Tissue Engineering of Cartilage Using a Random Positioning Machine

Articular cartilage is a skeletal tissue of avascular nature and limited self-repair capacity. Cartilage-degenerative diseases, such as osteoarthritis (OA), are difficult to treat and often necessitate joint replacement surgery. Cartilage is a tough but flexible material and relatively easy to damage. It is, therefore, of high interest to develop methods allowing chondrocytes to recolonize, to rebuild the cartilage and to restore joint functionality. Here we studied the in vitro production of cartilage-like tissue using human articular chondrocytes exposed to the Random Positioning Machine (RPM), a device to simulate certain aspects of microgravity on Earth. To screen early adoption reactions of chondrocytes exposed to the RPM, we performed quantitative real-time PCR analyses after 24 h on chondrocytes cultured in DMEM/F-12. A significant up-regulation in the gene expression of IL6, RUNX2, RUNX3, SPP1, SOX6, SOX9, and MMP13 was detected, while the levels of IL8, ACAN, PRG4, ITGB1, TGFB1, COL1A1, COL2A1, COL10A1, SOD3, SOX5, MMP1, and MMP2 mRNAs remained unchanged. The STRING (Search Tool for the Retrieval of Interacting Genes/Proteins) analysis demonstrated among others the importance of these differentially regulated genes for cartilage formation. Chondrocytes grown in DMEM/F-12 medium produced three-dimensional (3D) spheroids after five days without the addition of scaffolds. On day 28, the produced tissue constructs reached up to 2 mm in diameter. Using specific chondrocyte growth medium, similar results were achieved within 14 days. Spheroids from both types of culture media showed the typical cartilage morphology with aggrecan positivity. Intermediate filaments form clusters under RPM conditions as detected by vimentin staining after 7 d and 14 d. Larger meshes appear in the network in 28-day samples. Furthermore, they were able to form a confluent chondrocyte monolayer after being transferred back into cell culture flasks in 1 g conditions showing their suitability for transplantation into joints. Our results demonstrate that the cultivation medium has a direct influence on the velocity of tissue formation and tissue composition. The spheroids show properties that make them interesting candidates for cellular cartilage regeneration approaches in trauma and OA therapy.     

Influence of cold remote nitrogen oxygen plasma treatment on carbon fabric and its composites with specialty polymers

The parameters controlling performance of a fiber-reinforced polymer composite are type of matrix and fibers, their amount, aspect ratio, fiber orientation with respect to loading direction, fiber–matrix interface, and processing technique. In the case of carbon fiber reinforcement, fiber–matrix interface has always been a serious concern, because of chemical inertness of carbon fibers toward matrix and hence efforts are continued to enhance the fiber–matrix adhesion. A recent technique of cold remote nitrogen oxygen plasma was employed for surface treatment of carbon fabric (CF) to enhance its chemical reactivity and mechanical interaction toward matrix material. Untreated and plasma treated CF were used as bidirectional reinforcement for developing high performance composites with various specialty polymer matrices such as Polyetherimide, Polyethersulfone, and Polyetheretherketone. Treated CF reinforced composites showed appreciable improvement in most of the mechanical properties, which varied with type of plasma, its dozing and matrix used. X-ray Photoelectron Spectroscopy confirmed improvement in O/C and N/C ratio indicating inclusion of Oxygen and Nitrogen on the surfaces of fibers due to plasma treatment, which was responsible for enhanced adhesion. Similarly, Fourier Transform Infrared–Attenuated Total Reflectance Spectroscopy indicated presence of ether, carboxylic, and carbonyl functional groups on the plasma-treated surface of fibers. Raman spectroscopy indicated slight distortion in graphitic structure of treated CF. Scanning Electron Microscopy also indicated changes in the topography of treated CF, indicating enhanced mechanical interlocking with matrix.     

