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Environmental Pollution (Barking, Essex... Jul 2024Microplastics (MPs) are growing and ubiquitous environmental pollutants and represent one of the greatest contemporary challenges caused by human activities. Current...
Microplastics (MPs) are growing and ubiquitous environmental pollutants and represent one of the greatest contemporary challenges caused by human activities. Current research has predominantly examined the singular toxicological effects of individual polymers, neglecting the prevailing reality of organisms confronted with complex contaminant mixtures and potential synergistic effects. To fill this research gap, we investigated the lethal and sublethal effects of two common MPs, polystyrene (PS - 4.8-5.8 μm) and poly(methyl methacrylate) (PMMA - 1-40 μm), and their combination (MIX), on the pollinating insect Apis mellifera. For each treatment, we evaluated the oral toxicity of two ecologically relevant and one higher concentration (0.5, 5 and 50 mg/L) and analysed their effects on the immune system and worker survival. As immune activation can alter the cuticular hydrocarbon profile of honey bees, we used gas chromatography-mass spectrometry (GC-MS) to investigate whether MPs lead to changes in the chemical profile of foragers and behavioural assay to test whether such changes affect behavioural patterns of social recognition, undermining overall colony integrity. The results indicate an additive negative effect of PS and PMMA on bee survival and immune response, even at ecologically relevant concentrations. Furthermore, alterations in cuticle profiles were observed with both MPs at the highest and intermediate concentrations, with PMMA being mainly responsible. Both MPs exposure resulted in a reduction in the abundance of several cuticular compounds. Hive entry guards did not show increased inspection or aggressive behaviour towards exposed foragers, allowing them to enter the colony without being treated differently from uncontaminated foragers. These findings raise concerns not only for the health of individual bees, but also for the entire colony, which could be at risk if contaminated nestmates enter the colony undetected, allowing MPs to spread throughout the hive.
Topics: Bees; Animals; Microplastics; Environmental Pollutants; Polystyrenes; Polymethyl Methacrylate; Polymers
PubMed: 38703977
DOI: 10.1016/j.envpol.2024.124087 -
Aquatic Toxicology (Amsterdam,... Dec 2023Plastics, particularly microplastics (MPs) and nanoplastics (NPs), have been regarded as pollutants of emerging concern due to their effects on organisms and ecosystems,...
Plastics, particularly microplastics (MPs) and nanoplastics (NPs), have been regarded as pollutants of emerging concern due to their effects on organisms and ecosystems, especially considering marine environments. However, in terms of NPs, there is still a knowledge gap regarding the effects of size and polymer on marine invertebrates, such as benthic organisms. Therefore, this study aimed to understand, regarding behavioural, physiological, and biochemical endpoints (neurotransmission, energy metabolism, antioxidant status, and oxidative damage), the effects of 50 nm waterborne polymethylmethacrylate (PMMA) NPs (0.5 to 500 µg/L) on the marine benthic polychaete Hediste diversicolor, a key species in estuarine and coastal ecosystems. Results demonstrated that worms exposed to PMMA NPs had a shorter burrowing time than control organisms. Nevertheless, worms exposed to PMMA NPs (0.5 and 500 µg/L) decreased cholinesterase activity. Energy metabolism was decreased at 50 and 500 µg/L, and glycogen content decreased at all concentrations of PMMA NPs. Enzymes related to the antioxidant defence system (superoxide dismutase and glutathione peroxidase) displayed increased activities in H. diversicolor specimens exposed to concentrations between 0.5 and 500 µg/L, which led to no damage at the cell membrane and protein levels. In this study, polychaetes also displayed a lower regenerative capacity when exposed to PMMA NPs. Overall, the data obtained in this study emphasize the potential consequences of PMMA NPs to benthic worms, particularly between 0.5 and 50 µg/L, with polychaetes exposed to 50 µg/L being the most impacted by the analysed NPs. However, since sediments are considered to be sinks and sources of plastics, further studies are needed to better understand the impacts of different sizes and polymers on marine organisms, particularly benthic species.
