Polymeric nanoparticles: A promising strategy for treatment of Alzheimer's disease

Alzheimer's disease (AD), is characterised by two major hallmarks: the formation of extracellular β-amyloid (Aβ) plaques and the hyperphosphorylation of tau protein, thus leading to the formation of neurofibrillary tangles. These hallmarks cause synaptic loss, neuronal damage, and the development of neuroinflammation and oxidative stress, which promote AD progression. Thus, the goal of treating AD is eliminating these hallmarks, to prevent AD progression and decrease symptoms. However, current available therapies provide symptomatic relief rather than treating the underlying cause of the disease, because the restrictive nature of the blood brain barrier (BBB) impedes the entry of drugs, thereby affecting drug efficacy and bioavailability. Researchers are focusing on developing new therapeutic approaches to bypass the BBB, for achieving site-specific drug delivery with the highest possible bioavailability and the lowest adverse effects. Recently explored therapeutic strategies include use of biologic agents such as monoclonal antibodies. Aducanumab, a strong candidate for treating AD, has been granted accelerated Food and Drug Administration approval; however, safety concerns may hinder its future use. Thus, nanotechnological approaches have led to a new era of AD treatment. Nanoparticles (NPs), because of their small particle size, can cross the BBB, thus enhancing drug pharmacokinetic properties and enabling targeted drug delivery. Polymeric NPs have been extensively studied, because of their simple production, biodegradability, biocompatibility, and unique architecture. These NPs provide a flexible vesicle that can be easily tailored to achieve desired physicochemical features. In this review, various types of polymer-based-NPs are discussed, highlighting the properties of fabricated NPs, which have multiple benefits in AD treatment, including anti-amyloid, antioxidant, and anti-inflammatory effects.

Development and In Vivo Evaluation of Sustained Release Microparticles Loaded with Levothyroxine for Hypothyroidism Treatment

Hypothyroidism is a chronic condition combated by a daily oral supplementation of levothyroxine. In addition to the need for frequent dosing, oral administration may result in variable absorption of the drug leading to a failure in achieving normal thyroid function. Therefore, the development of a long-acting injectable system capable of delivering the drug is necessary. This work was aimed at developing sustained release microparticles loaded with levothyroxine. The microparticles were produced through the emulsification-solvent evaporation method using 2 grades of biocompatible and biodegradable polyesters: poly(ᴅ,ʟ-lactide-co-glycolide) (PLGA) and poly(ᴅ,ʟ-lactide) (PLA). Both polymers produced microparticles with very similar sizes (1.9 µm) and zeta potential values (around -22.0 mV). However, PLA microparticles had a significantly higher drug loading (6.1% vs. 4.4%, respectively) and encapsulation efficiency (36.8%, vs. 26.1%, respectively) when compared to PLGA counterparts. While both types of microparticles displayed a biphasic release pattern in vitro, a slower rate of release was observed with PLA microparticles. Moreover, a similar biphasic release pattern was found in vivo, with an initial phase of rapid release followed by a slower phase in the subsequent 10 days. These results indicate the possibility of developing levothyroxine loaded polyester microparticles as a potential long-acting thyroid hormone replacement therapy.

Warming temperatures exacerbate effects of microplastics in a widespread zooplankton species

The emergence of microplastics as a global contaminant of concern has coincided with climate change induced temperature warming in aquatic ecosystems. Warmer temperatures have been previously demonstrated to increase the toxicity of certain contaminants, but it is currently unclear if microplastics are similarly affected by temperature. As aquatic organisms simultaneously face microplastic pollution and both increasing and variable temperatures, understanding how temperature affects microplastic toxicity is pertinent in this era of human-induced global change. In this study, we investigate the effects of environmentally relevant microplastic exposure to Daphnia pulex survival, reproduction, and growth at three different temperatures. To simulate an environmentally relevant exposure scenario, we created microplastics with physicochemical characteristics often detected in nature, and exposed organisms to concentrations close to values reported in inland waters and 1-2 orders of magnitude higher. The three temperatures tested in this experiment included 12 °C, 20 °C, and 24 °C, to simulate cool/springtime, current, and warming scenarios. We found the highest concentration of microplastics significantly impacted survival and total offspring compared to the control at 20 °C and 24 °C, but not at 12 °C. The adverse effect of high microplastic concentrations on total offspring at warmer temperatures was driven by the high mortality of the juveniles. We observed no effect of microplastics on time to first reproduction or average growth rate at any temperature. Warmer temperatures exacerbated microplastic toxicity, although only for concentrations of microplastics not currently observed in nature, but these concentrations are possible in pollution hotspots, through pulses pollution events or future worsening environmental contamination. The results of our study illustrate the continued need to further investigate climate change related co-stressors such as warming temperatures in microplastic and pollution ecology, through environmentally realistic exposure scenarios.

Oligopeptide-based molecular labelling of (bio)degradable polyester biomaterials

Nowadays, a very important motivation for the development of new functional materials for medical purposes is not only their performance but also whether they are environmentally friendly. In recent years, there has been a growing interest in the possibility of labelling (bio)degradable polymers, in particular those intended for specific applications, especially in the medical sector, and the potential of information storage in such polymers, making it possible, for example, to track the ultimate environmental fate of plastics. This article presents a straightforward green approach that combines both aspects using an oligopeptide, which is an integral part of polymer material, to store binary information in a physical mixture of polymer and oligopeptide. In the proposed procedure the year of production of polymer films made of poly(l-lactide) (PLLA) and a blend of poly(1,4-butylene adipate-co-1,4-butylene terephthalate) and polylactide (PBAT/PLA) were encoded as the sequence of the appropriate amino acids in the oligopeptide (PEP) added to these polymers. The decoding of the recorded information was carried out using mass spectrometry technique as a new method of decoding, which enabled the successful retrieval and reading of the stored information. Furthermore, the properties of labelled (bio)degradable polymer films and stability during biodegradation of PLLA/PEP film under industrial composting conditions have been investigated. The labelled films exhibited good oligopeptide stability, allowing the recorded information to be retrieved from a green polymer/oligopeptide system before and after biodegradation. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay) study of the PLLA and PLLA/PBAT using the MRC-5 mammalian fibroblasts was presented for the first time.

Microplastic accumulation and ecological impacts on benthic invertebrates: Insights from a microcosm experiment

Microplastic (MP) pollution poses a global concern, especially for benthic invertebrates. This one-month study investigated the accumulation of small MP polymers (polypropylene and polyester resin, 3-500 μm, 250 μg L-1) in benthic invertebrates and on one alga species. Results revealed species-specific preferences for MP size and type, driven by ingestion, adhesion, or avoidance behaviours. Polyester resin accumulated in Mytilus galloprovincialis, Chamelea gallina, Hexaplex trunculus, and Paranemonia cinerea, while polypropylene accumulated on Ulva rigida. Over time, MP accumulation decreased in count but not size, averaging 6.2 ± 5.0 particles per individual after a month. MP were mainly found inside of the organisms, especially in the gut, gills, and gonads and externally adherent MP ranged from 11 to 35 % of the total. Biochemical energy assessments after two weeks of MP exposure indicated energy gains for water column species but energy loss for sediment-associated species, highlighting the susceptibility of infaunal benthic communities to MP contamination.

Utilization of used textiles for solid recovered fuel production

One of the current important issues is the management of used textiles. One method is recycling, but the processes are characterized by a high environmental burden and the products obtained are of lower quality. Used textiles can be successfully used to produce SRF (solid recovered fuels). This type of fuel is standardized by ISO 21640:2021. In the paper, an analysis of used textiles made from fibers of different origins was performed. These were acrylic, cotton, linen, polyester, wool, and viscose. A proximate and ultimate analysis of the investigated samples was performed, including mercury and chlorine content. The alternative fuel produced from used textiles will be characterized by acceptable parameters for consumers: a lower heating value at 20 MJ/kg (class 1-3 SRF), mercury content below 0.9 µg Hg/MJ (class 1 SRF), and a chlorine content below 0.2% (class 1 SRF). However, the very high sulfur content in wool (3.0-3.6%) and the high nitrogen content in acrylic may limit its use for power generation. The use of alternative fuel derived from used textiles may allow 3% of the coal consumed to be substituted in 2030. The reduction in carbon dioxide emissions from the substitution of coal with an alternative fuel derived from used textiles will depend on their composition. For natural and man-made cellulosic fibers, the emission factor can be assumed as for plant biomass, making their use for SRF production preferable. For synthetic fibers, the emission factor was estimated at the level of 102 and 82 gCO2/MJ for polyester and acrylic, respectively.

