Cytotoxic Effects of Alcohol Extracts from a Plastic Wrap (Polyvinylidene Chloride) on Human Cultured Liver Cells and Mouse Primary Cultured Liver Cells.

An increasing accumulation of microplastics and further degraded nanoplastics in our environment is suspected to have harmful effects on humans and animals. To clarify this problem, we tested the cytotoxicity of two types of plastic wrap on human cultured liver cells and mouse primary cultured liver cells. Alcohol extracts from plastic wrap, i.e., polyvinylidene chloride (PVDC), showed cytotoxic effects on the cells. Alcohol extracts of polyethylene (PE) wrap were not toxic. The commercially available PVDC wrap consists of vinylidene chloride, epoxidized soybean oil, epoxidized linseed oil as a stiffener and stabilizer; we sought to identify which component(s) are toxic. The epoxidized soybean oil and epoxidized linseed oil exerted strong cytotoxicity, but the plastic raw material itself, vinylidene chloride, did not. Our findings indicate that plastic wraps should be used with caution in order to prevent health risks.

A refractive optical device potentially masking an intraocular tumor.

A 62-year-old woman was referred with reduced vision in her left eye and suspected retinal detachment. Bilateral laser in situ keratomileusis with KAMRA corneal inlay insertion was performed in the left eye 2 years earlier. On examination, a shadow from the corneal inlay limited posterior segment examination even with dilated fundoscopy, but a temporal raised lesion extending over the macula was noted. Ocular ultrasound confirmed a large tumor consistent with malignant melanoma, requiring enucleation. It is unclear whether the patient had baseline dilated fundoscopy before corneal inlay implantation; however, a pinhole effect for the patient will cause a pinhole effect for the clinician, potentially limiting the fundal view. The authors emphasize the importance of appropriate informed consent patients, including discussion of rare risks and complications, which can have profound implications. In this case, the elective refractive procedure potentially masked an intraocular tumor. Enucleation may have been avoided if the lesion had been identified at an earlier stage.

Analysis of phthalate plasticizer migration from PVDC packaging materials to food simulants using molecular dynamics simulations and artificial neural network.

Based on the experimental data of gas chromatography-mass spectrometry, an improved artificial neural network was first established to predict the migration of 2-ethylhexyl phthalate (DEHP) plasticizer from poly(vinylidene chloride) (PVDC) into food simulants (ie., heptane, ethanol and water). The sensitivity analysis indicated that temperature acted as a crucial factor influencing the migration values of DEHP. Then, a combined experimental and molecular dynamic (MD) simulation was performed to understand the migration kinetics and the mechanism of DEHP. Hansen solubility parameters of three component (δd, δp, δh) were simplified into two-component solubility parameters (δvdW, δe), and the tuple was successfully applied to describe the interactions between PVDC and food simulants. The MD results showed that high interaction energy and fractional free volume in PVDC/DEHP/food simulant systems accelerated the migration of DEHP. These fundamental studies would provide significant insights into the migration of environmental contaminants.

Mechanical and biological performance of printed alginate/methylcellulose/halloysite nanotube/polyvinylidene fluoride bio-scaffolds.

Use of artificial cartilage due to its poor regenerative characteristics is a challenging issue in the field of tissue engineering. In this regard, three-dimensional printing (3D) technique because of its perfect structural control is one of the best methods for producing biological scaffolds. Proper biomaterials for cartilage repairs with good mechanical and biological properties and the high ability for 3D printing are limited. In this paper, a novel biomaterial consisting of Alginate (AL), Methylcellulose (MC), Halloysite Nanotube (HNT), and Polyvinylidene Fluoride (PVDF) was printed and characterized for cartilage scaffold applications. Calcium chloride (CaCl2) was used as a crosslinker for biomaterial after printing. Scanning Electron Microscopy (SEM), Energy-Dispersive X-Ray Spectroscopy (EDX), X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), tensile and compressive tests, chondrocytes seeding, cells staining, and MTT assay were carried out in the present work. The results show that in constant concentrations of AL, MC, and PVDF (40 mg/ml AL, 30 mg/ml MC, and 1% PVDF) when concentration of HNT increased from 20 mg/ml (S2) to 40 mg/ml (S14) tensile strength increased from 164 up to 381 kPa and compressive stress increased from 426 up to 648 kPa. According to spectroscopy and calorimetry results, Biomaterial shows an amorphous structure with good miscibility and a high percentage of water in its structure. PVDF reduces mechanical properties by 7% while increases cell viability by 8.75%. Histological studies and MTT assay results showed a high improvement in the percentage of living cells at the first 4 days of cell cultivation.

