Polyethylene Terephthalate Microfibers Research Articles

Merkel cells and corpuscles of Stannius as putative targets for polyethylene terephthalate microfibers in sheepshead minnow larvae

Polyethylene terephthalate (PET) fibers are contaminated in wastewater from various primary sources, such as washing textile waters. PET fibers in the environment can be degraded into microfibers because of weathering processes such as sunlight, physical wear, and heat. Although recent studies reported adverse effects of PET microfibers on aquatic organisms, the lack of information on their toxicity and mode of action hampers the risk assessment of PET microfibers. Therefore, this study aimed to investigate the biological effects of PET microfibers and their underlying mechanisms in early-staged sheepshead minnows (Cyprinodon variegatus). PET microfibers (about 13 μm diameter × 106 μm length) were prepared by cutting PET threads and treated to sheepshead minnow larvae at 10 and 100 mg/L for 10 days. No acute toxicity was found in the minnow, but PET microfibers significantly produced reactive oxygen species and reduced behavioral responses of traveled distance and maximum velocity. The transcriptomic data suggested that Merkel cells (flow sensors) and corpuscles of Stannius (calcium regulator) are putative targets, which were derived from oxidative stress, sensory neuropathy, cognitive impairment, and movement disorders. These findings underscore that although PET microfibers are not directly lethal to sheepshead minnows, they could impact their survival by damaging swimming-related key genes. This study provides new insights into how PET microfibers are toxic to aquatic organisms and disrupt ecosystems beyond survival and pathological changes.

Microcosm study of the effects of polyester microfibers on the indigenous marine amphipod (Cyphocaris challengeri) in the Strait of Georgia (BC, Canada)

Microplastics (MP) remain contaminants of great concern in the ocean because of their abundance, prevalence, and threat to marine organisms. Still, there is a great need for studies on the impact of MP on marine zooplankton. Here, we investigated the effects of polyethylene terephthalate (PET) microfibers (Mf) on the survival, Mf ingestion and retention, predation, and fecal pellets (FP) of the marine amphipod (Cyphocaris challengeri) at environmentally relevant concentrations (0, 10, 100, 1000, 10,000 and 50,000 Mf·L−1) and varied exposure time (24, 48 and 72 h). Our study demonstrated that exposure of C. challengeri to PET Mf did not affect their survival. The average number of ingested Mf and the Mf ingestion rate increased significantly with Mf concentrations. Nonetheless, the Mf ingestion rates by C. challengeri decreased significantly between 24 and 72 h in the two highest Mf treatments (10,000 and 50,000 Mf·L−1), suggesting careful rejection of the Mf or reduced feeding activity. Indeed, PET Mf significantly reduced the copepod feeding rate of the amphipods at Mf concentrations ≥1000 Mf·L−1 after 24 and 48 h of exposure duration. Over time, prey intake reduction in amphipods due to Mf ingestion could affect their reproductive outcome, growth, development, and cellular and ecosystem function. The encapsulation of PET Mf into the FP of C. challengeri significantly increased the FP density and sinking velocities, ultimately doubling the transfer rate of the FP from the surface waters to the sediments in SoG. Conversely, ingesting PET microfibers and their incorporation in FP will potentially enhance the role of C. challengeri in the biological C pump and sequestration in SoG. Our study showed that changes in Mf concentration had a more significant effect on C. challengeri Mf ingestion and ingestion rate, prey consumption, FP density and sinking velocity than the exposure time.

Long-term exposure of the Mediterranean mussels, Mytilus galloprovincialis to polyethylene terephthalate microfibers: Implication for reproductive and neurotoxic effects