Influence of the geographic location and house characteristics on the concentration of microplastics in indoor dust

Microplastics (MPs) are known for their ubiquity, having been detected in virtually any environmental compartment. However, indoor MPs concentrations are poorly studied despite being closely related to human exposure. The present study aims to evaluate the presence of MPs in settled atmospheric dust in 60 houses distributed in 12 districts of the metropolitan city of Lima, Peru, and investigate the influence of their geographical location and house characteristics. MPs concentration ranged from 0.01 to 33.9 MPs per mg of dust. Fibers and blue were the most frequent shape and color (98 % and 69 %, respectively). Also, 82 % of the particles were between 500 μm - 5 mm in size. A higher concentration of MPs was identified in the center-south of the city. The houses located on the highest floors (levels 4 to 13 to ground) displayed higher concentrations. MPs were primarily composed of polyester (PET), polypropylene (PP), and ethylene-vinyl acetate (EVA), among others. The polymers identified suggest that MPs derived from the fragmentation of components frequently found in houses, such as synthetic clothing, food storage containers, toys, carpets, floors, and curtains. The incorporation of MPs from the outside into dwellings is not ruled out. Future studies should evaluate the influence of consumption habits and housing characteristics on the abundance of MPs.

Energy-efficient trehalose-based polyester nanofiltration membranes for zero-discharge textile wastewater treatment

Recovery of water, salts, and hazardous dye from complex saline textile wastewater faces obstacles in separating dissolved ionic substances and recovering organic components during desalination. This study realized the simultaneous fractionation, desalination, and dye removal/recovery treatment of textile wastewater by using trehalose (Tre) as an aqueous monomer to prepare polyester loose nanofiltration (LNF) membrane with fine control microstructure via interfacial polymerization. Outperforming the NF270 commercial membrane, the Tre-1.05/TMC optimized membrane achieves zero-discharge textile wastewater treatment, cutting energy consumption by 295% and reducing water consumption by 42.8%. This efficiency surge results from remarkable water permeability (130.83 L m-2 h-1 bar-1) and impressive dye desalination (NaCl/ Direct Red 23 separation factor of 275) of the Tre-1.05/TMC membrane. For a deeper comprehension of filtration performance, the sieving mechanism of polyester LNF membranes was systematically elucidated. This strategic approach offers significant prospects for energy conservation, carbon emission mitigation, and enhanced feasibility of membrane-based wastewater treatment systems.

Editor's Choice -- Type IIIb Endoleaks: Fabric Perforations of Explanted New Generation Endoprostheses

OBJECTIVE

To analyse explanted endografts (EGs) and describe fabric degradation responsible for type IIIb endoleaks.

METHODS

As part of the European collaborative retrieval programme, 32 EGs with fabric defects on macroscopic evaluation were selected. The explanted EGs were processed and studied based on the ISO 9001 certified standard protocol. It includes instructions on the collection, transportation, cleaning, and examination of explanted material. The precise analysis was performed with a digital microscope of 20 - 200 times magnification. Possible perforation mechanisms were assessed in stress tests.

RESULTS

The median time to explantation of the 32 EGs was 54 months. The explants included 65 separate EG modules, with 46 (70.8%) having a combined 388 fabric perforations. Each EG had a median of 4.79 mm2 (interquartile range [IQR] 9.86 mm2) of cumulated hole area (an average of 0.13% of an EG's area). There were 239 (61.6%) expanded polytetrafluoroethylene (ePTFE; 11 EGs) and 149 (38.4%) polyethylene terephthalate (PET; 21 EGs) fabric ruptures, with no difference in hole distribution between these types of material. Overall, 126 (32.5%) stent related and 262 (67.5%) non-stent related fabric perforations were identified. Perforations caused by fabric fatigue in ePTFE (151, 63.2%) and material kinking in PET (41, 27.5%) were the most common. The stent related perforations were larger in size (0.80 mm2) than non-stent related perforations (0.19 mm2); p < .001. Wider interstent spaces and prolonged implantation duration were associated with an increased risk of stent related perforation development; p < .001 and p = .004, respectively. Large stent related perforations were also detected in the short term, suggesting mechanical issues as underlying causes.

CONCLUSION

The fabric of EGs may degrade and lead to the development of perforations. The largest perforations are stent related. Their occurrence and size depend on the implantation time and the EG shape affected by arterial tortuosity. The conclusions are limited to the samples from a select explant group.

Evidence of plastic pollution from offshore oceanic sources in southern Chilean Patagonian fjords

The Chilean Patagonian fjords are globally renowned as one of the few remaining pristine environments on Earth; however, their ecosystems are under significant threat from climatic and anthropogenic pressures. Of particular concern is the lack of research into the impact of plastic pollution on the waters and biodiversity of these fjords. In this study, the marine environment of a secluded and sparsely populated fjord system in southern Patagonia was sampled to assess microplastics in seawater, beaches, bottom sediment, and zooplankton. Microplastics were found to be widespread across the water surface of the fjord, but with low abundances of 0.01 ± 0.01 particles m-3 (mean ± SD). The presence of microplastics in sedimentary environments (e.g., beaches and bottom sediments, 15.6 ± 15.3 and 9.8 ± 24 particles kg of dry sediment-1, respectively) provided additional evidence of plastic debris accumulation within the fjord system. Furthermore, microplastics were already bioavailable to key zooplankton species of the Patagonian food web (0.01 ± 0.02 particles individual-1), suggesting bioaccumulation. A comprehensive examination of potential microplastic inputs originating from coastal runoff, coupled with distribution of water masses, suggested minimal local contribution of microplastics to the fjord, strongly indicating that plastic litter is likely entering the area through oceanic currents. The composition and type of microplastics, primarily consisting of polyester fibers (approx. 60 %), provided further support for the proposed distant origin and transportation into the fjord by oceanographic drivers. These results raise significant concern as reveal that despite a lack of nearby population, industrial or agricultural activity, remote Patagonian fjords are still impacted by plastic pollution originating from distant sources. Prioritizing monitoring efforts is crucial for effectively assessing the future trends and ecological impact of plastic pollution in these once so-called pristine ecosystems.

In vivo evaluation of a polyester and fiberglass composite intramedullary nail for femoral osteosynthesis in calves

The objective of this study was to test a composite of polyester resin and fiberglass in the form of an intramedullary nail for osteosynthesis of femoral fractures in calves. The methodology was established based on a previous study that used a bovine femur finite element model to simulate fractures, which were then stabilized by the same nails as proposed in this study. General anesthesia was induced in six calves followed by fracture creation via an oblique incision in the middle third of the femoral diaphysis, and osteosynthesis was immediately performed by retrograde insertion of the composite nail. Locking was achieved by drilling the bone and nail without using a jig and introducing two stainless steel screws proximal and two distal to the fracture line. Five of the six calves achieved complete fracture healing after 60 days. No signs of incompatibility or toxicity of the composite were observed. However, limitations were observed during the surgery, such as difficulty in drilling the nail and trimming the remainder portion of the nail that extended beyond the length of the bone. Small fragments produced by these maneuvers were considered irritating to soft tissues during the postoperative period. It was also found that small cracks in the nail tended to propagate in the form of longitudinal fractures. In conclusion, an intramedullary nail made of polyester resin and fiberglass (a low-cost and easy-to-acquire material) was considered biocompatible and capable of allowing bone healing of femoral fractures in young cattle. However, the development of solutions for the reported limitations is crucial prior to recommending the proposed composite for clinical use.

No Effect of Realistic Concentrations of Polyester Microplastic Fibers on Freshwater Zooplankton Communities

Zooplankton are a conduit of energy from autotrophic phytoplankton to higher trophic levels, and they can be a primary point of entry of microplastics into the aquatic food chain. Investigating how zooplankton communities are affected by microplastic pollution is thus a key step toward understanding ecosystem-level effects of these global and ubiquitous contaminants. Although the number of studies investigating the biological effects of microplastics has grown exponentially in the last decade, the majority have used controlled laboratory experiments to quantify the impacts of microplastics on individual species. Given that all organisms live in multispecies communities in nature, we used an outdoor 1130-L mesocosm experiment to investigate the effects of microplastic exposure on natural assemblages of zooplankton. We endeavored to simulate an environmentally relevant exposure scenario by manually creating approximately 270 000 0.015 × 1- to 1.5-mm polyester fibers and inoculating mesocosms with zero, low (10 particles/L), and high (50 particles/L) concentrations. We recorded zooplankton abundance and community composition three times throughout the 12-week study. We found no effect of microplastics on zooplankton abundance, Shannon diversity, or Pielou's evenness. Nonmetric multidimensional scaling plots also revealed no effects of microplastics on zooplankton community composition. Our study provides a necessary and realistic baseline on which future studies can build. Because numerous other stressors faced by zooplankton (e.g., food limitation, eutrophication, warming temperatures, pesticides) are likely to exacerbate the effects of microplastics, we caution against concluding that polyester microfibers will always have no effect on zooplankton communities. Instead, we encourage future studies to investigate the triple threats of habitat degradation, climate warming, and microplastic pollution on zooplankton community health. Environ Toxicol Chem 2024;43:418-428. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Polyester conversion by homogeneous catalysis for separating and recycling ammonia from biogas

Biogas is being promoted as a renewable and clean energy source. However, NH3 is a precursor of NOx and PM2.5 within the biogas, threatening ecological and human health. Therein, recycling waste NH3 from the biogas as a raw material of nitrogen fertilizer was tested by optimizing polyester as a sorbent material. After homogeneous catalysis, the converted polyester significantly increased the NH3 adsorption sites within polyester nanopores; correspondingly, the NH3 adsorption capacity increased from 0.56 mg·g-1 to 84.07 mg·g-1. Based on the structural characterization of polyesters, functional groups analysis before and after adsorption, and kinetic analysis during adsorption, chemical adsorption was identified as the dominant mechanism for NH3 adsorption. Moreover, selective adsorption and the regeneration experiments to optimize polyester indicated that NH3 could be efficiently separated from biogas with good regeneration performance. The results demonstrate the efficacy of recycling waste polyester and NH3 from the biogas.

