Chellan Rose

Phytosynthesis of silver nanoparticles using Coccinia grandis leaf extract and its application in the photocatalytic degradation

Silver nanoparticles were successfully synthesized from aqueous AgNO(3) through a simple green route using the leaf extract of Coccinia grandis as a reducing as well as capping agent. The results obtained from UV-vis spectrum, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier-transform infra red spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM) revealed that the biosynthesis of silver nanoparticles were in the size range of 20-30 nm and is crystallized in face centered cubic symmetry. Further, the thermal stability of nanoparticles was studied using thermo gravimetric analyzer (TGA) and differential scanning calorimeter (DSC). Photocatalytic property of the Ag nanoparticles was investigated by degradation of Coomassie Brilliant Blue G-250 under UV light. The results show that Ag nanoparticles have suitable activity for the degradation of Coomassie Brilliant Blue G-250.

Preparation and Characterization of Aloe Vera Blended Collagen-Chitosan Composite Scaffold for Tissue Engineering Applications

Collagen-Chitosan (COL-CS) scaffolds supplemented with different concentrations (0.1-0.5%) of aloe vera (AV) were prepared and tested in vitro for their possible application in tissue engineering. After studying the microstructure and mechanical properties of all the composite preparations, a 0.2% AV blended COL-CS scaffold was chosen for further studies. Scaffolds were examined by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA) to understand the intermolecular interactions and their influence on the thermal property of the complex composite. Swelling property in phosphate buffered saline (pH 7.4) and in vitro biodegradability by collagenase digestion method were monitored to assess the stability of the scaffold in a physiological medium in a hydrated condition, and to assay its resistance against enzymatic forces. The scanning electron microscope (SEM) image of the scaffold samples showed porous architecture with gradual change in their morphology and reduced tensile properties with increasing aloe vera concentration. The FTIR spectrum revealed the overlap of the AV absorption peak with the absorption peak of COL-CS. The inclusion of AV to COL-CS increased the thermal stability as well as hydrophilicity of the scaffolds. Cell culture studies on the scaffold showed enhanced growth and proliferation of fibroblasts (3T3L1) without exhibiting any toxicity. Also, normal cell morphology and proliferation were observed by fluorescence microscopy and SEM. The rate of cell growth in the presence/absence of aloe vera in the scaffolds was in the order: COL-CS-AV > COL-CS > TCP (tissue culture polystyrene plate). These results suggested that the aloe vera gel-blended COL-CS scaffolds could be a promising candidate for tissue engineering applications.

Application of a PDGF-containing novel gel for cutaneous wound healing

AIM The objective of this study was to develop an acellular provisional matrix to mimic the extracellular matrix (ECM) of a wound site, and to evaluate its potential for in vivo dermal regeneration. KEY POINTS This study evaluates the potential of a monomeric collagen-chitosan gel containing platelet-derived growth factor to enhance healing and reduce the time of wound closure. MAIN METHODS In the present study, we developed a novel composite consisting of the combination of collagen, chitosan and platelet-derived growth factor (PDGF). This biodegradable Molecular gel matrix was used as a biomimetic surface for cell attachment to promote healing of excision wounds (1.5 cm long x 1.5 cm width). The rate of wound contraction and the concentrations of collagen, hexosamine, uronic acid and growth factors in the granulation tissue were determined. The amount of antioxidants and lipid peroxide in the treated tissues was elevated compared to the control tissue; in particular, tissue from the group treated with the collagen-chitosan-PDGF matrix had remarkable increase in these parameters. Additionally, the histology and ultrastructure of re-epithelialized tissues at the wound site were recorded. SIGNIFICANCE This study reveals that the monomeric nature of biological molecules in association with PDGF exerted simultaneous biomimetic and chemotactic effects and promoted wound healing.

The effect of nerve growth factor on the early responses during the process of wound healing.

In this study, we investigated the role of nerve growth factor (NGF)-incorporated collagen on wound healing in rats. Full-thickness excision wounds were made on the back of female rats weighing about 150-160 g. Topical application of NGF-incorporated collagen, at a concentration of 1 microg/1.2 mg collagen/cm(2), once a day, for 10 days resulted in complete healing of wounds on the 15th day. The concentrations of collagen, hexosamine and uronic acid in the granulation tissue were determined. The NGF-incorporated collagen-treated rats required shorter duration for the healing with an increased rate of wound contraction. Histological and electron microscopical evaluations were also performed, which reveal the activation of fibroblasts and endoplasmic reticulum and therefore increased level of collagen synthesis due to NGF application. These results clearly indicate that the topical application of NGF-incorporated collagen enhanced the rate of healing of excision wounds.