Development and antimicrobial application of plantaricin BM-1 incorporating a PVDC film on fresh pork meat during cold storage.

AIMS: The aim of this study was to develop a plantaricin BM-1, a typical IIa bacteriocin produced by Lactocacillus plantarumBM-1, for active polyvinylidene chloride (PVDC) films and to determine the antimicrobial effect of plantaricin BM-1 incorporated into a PVDC film on fresh pork during 7 days of storage at 4°C. METHODS AND RESULTS: Plantaricin BM-1 solutions (20 480 AU ml-1 ) that absorbed into the PVDC film increased gradually and reached maximum volumes during exposure for up to 20 h. When soaked in water, the released amount of plantaricin BM-1 from the active PVDC film reached a maximum at 20 h. The plantaricin BM-1 active PVDC film had an obvious antilisterial effect in culture medium and fresh pork inoculated with Listeria monocytogenes. Furthermore, plantaricin BM-1-incorporated PVDC film was also significantly (P < 0·01) reduced to aerobic counts of approximately 1·5 log10 CFU per g after 7 days of storage at 4°C in pork meat, and the pH and total volatile basic nitrogen of pork meat were significantly (P < 0·01, P < 0·05) lower than those of the control. CONCLUSION: Plantaricin BM-1 active film has an excellent effect to prolong the shelf life of pork meat during cold storage. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study suggest a potential application of bacteriocin active film on meat preservation.

Modulating Surface Potential by Controlling the ß Phase Content in Poly(vinylidene fluoridetrifluoroethylene) Membranes Enhances Bone Regeneration.

Bioelectricity plays a vital role in living organisms. Although electrical stimulation is introduced in the field of bone regeneration, the concept of a dose-response relationship between surface potential and osteogenesis is not thoroughly studied. To optimize the osteogenic properties of different surface potentials, a flexible piezoelectric membrane, poly(vinylidene fluoridetrifluoroethylene) [P(VDF-TrFE)], is fabricated by annealing treatment to control its ß phases. The surface potential and piezoelectric coefficients (d33 ) of the membranes can be regulated by increasing ß phase contents. Compared with d33  = 20 pC N-1 (surface potential = -78 mV) and unpolarized membranes, bone marrow mesenchymal stem cells (BM-MSCs) cultured on the d33  = 10 pC N-1 (surface potential = -53 mV) membranes have better osteogenic properties. In vivo, d33  = 10 pC N-1 membranes result in rapid bone regeneration and complete mature bone-structure formation. BM-MSCs on d33  = 10 pC N-1 membranes have the lowest reactive oxygen species level and the highest mitochondrial membrane electric potential, implying that these membranes provide the best electrical qunantity for BM-MSCs' proliferation and energy metabolism. This study establishes an effective method to control the surface potential of P(VDF-Trfe) membranes and highlights the importance of optimized electrical stimulation in bone regeneration.

Migration of epoxidized soybean oil from polyvinyl chloride/polyvinylidene chloride food packaging wraps into food simulants.

Epoxidized soybean oil (ESBO) has been used in polyvinyl chloride (PVC)/polyvinylidene chloride (PVDC) food packaging cling film as a plasticizer and stabilizer. The aim of this study was to investigate the migration of ESBO from PVC/PVDC cling film, based on gas chromatography mass spectrometry (GC-MS). The specific migration of ESBO was evaluated using various food simulants (water, 4% acetic acid, 50% ethanol and n-heptane) for PVC and PVDC wrap products. ESBO did not migrate into water and 4% acetic acid for all the tested samples. However, it was released into 50% ethanol and n-heptane in several PVC/PVDC wraps, with maximum migration levels of 38.4 ± 0.7 and 37.4 ± 0.8 µg/mL, respectively. These results demonstrate that ESBO is capable of being released from PVC/PVDC wrap into amphiphilic/oily food and its migration should be regularly monitored.

Characterization of the thickness and distribution of latex coatings on polyvinylidene chloride beads by backscattered electron imaging.