Leaching of heavy metals from polyester microplastic fibers and the potential risks in simulated real-world scenarios

Heavy metals have been incorporated as additives into synthetic textiles to enhance their functional properties. However, these fibers are susceptible to shedding due to mechanical wear, and the release of heavy metals from microplastic fibers (MFs) remains largely uncharacterized. Therefore, this study sought to quantify the levels of heavy metals in textiles, evaluate their leaching capabilities under various scenarios, and ultimately assess the potential health risks associated with MFs ingestion. First, we determined the metal content in eight commonly used polyester textiles. Subsequently, we estimated the metal leaching capacities of specific MFs sourced from carpets, curtains, sweaters, and scarves in freshwater, human saliva, human lung fluid, and fish gastric fluid at distinct time intervals. The results indicated that carpets contained the highest amount of total metals, with a concentration of 218 ± 8 mg/kg. Ultraviolet weathering, coupled with longer exposure durations, led to surface coarsening of MFs, which may be the primary reason for the enhanced leaching of metals in freshwater. Furthermore, our findings revealed that carbonyl index was unsuitable for characterizing aging because polyester inherently contains carbonyl groups. Instead, the O/C ratio emerged as a more suitable indicator. The leached concentrations and percentages of metals from MFs exhibited the following order in biofluids: Sb>Mn>Cr and Cr>Mn>Pb in biofluids, respectively. Finally, the estimated daily intake of metals was significantly below the tolerable thresholds (0.0014-0.14 mg/kg/d for fish and 0.0036-1.0 mg/kg/d for humans), indicating a negligible risk of heavy metal exposure through MFs for both fish and humans. ENVIRONMENTAL IMPLICATION: In recent years, the ecological risks posed by heavy metal contaminants loaded onto microplastic fibers have become an increasing concern. Therefore, our study sought to characterize the accumulation of heavy metals on plastic fabrics and the potential for these loaded heavy metals to be released when microplastic fibers originating from these fabrics enter freshwater environments and interact with organisms. This vector-like behavior underscores the importance of investigating the ecological hazards associated with microplastic fibers carrying contaminants in both environmental and organismal contexts.

Prevalence of type II endoleak after elective endovascular aneurysm repair with polytetrafluoroethylene- or polyester-based endografts

OBJECTIVE

Type II endoleak is the most frequent complication after endovascular abdominal aneurysm repair. Polytetrafluoroethylene and polyester (PE) are the two most commonly used graft materials in endovascular aneurysm repair (EVAR) devices. Biological properties of the material might influence the appearance and persistence of type II endoleak (T2EL). Therefore, the aim of this study was to evaluate potential differences in the prevalence of T2EL after EVAR between polytetrafluoroethylene (PTFE) and PE endografts in patients electively treated for an infrarenal abdominal aortic aneurysm.

METHODS

A single-center, retrospective, observational study was conducted between January 2011 and January 2022. Preoperative, procedural, and follow-up data were derived from electronic health records. Imaging included computed tomography scans, and/or duplex ultrasound examination. The primary end point was the prevalence of T2EL diagnosed within 1 year after EVAR. Secondary end points included the prevalence of T2EL throughout follow-up, early (≤30 days) and late (>30 days) T2EL, the rate of T2EL disappearance during the follow-up period, the prevalence of type I and III endoleak, and T2EL-related reinterventions.

RESULTS

Follow-up was available for 394 patients, 245 in the PE and 149 in the PTFE group. The prevalence of T2EL diagnosed within 1 year after endovascular repair was 11.8% in the PE group and 21.5% in the PTFE group (P = .010). There was no significant difference in early (≤30 days) and late (>30 days) T2EL between groups (P = .270 and P = .311). There was no difference in the freedom from endoleak type II reinterventions between groups (P = .877).

CONCLUSIONS

The prevalence of T2EL after elective EVAR is significantly higher with the use of PTFE-based endografts compared with PE-based endografts. This difference is mostly based on T2EL diagnosed after 30 days of follow-up.

Significance of poly(ethylene terephthalate) (PET) substrate crystallinity on enzymatic degradation

Poly(ethylene terephthalate) (PET) is a semi-crystalline plastic polyester material with a global production volume of 83 Mt/year. PET is mainly used in textiles, but also widely used for packaging materials, notably plastic bottles, and is a major contributor to environmental plastic waste accumulation. Now that enzymes have been demonstrated to catalyze PET degradation, new options for sustainable bio-recycling of PET materials via enzymatic catalysis have emerged. The enzymatic degradation rate is strongly influenced by the properties of PET, notably the degree of crystallinity, XC. The higher the XC of the PET material, the slower the enzymatic rate. Crystallization of PET, resulting in increased XC, is induced thermally (via heating) and/or mechanically (via stretching), and the XC of most PET plastic bottles and microplastics exceeds what currently known enzymes can readily degrade. The enzymatic action occurs at the surface of the insoluble PET material and improves when the polyester chain mobility increases. The chain mobility increases drastically when the temperature exceeds the glass transition temperature, Tg, which is ∼40 °C at the surface layer of PET. Since PET crystallization starts at 70 °C, the ideal temperature for enzymatic degradation is just below 70 °C to balance high chain mobility and enzymatic reaction activation without inducing crystal formation. This paper reviews the current understanding on the properties of PET as an enzyme substrate and summarizes the most recent knowledge of how the crystalline and amorphous regions of PET form, and how the XC and the Tg impact the efficiency of enzymatic PET degradation.

Significance of Plastic Recycling with the Focus on Polyesters - Creating a Circular Economy

Plastics materials are essential in every part of our lives, resulting in their increasing production and consumption. Consequently, recycling of plastics has been of great importance in the last decades. Among all types of plastics, polyesters have become very appealing for numerous kinds of applications, making their recycling crucial. Several techniques have been developed for the recycling of plastics with the aim of eliminating the waste accumulated, as well as to create a circular economy.

Impact of sewing on microfiber release from polyester fabric during laundry

Microfibers released from textile materials are receiving greater attention due to their severe adverse effects on the environment. Although mitigation strategies have been developed for laundering, researchers uphold that it is crucial to start mitigating at the source. In that aspect, this research aims to analyze the cutting and sewing methods of knitted fabrics and their impact on the microfiber release of garments during laundry. The results of the study have confirmed that cutting and sewing methods have a significant impact on the microfiber release of a garment. The analysis of different cutting methods showed that laser and ultrasonic cutting methods reduce the microfiber release up to 20 times compared to the conventional scissor-cut edges. While comparing the different stitch types, the overlock stitch type showed reduced shedding than the other stitch types (flatlock stitch and single needle lockstitch). Our results also showed that the use of more needles increases the microfiber emission among different stitch variations of the same stitch type. For instance, a 45.27 % increase in microfiber emission was reported with the 4-thread overlock stitch (2 needles) than with the 3-thread stitch (1 needle). Regarding seam type, the proposed edge finishing seam (EFb) was effective in reducing 93 % of microfiber release as the edges are completely covered. When the effect of stitch density is considered, in the case of single needle lockstitch and flatlock stitch, the microfiber release is reduced with increased stitch density. However, a different trend was noted in the overlock stitch, which needed detailed exploration in the future. The results confirmed that a proper selection of stitch, stitch density, and seam type would reduce the microfiber release from a garment by up to 64.6 %.

