Papers by Keyword: Attachment

Abstract: Porosity and interconnectivity play an important role in the success of tissue engineering because it affects cells to live and grow. Coral has been used as a bone replacement material because the structures resemble bone and have mechanical bone properties. In this study, the synthetic coral scaffold was developed to mimic the natural coral. This study aims to investigate the porosity of the scaffold and its biocompatibility while it is attached to human gingival cells. Synthetic coral scaffold in various compositions were prepared, porosity percentage measurement and human gingival cell attachment test were done. An optimum ratio of the scaffold with gelatin: CaCO₃, having the highest porosity and cell attachment is obtained in 5:5. The result of this study presented that synthetic coral scaffold could provide the microenvironment to cells for life because it is supported by the highest percentage of porosity.

Abstract: Three point bending test of aluminum tubular structure with hat cross-section was carried out under impact condition. The structures which were strengthened with carbon fiber reinforced thermoplastic sheet attached to hat-top or hat-side were also tested. When the structure made with only aluminum was bent, one-lobe deformation mode arose in most cases, where the buckling lobe was formed at center exhibiting very low deformation resistance. This mode was found to be attributed to the low friction at central anvil by conducting the numerical simulation. The energy absorption performance was evaluated for a variety of structures. When the sheet attachment was applied for the structure with one-lobe deformation mode, the absorbed energy was improved drastically.

Abstract: We studied the surface properties of F. acidiphilum DSM 28986 by attenuated total reflection-Fourier transformed infra-red (ATR-FTIR) spectroscopy and microbial adhesion to hydrocarbon (MATH) techniques. In addition, extracellular polymeric substances (EPS) were extracted and characterized by conventional colorimetric analysis and fluorescence lectin-binding analysis (FLBA). Results showed that: 1) cells selectively adhered to mineral surfaces and showed maximum attachment to pyrite of approx. 50% within 30 min; 2) EPS synthesis by F. acidiphilum DSM 28986 was influenced by growth substrates; and 3) tightly-bound EPS (capsular EPS) were composed of carbohydrates and proteins. In contrast, loosely-bound EPS (colloidal EPS) were mainly characterized as carbohydrates. Monosaccharides like glucose, fucose, arabinose, galactose, mannose, and sialic acid were detected in the EPS of F. acidiphilum DSM 28986. This study provides first insight into surface characterization of the cell wall-lacking archaeon F. acidiphilum and facilitates the understanding of interactions of this organism with other acidophiles and metal sulfides.

Abstract: The presence of extracellular polymeric substances (EPS) and their relevance for biofilm formation on the mineral surface for a variety of microbial species play a fundamental role in the degradation of sulfide ores. EPS production is associated with induction or auto induction mechanisms as a response of bacteria to environmental conditions. In this study, we tested galactose as an inducer of EPS production in planktonic cells of Acidithiobacillus thiooxidans DSM 14887^T and their adherence to polymetallic mineral surfaces. Cells of At. thiooxidans were first adapted to grow at different concentrations of galactose (0.15, 0.25, 0.35%) using a modified 9K liquid medium and elemental sulfur as the energy source. In order to determine EPS production, the microorganisms were grown for 24 hours at different concentrations of galactose. Our results showed a cell adherence of 84% cells within 4 hours in presence of 0.15% galactose compared to 70% without galactose. The optimal concentration of galactose for maximal EPS production was 0.25% and for the attachment of cells it was 0.15%. Higher galactose concentrations inhibited microbial growth and decreased the number of cells attached to the mineral. While with a small amount of galactose in the culture media can shift the balance between sessile cells and planktonic cells, generating an increase in adhesion and therefore a possible increase of the bioleaching rate.

Abstract: For bone tissue engineering, corals have long history to be used as scaffold to promote bone regeneration. However the use of a lot of corals may damage their habitates. For this reason, a strategy to mimic coral in a synthetic form is needed. As an ideal scaffold, synthetic coral must provide structure and initial support for cell attachment and proliferation. The aim of this study was to investigate the attachment and proliferation of human Mesenchymal Stem Cells (h-MSC) on synthetic coral scaffold, to provide information on the behavior of h-MSC on the designated scaffold. Synthetic coral scaffolds were prepared from bovine gelatine and CaCO₃ with 5:5 in 10% w/v concentration in aquadest. Sodium citrate was used as dispersant in the suspension. Gelatin-CaCO₃ suspension was moulded in a plastic cover of 24 well plate, then freezed at -20°C for 24 hours, freeze dried for 24 hours and continued by dehydrothermal crosslinking for 72 hours. After the fabrication, synthetic coral scaffolds were subjects to cover the bottom of the well for cell culture. Human Mesenchymal Stem Cells (h-MSC) were seeded and divided into 2 groups, control group without scaffold and the one with scaffold. All groups were incubated for 3, 6, and 24 hours. Cells attatchment were determined by deduction of the cells unattached from total cells seeding. Proliferation of h-MSC were done in 3 groups ie., control group without scaffold, scaffold only and scaffold incorporated Platelet Rich Plasma (PRP) in the bottom of well. All groups were incubated for 24, 48 and 72 hours. Human Mesenchymal Stem Cells attached faster to synthetic coral scaffold than the control. Its proliferation behavior was faster in the scaffold incorporated PRP, showing better interaction of scaffold and cells with the incorporation of morphogenetic factor.