Surface designing of carbon fabric polymer composites with nano and micron sized PTFE particles

The new technique to tailor carbon fabric-polyethersulphone (CF-PES) composite surface with polytetrafluoroethylene (PTFE) nano particles; to improve wear performance has been reported. Cold remote nitrogen oxygen plasma (CRNOP) treatment was employed to alter the CF surface to promote fiber/matrix adhesion and further; inter laminar shear strength and wear performance of the composites. The atomic force microscopy and high resolution transmission microscopy; studies confirms the topographical modification on the fiber surface due to CRNOP treatment. The dipper ridges and perforations introduced on the fiber surface were analyzed with field emission scanning electron microscopy. The PTFE particles film formation on the worn composite surface was supportively analyzed by Raman spectroscopy and energy dispersive X-ray techniques. The topographical smoothening and rolling effect during the wearing of surface designed composites with PTFE nano particles; endorse to enhance its sliding wear properties and life.     

Passive direct formic acid microfabricated fuel cells

This paper reports on microscale silicon-based direct formic acid fuel cells (Si-DFAFCs) in which the fuel and the oxidant are supplied to the electrodes in a passive manner. Passive delivery of fuel and oxidant eliminates the need for ancillary components and associated parasitic losses. In this Si-DFAFC, an aqueous solution of formic acid is in direct contact with a Pd- or Pt-based anode and a Pt-based cathode is exposed to either a forced oxygen stream or quiescent air. In the presence of a forced oxygen flow on the cathode side the cell with Pd catalyst on the anode delivers a maximum power density of about 30 mW cm⁻² at room temperature, limited mostly by mass transfer at the anode, while in an all-passive mode (quiescent air on the cathode side) a maximum power density of 12.3 mW cm⁻² is obtained, limited by oxygen transport. This all-passive Si-DFAFC is fabricated using processes that are post-CMOS compatible, and thus can be integrated directly with envisioned MEMS applications, such as small sensors and actuators.     

Layer-by-layer deposition of zirconia thin films from aqueous solutions

Thin films of ZrO₂ and Y₂O₃-doped ZrO₂ were deposited using a novel yet simple layer-by-layer technique by means of electrostatic assembling and surface precipitation via dipping substrates alternately in cationic and anionic precursor solutions. Uniform films have been made. A constant growth rate of 5.4 ± 0.3 nm per deposition cycle for the dehydrated nanocrystalline films was achieved. This generic technique can be adapted to make other oxide films and novel multilayers or functionally-graded coatings.     

Improvement of Riboflavin Production by Lactobacillus fermentum Isolated from Yogurt

The riboflavin production by Lactobacillus fermentum isolated from yogurt was improved by inactivation of folE gene. Guanosine triphosphate (GTP) serves as the precursor for both folate as well as riboflavin biosynthesis. The folE gene of Lb. fermentum, which codes for GTP cyclohydrolase I was inactivated by the insertion of erythromycin resistance gene cassette through recombination and the riboflavin production by the parental and mutant strains were estimated. Inactivation of the folE gene involved in folate biosynthesis pathway resulted in enhanced level of riboflavin production by Lb. fermentum, since more amount of GTP molecules are made available for the GTP cyclohydrolase II mediated riboflavin biosynthesis pathway. In a chemically defined medium, the Lb. fermentum produced 2.29 mg L^?1 of riboflavin at 24 h of fermentation. Whereas the folE disrupted mutant Lb. fermentum GKJFE produced approximately 50% more riboflavin (3.49 mg L^?1) than that of the parental strain at 72 h of fermentation.     

Folic acid fortification of parboiled rice: Multifactorial analysis and kinetic investigation

Folic acid fortification of parboiled rice has been systematically studied to obtain quantitative insights into the role of key process variables. Parboiling was conducted with brown rice soaked at 70 °C for 1, 2 and 3 h with four different fortificant concentrations added and dried parboiled rice was milled for three durations (i.e. 0, 60 and 120 s). Both residual folate concentration in treated parboiled rice and pH of the soaking water after soaking stages were measured. Multifactorial model was developed to describe the residual folate retention behaviour and suggested that both soaking and milling were significant factors in folic acid fortification. The optimum soaking time was deduced to be 1.97 h. Folate retention rate followed a 1st order kinetics while the rates of natural rice hydrolysis and folate uptake were both time-dependent.