Microorganisms that produce enzymes active on biodegradable polyesters are ubiquitous

Biodegradability standards measure ultimate biodegradation of polymers by exposing the material under test to a natural microbial inoculum. Available tests developed by the International Organization for Standardization (ISO) use inoculums sampled from different environments e.g. soil, marine sediments, seawater. Understanding whether each inoculum is to be considered as microbially unique or not can be relevant for the interpretation of tests results. In this review, we address this question by consideration of the following: (i) the chemical nature of biodegradable plastics (virtually all biodegradable plastics are polyesters) (ii) the diffusion of ester bonds in nature both in simple molecules and in polymers (ubiquitous); (iii) the diffusion of decomposers capable of producing enzymes, called esterases, which accelerate the hydrolysis of esters, including polyesters (ubiquitous); (iv) the evidence showing that synthetic polyesters can be depolymerized by esterases (large and growing); (v) the evidence showing that these esterases are ubiquitous (growing and confirmed by bioinformatics studies). By combining the relevant available facts it can be concluded that if a certain polyester shows ultimate biodegradation when exposed to a natural inoculum, it can be considered biodegradable and need not be retested using other inoculums. Obviously, if the polymer does not show ultimate biodegradation it must be considered recalcitrant, until proven otherwise.

Impact of quantification method on microfiber assessment - A comparative analysis between mass and count based methods

Microfiber from textiles is one of the new anthropogenic pollutants which attracted a wide range of researchers. Domestic laundry, being the most common cause of microfiber release from textiles, is widely studied. Studies exhibit a broad range of quantities of microfibers owing to the distinct quantification methodologies employed due to their convenience and resource availability. Out of several such estimation processes, reporting microfiber quantity in numbers or mass (mg or g) is quite common with respect to the unit area or weight of the textile used. However, results reported by different literature vary significantly. Hence, this study aims to analyze the microfiber release from knitted polyester fabric using count- and mass-based methods. Four different fabrics were used for this study with three different counting processes from literature along with direct weight difference estimation. The results of the direct counting method showed that the average microfiber release of selected fabrics is 13.28-33.16 microfibers per sq.cm, whereas, the direct weight estimation showed an average weight of 0.0664 ± 0.0289 mg/sq.cm. The subsequent conversion showed a release of 887.89 ± 633.49 microfibers/sq.cm of the fabric. Further, the microfiber mass was also estimated using the number of microfiber count and found that a sq.cm of fabric releases up to 0.0010-0.0024 mg of microfibers. While comparing the results, the weight-based estimation showed a significantly higher microfiber release (41.3-42.9 times) than the direct counting method. The deposition of surfactants in detergents, contaminants from the water, atmospheric contaminants, and finishes released from the fabric can be the sources of additional weights noted in the direct mass estimation. As the weight-based method is quite simple and the fastest way to quantify the microfibers, future studies must focus on this area to reduce the error percentage in quantification.

Integrated Photochromic-Photothermal Processes for Catalytic Plastic Upcycling

Incorporating high-energy ultraviolet (UV) photons into photothermal catalytic processes may enable photothermal-photochemical synergistic catalysis, which represents a transformative technology for waste plastic recycling. The major challenge is avoiding side reactions and by-products caused by these energetic photons. Here, we break through the limitation of the existing photothermal conversion mechanism and propose a photochromic-photothermal catalytic system based on polyol-ligated TiO2 nanocrystals. Upon UV or sunlight irradiation, the chemically bonded polyols can rapidly capture holes generated by TiO2 , enabling photogenerated electrons to reduce Ti4+ to Ti3+ and produce oxygen vacancies. The resulting abundant defect energy levels boost sunlight-to-heat conversion efficiency, and simultaneously the oxygen vacancies facilitate polyester glycolysis by activating the nucleophilic addition-elimination process. As a result, compared to commercial TiO2 (P25), we achieve 6-fold and 12.2-fold performance enhancements under thermal and photothermal conditions, respectively, while maintaining high selectivity to high-valued monomers. This paradigm-shift strategy directs energetic UV photons for activating catalysts and avoids their interaction with reactants, opening the possibility of substantially elevating the efficiency of more solar-driven catalysis.

A spit in time: identification of saliva stains and assessment of total DNA recovery up to 180 days after deposition

The main aim of this work was to validate the detection of saliva samples from denim, cotton, and polyester fabrics aged up to six months, applying rapid immunochromatographic tests resulting in the analysis of nuclear and mitochondrial DNA recovered. A comparison was also carried out between two saliva detection tests, Laboratory and Crime Scene. 50 μl saliva samples (three per time and test) were deposited on denim, cotton, and polyester fabrics. After 1, 3, 7, 14, 21, 30, 60, 90, 150, and 180 days of storage at room temperature, the samples were recovered by swabbing and detected by SERATEC® Amylase (Laboratory) test and SERATEC® SALIVA CS (Crime Scene) test (SERATEC®, Göttingen, Germany). DNA was isolated from the swab extraction buffer applying a silica-based methodology, and quantified based on fluorescent and human-specific quantifications. Then, it was submitted to STR profiling and mtDNA sequencing. According to our results, saliva stains up to six months after deposition remain valid specimens. The intensity of the bands varied among fabric type and time. Total DNA was successfully recovered from all tested samples, though with the limitations of obtaining partial nuclear DNA profiles from the oldest samples. In contrast, complete characterization of mtDNA was achieved from all samples. Lab and CS tests performed similar on the detection of saliva, as well as, DNA yield and profiling. Future research will be able to expand these results, analyzing the stability of other body fluids and the sensitivity of rapid immunochromatographic tests to detect them.

Polymeric Networks Derived from UV-Curing of Bio-Based Polyesters for Methyl Violet Removal

In this study, firstly, the syntheses and characterizations of biobased polyesters with different acid values obtained from the condensation reaction of biobased itaconic acid and polyethylene glycol were investigated. Then, UV curing was applied to form polymeric networks as adsorbent material from these polyesters containing different acids. Fourier transform infrared spectrometry (FTIR), Nuclear Magnetic Resonance Spectroscopy (NMR), X-ray Photoelectron Spectroscopy (XPS), Gel Permeation Chromatography (GPC) and scanning electron microscope (SEM) were used for the characterization of polymeric networks. The effects of the parameters of contact time, initial dye concentration, pH, temperature, amount of adsorbent on adsorption were investigated by batch method. In addition, adsorption equilibrium data were analyzed by Langmuir, Freundlich, Tempkin, Elovich, Redlich-Peterson, Harkin-Jura and Jossens adsorption models. Kinetic and thermodynamic studies were performed at 298, 308, 318 and 328 K and desorption studies were also examined. Comparison studies for the effects of the acid values of the adsorbent materials on the removal of methyl violet (MV) organic pollutant from aqueous solutions were analyzed. According to the pseudo-second-order model, the adsorption capacities were found to be ≥ 357.14 mg/g for the adsorbents. From the thermodynamic data, it was determined that the mechanism was exothermic and spontaneous. As a result of the third reuse, it was found that the adsorbents had a removal efficiency of ≥ 72.36%. According to the results observed the increase in the acidities in the chemical structure of bio-based polymeric networks enhances the adsoption properties.

Consumption of commercially sold dried fish snack "Charales" contaminated with microplastics in Mexico

Inadvertent human exposure to microplastics by the ingestion of microplastic-contaminated processed foods poses health risks and new preventative issues; nevertheless, investigations analyzing microplastic occurrences in commercially dried fish for direct human consumption are scarce. This study assessed the abundance and characteristics of microplastics in 25 commercially sold dried fish products (4 supermarkets, 3 street vendors, and 18 traditional agri-product farmers' markets) from two widely consumed and commercially important Chirostoma species (C. jordani and C. patzcuaro) in Mexico. Microplastics were detected in all the samples examined, with abundances ranging from 4.00 ± 0.94 to 55.33 ± 9.43 items g^-1. C. jordani dried fish samples had higher mean microplastic abundance (15.17 ± 5.90 items g^-1) than the C. patzcuaro dried fish samples (7.82 ± 2.90 items g^-1); nevertheless, there was no statistically significant difference in microplastic concentrations between the samples. The most prevalent type of microplastic was fiber (67.55%), followed by fragment (29.18%), film (3.00%), and sphere (0.27%). Non-colored microplastics (67.35%) predominated, while microplastic sizes varied from 24 to 1670 μm, with sizes less than 500 μm (84%) being the most common. ATR-FTIR analysis revealed polyester, acrylonitrile butadiene styrene, polyvinyl alcohol, ethylene-propylene copolymer, nylon-6 (3), cellophane, and viscose in the dried fish samples. Overall, this study's findings are the first in Latin America to demonstrate microplastic contamination in dried fish for human consumption, underscoring the need for developing countermeasures to prevent plastic pollution in fish-caught regions and reduce the risks of human exposure to these micropollutants.

