Papers by Keyword: ePTFE

Abstract: Polymer films are plasma treated to improve surface properties making them hydrophilic or hydrophobic. Expanded polytetrafluoroethylene (ePTFE) is used in a wide variety of applications but only a few report on plasma treated ePTFE. Within these very few studies on ePTFE, the use of ultra-thin membrane could hardly be found. The purpose of this study is to investigate the effect of plasma treatment (Argon-Oxygen) on the hydrophobicity of ultra-thin ePTFE membrane (4um thickness). This study used nine (9) experimental legs of ePTFE subjected to respective plasma power (150W, 315W and 600W) and exposure time (300s, 450s and 600s) for each leg. Contact angle was measured prior and after subjecting to plasma condition using contact angle meter. Energy pen was also used to verify its hydrophobicity. Scanning electron microscopy (SEM) with 10,000x magnification was used to check for any change in surface after exposing to each condition. The findings showed that the membrane surface changed after exposure to plasma. All legs became hydrophilic. 102◦ contact angle was measured from raw sample, but the samples exposed to plasma had contact angles ranging from max of 68◦ to min of 48◦. The results showed that the degree of surface change could be correlated to the plasma parameters applied. Furthermore, the highest radio frequency (RF) power applied resulted to contact angle in the range of 60◦ while the lowest RF power applied resulted to the lowest contact angle, in the range of 40◦, measured. On the other hand, no particular trend was observed based on exposure time. Based on the gathered results, the ultra-thin ePTFE, in order to maintain its hydrophobicity, must not be applied with argon-oxygen plasma treatment. However, if the ultra-thin ePTFE is to be made hydrophilic, argon-oxygen plasma treatment could be applied while adjusting the plasma parameters to meet the desired hydrophilicity level.

Abstract: The aim of this study is to induce bone from immature muscular tissue in vitro using recombinant human BMP (rhBMP)-2 and expanded polytetrafluoroethylene (ePTFE) as a scaffold. Commercially available rhBMP-2 was used in this experiment. IMTs were harvested from the forelimbs of 20th Sprague-Dawley embryonic rats and placed into a homogenizer with 10ng/μl of rhBMP-2 and then homogenized. The homogenized IMT was placed on ePTFE and cultured for 2 weeks. The analyses of histological observation, electron probe micro analyzer (EPMA), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were carried out following culture. The bone-like tissue, which was made up of osteoblast-like cells and osteoids, was partially observed by H-E staining. Moreover, strong mineral deposition was observed in the extracellular matrix by von Kossa staining. Ca, P and O were detected in the extracellular matrix by EPMA and were confirmed to be at almost the same position based on the findings of synchronized images. XRD patterns and FTIR spectra of specimen were found to have typical hydroxyapatite crystal peaks and spectra, respectively. These results suggest that rhBMP-2 induced IMT differentiation into bone-like tissue in vitro.

Abstract: Clinical applications of expanded polytetrafluoroethylene (ePTFE) as a small diameter graft have been limited due to its limited patency rates, even though its demands are high. After fabricating the biodegradable PLGA layers on both the inside and outside of ePTFE, long-term in vitro smooth muscle cell culture was performed on the luminal scaffold surface. The fabricated hybrid ePTFE scaffolds were designed to have three distinctive layers and porous structures in the biodegradable layers generated by gas-foaming of the ammonium bicarbonate porogens, i.e. two layers of poly(lactide-co-glycolide) (PLGA) as biodegradable layers for tissue engineering and an ePTFE layer in the middle as a non-biodegradable layer. We evaluated the regenerated vascular tissues after applying either static or pulstile flow on a smooth muscle cells-seeded hybrid scaffold. Analysis of the engineered tissues was performed with SEM for morphological observation and H&E staining for observation of tissue development dependent upon a mode of culture system, flow patterns and scaffold species.

Abstract: Filtration medium is one of the most important parts of air-filtration. A Micro-filtration membrane made by expanded poly-tetra-fluoric-ethylene (ePTFE) was introduced in the dust removal process in our previous work. Compared with conventional fabric media, ePTFE membrane has many advantages, such as low residual pressure drop and high efficiency of dust removal, etc., because of its characteristics of micro-porous structure and slippery surface. More importantly, the useful life of ePTFE membrane is longer and the operating costs are lower during the surface-filtration process. In this paper, the residual pressure drop of the ePTFE micro-filtration membrane and conventional needle-felts fabric filtration medium were compared. The results clearly show that the residual pressure drop of the conventional filter medium increases after several filtration cycles, but that of the ePTFE membrane remains constant.