In vitro anti inflammatory activity of Aloe vera by down regulation of MMP-9 in peripheral blood mononuclear cells

AIM OF THE STUDY The anti-inflammatory activity of Aloe vera was investigated through MMP inhibition studies. The effect of Aloe vera on MMP-9 inhibition was tested on peripheral blood mononuclear cells (PBMC). MATERIALS AND METHODS Peripheral blood mononuclear cells (PBMC) were isolated from the heparinised venous blood by Ficoll Diatrizoate gradient centrifugation. The cell count and viability was determined using dye exclusion technique. Cytotoxicity was evaluated by MTT assay. Activation of MMP-9 was visualized by gelatin zymography. Inhibition of MMP-9 in the presence of aqueous extract of Aloe vera was detected by gelatin zymography and confirmed by RT-PCR. RESULTS Peripheral blood mononuclear cells (PBMC) showed significant inhibition in the activity of MMP-9, indicating the in vitro inhibitory effect of Aloe vera on MMP-9. Zymographic analysis and RT-PCR showed that it caused a significant reduction in the production of MMP-9 in a concentration dependent manner. CONCLUSION The inhibition of MMP-9 production in the cells was detected by gelatin zymography and was confirmed by RT-PCR.

The interaction of sodium dodecyl sulfate and urea with cat-fish collagen solutions in acetate buffer: hydrodynamic and thermodynamic studies

Cat-fish collagen was extracted and characterized. Shrinkage temperature of cat-fish collagen is 54.5 degrees C. SDS-PAGE pattern indicated that the cat-fish collagen is Type I in nature. The ratio of proline and hydroxyproline is 1:2 and it suggests cat-fish collagen is vertebrate. The molecular weight of cat-fish collagen was determined by using molecular sieve chromatography and it was found to be 3 20,000 Da. The mutual interaction of cat-fish collagen with SDS and urea was studied at various temperatures. The results suggest that the aggregation of collagen is facilitated by the presence of SDS, whereas hindered by urea. The various thermodynamic parameters were estimated from viscosity measurements and the transfer of collagen into SDS micelles, urea and the reverse phenomenon was analysed. These transfer properties are temperature-dependent. Our thermodynamic results are also able to predict the exact denaturation temperature as well as the structural order of water in the collagen in various environments. The hydrated volumes, Vh of collagen in buffer, SDS, and urea environments using Simha-Einstein equation and intrinsic viscosity were also calculated. The low intrinsic viscosity [eta] and high Vh value of collagen in an SDS environment compared to buffer and other environments suggested a more workable system in cosmetic and dermatological preparations. The one and two-hydrogen-bonded models of this collagen in various environments have been analysed. The calculated thermodynamic parameters varied with the concentration of collagen as well as concentration of additives. The change of thermodyanamic parameters from coiled-coil to random-coil conformation upon denaturation of collagen were calculated from the amount of proline and hydroxyproline residues and compared with viscometric results. Denaturation enthalpy of the catfish collagen in buffer, SDS and urea environments has also been determined by differential scanning calorimetric (DSC) measurements, and the results are in good agreement with the viscosity-derived values. The assymmetry and molecular geometry of this collagen in buffer, SDS and urea environments are also computed. Overall, our hydrodynamic and thermodynamic results suggest that the stability of the collagen in the additive environments is in the following order: SDS > buffer > urea.

Differential anti-inflammatory and anti-fibrotic activity of transplanted mesenchymal vs. hematopoietic stem cells in carbon tetrachloride-induced liver injury in mice

Bone marrow stem cells nullify acquired and non-acquired diseases of liver through multiple strategies including antiinflammation. However, little is known about the in vivo mechanism of immunomodulation by stem cells in mediating liver cirrhosis. Mesenchymal stem cells (MSC) or hematopoietic stem cells (HSC) isolated from bone marrow of male mice were transplanted into female mice with acute liver inflammation. Serum levels of liver proteins and aminotransferase as well as hepatic antioxidant enzymes were estimated. Immunostaining for the expression of tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), alpha smooth muscle actin (alpha-SMA) and type I collagen proteins was carried out and the expression of these mRNAs was also studied. After post-transplantation, the levels of serum albumin and aminotransferases became normal and the levels of antioxidants were significantly high in the MSC treated mice compared to HSC and control mice. Necrotic cells and invasion of neutrophils were not observed in histological sections of liver of MSC treated mice. Immunostaining showed that IL-6 and TNF-alpha were not expressed in the MSC treated mice when compared to the control and HSC treated mice. alpha-SMA representing activated myofibroblasts and type I collagen were not expressed in MSC treated group. These inflammatory and fibrogenic results were further confirmed by reverse transcription-polymerase chain reaction (RT-PCR). The acute inflammation ended with the formation of fibrosis in the HSC and control groups by the uncontrolled immunoreactions. Protection mechanism of MSC therapy against injury and fibrosis in the liver occurs by the suppression of inflammation. Our findings suggest that bone marrow MSC are capable of alleviating the immunoreactions leading to the fibrosis in the liver.