Topics: Animals; Antioxidants; Polymethyl Methacrylate; Microplastics; Plastics; Ecosystem; Water Pollutants, Chemical; Polychaeta
PubMed: 37931377
DOI: 10.1016/j.aquatox.2023.106743 -
Environmental Science and Pollution... Oct 2023The antibacterial activity of a variety of modified poly(methyl methacrylate) Schiff bases against common microbial infections and removal of methylene blue (MB) dye...
The antibacterial activity of a variety of modified poly(methyl methacrylate) Schiff bases against common microbial infections and removal of methylene blue (MB) dye were screened. The Schiff bases were synthesized from the reaction of the modified (PMMA) with vanillin (PMMA) and cinnamaldehyde (PMMA). By using Fourier transformer infrared (FT-IR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), the structures of the nanofibers of the synthesized Schiff bases were confirmed. The modified Kirky-Bauer method was used to screen the antibacterial activities of all the obtained materials against various bacterial species, including gram-positive bacterial (Bacillus subtilis (4k1p), Staphylococcus aureus), Gram-negative bacteria (Escherichia coli (7ab3), Pseudomonas aeruginosa). Inhibition zones against gram-positive bacteria ranged in diameter from 7 to 14 mm, whereas for the Gram-negative bacteria, the inhibition zones found to be ranged between 6 and 13 mm. With a minimum bactericidal concentration (MBC) of 8 mg/mL and a minimum inhibitory concentration (MIC) of 2 mg/mL, (PMMA) shown the greatest antibacterial activity. Lastly, molecular docking research was done to better understand the interactions between this series' targets and inhibitors for (PMMA) and (PMMA) (4k1p and 7ab3). Molecular modeling of these surface-adsorbed polymers indicated that (PMMA) binds more strongly with Nitrogen than does (PMMA) through extra hydrogen-bonding interactions. All the developed materials were evaluated for the removal of 0.1 g/L methylene blue dye (MB) from an aqueous solution. The elimination percentage of MB dye ranged from 26.67% by using 0.05 g powder of (PMMA) to 85.63% by employing 0.05 g nanofibers of (PMMA).
Topics: Polymethyl Methacrylate; Molecular Docking Simulation; Schiff Bases; Spectroscopy, Fourier Transform Infrared; Methylene Blue; Anti-Bacterial Agents; Polymers; Microbial Sensitivity Tests
PubMed: 37759061
DOI: 10.1007/s11356-023-30043-4 -
BMC Oral Health Dec 2023Flexible denture base polymers have gained popularity in modern dentistry however, their biofilm formation tendency, adversely affecting the oral tissue heath, remains a...
BACKGROUND
Flexible denture base polymers have gained popularity in modern dentistry however, their biofilm formation tendency, adversely affecting the oral tissue heath, remains a concern. Consequently, this study aimed to evaluate surface roughness and biofilm formation tendency of two types of denture base resins manufactured with two techniques before and after surface coating with chlorohexidine (CHX) NPs.
MATERIALS AND METHODS
Acetal (AC) and Polymethyl-methacrylate (PMMA) resins manufactured by conventional and CAD/CAM methods were shaped into disk (10 X 10 X 1 mm). They were dipped for 8 h and 24 h in colloidal suspension prepared by mixing aqueous solution of CHX digluconate and hexa-metaphosphate (0.01 M). Surface roughness, optical density (OD) of microbial growth media and biofilm formation tendency were evaluated directly after coating. Elutes concentrations of released CHX were evaluated for 19 days using spectrophotometer. Three-way ANOVA and Tukey's post-hoc statistical analysis were used to assess the outcomes.
RESULTS
AC CAD/CAM groups showed statistically significant higher roughness before and after coating (54.703 ± 4.32 and 77.58 ± 6.07 nm, respectively). All groups showed significant reduction in OD and biofilm formation tendency after surface coating even after 19 days of CHX NPs release.
CONCLUSIONS
Biofilm formation tendency was highly relevant to surface roughness of tested resins before coating. After CHX NPs coating all tested groups showed significant impact on microbial growth and reduction in biofilm formation tendency with no relation to surface roughness. Significant antimicrobial effect remained even after 19 days of NPs release and specimens storage.
Topics: Humans; Polymethyl Methacrylate; Denture Bases; Acetals; Surface Properties; Materials Testing; Methacrylates
PubMed: 38066495
DOI: 10.1186/s12903-023-03718-0 -
Journal of Orthopaedic Surgery and... Aug 2023Polymethylmethacrylate (PMMA) bone cement loaded with enoxaparin sodium (PMMA@ES) has been increasingly highlighted to affect the bone repair of bone defects, but the...