As one of major types of microplastics (MPs), microfibers (MFs) are widely found in the marine ecosystem and can induce diverse impacts on various marine organisms. Sedentary species, such as mussels, can act as bioindicators for monitoring marine contamination. Hence, in this study, we used mussels (Mytilus galloprovincialis) to examine the toxicity of polyethylene terephthalate (PET) MFs of 100 μm size at concentrations of 0.0005, 0.1, 1, 10, and 100 mg/L for 32 days. PET MFs accumulated only in the stomachs and intestines of the mussels and caused digestive tubule atrophy. After exposure to PET MFs, no alteration in the mortality rate, shell height, length, and weight of the mussels was observed. However, the gonadal index decreased with increasing concentrations of PET MFs. This is because PET MFs decrease the sex hormones estradiol and testosterone in mussels, even at environmentally relevant concentrations. Furthermore, chronic exposure to PET MFs increased the activities of antioxidant-related (catalase and superoxide dismutase) and neurotoxicity-related (acetylcholine esterase) enzymes in the digestive gland and gill tissues of mussels. In addition, cellular immune parameters of apoptosis and DNA damage were observed in mussel hemocytes. Thus, this study demonstrates the risks of MPs in real marine environments by assessing how long-term exposure to low concentrations of PET MFs can cause potential sublethal impacts and reproductive failure in mussels.

Fabrication and characterization of polymeric nano/micro fibers containing silver nanoparticles for biomedical applications

Polyethylene terephthalate (PET) pre-prepared nano/micro fibers were treated by sodium hydroxide (NaOH) aqueous solution and then AgNPs were loaded on them through the soaking process. In total, eight samples were created. Then they were characterized by field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM), X-ray energy diffraction (EDS) spectroscopy and Fourier transform infrared (FTIR). Disk diffusion and colony counting tests were also performed. Samples containing AgNPs had growth inhibition zones with diameters between 19 and 26 mm while control samples had no inhibition zone. PET microfibers containing AgNPs had a larger inhibition zone on Staphylococcus aureus compared to other samples. The innovation of this research is the placement of AgNPs on the hydrophilic PET micro/nano fibers.

Impact of polyethylene terephthalate microfiber length on cellular responses in the Mediterranean mussel Mytilus galloprovincialis

Many studies have investigated the toxic effects of microplastics in marine organisms, but most studied nano-sized round microplastics at high concentrations and were not environmentally relevant. To understand the cellular toxicity of polyethylene terephthalate microfibers (PET-MFs) by length (50 and 100 μm), Mediterranean mussels (Mytilus galloprovincialis) were exposed to environmental (0.5 μg/L) and high (100 mg/L) MF concentrations for four days. Short PET-MFs accumulated in the lower intestinal organs of the mussels, but long PET-MFs were only observed in the upper intestinal organs. Both sized PET-MFs affected necrosis, DNA damage, reactive oxygen species, nitric oxide, and acetylcholinesterase (AChE) activity. Significant MF length-dependent effects occurred at environmentally relevant concentrations for DNA damage (100 μm MFs) and AChE activity (50 μm MFs). However, length effects disappeared at the higher exposure concentration. The current study provides potentially sensitive indicators to detect MFs exposure and the ecotoxicological implications of MFs in marine ecosystems.

Multigenerational effects of polyethylene terephthalate microfibers in Caenorhabditis elegans

Microfibers (MFs) have recently become an increasingly prevalent pollutant in ecosystems and pose a direct threat to organisms and an indirect threat via adsorption of other pollutants. Here, we used Caenorhabditis elegans to study multigenerational effects of polyethylene terephthalate (PET) MFs (diameter 17.4 μm) by observing the maternal generation (P0) to the seventh offspring generation (F7) with continuous MF exposure. Exposure to 250-μm PET MFs decreased locomotion behavior and induced intestinal reactive oxygen species (ROS) in the P0 generation compared with other PET MF sizes. Moreover, no notably negative effects on survival were observed in any generation during continuous exposure to 250-μm PET MFs. However, the reproduction rate clearly decreased in the F2 and F3 generations but gradually recovered in the F4–F7 generations. Developmental abnormalities showed a close relationship with body length. Although some recovery was confirmed, there were significant decreases in body length in the F2–F5 generations. Interestingly, growth inhibition was also observed in the F6 generation without MF exposure. ROS production and dermal damage in the P0–F5 generations might have resulted in the toxicological responses. To the best of our knowledge, this is the first study to provide evidence of multigenerational toxicity of MFs in C. elegans.

