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PloS One 2022Lithography based additive manufacturing techniques, specifically digital light processing (DLP), are considered innovative manufacturing techniques for orthopaedic...
Lithography based additive manufacturing techniques, specifically digital light processing (DLP), are considered innovative manufacturing techniques for orthopaedic implants because of their potential for construction of complex geometries using polymers, metals, and ceramics. Hydroxyapatite (HA) coupons, printed using DLP, were evaluated for biological performance in supporting viability, proliferation, and osteogenic differentiation of the human cell line U2OS and human mesenchymal stem cells (MSCs) up to 35 days in culture to determine feasibility for future use in development of complex scaffold geometries. Contact angle, profilometry, and scanning electron microscopy (SEM) measurements showed the HA coupons to be hydrophilic, porous, and having micro size surface roughness, all within favourable cell culture ranges. The study found no impact of leachable and extractables form the DLP printing process. Cells seeded on coupons exhibited morphologies comparable to conventional tissue culture polystyrene plates. Cell proliferation rates, as determined by direct cell count and the RealTime-GloTM MT Cell Viability Assay, were similar on HA coupons and standard tissue culture polystyrene plates). Osteogenic differentiation of human MSCs on HA coupons was confirmed using alkaline phosphatase, Alizarin Red S and von Kossa staining. The morphology of MSCs cultured in osteogenic medium for 14 to 35 days was similar on HA coupons and tissue culture polystyrene plates, with osteogenic (geometric, cuboidal morphology with dark nodules) and adipogenic (lipid vesicles and deposits) features. We conclude that the DLP process and LithaBone HA400 slurry are biocompatible and are suitable for osteogenic applications. Coupons served as an effective evaluation design in the characterization and visualization of cell responses on DLP printed HA material. Results support the feasibility of future technical development for 3D printing of sophisticated scaffold designs, which can be constructed to meet the mechanical, chemical, and porosity requirements of an artificial bone scaffold.
Topics: Cell Differentiation; Cell Proliferation; Cells, Cultured; Durapatite; Humans; Osteogenesis; Polystyrenes; Stereolithography; Tissue Scaffolds
PubMed: 35939440
DOI: 10.1371/journal.pone.0272283 -
International Journal of Molecular... Nov 2023Polymers' controlled pyrolysis is an economical and environmentally friendly solution to prepare activated carbon. However, due to the experimental difficulty in...
Polymers' controlled pyrolysis is an economical and environmentally friendly solution to prepare activated carbon. However, due to the experimental difficulty in measuring the dependence between microstructure and pyrolysis parameters at high temperatures, the unknown pyrolysis mechanism hinders access to the target products with desirable morphologies and performances. In this study, we investigate the pyrolysis process of polystyrene (PS) under different heating rates and temperatures employing reactive molecular dynamics (ReaxFF-MD) simulations. A clear profile of the generation of pyrolysis products determined by the temperature and heating rate is constructed. It is found that the heating rate affects the type and amount of pyrolysis intermediates and their timing, and that low-rate heating helps yield more diverse pyrolysis intermediates. While the temperature affects the pyrolytic structure of the final equilibrium products, either too low or too high a target temperature is detrimental to generating large areas of the graphitized structure. The reduced time plots (RTPs) with simulation results predict a PS pyrolytic activation energy of 159.74 kJ/mol. The established theoretical evolution process matches experiments well, thus, contributing to preparing target activated carbons by referring to the regulatory mechanism of pyrolytic microstructure.
Topics: Polystyrenes; Molecular Dynamics Simulation; Pyrolysis; Temperature; Heating
PubMed: 38003591
DOI: 10.3390/ijms242216403 -
Proceedings of the National Academy of... Aug 2022Plastic waste represents one of the most urgent environmental challenges facing humankind. Upcycling has been proposed to solve the low profitability and high market...
Plastic waste represents one of the most urgent environmental challenges facing humankind. Upcycling has been proposed to solve the low profitability and high market sensitivity of known recycling methods. Existing upcycling methods operate under energy-intense conditions and use precious-metal catalysts, but produce low-value oligomers, monomers, and common aromatics. Herein, we report a tandem degradation-upcycling strategy to exploit high-value chemicals from polystyrene (PS) waste with high selectivity. We first degrade PS waste to aromatics using ultraviolet (UV) light and then valorize the intermediate to diphenylmethane. Low-cost AlCl catalyzes both the reactions of degradation and upcycling at ambient temperatures under atmospheric pressure. The degraded intermediates can advantageously serve as solvents for processing the solid plastic wastes, forming a self-sustainable circuitry. The low-value-input and high-value-output approach is thus substantially more sustainable and economically viable than conventional thermal processes, which operate at high-temperature, high-pressure conditions and use precious-metal catalysts, but produce low-value oligomers, monomers, and common aromatics. The cascade strategy is resilient to impurities from plastic waste streams and is generalizable to other high-value chemicals (e.g., benzophenone, 1,2-diphenylethane, and 4-phenyl-4-oxo butyric acid). The upcycling to diphenylmethane was tested at 1-kg laboratory scale and attested by industrial-scale techno-economic analysis, demonstrating sustainability and economic viability without government subsidies or tax credits.