Polyvinylidene chloride (PVDC) co-polymer resins are commonly formulated with a variety of solid additives for the purpose of processing or stabilization. A homogeneous distribution of these additives during handling and processing is important. The Dow Chemical Company developed a process to incorporate solid materials in latex form onto PVDC resin bead surfaces using a coagulation process. In this context, we present a method to characterize the distribution and thickness of these latex coatings. The difference in backscattered electron signal from the higher mean atomic number PVDC core and lower atomic number latex coating in conjunction with scanning electron microscopy (SEM) imaging using a range of accelerating voltages was used to characterize latex thickness and distribution across large numbers of beads quickly and easily. Monte Carlo simulations were used to quantitatively estimate latex thickness as a function of brightness in backscatter electron images. This thickness calibration was validated by cross-sectioning using a focused ion-beam SEM. Thicknesses from 100 nm up to about 1.3 µm can be determined using this method.

Enhanced bioactivity of polyvinylidene chloride films using argon ion bombardment for guided bone regeneration.

Polyvinylidene chloride (PVDC) is a long chain carbon synthetic polymer. The objective of this study was to improve the bioactivity of PVDC films through surface modification using argon (Ar) ion bombardment to create Ar-modified PVDC films (Ar-PVDC) to address the clinical problems of guided bone regeneration (GBR), which is technique-sensitive, and low bone regenerative ability. First, the effects of Ar ion bombardment, a low temperature plasma etching technique widely used in industry, on PVDC film wettability, surface chemistry, and morphology were confirmed. Next, fibroblast-like and osteoblast-like cell attachment and proliferation on Ar-PVDC were assessed. As a preclinical in vivo study, Ar-PVDC was used to cover a critical-sized bone defect on rat calvaria and osteoconductivity was evaluated by micro-computed tomography analysis and histological examinations. We found that the contact angle of PVDC film decreased by 50° because of the production of -OH groups on the PVDC film surface, though surface morphological was unchanged at 30 min after Ar ion bombardment. We demonstrated that cell attachment increased by about 40% and proliferation by more than 140% because of increased wettability, and 2.4 times greater bone regeneration was observed at week 3 with Ar-PVDC compared with untreated PVDC films. These results suggest that Ar ion bombardment modification of PVDC surfaces improves osteoconductivity, indicating its potential to increase bone deposition during GBR.

Lanthanide near infrared imaging in living cells with Yb3+ nano metal organic frameworks.

We have created unique near-infrared (NIR)-emitting nanoscale metal-organic frameworks (nano-MOFs) incorporating a high density of Yb(3+) lanthanide cations and sensitizers derived from phenylene. We establish here that these nano-MOFs can be incorporated into living cells for NIR imaging. Specifically, we introduce bulk and nano-Yb-phenylenevinylenedicarboxylate-3 (nano-Yb-PVDC-3), a unique MOF based on a PVDC sensitizer-ligand and Yb(3+) NIR-emitting lanthanide cations. This material has been structurally characterized, its stability in various media has been assessed, and its luminescent properties have been studied. We demonstrate that it is stable in certain specific biological media, does not photobleach, and has an IC50 of 100 µg/mL, which is sufficient to allow live cell imaging. Confocal microscopy and inductively coupled plasma measurements reveal that nano-Yb-PVDC-3 can be internalized by cells with a cytoplasmic localization. Despite its relatively low quantum yield, nano-Yb-PVDC-3 emits a sufficient number of photons per unit volume to serve as a NIR-emitting reporter for imaging living HeLa and NIH 3T3 cells. NIR microscopy allows for highly efficient discrimination between the nano-MOF emission signal and the cellular autofluorescence arising from biological material. This work represents a demonstration of the possibility of using NIR lanthanide emission for biological imaging applications in living cells with single-photon excitation.

FT-IR and DSC studies of poly(vinylidene chloride-co-acrylonitrile) complexed with LiBF4.

Poly(vinylidene chloride-co-acrylonitrile) (PVdC-co-AN) based solvent free electrolytes were prepared for different compositions of PVdC-co-AN and LiBF4 using solution casting technique. The ionic conductivity, thermal behavior, complexation and structure of polymer electrolytes have been investigated as a function of LiBF4 content at different weight ratios. DSC studies revealed that the glass transition temperature Tg decreases with the increase of salt concentration up to an optimum level. The change in the glass transition temperature (Tg) with respect to the LiBF4 concentration is reflected in the bulk resistance of the electrolytes and the sample containing 6 wt.% of LiBF4 exhibited minimum bulk resistance compared to other samples. FT-IR studies confirm the interaction of polymer and salt which is mainly between Li-cation and nitrogen atom of C≡N group. The crystalline phase of polymer host is completely changed on the addition of Li salt.