BACKGROUND
Polymethylmethacrylate (PMMA) bone cement loaded with enoxaparin sodium (PMMA@ES) has been increasingly highlighted to affect the bone repair of bone defects, but the molecular mechanisms remain unclear. We addressed this issue by identifying possible molecular mechanisms of PMMA@ES involved in femoral defect regeneration based on bioinformatics analysis and network pharmacology analysis.
METHODS
The upregulated genes affecting the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) were selected through bioinformatics analysis, followed by intersection with the genes of ES-induced differentiation of BMSCs identified by network pharmacology analysis. PMMA@ES was constructed. Rat primary BMSCs were isolated and cultured in vitro in the proliferation medium (PM) and osteogenic medium (OM) to measure alkaline phosphatase (ALP) activity, mineralization of the extracellular matrix, and the expression of RUNX2 and OCN using gain- or loss-of-function experiments. A rat femoral bone defect model was constructed to detect the new bone formation in rats.
RESULTS
ATF2 may be a key gene in differentiating BMSCs into osteoblasts. In vitro cell assays showed that PMMA@ES promoted the osteogenic differentiation of BMSCs by increasing ALP activity, extracellular matrix mineralization, and RUNX2 and OCN expression in PM and OM. In addition, ATF2 activated the transcription of miR-335-5p to target ERK1/2 and downregulate the expression of ERK1/2. PMMA@ES induced femoral defect regeneration and the repair of femoral defects in rats by regulating the ATF2/miR-335-5p/ERK1/2 axis.
CONCLUSION
The evidence provided by our study highlighted the ATF2-mediated mechanism of PMMA@ES in the facilitation of the osteogenic differentiation of BMSCs and femoral defect regeneration.
Topics: Animals; Rats; Polymethyl Methacrylate; Bone Cements; Core Binding Factor Alpha 1 Subunit; Osteogenesis; Calcinosis; MicroRNAs
PubMed: 37653390
DOI: 10.1186/s13018-023-04017-8 -
Dental Materials : Official Publication... Feb 2024To introduce a versatile fabrication process to fabricate zirconia/PMMA composites for chairside CAD/CAM dental restorations. These zirconia composites have nacre-like...
OBJECTIVES
To introduce a versatile fabrication process to fabricate zirconia/PMMA composites for chairside CAD/CAM dental restorations. These zirconia composites have nacre-like lamellar microstructures, competent and tooth-matched mechanical properties, as well as crack resistance behaviours.
METHODS
Bi-directional freeze casting was used to fabricate ceramic green bodies with highly aligned lamellar structure. Pressure was then applied to control the ceramic volume fraction. PMMA was infiltrated into the ceramic scaffold. Mechanical tests including 3-point bending, Vickers hardness, and fracture toughness were performed on the composites. The machinability of the composites was also characterised.
RESULTS
Two types of nacre-like zirconia/PMMA composites, i.e., 3Y-YZP/PMMA and 5Y-PSZ/PMMA composites were fabricated. The microstructure created was similar to the 'brick and mortar' structure of nacre. Excellent flexural strength (up to 400 MPa and 290 MPa for 3Y-TZP/PMMA and 5Y-PSZ/PMMA composite, respectively), tuneable hardness and elastic modulus within the range similar to enamel, along with improved crack-resistance behaviour were demonstrated on both zirconia composites. In addition, both zirconia/PMMA composites showed acceptable machinability, being easy to mill, as would be required to produce a dental crown.
SIGNIFICANCE
Nacre-like zirconia/PMMA composites therefore exhibit the potential for use in the production of chairside CAD/CAM dental restorations.
Topics: Polymethyl Methacrylate; Nacre; Materials Testing; Ceramics; Zirconium; Dental Materials; Computer-Aided Design; Surface Properties
PubMed: 38040580
DOI: 10.1016/j.dental.2023.11.017 -
Journal of Prosthodontic Research Jan 2024This study aimed to synthesize heat-cured poly(methyl methacrylate) (PMMA) acrylic formulated with copper nanoparticles (nCu) for producing dentures with antimicrobial...