Abundance and composition of microplastics in Tampico beach sediments, Tamaulipas State, southern Gulf of Mexico

The abundance and characteristics of microplastics (MPs) in coastal sediments from the Tampico beach, Gulf of Mexico was investigated. The MPs were extracted by a density separation method with saturated solutions of NaCl and ZnCl₂, the sediment-solution relationship was 1:3. MPs were classified according to its shape, color, and size under a stereoscopic microscope. Identification of MPs surface was carried out by a Scanning Electron Microscope (SEM). The polymer types were detected by a Fourier-transformed infrared (FTIR) Spectroscopy. Number of MPs in 20 g of sediments varies from 256 to 283 particles. The average abundance of MPs per kg was inferred as ∼13,392 microplastic particles. Fiber was the only MP particle identified in the Tampico beach, its size varied from 1.76 mm to 3.92 mm. Fibers identified were mostly transparent, blue, white, black, multicolor, yellow, pink, and red. Six different polymers were identified, i.e., polyester (PES), polyethylacrylate (PEA), cellophane, polyacrylonitrile (PAN), polystyrene acrylonitrile (SAN), and polyvinyl acetate ethylene (PVAE). PES is the most prevalent polymer in all samples.

Exploring structure-activity relationships for polymer biodegradability by microorganisms

Research on the environmental biodegradation or microbial biodegradation of polymers has substantially increased recently due to growing demand for biodegradable polymers for certain applications. Environmental biodegradation of a polymer depends on the intrinsic biodegradability of the polymer and the characteristics of the receiving environment. The intrinsic biodegradability of a polymer is determined by the chemical structure and resulting physical properties (e.g., glass transition temperature, melting temperature, modulus of elasticity, crystallinity, and crystal structure) of the polymer. Quantitative structure-activity relationships (QSARs) on biodegradability have been well-established for discrete (non-polymeric) organic chemicals, but not for polymers due to the absence of adequate biodegradability data based on consistent and standardized biodegradation tests with appropriate characterization and reporting of the polymers tested. This review summarizes empirical structure-activity relationships (SARs) for biodegradability of polymers in laboratory studies involving various environmental matrices. In general, polyolefins with carbon-carbon chain are not biodegradable, while polymers containing labile bonds such as ester, ether, amide, or glycosidic bonds in their polymer chain may be favorable for biodegradation. Under a univariate scenario, polymers with higher molecular weight, higher crosslinking, lower water solubility, higher degree of substitution (i.e., higher average number of substituted functional groups per monomer unit), and higher crystallinity may result in reduced biodegradability. This review paper also highlights some of the challenges that hamper QSAR development for polymer biodegradability and stresses the need for better characterization of polymer structures used in biodegradation studies and emphasizes the necessity for consistent testing conditions for the ease of cross-comparison and quantitative modeling analysis during future QSAR development.

A Systematic Review on Polyester Scaffolds in Dental Three-dimensional Cell Printing: Transferring Art from the Laboratories to the Clinics

Objective

The purpose of this systematic review is to describe developments in three-dimensional (3D) cell printing in the formation of dental pulp tissue using polyester as a scaffold to revitalize the damaged dental pulp tissue.

Materials and methods

A literature search for all the data published in PubMed and Google Scholar from January 2000 to April 2022 was conducted. Articles with the keywords 3D cell printing, scaffolds, polyester, dental pulp, and dentistry were used. Inclusion criteria consisted of any publication in electronic or print media directly studying or commenting on the use of polyester scaffolds in 3D cell printing technology in the regeneration of dental pulp. A total of 528 articles were selected, of which 27 duplicates and 286 irrelevant articles were discarded. A total of 215 articles were finally included in the systematic review.

Result and conclusion

For dental pulp regeneration, several scaffolds have been discovered to be appealing. Polylactic acid (PLA), polyglycolic acid (PGA), and their copolymers are nontoxic and biocompatible synthetic polyesters that degrade by hydrolysis and have received Food and Drug Administration (FDA) approval for a variety of applications. This review paper is intended to spark new ideas for using a certain scaffold in a specific regenerative approach to produce the desired pulp-dentin complex.

Recovery rates of selected body odor substances in different textiles applying various work-up and storage conditions measured by gas chromatography-mass spectrometry

BACKGROUND

Body odor is an important aspect in interpersonal communication. For psychological and chemical research on body odors, suitable procedures for sampling and application, and analysis of body odors are essential. In this study, different textile fabrics (polyester, cotton, and Gazin gauze) were comparatively evaluated in view of their potential suitability for body odor sampling by determining recovery rates of selected body odor substances. In addition, the impact of sample preparation and storage conditions on the recovery rates was determined.

RESULTS

The recovery rates of dimethyl disulfide, (E)-non-2-enal, 5α-androst-16-en-3-one, 6-methylhept-5-en-2-one, heptanal and 3-sulfanylhexan-1-ol were determined under different conditions of storage (storage for 30 min at room temperature or storage for 30 min at room temperature followed by freezing at - 80 °C for 4 weeks) and sample work-up (solvent extraction with and without solvent-assisted flavour evaporation, in the following: SAFE). SAFE led to overall lower recovery rates with a significant effect for (E)-non-2-enal and 5α-androst-16-en-3-one. Nevertheless, the results showed that SAFE can be an essential step when working with a complex matrix. When comparing the different fabrics, except for (E)-non-2-enal no difference between the recovery rates obtained for cotton and polyester became evident. Gazin gauze showed lower recovery rates for all compounds. Finally, our results showed that the here investigated target compounds are stable during storage for four weeks at - 80 °C.

SIGNIFICANCE AND NOVELTY

The results show on the one hand that the here investigated compounds were stable during storage and that the fiber type had limited influence on overall recovery rates. On the other hand, they highlight the limitations of using textile materials for sampling of volatile substances, especially with regard to low recovery rates for certain substances and the necessity of material pre-treatment or distillation steps for enabling GC-MS analysis after solvent extraction.

Characterization of fiber fragments released from polyester textiles during UV weathering

Synthetic textiles are considered a prime source of microplastics fibers which are a prevalent shape of microplastic pollution. Whilst the release mechanisms and formation of such microplastic fibers have been so far mainly studied in connection with laundry washing, there are some studies emerging that describe also other release pathways for microplastic fibers such as abrasion during wearing. The aim of this study was to consider weathering as another process contributing to the formation of microplastic fibers and their presence in the environment. Four types of polyester fabrics were selected and exposed to artificial weathering by UV-light for two months. The fabrics were extracted every 15 days to quantify and characterize the formed microplastics. Microplastic fibers with the diameter matching the size of the fibers in the textiles were observed. However, additional microplastic fibers of different shapes were also formed. These included partially broken fibers, thin fibers with a diameter below the size of the fiber in the fabrics, fibers flattened into a ribbon, and non-fibrous microplastics. The released microplastics evinced physical alterations on their surface in the form of pits and cracks. The released microplastics exhibited a steep increase in number with progressing weathering; from hundreds of fibers per gram of textile from unaged fabrics, to hundred thousands fibers (150,000-450,000 MPF/g) after 2 months of weathering. Additional 10,000-52,000 unfibrous microplastics/g were released from the weathered fabrics. While plain fabrics showed higher releases than interlock and fleece, further research is needed to evaluate the importance of the textile architecture on the weathering process in comparison with the production history of the fabrics. Based on a comparison with washing studies with the same textiles, we can estimate that the potential of weathered fabrics to be a source of microplastic fibers can be 20-40 times larger than washing only.

Chemically Recyclable Polyethylene-like Sulfur-Containing Plastics from Sustainable Feedstocks

The green revolution in plastics should be accelerated due to growing sustainability concerns. Here, we develop a series of chemically recyclable polymers from the first reported cascade polymerization of H₂ O, COS, and diacrylates. In addition to abundant feedstocks, the method is efficient and air-tolerant, uses common organic bases as catalysts, and yields polymers with high molecular weights under mild conditions. Such polymers, structurally like polyethylene with low-density in-chain polar groups, manifest impressive toughness and ductility comparable to high-density polyethylene. The in-chain ester group acts as a breaking point, enabling these polymers to undergo chemical recycling through two loops. The structures and properties of these polymers also have an immeasurably expanded range owing to the versatility of our method. The readily available raw materials, facile synthesis, and high performance make these polymers promising prospects as sustainable materials in practice.

PEGylated and functionalized polylactide-based nanocapsules: An overview

Polymeric nanocapsules (NC) are versatile mixed vesicular nanocarriers, generally containing a lipid core with a polymeric wall. They have been first developed over four decades ago with outstanding applicability in the cosmetic and pharmaceutical fields. Biodegradable polyesters are frequently used in nanocapsule preparation and among them, polylactic acid (PLA) derivatives and copolymers, such as PLGA and amphiphilic block copolymers, are widely used and considered safe for different administration routes. PLA functionalization strategies have been developed to obtain more versatile polymers and to allow the conjugation with bioactive ligands for cell-targeted NC. This review intends to provide steps in the evolution of NC since its first report and the recent literature on PLA-based NC applications. PLA-based polymer synthesis and surface modifications are included, as well as the use of NC as a novel tool for combined treatment, diagnostics, and imaging in one delivery system. Furthermore, the use of NC to carry therapeutic and/or imaging agents for different diseases, mainly cancer, inflammation, and infections is presented and reviewed. Constraints that impair translation to the clinic are discussed to provide safe and reproducible PLA-based nanocapsules on the market. We reviewed the entire period in the literature where the term "nanocapsules" appears for the first time until the present day, selecting original scientific publications and the most relevant patent literature related to PLA-based NC. We presented to readers a historical overview of these Sui generis nanostructures.

