No abstract

Original perfluoropolyethers (PFPE)-based oligomeric polyesters (FOPs) of different macromolecular architecture were synthesized via polycondensation as low surface energy additives to engineering thermoplastics. The oligomers do not contain long-chain perfluoroalkyl segments, which are known to yield environmentally unsafe perfluoroalkyl carboxylic acids. To improve the compatibility of the materials with polyethylene terephthalate (PET) we introduced isophthalate segments into the polyesters and targeted the synthesis of lower molecular weight oligomeric macromolecules. The surface properties such as morphology, composition, and wettability of PET/FOP films fabricated from solution were investigated using atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. It was demonstrated that FOPs, when added to PET film, readily migrate to the film surface and bring significant water and oil repellency to the thermoplastic boundary. We have established that the wettability of PET/FOP films depends on three main parameters: (i) end-groups of fluorinated polyesters, (ii) the concentration of fluorinated polyesters in the films, and (iii) equilibration via annealing. The most effective water/oil repellency FOP has two CF-PFPE-tails. The addition of this oligomeric polyester to PET allows (even at relatively low concentrations) reaching a level of oil repellency and surface energy comparable to that of polytetrafluorethylene (PTFE/Teflon). Therefore, the materials can be considered suitable replacements for additives containing long-chain perfluoroalkyl substances.

Human gingival fibroblasts (HGFs) are responsible for connective tissue repair and scarring, and are exposed to mechanical forces under physiological and pathological conditions. The exact mechanisms underlying gingival tissue reconstruction under mechanical forces remain unclear. The present study aimfed to investigate the effects of mechanical forces on the proliferation and extracellular matrix synthesis in HGFs by establishing a 3-dimensional (3D) HGF culture model using poly(lactide-co-glycolide) (PLGA) scaffolds. HGFs were cultured in 3D PLGA scaffolds and a mechanical force of 0, 5, 15, 25 or 35 g/cm 2 was applied to HGFs for 24 h. A mechanical force of 25 g/cm 2 induced the highest proliferation rate, and thus was selected for subsequent experiments. Cell viability was determined using the MTT assay at 0, 24, 48 and 72 h. The expression levels of type I collagen (COL-1) and matrix metallopeptidase (MMP)-1 were examined by reverse transcription-quantitative polymerase chain reaction and ELISA, and transforming growth factor (TGF)-β expression was evaluated by ELISA. The application of mechanical force on HGFs cultured on the 3D PLGA scaffolds resulted in a significant increase in cell proliferation and COL-1 expression, as well as a decrease in MMP-1 expression. A TGF-β1 inhibitor was also applied, which attenuated the effects of mechanical force on HGF proliferation, and COL-1 and MMP-1 expression, thus suggesting that TGF-β signaling pathways may mediate the mechanical force-induced alterations observed in HGFs. In conclusion, these findings helped to clarify the mechanisms underlying mechanical force-induced HGF proliferation and ECM synthesis, which may promote the development of targeted therapeutics to treat various diseases, including gingival atrophy caused by orthodontic treatment.

For decades, water and oil repellency of engineering thermoplastics has been achieved with introduction of long-chain perfluoroalkyl substances and moieties (C n F2n+1, n ≥ 7). However, their bioaccumulative and toxicological impact is now widely recognized and, consequently, the substances have been phased out of industrial production and applications. To this end, we have synthesized fluorinated oligomeric triblock polyesters (FOPBs), which do not possess the long-chain perfluoroalkyl segments and serve as effective low-surface-energy additives to engineering thermoplastics. More specifically, we obtained original perfluoropolyether (PFPE)-based triblock copolymers, in which two identical fluorinated blocks were separated by a short nonfluorinated polyester block made of poly­(ethylene isophthalate) (PEI). It was found that when FOPBs were added to poly­(ethylene terephthalate), nylon-6, and poly­(methyl methacrylate) films they readily migrate to the film surface and in doing so imparted significant water and oil repellency to the thermoplastic boundary. The water/oil wettability of the films modified with FOPB is considerably lower than the wettability of the films modified with an analogous PFPE-based polyester, which differs from FOPB only by the absence of the short nonfluorinated PEI middle block. We associate the superiority of the triblock copolymers in terms of water and oil repellency with their ability to form brushlike structures on polymer film surfaces.

Background:The stability of orthodontic treatment is thought to be significantly affected by the compression and retraction of gingival tissues, but the underlying molecular mechanism is not fully elucidated. The objectives of our study were to explore the effects of mechanical force on the ECM-integrin-cytoskeleton linkage response in human gingival fibroblasts (HGFs) cultured on 3-dimension (3D) lactide-co-glycolide (PLGA) biological scaffold and to further study the mechanotransduction pathways that could be involved. Material/Methods:A compressive force of 25 g/m 2 was applied to the HGFs-PLGA 3D co-cultured model. Rhodamine-phalloidin staining was used to evaluate the filamentous actin (F-actin) cytoskeleton. The expression level of type I collagen (COL-1) and the activation of the integrin a 5 b 1 /focal adhesion kinase (FAK) signaling pathway were determined by using real-time PCR and Western blotting analysis. The impacts of the applied force on the expression levels of FAK, phosphorylated focal adhesion kinase (p-FAK), and COL-1 were also measured in cells treated with integrin a 5 b 1 inhibitor (Ac-PHSCN-NH 2, ATN-161). Results:Mechanical force increased the expression of integrin a 5 b 1 , FAK (p-FAK), and COL-1 in HGFs, and induced the formation of stress fibers. Blocking integrin a 5 b 1 reduced the expression of FAK (p-FAK), while the expression of COL-1 was not fully inhibited. Conclusions:The integrin a 5 b 1 /FAK signaling pathway and actin cytoskeleton appear to be involved in the mechanotransduction of HGFs. There could be other mechanisms involved in the promotion effect of mechanical force on collagen synthesis in addition to the integrin a 5 b 1 pathway.