Abstract: Pearl is a bio-originated valuable natural gem and it is also cultivated or harvested for jewellery. In this paper, the material aspects of pearl have been investigated experimentally and it has been found that it has a very high static dielectric constant ~ 105. The functional nature of the material is also established in this work. The beautiful lustre of natural pearl is explained by nano-optics and the layered structure of the material. The origin of super-dielectric nature of pearl has been explained by lightning rod effect (LRE) that causes ultra-high polarization of the dielectric background. The LRE is due to the presence of very small sized nano-particles in the natural pearl. Its electrical conductivity is mostly ionic, only less than 10% of the total conductivity is electronic. The scope of tailoring of its electro-activity has been probed.
Abstract: Dental pulp cell research might open a promising application in tooth tissue regeneration. The aim of this study is to establish a protocol for in vitro culture the human dental pulp stem cells to apply in tissue engineering. Human premolar and impacted third molars were collected and disinfected. Dental pulp fragments were cultured with Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12 (DMEM/F12) medium supplemented with 10% Fetal Bovine Serum (FBS). Dental pulp stem cells (DPSCs) were identified using proliferation assay, RT-PCR and flow cytometry. Growth of DPSCs on dentin surface was assessed by MTT assay. The study showed that we successfully isolated, cultured and characterized dental pulp cells by outgrowth method. Cultured population of cells expressed in high level of Oct4, CD146, CD90, CD44. DPSCs proliferated on chemically and mechanically treated dentin surface. This research provides important information and a basis for further investigations to establish dental tissue engineering protocols.
Abstract: This manuscript discusses peri-implantitis around dental implants and the current methodologies of surgical and non-surgical approaches towards treating peri-implantitis. Mechanical, chemical cleansing and reactivation of infected implant surface along with recent advances like the use of Laser and Photodynamic therapy (PDT) have also been reviewed in this literature. Bone regenerative treatment methods for the treatment of peri-implantitis using non-resorbable membranes (Guided Bone Regeneration), autogenous bone grafts and bone substitute materials with recombinant human bone morphogenetic protein-2 (rhBMP-2) and other growth factors have also been reviewed in this manuscript.
Abstract: The objectives in this study were to compare the removal of 2-M via different dialyzers (high- and low flux) under equilibrium or sink conditions, wherein there was highly selective antibody-based facilitated transport into a small volume dialysate reservoir. Using an in vitro haemodialysis model we perfused high-flux polymethylmethacrylate (PMMA), high-flux cellulose diacetate (CDA), and a low-flux polysulfone (PSF) membranes with known amounts of 2-M through the intracapillary space. Anti-2-M antibodies added to the extracapillary space were shown to create sink conditions across the membrane when its pore size is sufficiently large for diffusion and if 2-M is not strongly adsorbed to the membrane surface. Our results indicate that 2-M (~12kDa) does not penetrate low-flux dialyzers and that its adsorption to intracapillary PSF surfaces does not substantially affect clearance. 2-M strongly adsorbed to high-flux PMMA dialyzers (ko = 0.0271+0.002 min-1), but without significant clearance enhancement due to circulating antibodies. A significant clearance enhancement (101.2%+24.89) for 2-M due to immunoextraction was observed in the high-flux cellulose acetate dialyzers, but without passive adsorption to the surface. These studies demonstrate the utility of in vitro haemodialysis experiments to elucidate midsize molecule clearance in dialysis membranes under controlled conditions. The use of anti-2-M antibodies as dialysate additives might be feasible in the removal of 2-M from whole blood, highlighting the advantages of selective antibody-based extraction of disease-causing toxins into potentially simple extracorporeal devices with small volume receiver compartments.
