Browsing by Author "Krishnan, K"

Now showing 1 - 3 of 3
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    Bonding agent is a decisive factor in determining the marginal leakage of dental composites subjected to thermal cycling: an in vitro study
    (JOURNAL OF ORAL REHABILITATION, 2001) Mathew, M; Nair, EKP; Krishnan, K
    The marginal leakage at the dentine/composite interface in Class II composite restorations subjected to thermal cycling has been effectively evaluated using the silver staining technique. The presence of a bonding agent at the dentine/composite interface is found to improve adhesion. Scanning electron and optical microscopic observations of sectioned specimens reveal that applying a second coat of bonding agent on the dentinal surface helps in reducing microleakage compared to a single coat application, in all three radiopaque composite/bonding agent systems studied (Z1001Single Bond, Spectrum TPH/Prime & Bond 2.1 and Chitra/Chitrabond 1.0). Thermal cycling during in vitro studies was found to provide a more appropriate representation of the adhesive behaviour of the composite in clinical situations.
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    Feasibility of Dermal Substitute Construction on Hybrid Scaffold Made of Poly(epsilon-caprolactone) and Bio Mimetic Fibrin Composite
    (JOURNAL OF BIOMATERIALS AND TISSUE ENGINEERING, 2014) Nair, RP; Krishnan, K; Krishnan, L
    Non-healing wounds can be a major problem in diabetic and burn victims. Identified causes of chronic wound formation include angiopathy, neuropathy, infection and loss of extra cellular matrix (ECM) due to increased protease action. Currently available conventional therapy is not efficient enough to promote wound healing. Tissue-engineered skin substitutes are now considered a better strategy for chronic wound management. Non-toxic scaffolds on which cells grow and replace the lost ECM are important components for tissue engineering. Degradable polymers are preferred because they may be absorbed by the time the tissue regenerate. We attempted to fabricate a degradable membrane-like and porous poly(epsilon-caprolactone)(PCL) scaffold to favour in-growth of cells, penetration of nutrients and oxygen. Modifying porous PCL membrane using a fibrin-based bionnimetic matrix could promote cell attachment and growth of tissue. The benefit of such a hybrid scaffold for long-term cell growth and ECM deposition, parallel to the degradation of polymer and diminution of mechanical property, was evaluated. We concluded that the hybrid scaffold we developed is suitable for dermal tissue construction in vitro. When grown on the hybrid scaffold, cells synthesized and deposited insoluble ECM proteins, thus proposing better epithelialization and angiogenesis when such dermal tissue constructs are implanted for treating non-healing chronic wounds.
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    Functional stability of endothelial cells on a novel hybrid scaffold for vascular tissue engineering
    (BIOFABRICATION, 2010) Pankajakshan, D; Krishnan, K; Krishnan, LK
    Porous and pliable conduits made of biodegradable polymeric scaffolds offer great potential for the development of blood vessel substitutes but they generally lack signals for cell proliferation, survival and maintenance of a normal phenotype. In this study we have prepared and evaluated porous poly(epsilon-caprolactone) (PCL) integrated with fibrin composite (FC) to get a biomimetic hybrid scaffold (FC PCL) with the biological properties of fibrin, fibronectin (FN), gelatin, growth factors and glycosaminoglycans. Reduced platelet adhesion on a human umbilical vein endothelial cell-seeded hybrid scaffold as compared to bare PCL or FC PCL was observed, which suggests the non-thrombogenic nature of the tissue-engineered scaffold. Analysis of real-time polymerase chain reaction (RT-PCR) after 5 days of endothelial cell (EC) culture on a hybrid scaffold indicated that the prothrombotic von Willebrand factor and plasminogen activator inhibitor (PAI) were quiescent and stable. Meanwhile, dynamic expressions of tissue plasminogen activator (tPA) and endothelial nitric oxide synthase indicated the desired cell phenotype on the scaffold. On the hybrid scaffold, shear stress could induce enhanced nitric oxide release, which implicates vaso-responsiveness of EC grown on the tissue-engineered construct. Significant upregulation of mRNA for extracellular matrix (ECM) proteins, collagen IV and elastin, in EC was detected by RT-PCR after growing them on the hybrid scaffold and FC-coated tissue culture polystyrene (FC TCPS) but not on FN-coated TCPS. The results indicate that the FC PCL hybrid scaffold can accomplish a remodeled ECM and non-thrombogenic EC phenotype, and can be further investigated as a scaffold for cardiovascular tissue engineering.