Chironomus sp. as a Bioindicator for Assessing Microplastic Contamination and the Heavy Metals Associated with It in the Sediment of Wastewater in Sohag Governorate, Egypt

The consequences of plastic waste pollution have imposed wide global concerns. One of these consequences is the production of micro- and nanosized particles (MNPLs) from aged plastics. The problem of MNPLs is magnified by their potential to transport various contaminants due to their large surface area and other variable physiochemical properties. From this point on, it is important to know the real concentration of MNPLs in our environment and their potential to internalize wild organisms as well as transfer contaminants that are completely highlighted. As a result, our study is the first to detect MP pollution in the upper Egypt wastewater environment. It could be utilized as a baseline to estimate MP wastes and develop management techniques, particularly in Sohag Governorate. The concentration and characterization of MPs in sludge, water, Chironomus sp. larvae, and their tubes were studied in this work. Chironomus sp. is a reliable bioindicator prevalent in such contaminated environments, and it was used to demonstrate how MPs invade biological barriers. Our results found that red and blue polyester fibers are much more prevalent than other polymers, colors, and shapes of MPs. While each dry kilogram of wastewater sludge contains 310 ± 84 particles, this amount is reduced to 1.55 ± 0.7 per liter in the water column. Biologically, the present study succeeded in detecting the MPs inside the wild organism, with concentrations reaching 71 ± 21 and 4.41 ± 1.1 particles per gram wet weight in Chironomus sp. larvae and their tubes (chironomid tubes), respectively. The potential hazard of MPs stems from their propensity to transfer pollutants. At this point, our findings revealed a corresponding and significant concentration of various heavy metals (Cu, Pb, Cd, and Ni) detected in MPs or Chironomus sp. versus sludge. In conclusion, our findings not only proved the presence of MPs in wastewater but also demonstrated their ability to internalize cross-wild organisms, allowing toxins to accumulate inside their bodies, raising concerns about the possible health impacts of plastic pollution.

Functionalization of cellulosic and polyester textiles using reduced Schiff base (RSB) of eco-friendly vanillin

Vanillin is an active ingredient found in the crop 'vanilla' and is traditionally extracted from the 'vanilla pod'. Vanillin intrinsically is not a suitable candidate for imparting durable functional features into textile substate due to its smaller chemical structure which leads to leaching of the same during washing operation. To enlarge the structure, in the present study, vanillin has been converted into 4-(benzylamino) methyl))-2-methoxyphenol vanillin derivative (reduced Schiff base) with considerable amount of yield by using a simple one-step process and the synthesized product has been characterized by 1H, C13 NMR, FTIR, and Raman analysis. Thereafter, the reduced Schiff base of vanillin (RSB) has been integrated on cotton as well as polyethylene terephthalate (PET) fabric using high temperature high pressure (HT-HP) technique for imparting multiple functionalities. FESEM EDX analysis has confirmed the integration of RSB on both the fabrics by revealing uniform presence of the nitrogen (of the synthesized derivative) on the treated textile materials. Both types of functionalized textiles have demonstrated appealing color shades with an excellent antimicrobial activity of about 90% against Escherichia coli (E. coli) bacteria. The treated fabrics could cater pleasing fragrance and exhibit 90% antioxidant properties. Moreover, enlarged vanillin derivative in the form of RSB can retain its properties in the fabrics even after repeated machine launderings. RSB-treated cotton fabric has shown ultra-violet protection factor (UPF) of 38 which drops to 24 after washing whereas in case of PET treated fabric, the observed UPF values are 265 and 164 before and after washing, respectively. The RSB treatment has been found to be cytotoxically secure and biocompatible as tested on the PET fabric. Other required properties of the treated fabrics such as water absorbency, flexibility, etc. have also been found to be intact. Thus, the presented study reveals a new class of safe material that can be derived from eco-friendly vanillin and has the potential to replace hazardous chemicals that are currently used in textile chemical processing industries.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10570-023-05085-z.

Microfiber mitigation from synthetic textiles - impact of combined surface modification and finishing process

The use of proper mitigation strategies to control the impact of microfiber pollution is need of the hour requirement. Though several laundry aids were developed to reduce the environmental impact caused by synthetic microfiber, due to the lack of awareness among the public, their effectiveness was limited. Hence, the mitigation measures at the production stage of textile materials can be a proactive solution with greater effectiveness in mitigating the issue at different stages rather than focussing only on domestic laundering. In this aspect, few recent attempts have been made to control the microfiber release from textiles by the surface finishing process. Thus, the current research focused on utilizing the surface modification process and surface finishing process to reduce the microfiber release behavior of knitted polyester fabrics. In this study, polyester knitted fabric (PES) was surface finished with chitosan (PES-Ch), sericin (PES-Se), and polyvinyl alcohol (PES-PVA), and their effectiveness in reducing microfiber shedding during laundry was analyzed. These finishes are applied directly on the polyester fabric and also after surface modification by alkali (Al) and enzyme (En) pre-treatments. The results reported that at the first wash, directly finished samples showed a reduction of 30-40% in microfiber shedding, and the samples finished after alkali pre-treatment showed a significant reduction of 47-84.29% (p < 0.05). Reduction in microfiber release was noted in the order of chitosan finish with alkali pre-treatment (PES-Al-Ch) > chitosan finish (PES-Ch) > sericin finish with alkali pre-treatment (PES-Al-Se) > polyvinyl alcohol finish with alkali pre-treatment (PES-Al-PVA) > polyvinyl alcohol finish (PES-PVA) for both fiber count and mass. In the case of enzyme pre-treatment, no reduction was reported, irrespective of the finishes applied. Repeated wash test results showed that the finishes could withstand and effectively control the microfiber release from the polyester fabric even after 20 washes. The performance of PES-Al-Ch fabric was superior among other modifications up to the fifth wash (with an 83.55% reduction in microfiber release). At extended washes like the 15th and 20th wash, the performance of PES-Al-PVA fabric was found to be better, with 94% and 95% microfiber reduction, respectively.

Abundance and distribution of microplastics in surface waters of the Kattegat/ Skagerrak (Denmark)

Microplastics (MPs) are ubiquitous pollutants in the ocean, and there is a general concern about their persistence and potential effects on marine ecosystems. We still know little about the smaller size-fraction of marine MPs (MPs <300 μm), which are not collected with standard nets for MPs monitoring (e.g., Manta net). This study aims to determine the concentration, composition, and size distribution of MPs down to 10 μm in the Kattegat/Skagerrak area. Surface water samples were collected at fourteen stations using a plastic-free pump-filter device (UFO sampler) in October 2020. The samples were treated with an enzymatic-oxidative method and analyzed using FPA-μFTIR imaging. MPs concentrations ranged between 11 and 87 MP m^-3, with 88% of the MPs being smaller than 300 μm. The most abundant shape of MPs were fragments (56%), and polyester, polypropylene, and polyethylene were the dominant synthetic polymer types. The concentration of MPs shows a significant positive correlation to the seawater density. Furthermore, there was a tendency towards higher MPs concentrations in the Northern and the Southern parts of the study area. The concentration of MPs collected with the UFO sampler was several orders of magnitude higher than those commonly found in samples collected with the Manta net due to the dominance of MP smaller size fractions. Despite the multiple potential sources of MPs in the study area, the level of MPs pollution in the surface waters was low compared (<100 MP m^-3) to other regions. The concentrations of MPs found in the studied surface waters were six orders of magnitude lower than those causing negative effects on pelagic organisms based on laboratory exposure studies, thus is not expected to cause any impact on the pelagic food web.

A review on polyester and polyester-amide thin film composite nanofiltration membranes: Synthesis, characteristics and applications

Nanofiltration (NF) membranes have been widely used in various fields including water treatment and other separation processes, while conventional thin film composite (TFC) membranes with polyamide (PA) selective layers suffer the problems of fouling and chlorine intolerance. Due to the abundant hydrophilic hydroxyl groups and ester bonds free from chlorine attack, the TFC membranes composed of polyester (PE) or polyester-amide (PEA) selective layers have been proven to possess enhanced anti-fouling properties and superior chlorine resistance. In this review, the research progress of PE and PEA nanofiltration membranes is systematically summarized according to the variety of hydroxyl-containing monomers for membrane fabrication by the interfacial polymerization (IP) reaction. The synthesis strategies as well as the mechanisms for tailoring properties and performance of PE and PEA membranes are analyzed, and the membrane application advantages are demonstrated. Moreover, current challenges and future perspectives of the development of PE and PEA nanofiltration membranes are proposed. This review can offer guidance for designing high-performance PE and PEA membranes, thereby further promoting the efficacy of nanofiltration.