Topics: Plastics; Polystyrenes; Recycling; Refuse Disposal; Solvents
PubMed: 35969757
DOI: 10.1073/pnas.2203346119 -
Sensors (Basel, Switzerland) Jul 2022(1) Background: A sustainable casting system that combines the use of a polystyrene bag, a prosthetic liner and a vacuum system was developed to reduce fabrication time...
(1) Background: A sustainable casting system that combines the use of a polystyrene bag, a prosthetic liner and a vacuum system was developed to reduce fabrication time while maintaining comfort for the trans-tibial prosthesis user. (2) Methods: Eight prosthetists (28.7 ± 8.25 years old) fit ten trans-tibial prosthesis wearers (46 ± 12.4 years old) with two types of total surface bearing (TSB) prostheses; a polystyrene bead (PS) prosthesis and a plaster of paris (POP) prosthesis. Duration of casting and combined mean peak pressure was measured at six locations on the residual limb using Force Sensing Resistors (FSR). A pressure uniformity score (%) was determined. Socket Comfort Scale (SCS) was also measured. (3) Results: Duration of casting for the POP method was 64.8 ± 9.53 min and 7.8 ± 2 min for the PS method, ( = 0.006). Pressure uniformity in the POP prosthesis was 79.3 ± 6.54 and 81.7 ± 5.83 in the PS prosthesis ( = 0.027). SCS in both prosthesis types were equivalent. (4) Conclusion: A rapid fit PS prosthesis was developed, with significantly shorter duration than the traditional POP method. Socket pressure uniformity was confirmed and improved in the PS method. Socket comfort was equal between the two prothesis types.
Topics: Amputation Stumps; Artificial Limbs; Polystyrenes; Prosthesis Design; Tibia; Walking
PubMed: 35890905
DOI: 10.3390/s22145224 -
Journal of Hazardous Materials Oct 2022The effects of polystyrene microplastic (PS-MP) size on neurotoxicity remain to be evaluated at various microsizes, and the seizurogenic effects of PS-MPs are unknown....
The effects of polystyrene microplastic (PS-MP) size on neurotoxicity remain to be evaluated at various microsizes, and the seizurogenic effects of PS-MPs are unknown. This study aimed to evaluate the swimming behavior of zebrafish larvae under light-dark transitions after exposure to four PS-MP sizes (i.e., 1, 6, 10, and 25 μm) at concentrations of 500, 5,000, and 50,000 particles/mL. Changes in electroencephalographic signals, seizure-related gene expression, and neurochemical concentrations were measured. Locomotor activity was inhibited only by 10-μm PS-MPs. According to electroencephalographic signals, the number and total duration of seizure-like events significantly increased by 10-μm PS-MPs, which was confirmed by the altered expression of seizure-related genes c-fos and pvalb5. Additionally, an increase in the levels of neurochemicals choline, betaine, dopamine, 3-methoxytyramine, and gamma-aminobutyric acid indicated that the observed hypoactivity and seizure-like behavior were associated with the dysregulation of the cholinergic, dopaminergic, and GABAergic systems. Overall, these findings demonstrate that exposure to PS-MPs can potentially cause seizurogenic effects in developing zebrafish embryos, and we highlight that PS-MPs 10 µm in size dominantly affect neurotoxicity.
Topics: Animals; Microplastics; Plastics; Polystyrenes; Seizures; Zebrafish
PubMed: 36104895
DOI: 10.1016/j.jhazmat.2022.129616 -
Chemosphere Sep 2023Sorption studies involving microplastics (MPs) are essential to understand the mechanisms implicated in contaminant retention. In this research, a complete study of the...
Sorption studies involving microplastics (MPs) are essential to understand the mechanisms implicated in contaminant retention. In this research, a complete study of the sorption behaviour of a hormonal contraceptive -levonorgestrel- in MPs of different composition in two distinct matrices was performed, using high-performance liquid chromatography coupled to a UV detector for the determination of levonorgestrel. Characterization of the studied MPs was achieved by X-ray diffraction, differential scanning calorimetry, and Fourier-transformed infrared spectroscopy. Kinetic and isotherm studies were performed using a batch design under controlled conditions: 500 mg of MPs pellets of 3-5 mm diameter, agitation at 125 rpm, and 30 °C. The comparison of results in ultrapure water and artificial seawater, revealed changes in sorption capacity, and the predominant sorption mechanisms involved. Overall, all studied MPs showed sorption affinity towards levonorgestrel, being low-density polyethylene the one with the highest sorption capacity in ultrapure water and polystyrene in seawater.