Transfer and effects of PET microfibers in Chironomus riparius

Multiple studies in freshwater environments have verified that microplastic particles are present in water columns, sediment, and aquatic organisms. These studies indicated that certain freshwater ecosystems may act as temporary sinks of microplastic particles, leading to accumulation in the sediment and the ingestion by benthic organisms. Polyethylene terephthalate (PET) is one of the non-buoyant polymers that has been frequently found in aquatic sediments. This study aims to investigate a possible transfer of PET microfibers from aquatic to the terrestrial habitats and addressed selected effects (i.e. survival, general stress response, and growth) of PET microfibers using Chironomus riparius, a frequently applied model organism in ecotoxicological research. To assess the growth and development of C. riparius, a modified 28-day sediment chronic toxicity test was conducted, in which the main endpoint is time until emergence of the larvae. In this assay, C. riparius were exposed to artificial sediments spiked with PET microfibers. In addition, weight and head capsule lengths of the larvae were also measured. As a general stress response marker on the molecular level, Heat Shock Protein 70 (HSP70) levels were measured in two involved life stages, i.e. larvae and adults. Using staining method, ingestion of PET microfibers was verified in the adult sample. Our results clearly demonstrated that ingested microfibers by C. riparius larvae can be carried through subsequent life stages and end up in the adults. Accordingly, this is the first proof of aquatic-terrestrial transfer of PET microfibers for C. riparius. However, toxicity test results showed that there was no significant effect on the time until emergence, weight or head capsule lengths in the organisms exposed to PET microfibers compared to control organisms. HSP70 measurements showed no significant effects between control and exposure groups in the same life stage. The result suggests that PET microfibers in the applied concentration do not exert adverse effects both on organism and subcellular level in one generation.

Synergistic Influences of Stearic Acid Coating and Recycled PET Microfibers on the Enhanced Properties of Composite Materials.

This study aims to produce novel composite artificial marble materials by bulk molding compound processes, and improve their thermal and mechanical properties. We employed stearic acid as an efficient surface modifying agent for CaCO3 particles, and for the first time, a pretreated, recycled, polyethylene terephthalate (PET) fibers mat is used to reinforce the artificial marble materials. The innovative aspects of the study are the surface treatment of CaCO3 particles by stearic acid. Stearic acid forms a monolayer shell, coating the CaCO3 particles, which enhances the compatibility between the CaCO3 particles and the matrix of the composite. The morphology of the composites, observed by scanning electron microscopy, revealed that the CaCO3 phase was homogeneously dispersed in the epoxy matrix under the support of stearic acid. A single layer of a recycled PET fibers mat was pretreated and designed in the core of the composite. As expected, these results indicated that the fibers could enhance flexural properties, and impact strength along with thermal stability for the composites. This combination of a pretreated, recycled, PET fibers mat and epoxy/CaCO3-stearic acid could produce novel artificial marble materials for construction applications able to meet environmental requirements.

Fabrication of interweaving hierarchical fibrous composite (iHFC) membranes for high-flux and robust direct contact membrane distillation

The industrialization of membrane distillation (MD) is hindered by lack of desirable membranes with high performance. Recently, the engineered electrospun nanofibrous membranes (ENMs), such as dual- or multi-layered ENMs, have displayed superior permeations in MD compared with traditional membranes. However, it is still far from satisfactory due to membrane delamination and performance loss after long-term operation. Herein, inspired by the structure of nest with interweaved branches, we fabricated the interweaving hierarchical fibrous composite (iHFC) membrane comprising the interconnected poly(vinylidene fluoride-co-hexafluoropropylene) (PH) nanofibers and polyethylene terephthalate (PET) microfibers via convectional electrospinning. The hydrophobic PH nanofibers provide an enhanced anti-wetting property and high salt rejection. The PET microfibers could significantly both lower the resistance of mass transfer and improve the heat insulation. Results show that the optimized iHFC membrane having the ratio of PH/PET 1.5/0.8 and membrane thickness 80 μm exhibits both high permeation flux of 65 LMH and stable high performance over 60 h when operated at 40 °C temperature difference. Moreover, the interweaving structure endows the iHFC membrane great mechanical strength and excellent long-term stability. It is believed that the strategy explored, and the unique membrane developed here could pave a path to boost the industrialization of MD membranes.