Patch angioplasty during carotid endarterectomy using different materials has similar clinical outcomes

OBJECTIVE

Patch angioplasty during carotid endarterectomy (CEA) is commonly used to treat carotid artery stenosis. However, the choice of which patch to use remains a matter of debate. Autologous venous material has disadvantages such as wound-related problems at the harvest site and a prolonged intervention time. These limitations can be bypassed when synthetic or biological patches are used. Both materials have been associated with divergent advantages and disadvantages. Therefore, the aim of our study was to compare the long-term follow-up outcomes in patients who underwent CEA and closure with either a bovine pericardial patch (BPP) or polyester patch.

METHODS

A retrospective cohort study was conducted including all patients who underwent primary CEA and closure with a BPP or a polyester patch between January 2010 and December 2020 at our tertiary referral center. In 2015, the BPP was introduced as an alternative for polyester. The primary outcome was the occurrence of transient ischemic attack (TIA) or cerebrovascular accident (CVA) during follow-up and secondary outcomes included restenosis, reintervention, all-cause mortality, and patch infection. Cox proportional hazard models were used and hazard ratios with 95% confidence intervals were used to predict these outcomes.

RESULTS

We included 417 CEA patients; 254 patients (61%) received a BPP and 163 received (39%) a polyester patch. The mean age was 70.2 ± 8.7 years and 67% were male. The median follow-up time was 15 months (range, 12-27 months) for BPP and 42 months (range, 16-60 months) for polyester (P < .001). Postoperative hematoma (≤30 days) was significantly lower in the BPP cohort (2% BPP vs 6% polyester; P = .047). No other significant differences on short-term outcomes were found. Univariable Cox regression analyses showed no significant differences between the effect estimates of polyester and BPP on TIA or CVA (P = .106), restenosis (P = .211), reintervention (P = .549), or all-cause mortality (P = .158). No significant differences were found after adjusting for confounders in the multivariable analyses: TIA or CVA (P = .939), restenosis (P = .057), reintervention (P = .193) and all-cause mortality (P = .742). Three patients with a polyester patch had patch infection compared with none of the patients in the group who received a BPP.

CONCLUSIONS

This large retrospective study showed comparable safety and durability of both BPP and polyester suggesting that both patch types can be safely applied for CEA with patch angioplasty. Patch infection was rare and was absent in the BPP group.

3D printed matrix solid forms: Can the drug solubility and dose customisation affect their controlled release behaviour?

The use of 3D printing in pharmaceutics has grown over the last years, along with the number of studies on the impact of the composition of these formulations on their pharmaceutical and biopharmaceutical properties. Recently, we reported the combined effect of the infill percentage and the presence of a pore former on the drug release behaviour of 3D printed matrix solid forms prepared by fused deposition modelling. However, there are some open questions about the effect of the drug solubility and the size of these dosage forms on their controlled release properties. Therefore, we produced poly(Ɛ-caprolactone) filaments containing different soluble forms of dexamethasone (free acid, DEX; acetate ester, DEX-A; and phosphate salt, DEX-P), which showed suitable mechanical properties and printability. 3D printed solid forms were produced in two different sizes. The formulations composed of DEX-P released about 50% of drug after 10 h, while those containing DEX or DEX-A released about 9%. The drug release profiles from the 3D printed forms containing the same drug form but with different sizes were almost completely overlapped. Therefore, these 3D printed matrix solid forms can have their drug content customised by adjusting their size, without changing their controlled release behaviour.

Biodegradation of renewable polyurethane foams in marine environments occurs through depolymerization by marine microorganisms

Accumulation of plastics in the Earth's oceans is causing widespread disruption to marine ecosystems. To help mitigate the environmental burden caused by non-degradable plastics, we have previously developed a commercially relevant polyurethane (PU) foam derived from renewable biological materials that can be depolymerized into its constituent monomers and consumed by microorganisms in soil or compost. Here we demonstrate that these same PU foams can be biodegraded by marine microorganisms in the ocean and by isolated marine microorganisms in an ex situ seawater environment. Using Fourier-transform infrared (FTIR) spectroscopy, we tracked molecular changes imparted by microbial breakdown of the PU polymers; and utilized scanning electron microscopy (SEM) to demonstrate the loss of physical structure associated with colonization of microorganisms on the PU foams. We subsequently enriched, isolated, and identified individual microorganisms, from six marine sites around San Diego, CA, that are capable of depolymerizing, metabolizing, and accumulating biomass using these PU foams as a sole carbon source. Analysis using SEM, FTIR, and gas chromatography-mass spectrometry (GCMS) confirmed that these microorganisms depolymerized the PU into its constitutive diols, diacids, and other PU fragments. SEM and FTIR results from isolated organismal biodegradation experiments exactly matched those from ex situ and ocean biodegradation samples, suggesting that these PU foam would undergo biodegradation in a natural ocean environment by enzymatic depolymerization of the PU foams and eventual uptake of the degradation products into biomass by marine microorganisms, should these foams unintentionally end up in the marine environment, as many plastics do.

Microplastics in atmospheric dust samples of Sistan: sources and distribution

In this work, the amount and physical and chemical characteristics of airborne microplastics (MPs) pollution in dust samples in Sistan, located in the eastern part of Iran, is reported. Sampling stations were selected according to the wind direction and population density. MPs were collected by a static dust sampler and analyzed by optical microscopy and FT-IR spectroscopy. Results showed that the distribution frequency of MPs in residential and non-residential areas was 6 to 11 pieces per 100 g (pcs/100 g) with an average abundance of 9.8 pcs/100 g. Fragmented MPs were approximately consisted 64% of total MPs and their sizes were in the range of 0.9-3.8 mm. Polyethylene (49%), polystyrene (21%) and polyester (18%) were the main MPs presented in the dust samples. It was observed that population density and wind direction were the most important parameters affecting MPs pollution in dust.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-022-00833-y.

End-of-life biodegradation? how to assess the composting of polyesters in the lab and the field

The aerobic composting of biodegradable plastics can be a promising solution to the growing issue of waste accumulation. Therefore, this article offers a review of papers investigating the biodegradability of polyesters (PLA, PHB, PBS and PCL) in home- and industrial composting. Not only the thermal and biodegradation properties are discussed, but also a comparison is made between the different polyesters under the same composting conditions. From this review, it becomes clear that composting shows promise for polyester waste management. However, although several methods for assessing the composting properties of polyester have been developed, the fact that they rarely follow the same standards does not allow for a comparative analysis that would clearly define composting as the most viable solution.

Controlling factors of microplastic fibre settling through a water column

Microplastic fibres are the most abundant microplastics in waterways worldwide. The settling of fibres is distinct from other particles because of their aspect ratio and shape. In this paper, we test the hypothesis that length, curliness, and settling orientation control the settling velocity of microplastic fibres in a suite of laboratory experiments. Using a Particle Tracking Velocimetry method, we measured the settling velocity of 683 polyester microplastic fibres of 1 to 4 mm in length. Experimental findings support our hypothesis that for microplastic fibre longer than 1 mm, changing settling orientation from horizontal to vertical can increase 1.7 times the settling velocity. Fibre curliness can significantly reduce the settling velocity, where a curly fibre 1.3 times longer than a straight fibre can settle 1.75 times slower. In contrast, short microplastic fibres (less than 1 mm) mostly settle horizontally, and their settling velocity is unaffected by curliness. The drag force exerting on settling microplastic fibres was analysed, and the sphere-equivalent diameter was found to be a good representation of microplastic fibre size to predict the drag coefficient. Measured settling velocity ranges between 0.1 and 0.55 mm/s and exhibits a slight increase with the increasing length of the fibres. This low-velocity range raises concerns that microplastic fibres can favour biological flocculation, form clustered aggregates with microorganisms, feed aquatic organisms and cause bioaccumulation at higher trophic levels.

Transfer of bacteria between fabric and surrogate skin

BACKGROUND

Contaminated textiles serve as fomites in healthcare settings. The extent of transfer of pathogens from fabrics depends on the surface properties of the 2 contact surfaces.

METHODS

In the current study, the effect of surface energy and surface roughness of fabrics on the transfer of Escherichia coli and Staphylococcus aureus to and from textiles to surrogate skin were determined. Three fabrics (100% cotton, 100% polyester, and 50-50 blend of cotton and polyester) having identical constructional parameters, were characterised on the basis of surface roughness, and energy. Assessment of transfer of bacteria was carried out by bringing the matrix seeded with inoculum in contact with the sterilized matrix for a predetermined period of time, followed by dislodging of cells from the recipient surface by vortexing, and plating.