Hepatocyte growth factor incorporated chitosan nanoparticles augment the differentiation of stem cell into hepatocytes for the recovery of liver cirrhosis in mice

BackgroundShort half-life and low levels of growth factors in the niche of injured microenvironment necessitates the exogenous and sustainable delivery of growth factors along with stem cells to augment the regeneration of injured tissues.MethodsHere, recombinant human hepatocyte growth factor (HGF) was incorporated into chitosan nanoparticles (CNP) by ionic gelation method and studied for its morphological and physiological characteristics. Cirrhotic mice received either hematopoietic stem cells (HSC) or mesenchymal stemcells (MSC) with or without HGF incorporated chitosan nanoparticles (HGF-CNP) and saline as control. Biochemical, histological, immunostaining and gene expression assays were carried out using serum and liver tissue samples. One way analysis of variance was used for statics applicationResultsSerum levels of selected liver protein and enzymes were significantly increased in the combination of MSC and HGF-CNP (MSC+HGF-CNP) treated group. Immunopositive staining for albumin (Alb) and cytokeratin 18 (CK18), and reverse transcription-polymerase chain reaction (RT-PCR) for Alb, alpha fetoprotein (AFP), CK18, cytokeratin 19 (CK19) ascertained that MSC-HGF-CNP treatment could be an effective combination to repopulate liver parenchymal cells in the liver cirrhosis. Zymogram and western blotting for matrix metalloproteinases 2 and 9 (MMP2 and MMP9) revealed that MMP2 actively involved in the fibrolysis of cirrhotic tissue. Immunostaining for alpha smooth muscle actin (αSMA) and type I collagen showed decreased expression in the MSC+HGF-CNP treatment. These results indicated that HGF-CNP enhanced the differentiation of stem cells into hepatocytes and supported the reversal of fibrolysis of extracellular matrix (ECM).ConclusionBone marrow stem cells were isolated, characterized and transplanted in mice model. Biodegradable biopolymeric nanoparticles were prepared with the pleotrophic protein molecule and it worked well for the differentiation of stem cells, especially mesenchymal phenotypic cells. Transplantation of bone marrow MSC in combination with HGF-CNP could be an ideal approach for the treatment of liver cirrhosis.

Inducible chromate reductase exhibiting extracellular activity in Bacillus methylotrophicus for chromium bioremediation.

Chromium toxicity is one of the major causes of environmental pollution due to its heavy discharge in industrial wastewaters. Chromate reduction is a viable method to detoxify hexavalent chromium to nontoxic trivalent species mediated by enzymes and metabolites. A new Bacillus methylotrophicus strain was isolated from tannery sludge and was an efficient candidate for chromate reduction. An initial chromate reductase activity of 212.84 U/mg protein was obtained at 48 h in a low-cost defined medium formulation with 0.25 mM chromate. The extracellular enzyme was inducible at 12h substrate addition with 312.99 U/mg at 48 h. Reduced glutathione was required for enhanced specific activity of 356.48 U/mg. Enzyme activity was optimum at pH 7.0 and at 30 °C, and was stable in the presence of EDTA, DTT and metal ions. The enzyme exhibited a Vmax of 59.89 μM/min/mg protein and a Km of 86.5 μM, suggesting feasibility of the reaction with K₂Cr₂O₇ as substrate. Application of the crude reductase in tannery effluent resulted in 91.3% chromate reduction at 48 h. An enzyme-mediated chromate reduction process has therefore been developed for bioremediation of toxic chromium sp. in industrial effluents.

Facile production of ZnS quantum dot nanoparticles by Saccharomyces cerevisiae MTCC 2918.

Microbial synthesis of nanoparticles is a green route towards ecofriendly measures to overcome the toxicity and non-applicability of nanomaterials in clinical uses obtained by conventional physical and chemical approaches. Nanoparticles in the quantum regime have remarkable characteristics with excellent applicability in bioimaging. Yeasts have been commercially exploited for several industrial applications. ZnS nanoparticles as semiconductor quantum dots have mostly been synthesized by bacterial species. Here in, we have attempted to produce ZnS nanoparticles in quantum regime by Saccharomyces cerevisiae MTCC 2918 fungus and characterize its size and spectroscopic properties. Intracellular ZnS nanoparticles were produced by a facile procedure and freeze thaw extraction using 1mM zinc sulfate. The ZnS nanoparticles showed surface plasmon resonance band at 302.57nm. The ZnS nanoparticles were in low yield and in the size range of 30-40nm. Powder XRD analysis revealed that the nanoparticles were in the sphalerite phase. Photoluminescence spectra excited at 280nm and 325nm revealed quantum confinement effects. This suggests that yeasts have inherent sulfate metabolizing systems and are capable fungal sources to assimilate sulfate. Further insights are required to identify the transport/reducing processes that may have caused the synthesis of ZnS nanoparticles such as an oxidoreductase enzyme-mediated mechanism.