Abstract: Bioglass Ceramics having molar composition 40SiO2-(44-X)CaO-10MgO-6P2O5-XCaF2 (where X = 0 to 8%) were prepared by conventional melting process in an electric globar furnace at 1400±10°C. Controlled crystallizations were carried out to convert the bioglasses to their corresponding ceramics. Nucleation and crystallization regimes were carried out by differential thermal analysis. The crystalline phases termed hydroxy fluoroapatite, akermanite and wollastonite were identified by using x-ray diffraction analysis. The investigation of bioactivity for the prepared glass and glass ceramics was done by infrared absorption and infrared reflection spectra after immersion in simulated body fluid (SBF) for different periods at 37.8°C. Scanning electron microscope (SEM) analysis was carried out to investigate the surface texture. Micrographs show the formation of HCA layer on the surface of the bioglass ceramics samples after 7 days of SBF treatment. The surfaces of the samples were completely covered with irregular and needle-like aggregates of Ca–P layer. The released ions were estimated by atomic absorption spectroscopy. The chemical durability of these materials was determined by pH measurement methods and it was found that pH of the solution increases up from 1 to 7 days. Further, pH decreases with increasing time period, from 15 to 30 days in SBF solution.
Abstract: A new stress function modelling the fails in biological tissue is here proposed. Under the assumption that the cell membrane may be modelled as neo-Hookean materials, we develop the problem in the framework of non-linear elasticity. We attempt to model the ice nucleation phenomenon when freezing and thawing occurs in cellular cryo-preservation. The ice seed generated surface can be either soft or wrinkled and, when the latter emerges a punch contact against the cell membrane takes place. Restricting our attention on opportune mono-dimensional sub-set, we extend the multiple critical points theorem at our model. We find a particular solution in agreement to the classical fracture models besides a response function in accordance to the stress and strain field distribution in biological materials.
Abstract: In this paper, the authors describe a rapid prototyping method to produce vascularized tissue such as liver scaffold for tissue engineering applications. A scaffold with an interconnected channel was designed using a CAD environment. The data were transferred to a Polyjet 3D Printing machine (Eden 250, Object, Israel) to generate the models. Based on the 3D Printing model, a PDMS (polydimethyl-silicone) mould was created which can be used to cast the biodegradable material. The advantages and limitations of Rapid Prototyping (RP) techniques as well as the future direction of RP development in tissue engineering scaffold fabrication were reviewed.
Abstract: Vascular endothelial growth factor (VEGF) and bone morphogenetic proteins (BMP-7) are key regulators of angiogenesis and osteogenesis during bone regeneration. The aim of this study was to investigate the possibility of realizing sequential release of the two growth factors using a novel composite scaffold. Poly(lactic-co-glycolic acid) (PLGA)-Akermanite (AK) microspheres were used to make the composite scaffold, which was then loaded with BMP-7, followed by embedding in a gelatin hydrogel matrix loaded with VEGF. The release profiles of the growth factors were studied and selected osteogenic related markers of bone marrow stromal cells (BMSCs) were analysed. It was shown that the composite scaffolds exhibited a fast initial burst release of VEGF within the first 3 days and a sustained slow release of BMP-7 over the full period of 20 days. The in vitro proliferation and differentiation of the BMSCs cultured in the osteogenic medium were enhanced by 1 to 2 times, resulting from the additionally and sequentially release of growth factors from the PLGA-AK/gelatin composite scaffolds.
Abstract: SiO2-hemoglobin-poly(L-lactide) (SiO2-Hb-PLLA) microspheres were prepared in a process of solution-enhanced dispersion by supercritical CO2 (SEDS). SiO2 nanoparticles were loaded with Hb by adsorption firstly and then the Hb-SiO2 nanoparticles were further coated with PLLA by the SEDS process. The resulted microcapsules were characterized by scanning electron microscope (SEM), laser diffraction particle size analyser and Fourier transform infrared spectrometer (FTIR). The drug release profiles were also determined. The Hb-SiO2-PLLA microspheres have a narrow particle size distribution (PDI 0.189) with a mean particle size of 897nm and a drug loading of 7.1%. After coating with PLLA, the drug release from SiO2-Hb-PLLA showed a sustained process mainly in zero-order kinetics; only 3.7% drug was released in the first 24 hours, versus 51.9% for those without coating, which revealed that the coating of PLLA significantly retarded the drug release. The results also indicate that the SEDS process is a typical physical process to produce protein-loaded polymer microspheres without changing the molecular structure of proteins, which is potential in the application of designing proteins drug delivery system.