PURPOSE
This study aimed to synthesize heat-cured poly(methyl methacrylate) (PMMA) acrylic formulated with copper nanoparticles (nCu) for producing dentures with antimicrobial properties and ability to prevent denture stomatitis (DS).
METHODS
nCu/PMMA nanocomposites were prepared through in situ formation of nCu into methyl methacrylate (MMA). The fabricated material was characterized using scanning electron microscopy, spectroscopy (energy-dispersive X-ray, attenuated total reflectance-Fourier-transform infrared, and X-ray photoelectron spectroscopy), X-ray diffraction analysis, and mechanical flexural tests (ISO 20795-1:2008). Antimicrobial activity against Candida albicans and oral bacteria was determined. MTS assay (ISO 10993-5:2009) and copper release experiments were conducted to assess cytotoxicity. In the clinical trial, participants wearing nCu/PMMA (n=25) and PMMA (n=25) dentures were compared; specifically, DS incidence and severity and Candida species proliferation were assessed for 12 months. Data were analyzed using analysis of variance with Tukey's post hoc test (α=0.05).
RESULTS
nCu/PMMA nanocomposite loaded with 0.045% nCu exhibited the maximum antimicrobial activity against C. albicans and other oral bacteria without producing cytotoxicity in the wearer. nCu/PMMA dentures retained their mechanical and aesthetic properties as well as inhibited the growth of Candida species on both denture surface and patient palate. DS incidence and severity were lower in the nCu/PMMA denture group than in the PMMA denture group.
CONCLUSIONS
PMMA acrylic produced with copper nanotechnology is antimicrobial, biocompatible, and aesthetic and can reduce DS incidence. Thus, this material may act as a novel preventive alternative for oral infections associated with denture use.
Topics: Humans; Polymethyl Methacrylate; Copper; Denture Bases; Anti-Infective Agents; Nanoparticles; Candida albicans; Materials Testing
PubMed: 37211413
DOI: 10.2186/jpr.JPR_D_22_00227 -
Dental and Medical Problems 2023Nanoparticles (NPs) have gained significant attention in various fields due to their unique properties and potential applications. Polymethyl methacrylate (PMMA) is an...
BACKGROUND
Nanoparticles (NPs) have gained significant attention in various fields due to their unique properties and potential applications. Polymethyl methacrylate (PMMA) is an acrylic resin widely used in dentistry and medicine. However, the effect of different types of NP fillers on the physical properties of PMMA-based resins has not been thoroughly explored in the literature.
OBJECTIVES
The present study aimed to evaluate the effects of 3 different types of NP fillers on the physical properties of an experimental PMMA-based resin as a function of the NP content and concentration.
MATERIAL AND METHODS
Ten groups (n = 10) were designed. The specimens were composed of an acrylic resin, silicon dioxide (SiO2), cerium dioxide (CeO2), and titanium dioxide (TiO2) at the following ratios (wt%): group 1 (G1) - control; group 2 (G2) - 0.5% SiO2; group 3 (G3) - 1% SiO2; group 4 (G4) - 3% SiO2; group 5 (G5) - 0.5% CeO2; group 6 (G6) - 1% CeO2; group 7 (G7) - 3% CeO2; group 8 (G8) - 0.5% TiO2; group 9 (G9) - 1% TiO2; and group 10 (G10) - 3% TiO2. Transmission electron microscopy (TEM) was used to assess the quality of NP dispersion. Thermal stability was assessed with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effects of the abovementioned NPs on the properties of the resin were evaluated using the Archimedes principle for density, the Vickers hardness (VH) test and the impact strength (IS) test. Data analysis employed the oneand two-way analysis of variance (ANOVA), followed by Duncan's post hoc test at a significance level of 0.05.
RESULTS
Transmission electron microscopy showed partial NP dispersion. All types of NPs enhanced the mechanical properties of the acrylic resin except for IS, which was similar to that of the control group. Among the types of NPs, irrespective of the weight percentage, CeO2 showed higher thermal stability and higher IS for 0.5 wt% and 1 wt% as compared to other groups, as well as the highest values of density at 0.5 wt%, 1 wt% and 3 wt%. Titanium oxide at 1 wt% presented a higher VH as compared to other groups. The fracture pattern was the same for all groups.