Abstract: Biofilm formation of microorganisms on relevant surfaces is of great importance for biomining and acid mine drainage (AMD). Thermo-acidophilic archaea like Acidianus, Sulfolobus and Metallosphaera are of special interest due to their ability to enhance leaching rates. Visualization and investigation of microbial attachment and biofilm formation of metal-oxidizing organisms up to now has been done mostly with mesophilic or moderately thermophilic bacteria. In this study, attachment and biofilms by the crenarchaeota Sulfolobus metallicus DSM 6482^T and a new isolate Acidianus sp. DSM 29099 on sulfur or pyrite were analyzed. Confocal laser scanning microscopy (CLSM) combined with fluorescent dyes specific for nucleic acids or glycoconjugates were used to monitor biofilm formation on surfaces. The data indicate that cell attachment and the subsequently formed biofilm structures were species and substrate dependent. The investigation of binary biofilms on pyrite showed that both species were heterogeneously distributed on pyrite surfaces in the form of individual cells or microcolonies. In addition, physical contact between the two species was visible, as revealed by specific lectins able to distinguish single species.

Abstract: This study focused on colonization and biofilm formation of a new crenarchaeote Acidianus sp. DSM 29099 on pyrite and chalcopyrite. Confocal laser scanning microscopy (CLSM) in combination with several fluorescent stains was applied to examine spatial distribution of cells and biofilms, as well as extracellular polymeric substances (EPS) production on the substrates. Around 60% and 35% of the inoculum adhered to pyrite and chalcopyrite within 2 h, respectively. Cells of Acidianus sp. DSM 29099 were heterogeneously distributed on both pyrite and chalcopyrite surfaces, while large mineral surfaces remained uncolonized. Biofilm cells on pyrite were often found to be embeded in EPS. EPS residues like mannose and glucose were possibly involved in intial attachment to pyrite. A mature biofilm on pyrite was developed after 2-4 days of incubation.

Abstract: In this study, initial attachment to and biofilm formation of Sulfobacillus thermosulfidooxidans DSM 9293^T on pyrite in the presence of Leptospirillum ferriphilum DSM 14647^T were investigated. Interactions of S. thermosulfidooxidans^T and L. ferriphilum^T were studied by means of monitoring attachment behavior and biofilm formation on pyrite. Our preliminary results showed that 1): Pre-established biofilms of L. ferriphilum^T had effects on attachment of S. thermosulfidooxidans^T to pyrite; 2): physical contact between cells of L. ferriphilum^T and S. thermosulfidooxidans^T on pyrite were visible 3): Pyrite leaching by cells of S. thermosulfidooxidans^T was inhibited by the presence of inactive cells of L. ferriphilum^T.

Abstract: Biofilm development of F. acidiphilum BRGM4 on polycarbonate filters floating on liquid medium and pyrite surfaces were studied by confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) combined with epifluorescence microscopy (EFM). Results show that F. acidiphilum biofilms were heterogeneously distributed, and varied among different growth conditions, such as inorganic phosphate (P_i) starvation and glucose supplementation. Biofilm and planktonic cells showed significant morphological differences. Capsular EPS were observed in both biofilm and planktonic cells. Cells showed preferential attachment to the cracks/defects of pyrite surfaces.

Abstract: Integrin, a component of the hemidesmosome, plays a role for epithelial cell migration and adhesion. This study investigated the process of peri-implant epithelium (PIE) formation after implantation, and compared it to the process of oral mucosa healing after tooth extraction. At the healing site of extraction socket without implant, the original junctional epithelium (JE) had disappeared at week 2, and the oral epithelium (OE) with integrin-α3 positive basal cells extending from the sides of the wound, then joined in the middle of the extraction socket. On the other hand in implant group, newly formed epithelium with integrin-α3 positive cells from the OE extended apically 1 week after implantation. After 3 weeks, basal cells of the new epithelium consisted of those with integrin-α3 positive but β4 negative. Finally, after 4 weeks, integrin-β4 was expressed at the implant-PIE interface. These findings suggest that integrin α3β1 plays a role in cell migration during PIE formation from OE. Furthermore, after the completion of PIE constitution, integrin α6β4 contributes to the attachment to titanium.