Influence of oxygen on wound healing dynamics: assessment in a novel wound mouse model under a variable oxygen environment.

INTRODUCTION: Although oxygen is essential for the wound healing process, tissue hypoxia is known to stimulate angiogenesis. To explore these inconsistent findings, we estimated the influence of the oxygen environment on wound healing with our original model. METHODS: Experiment 1 (Establishment of the model): To modify the topical oxygen tension, oxygen impermeable (polyvinylidene chloride) and permeable (polymethylpentene) membranes were applied to symmetrical excisional wounds in ddy mice (n = 6). Oxygen tension under the membrane was quantified with a device using photo-quenching technique. Experiment 2 (Influence of oxygen environment on wound healing): The wound area, granulation thickness and vascular density were analyzed under different oxygen environments (n = 24). RESULTS: Experiment 1: The permeable group maintained equivalent oxygen level to atmosphere (114.1±29.8 mmHg on day 7), while the impermeable group showed extremely low oxygen tension (5.72±2.99 mmHg on day 7). Accordingly, each group was defined as the normoxia group and the hypoxia group. Experiment 2: Percent decrease in wound size was significantly enhanced in the normoxia group (11.1±1.66% on day 7) in comparison with the hypoxia group (27.6±3.47% on day 7). The normoxia group showed significantly thicker granulation tissue than the hypoxia group (491.8±243.2 vs. 295.3±180.9 µm). Contrarily, the vascular density of the hypoxia group significantly increased on day 7 (0.046±0.025 vs. 0.011±0.008 mm(2)/mm(2)). CONCLUSIONS: Our original model successfully controlled local oxygen concentration around the wound, and the hypoxic wounds showed increased angiogenesis but with a smaller amount of granulation tissue and delayed wound closure. Enhanced neovascularization in the hypoxic group likely implies compensative response to an insufficient ambient oxygen supply.

Osteoanagenesis after transplantation of bone marrow-derived mesenchymal stem cells using polyvinylidene chloride film as a scaffold.

The aim of this study was to develop a new cell transplantation technique for osteoanagenesis at bone defect sites. Polyvinylidene chloride (PVDC) film was evaluated because of its good biocompatibility and flexibility. We used this film as both a cell scaffold and a barrier membrane. Initially, the cell compatibility of the PVDC film for fibroblast-like cells and osteoblast-like cells was confirmed. Subsequently, bone marrow cells were obtained from rats and cultured on PVDC films in two kinds of medium. The PVDC films with bone marrow-derived mesenchymal stem cells (MSCs) were then applied to critical-sized bone defects in the calvarial bone of rats. After the transplantation, the surgical sites were dissected out and evaluated by soft X-ray radiography, micro-CT analysis and histological examinations. The bone marrow-derived MSC-transplanted rats showed greater bone regeneration than the control rats. Therefore, PVDC film is considered to be useful as a scaffold for bone regeneration.

Neurite extension of primary neurons on electrospun piezoelectric scaffolds.

Neural tissue engineering may be a promising option for neural repair treatment, for which a well-designed scaffold is essential. Smart materials that can stimulate neurite extension and outgrowth have been investigated as potential scaffolding materials. A piezoelectric polymer polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) was used to fabricate electrospun aligned and random scaffolds having nano- or micron-sized fiber dimensions. The advantage of using a piezoelectric polymer is its intrinsic electrical properties. The piezoelectric characteristics of PVDF-TrFE scaffolds were shown to be enhanced by annealing. Dorsal root ganglion (DRG) neurons attached to all fibrous scaffolds. Neurites extended radially on random scaffolds, whereas aligned scaffolds directed neurite outgrowth for all fiber dimensions. Neurite extension was greatest on aligned, annealed PVDF-TrFE having micron-sized fiber dimensions in comparison with annealed and as-spun random PVDF-TrFE scaffolds. DRG on micron-sized aligned, as-spun and annealed PVDF-TrFE also had the lowest aspect ratio amongst all scaffolds, including non-piezoelectric PVDF and collagen-coated substrates. Findings from this study demonstrate the potential use of a piezoelectric fibrous scaffold for neural repair applications.

Formation of defect-free latex films on porous fiber supports.