Topics: Microplastics; Polystyrenes; Polyethylene; Polypropylenes; Plastics; Levonorgestrel; Water; Water Pollutants, Chemical; Adsorption
PubMed: 37244556
DOI: 10.1016/j.chemosphere.2023.139042 -
Particle and Fibre Toxicology Dec 2023Nanoplastics (NPs) are omnipresent in our lives as a new type of pollution with a tiny size. It can enter organisms from the environment, accumulate in the body, and be...
BACKGROUND
Nanoplastics (NPs) are omnipresent in our lives as a new type of pollution with a tiny size. It can enter organisms from the environment, accumulate in the body, and be passed down the food chain. Inflammatory bowel disease (IBD) is a nonspecific intestinal inflammatory disease that is recurrent and prevalent in the population. Given that the intestinal features of colitis may affect the behavior and toxicity of NPs, it is imperative to clarify the risk and toxicity mechanisms of NPs in colitis models.
METHODS AND RESULTS
In this study, mice were subjected to three cycles of 5-day dextran sulfate sodium (DSS) exposures, with a break of 7 to 11 days between each cycle. After the first cycle of DSS exposure, the mice were fed gavagely with water containing 100 nm polystyrene nanobeads (PS-NPs, at concentrations of 1 mg/kg·BW, 5 mg/kg·BW and 25 mg/kg·BW, respectively) for 28 consecutive days. The results demonstrated that cyclic administration of DSS induced chronic inflammation in mice, while the standard drug "5-aminosalicylic acid (5-ASA)" treatment partially improved colitis manifestations. PS-NPs exacerbated intestinal inflammation in mice with chronic colitis by activating the MAPK signaling pathway. Furthermore, PS-NPs aggravated inflammation, oxidative stress, as well as hepatic lipid metabolism disturbance in the liver of mice with chronic colitis.
CONCLUSION
PS-NPs exacerbate intestinal inflammation and injury in mice with chronic colitis. This finding highlights chronically ill populations' susceptibility to environmental hazards, which urgent more research and risk assessment studies.
Topics: Mice; Animals; Polystyrenes; Lipid Metabolism; Colitis; Inflammation; Oxidative Stress; Liver; Chronic Disease; Mice, Inbred C57BL; Disease Models, Animal
PubMed: 38110964
DOI: 10.1186/s12989-023-00560-8 -
Sensors (Basel, Switzerland) Apr 2021Diabetes patients are at risk of having chronic wounds, which would take months to years to resolve naturally. Chronic wounds can be countered using the electrical...
Diabetes patients are at risk of having chronic wounds, which would take months to years to resolve naturally. Chronic wounds can be countered using the electrical stimulation technique (EST) by dielectrophoresis (DEP), which is label-free, highly sensitive, and selective for particle trajectory. In this study, we focus on the validation of polystyrene particles of 3.2 and 4.8 μm to predict the behavior of keratinocytes to estimate their crossover frequency () using the DEP force () for particle manipulation. MyDEP is a piece of java-based stand-alone software used to consider the dielectric particle response to AC electric fields and analyzes the electrical properties of biological cells. The prototypic 3.2 and 4.8 μm polystyrene particles have values from MyDEP of 425.02 and 275.37 kHz, respectively. Fibroblast cells were also subjected to numerical analysis because the interaction of keratinocytes and fibroblast cells is essential for wound healing. Consequently, the predicted from the MyDEP plot for keratinocyte and fibroblast cells are 510.53 and 28.10 MHz, respectively. The finite element method (FEM) is utilized to compute the electric field intensity and particle trajectory based on DEP and drag forces. Moreover, the particle trajectories are quantified in a high and low conductive medium. To justify the simulation, further DEP experiments are carried out by applying a non-uniform electric field to a mixture of different sizes of polystyrene particles and keratinocyte cells, and these results are well agreed. The alive keratinocyte cells exhibit force in a highly conductive medium from 100 kHz to 25 MHz. 2D/3D motion analysis software (DIPP-MotionV) can also perform image analysis of keratinocyte cells and evaluate the average speed, acceleration, and trajectory position. The resultant force can align the keratinocyte cells in the wound site upon suitable applied frequency. Thus, MyDEP estimates the Clausius-Mossotti factors (CMF), FEM computes the cell trajectory, and the experimental results of prototypic polystyrene particles are well correlated and provide an optimistic response towards keratinocyte cells for rapid wound healing applications.
