L, the 96 h inhibition ratios (IR) with particle sizes of 0.1 µm, 1.0 µm and 100 µm on G. aeruginosum were 55.9%, 63.7% and 6.0% for PS, respectively, and 3.0%, 4.1% and -0.6% for PMMA, respectively. The most significant changes in ROS, TP, MDA, SOD and CAT were observed at 75 mg/L 1.0 µm of PS when treated for 96 h. When exposed to nanoplastics (NPs) and microplastics (MPs), the algae cells were damaged, and the antioxidant system was activated. Extracellular polymeric substance (EPS) could help to detoxify the algae. In general, PS was more toxic than PMMA. The toxicity of small MNPs (0.1 µm and 1.0 µm) was related to the concentrations, while large MNPs (100 µm) did not.


Assuntos
Dinoflagelados , Poluentes Químicos da Água , Matriz Extracelular de Substâncias Poliméricas , Plásticos , Polimetil Metacrilato , Poliestirenos
20.
Environ Sci Technol ; 55(17): 11680-11692, 2021 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-34374532

RESUMO

Microplastics (MPs) are an emerging threat to ecological conservation and biodiversity; however, little is known of the types and possible impacts of MPs in pollinators. To examine whether MPs were present in honeybees, we analyzed the honeybee samples collected in fields from six provinces in China. Four types MPs were identified in honeybee including polystyrene (PS) by Raman spectroscopic analysis, and these plastic polymers were detected in 66.7% bee samples. Then, we assessed the physical and biological impacts of PS of three sizes (0.5, 5, and 50 µm) on bees for 21 days. Next, we measured how the presence of PS affected the Israeli acute paralysis virus proliferation, a small RNA virus associated with bee colony decline. Experimental evidence showed that a large mass of PS was ingested and accumulated within the midgut and enhanced the susceptibility of bees to viral infection. Not only histological analysis showed that PS, especially 0.5 µm PS, damaged the midgut tissue and was subsequently transferred to the hemolymph, trachea, and Malpighian tubules, but also qPCR and transcriptomic results indicated that genes correlated with membrane lipid metabolism, immune response, detoxification, and the respiratory system were significantly regulated after PS ingestion. Our results highlight neglected MP contamination to the bees, a pollination ecosystem stressed by the anthropogenic pollution, and have implications for human health via ingestion of bee products.


Assuntos
Microplásticos , Viroses , Animais , Abelhas , Ingestão de Alimentos , Ecossistema , Plásticos , Poliestirenos
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