We present here the creation of a defect-free polyvinylidene chloride barrier layer on the lumen-side of a hollow fiber sorbent. Hollow fiber sorbents have previously been shown to be promising materials for enabling low-cost CO(2) capture, provided a defect-free lumen-side barrier layer can be created. Film experiments examined the effect of drying rate, latex age, substrate porosity (porous vs nonporous), and substrate hydrophobicity/hydrophilicity. Film studies show that in ideal conditions (i.e., slow drying, fresh latex, and smooth nonporous substrate), a defect-free film can be formed, whereas the other permutations of the variables investigated led to defective films. These results were extended to hollow fiber sorbents, and despite using fresh latex and relatively slow drying conditions, a defective lumen-side layer resulted. XRD and DSC indicate that polyvinylidene chloride latex develops crystallinity over time, thereby inhibiting proper film formation as confirmed by SEM and gas permeation. This and other key additional challenges associated with the porous hollow fiber substrate vs the nonporous flat substrate were overcome. By employing a toluene-vapor saturated drying gas (a swelling solvent for polyvinylidene chloride) a defect-free lumen-side barrier layer was created, as investigated by gas and water vapor permeation.

[Study of amount of evaporation residue in extracts from plastic kitchen utensils into four food-simulating solvents].

The amount of evaporation residue was investigated as an index of total amount of non-volatile substances that migrated from plastic kitchen utensils into four food-simulating solvents (water, 4% acetic acid, 20% ethanol and heptane). The samples were 71 products made of 12 types of plastics for food contact use. The amount was determined in accordance with the Japanese testing method. The quantitation limit was 5 µg/mL. In the cases of polyethylene, polypropylene, polystyrene, acrylonitrile styrene resin, acrylonitrile butadiene styrene resin, polyvinyl chloride, polyvinylidene chloride, polymethylpentene, polymethylmethacrylate and polyethylene terephthalate samples, the amount was highest for heptane and very low for the other solvents. On the other hand, in the cases of melamine resin and polyamide samples, the amount was highest for 4% acetic acid or 20% ethanol and lowest for heptane. These results enabled the selection of the most suitable solvent, and the rapid and efficient determination of evaporation residue.

GC/MS method for the determination of adipate plasticizers in ham sausage and its application to kinetic and penetration studies.

A GC/MS method was developed and successfully validated for the determination of adipate plasticizers in ham sausage migrated from polyvinylidene chloride (PVDC) packaging film. The sample pretreatment includes liquid extraction, solvent evaporation, and reconstitution before and after solid phase extraction (SPE). For the 5 adipate plasticizers studied, the SPE process with Oasis MAX cartridge showed an extraction efficiency from 85.7% to 106%, and the calibration curves are all linear in the range of 5 to 1000 ng/g with correlation coefficients greater than 0.998. The method proved to be accurate and precise; the average intraday recovery ranges from 85.4% to 114.6% with a %CV value from 2.5 to 11.3, and the average interday recovery from 83.6% to 118.5% with a %CV value from 2.8 to 15.6, respectively, for the adipate plasticizers. The method is sensitive and was effectively applied in the kinetic and penetration studies of the adipate plasticizers migrating from food-grade PVDC packaging film into ham sausage. The experimental data showed that approximately 6.8% of dibutyl adipate (DBA) in the packaging film migrated into the ham sausage in 4 mo and the migration reached the innermost portion of the sausage in 6 mo.

Behavior and products of mechano-chemical dechlorination of polyvinyl chloride and poly (vinylidene chloride).

The mechano-chemical (MC) dechlorination of polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC) was performed by mechanical milling PVC/PVDC powder with zinc powder in a planetary ball mill, and the products of dechlorination were characterized by Infrared spectra (IR), X-ray diffraction (XRD), Raman spectroscopy, gas chromatography-mass spectrometry (GC-MS), and 13C solid-state nuclear magnetic resonance (NMR). The experimental results show that PVC/PVDC can be easily dechlorinated by milling with zinc powder, and formed various kinds of inorganic and organic products. Inorganic compounds included Zn2OCl(2).2H2O, Zn5(OH)8Cl2.H2O etc., and organic products involved diamond-like carbon, carbyne fragment, polyacetylene etc. Organic products formed following the paths of dechlorination, dehydrochlorination, crosslink, and oxidation. The mechano-chemical dechlorination process of PVC/PVDC may be an effective approach for carbyne synthesizing in the appropriate condition.

Adaptive optics instrumentation in submillimeter/terahertz spectroscopy with a flexible polyvinylidene fluoride cladding hollow waveguide.

A simple instrument has been developed to carry out temperature dependent submillimeter/terahertz-wave spectroscopy using a polyvinylidene fluoride flexible hollow waveguide and an eggplant-shape launching lens.