Topics: Computer Simulation; Electrophoresis; Humans; Keratinocytes; Polystyrenes; Wound Healing
PubMed: 33922993
DOI: 10.3390/s21093007 -
Environment International Nov 2021Microplastics are ubiquitously present in the environment, accumulate in aquaculture water, and cause toxicological effects on aquatic organisms. Besides, microplastics...
Microplastics are ubiquitously present in the environment, accumulate in aquaculture water, and cause toxicological effects on aquatic organisms. Besides, microplastics provide ecological niches for microorganisms in aquatic environments. However, the effects of microplastics on microbial balance and function in surrounding water are still unclear, especially for aquaculture water. Therefore, 16S rRNA gene sequencing was employed to uncover polystyrene microplastics (PS)-induced microbial dysbiosis in surrounding seawater cultivating marine medaka (Oryzias melastigmas) and to screen related potential bacterial biomarkers. We found that Proteobacteria and Bacteroidetes were the dominant phyla in each group, accounting for more than 95% of the total abundance, and that 26 bacterial taxa belonging to Proteobacteria and Bacteroidetes were significantly altered in surrounding seawater after 10- and 200-µm PS exposure. Functional analysis revelated that photosynthesis, carbon metabolism (such as carbon fixation, glycolysis, tricarboxylic acid cycle, and glycan biosynthesis and metabolism), amino acid metabolism, lipid synthesis, and nucleotide metabolism were decreased, while environmental stress responses, such as xenobiotics biodegradation and metabolism, glutathione metabolism, and taurine and hypotaurine metabolism, were increased in surrounding seawater microbiota after separate 10- and 200-µm PS exposure. Pathway analysis and correlation networks demonstrated that changes in relative abundances of bacterial taxa belonging to Proteobacteria and Bacteroidetes were highly correlated with those in the liver metabolism of marine medaka. Subsequently, 8 bacterial taxa were discovered to be able to be used separately as the potential biomarker for assessing the surrounding seawater microbial dysbiosis and metabolic responses of marine medaka, with a diagnostic accuracy of 100.0%. This study provides novel insights into toxicological effects of microplastics on microbial dysbiosis and function in surrounding water and ecosystems, and suggests potential roles of biomarkers involved in surrounding microbial dysbiosis in assessing microplastic ecotoxicology, microbial dysbiosis, and the health status of organisms at higher trophic levels.
Topics: Aquatic Organisms; Dysbiosis; Humans; Microbiota; Microplastics; Plastics; Polystyrenes; RNA, Ribosomal, 16S
PubMed: 34161907
DOI: 10.1016/j.envint.2021.106724 -
Ecotoxicology and Environmental Safety Sep 2023As a new type of environmental pollutant, microplastics have been garnered increasing attention, especially in regard to their effects on the reproductive system....
As a new type of environmental pollutant, microplastics have been garnered increasing attention, especially in regard to their effects on the reproductive system. However, researchers have yet to report whether prevention and treatment measures exist for reproductive injury caused by microplastics. The aim of this study was therefore to explore the mechanism of spermatogenic injury induced by polystyrene microplastics (PS-MPs) and the intervention effect of probiotics based on the gut microbiota-testis axis. Mice were orally exposed for 35 days to 5 µm of PS-MPs with a gavage dose was 0.1 mg/day, and the intervention group was given probiotics (Lactobacillus, Bifidobacterium longum, and Enterococcus) orally. Fecal samples were then subjected to 16 S rRNA sequencing analysis, and sperm motion was analyzed by a Hamilton-Thorne Sperm analyzer. The results showed that PS-MPs exposed mice had significant spermatogenic dysfunction and testicular inflammation. In addition, the intestinal microbial structure of exposed mice changed significantly; the abundance of Lactobacillus decreased, and the abundance of Prevotella increased. Furthermore, with fecal microbiota transplantation, the recipient mice showed a significant decrease in sperm quality. However, probiotics supplementation helped inhibit the activation of IL-17A signaling driven by gut microbes, thereby alleviating the inflammatory response and improving sperm quality decline caused by PS-MPs. These results may provide a scientific basis for further understanding of the mechanism of male reproductive damage caused by environmental pollutants such as microplastics and for novel reproductive damage intervention measures.
Topics: Male; Animals; Mice; Microplastics; Plastics; Polystyrenes; Semen; Environmental Pollutants; Lactobacillus; Probiotics
PubMed: 37441951
DOI: 10.1016/j.ecoenv.2023.115248