RESULTS AND DISCUSSION

Results showed that 100% polyester attracted the highest number of bacterial cells compared to the others. It also released the maximum number of bacteria upon coming in contact with surrogate skin. Properties of fabrics like absorbency, surface energy, and surface roughness, simultaneously affected transfer.

CONCLUSIONS

It is advisable to minimize the use of 100% polyester in healthcare settings to curb the transfer load of bacteria from one surface to another.

In vivo biocompatible shape memory polyester derived from recycled polycarbonate e-waste for biomedical application

From the last few decades, the usage of polycarbonate (PC) has tremendously increased due to its engineering properties such as outstanding mechanical strength, superior toughness, and good optical transparency. Owning to these properties, PC has widespread applications in the field of electronics, construction, data storage, automotive industry and subsequently resulted in an ever-increasing volume of post-consumer PC e-waste, which also increases the environmental pollution with time due to its nonbiodegradability nature. Therefore, recycling of PC has become a significant challenge throughout the globe. Herein, we first time reported synthesis of a family of low-cost biodegradable and biocompatible biopolymers using solvent and catalyst free melt polycondensation reaction of recycled PC e-waste derived monomer bis(hydroxyethyl ether) of bisphenol A (BHEEB) along with other renewable resources such as sebacic acid, citric acid and mannitol. The synthesis of the polyester was confirmed by FTIR spectroscopy, NMR spectroscopy, XRD and DSC. The mechanical properties and biodegradation behaviour of the polyester can be fine-tuned by simply varying the monomer feed ratio. In addition to that, the polyester demonstrated excellent shape memory property in ambient temperature along with outstanding recovery properties. In addition to this, the synthesized polyester showed exceptional in vitro and in vivo cytocompatibility as well as cell proliferation rate against mouse fibroblast cells (NIH-3 T3) and biocompatibility, respectively. Therefore, the novel polyesters derived from recycled PC e-waste may be potential resorbable biomaterial for tissue engineering applications in future.

Advancing the Development of Recyclable Aromatic Polyesters by Functionalization and Stereocomplexation

The development of innovative synthetic polymer systems to overcome the trade-offs between the polymer's depolymerizability and performance properties is in high demand for advanced material applications and sustainable development. In this contribution, we prepared a class of aromatic cyclic esters (M1-M5) from thiosalicylic acid and epoxides by facile one-pot synthesis. Ring-opening polymerization of Ms afforded aromatic polyesters P(M)s with high molecular weights and narrow dispersities. The physical and mechanical properties of P(M)s can be modulated by stereocomplexation and regulation of the side-chain flexibility of the polymers, ultimately achieving high-performance properties such as high thermal stability and crystallinity (T_m up to 209 °C), as well as polyolefin-like high mechanical strength, ductility, and toughness. Furthermore, the functionalizable moieties of P(M)s have driven a wide array of post-polymerization modifications toward access to value-added materials. More importantly, the P(M)s were able to selectively depolymerize into monomers in excellent yields, thus establishing its circular life cycle.

Forensic examination of textile fibres using Raman imaging and multivariate analysis

Vibrational spectroscopic techniques have shown to be highly suitable for the identification and comparison of textile fibres and clothing fabrics. On the other hand, new chemical imaging modes based on these spectroscopic techniques are becoming useful in multiple fields. This is particularly important to, for instance, chemically visualize and screen different samples including forensic evidence (crime scene investigation), chemical and food products (quality control), biological tissues and living beings (medical imaging), among others. This study explores the forensic examination and selective chemical visualization of textile fibres and clothing fabrics using Raman imaging. Four experiments were performed, which were focused on the screening of (i) white different materials made of 100 % cotton (gauze, cotton wool, t-shirt, and swab), (ii) polyester and cotton fabrics evidence of the same colour, (iii) five different coloured cotton fabrics, and (iv) textile fibres of different materials (acrylic, cotton, nylon, polyester, and silk). Several methods of multivariate chemometric analysis including principal component analysis (PCA), multivariate analysis of variance (MANOVA), and multivariate curve resolution (MCR) were applied to enhance the limited visual comparison of the spectra accomplished with the unaided eye. The results evidenced the suitability of Raman imaging to statistically discriminate textile fibres and fabrics due to the chemical composition of both the clothing material and the dyestuff.

Microplastics in urban stormwater-developing a methodology for its monitoring

This study presents microplastics results for stormwater collected in retention ponds. A novel procedure was developed to collect microplastic (MP) particles by filtering stormwater using a purpose-built cascade filtration setup which included 4 steel filters of pore size, 48.5, 170, 2500 and 5000 μm. Based on the methodologies proposed in the literature, a novel procedure was developed incorporating a combination of optical and FTIR methods for quantification and identification of microplastics. The developed methodology was applied for determining and characterising MP from two retention ponds. Average concentrations of 2067 and 2133 MP/m³ were observed, respectively, for dry and wet periods at site 1. Similar concentrations were observed for site 2. The results showed a slight increase in the microplastics concentration for the wet period. Most MP particles existed in the size range 48.5-170 μm and 170-2500 μm. Among the type of MP particles, polyester was significantly more abundant than other types of plastics (78-94%). Comparing the data obtained in this study with those from the literature, it was apparent that the stormwater originated from two urban catchments has been subjected to considerable microplastic contamination. This can be attributed to anthropogenic activities in urban areas. Microplastic particles in the stormwater can have an adverse impact on aquatic life present in the receiving water bodies. Also, the presence of MP may suggest the existence of nanoplastics in urban stormwater. This finding can have broader implications for urban stormwater management.

Microplastics accumulation in functional feeding guilds and functional habit groups of freshwater macrobenthic invertebrates: Novel insights in a riverine ecosystem

Microplastics pose a major threat for aquatic ecosystems, but the contamination dynamics in organisms inhabiting freshwater ecosystems is still little studied. Largely used for biomonitoring, macrobenthic invertebrates provide a pivotal trophic resource for many fish and bird species. In this study, we investigated the microplastics contamination in a macrobenthic invertebrate community (2772 individuals belonging to 33 taxa identified) in a high-plain riverine ecosystem (Vipacco River, northeast Italy) and compared the amount of microplastics accumulated in functional feeding guilds/functional habit groups. Microplastics (cellulosic fibers associated with polyester) were found in 48.5% of the taxa, with the highest amount detected in the collector-gatherers, followed by predators. The collector-gatherers showed a significantly higher microplastic accumulation than the other functional feeding guilds, whereas there was no difference among the functional habit groups. The main source of microplastics pollution was most likely urban wastewater discharge points located along the river. Our study reports a novel approach about microplastic pollution assessment in lotic environments, as it focuses into the microplastic contamination dynamics in an entire macrobenthic invertebrate community perspective and underlines the need for further study.

The deposition of atmospheric microplastics in Jakarta-Indonesia: The coastal urban area

The air pollution in Jakarta has been recorded regularly; meanwhile, the information of atmospheric microplastics is still unknown. This study examines the characteristics (shape, size, and polymer) and deposition rate of atmospheric microplastics in Jakarta. The sample was obtained by putting a rain gauge for 12 months. All microplastic samples were analyzed for polymer using FT-IR. The lowest to the highest percentage of atmospheric microplastic based on shape were foam<fragment<fiber, meanwhile based on size were of 500-1000 μm < 300-500 μm. The detected polymers included polyester, polystyrene, polybutadiene, and polyethylene. The microplastics deposition rate ranged from 3 to 40 particles m^-2d^-1, with an average of 15 particles m^-2d^-1. The rainy season's deposition rate (23.422 particles m^-2d^-1) was higher than the dry season (5.745 particles m^-2d^-1). Our study proves that the atmospheric microplastic exists in Jakarta's air and needs to be considered to monitor by the government regularly.

Chemical characterization of variably degraded fibre glass reinforced plastic from the marine environment

Glass reinforced plastic (GRP) constitutes the commonest component of small sea going craft of all descriptions. This study provides a baseline molecular and elemental account of GRP's recovered from the marine environment. Fourteen samples of GRP sourced from scrapyards and one sample sourced from a GRP boat manufacturer were examined. Samples were analysed by x-ray fluorescence and mid infrared (MIR). The latter technique confirmed that all samples contained the same polyester resin, poly diallyl phthalate (PDP). The two techniques in combination indicate the presence of aluminium calcium borosilicate E-glass fibres (E denotes electrical) of variable origins. MIR results are consistent with hydrolysis of polyester, weakening of the glass fibre resin interface facilitating exposure of e-type fibres to water which accelerates fibre breakage. The implication being that aging of GRP in the marine environment represent sources for micro (<5 mm) and macro plastic release, plus fragmented asbestiform-like silicate fibres.