CONCLUSIONS
Incorporating the tested NPs into the acrylic resin resulted in enhanced physical properties, primarily attributed to a lower NP content.
Topics: Humans; Acrylic Resins; Polymethyl Methacrylate; Silicon Dioxide; Materials Testing; Surface Properties; Nanoparticles
PubMed: 37966919
DOI: 10.17219/dmp/171844 -
Journal of Yeungnam Medical Science Nov 2023Residual monomer tests using high-performance liquid chromatography and cytotoxicity tests were performed to analyze the effect on the oral mucosa of a self-curing resin...
BACKGROUND
Residual monomer tests using high-performance liquid chromatography and cytotoxicity tests were performed to analyze the effect on the oral mucosa of a self-curing resin for provisional crown production.
METHODS
A cytotoxicity test was performed to confirm whether leaked residual monomers directly affected oral mucosal cells. The cytotoxicity of the liquid and solid resin polymers was measured using a water-soluble tetrazolium (WST) test and microplate reader.
RESULTS
In the WST assay using a microplate reader, 73.4% of the cells survived at a concentration of 0.2% liquid resin polymer. The cytotoxicity of the liquid resin polymer was low at ≤0.2%. For the solid resins, when 100% of the eluate was used from each specimen, the average cell viability was 91.3% for the solid resin polymer and 100% for the hand-mixed self-curing resin, which is higher than the cell viability standard of 70%. The cytotoxicity of the solid resin polymer was low.
CONCLUSION
Because the polymerization process of the self-curing resin may have harmful effects on the oral mucosa during the second and third stages, the solid resin should be manufactured indirectly using a dental model.
PubMed: 37098682
DOI: 10.12701/jyms.2023.00080 -
BMC Oral Health Feb 2024The prevalence of adults with partially dental arches is expected to be more than imagined and patients requiring replacement of missing teeth are slowly increasing in...
Evaluation and assessment of the wettabilty and water contact angle of modified poly methyl methacrylate denture base materials against PEEK in cast partial denture framework: an in vitro study.
INTRODUCTION
The prevalence of adults with partially dental arches is expected to be more than imagined and patients requiring replacement of missing teeth are slowly increasing in number too. Removable partial dentures are known to provide for substantial replacement for the missing teeth with also added advantages when compared to fixed or implant prosthesis, mainly in elderly patients. Denture base material performance and durability are greatly influenced by wettability and water contact angle. In the case of dentures; adequate moisture distribution is necessary to ensure excellent wettability which has an influence on comfort and oral health. The purpose of conducting this study was to find out whether the advancements made using PEEK (Polyether ether ketone) would prove to be more beneficial than the current upgrades in the current material spectrum.
MATERIALS AND METHODS
This study was performed under in vitro conditions. All the fabrication and processing was done only by one operator. The materials used were divided into three groups each comprising 20 samples. Group A was modified polymethylmethacrylate (Bredent Polyan), Group B was polyoxymethylene acetal resin (Biodentaplast) and Group C was PEEK. An Ossila Goniometer was used to measure the contact angle. The three types of liquids used for the testing included distilled water, natural saliva and mouth wetting solution (Wet Mouth Liquid, ICPA India). Human saliva was collected from an individual with no medical conditions and normal salivary secretion.
RESULTS
The data was analyzed using One-way ANOVA test and a pairwise comparison using the Post Hoc Tukey's Honest Significant Difference. Table 1 consists of the mean water contact angles of the denture base materials and mean contact angles of various denture base materials. In saliva, mouth wetting solution and distilled water, the highest mean and least mean contact angle was seen in Polyan and Biodentaplast respectively. A signicant difference was seen between PEEK and Polyan and Biodentaplast and Polyan on further comparison.
CONCLUSION
From the resources and the materials at our disposal, it could be concluded that Polyan, Biodentaplast and PEEK and could be used as viable options in cast partial denture framework.
Topics: Acrylic Resins; Benzophenones; Denture Bases; Denture, Partial; Ketones; Materials Testing; Methacrylates; Polyethylene Glycols; Polymers; Polymethyl Methacrylate; Water; Wettability
PubMed: 38368396
DOI: 10.1186/s12903-023-03716-2