Hierarchical micro/nanofibrous filter for effective fine-particle capture

Hierarchical micro/nanofibrous filters are fabricated by blending electrospun polyurethane (PU) nanofiber with polyethylene terephthalate (PET) microfibers followed by spunlace reinforcement. PET microfibers mainly act as a skeletal framework and PU nanofiber is employed for capturing fine particles. The incorporation of PU nanofiber optimizes inner structures and improves filtration properties of hybrid filters. The mean pore size decreases and pore size distribution shifts to smaller pore sizes with the increased content of PU nanofiber. When the PU nanofiber accounts for 1.87%, the composite filter exhibits a high filtration efficiency (76.63%) for PM0.26 and low pressure drop (17.3 Pa) under an airflow velocity of 5.3 cm/s. This composite filter exhibits a high quality factor of 0.084 Pa−1. Furthermore, the removal efficiency for PM2.5 reaches to 99.93% with a low terminal pressure drop of 26.3 Pa. The composite filters with excellent filtration performances prepared can be applied to industrial production and commercial applications.

Hybrid nanopaper of cellulose nanofibrils and PET microfibers with high tear and crumpling resistance

Cellulose nanofibrils (CNF), once filtered and dried, have the particularity to form a highly cohesive network, nanopaper. One of the drawbacks of all CNF nanopapers is their relative brittleness and low tear resistance, measured as the force needed for crack propagation after introducing a notch. In this work, hybrid nanopapers with drastically improved tear and crumpling resistance were produced by introducing polyethylene terephthalate (PET) microfibers into the CNF suspension prior to sheet fabrication. The PET microfibers were well dispersed in the CNF suspension and subsequently evenly distributed in the formed sheets. Incorporation of 10 wt% PET fibers increased the dry tear resistance with notch by a factor of 10 while still maintaining most of the mechanical properties. This effect is attributed to the loosely bound PET fibers which limit the crack propagation by dissipating the energy. It was also possible to improve the wet tear resistance by a factor of 4. Furthermore, incorporation of PET fibers allowed for crumpling of nanopaper that previously was so brittle it shattered from the deformation. Finally, incorporation of PET fibers also improved the crumpling resistance of wet samples. The improved wet properties, together with a higher and tunable porosity, open up the possibility to use these hybrid nanopaper sheets in filtration applications.

Electrospun PET supported-ionic liquid-stabilized CdS catalyst for the photodegradation of Rhodamine B under visible light

We report the first synthesis of cadmium sulfide (CdS) nanowhiskers prepared by the sonochemical precipitation method using the green ionic liquid (IL), 1-octyl-3-methylimidazolium lauryl sulfate, [OMIM]LS. The synthesized IL-stabilized CdS was immobilized in polyethylene terephthalate (PET) fibers. The PET microfibers used as a support were produced via electrospinning of viscous PET solution. The whiskers assemble in an urchin-like crystal habit and exhibit a band-edge emission due to exciton recombination at 453.7nm and a trap state emission due to surface defects at 648.1nm. The catalyst/polymer ensemble was tested for its photocatalytic activity in the degradation of a model dye, Rhodamine B under visible light. The degradation rate of polymer-supported CdS catalyst is twice compared with the efficiency of the unsupported material.

X-ray diffraction and Raman scattering studies of proton-induced, modified polyethylene terephthalate microfiber

Polyethylene terephthalate (PET) microfiber of 1.5 denier per filament (dpf) has been irradiated with 3-MeV proton at two different fluences: 1 × 1013 and 1 × 1015p/cm2. Molecular deformation because of in-air proton irradiation straining of PET filaments has been investigated. Study of the effects of irradiation by using X-ray diffraction (XRD), Raman spectroscopy and Instron technique shows microstress and crosslinks on the surface of fiber (as revealed from XRD line shift and Raman shift). However, the Young's modulus is found to be larger at an irradiation dose of 1 × 1013p/cm2.

Microstrain analysis of proton irradiated PET microfiber

The microstrain developed due to the molecular deformation of polymeric material because of MeV proton irradiation causes shifting of peak position of both X-ray diffraction lines and Raman bands in polyethylene terephthalate (PET) microfiber. This was investigated using X-ray diffractometer and micro-Raman spectrometer. In the present work, the PET microfiber of 1.5dpf was irradiated with 3MeV proton at small fluences 1×1010p/cm2 to 1×1012p/cm2. The radiation induced microstrain developed in PET microcrystallites and its size effect was investigated applying XRD. The shift of 0.5cm−1 in the Raman peak position of 1616cm−1 to a lower value due to proton irradiation at small fluences confirmed the development of microstrain.