Electrochemical evidence for asialoglycoprotein receptor – mediated hepatocyte adhesion and proliferation in three dimensional tissue engineering scaffolds

Asialoglycoprotein receptor (ASGPR) is one of the recognition motifs on the surface of hepatocytes, which promote their adhesion to extracellular matrix in liver tissue and appropriate artificial surfaces. ASGPR-mediated adhesion is expected to minimize trans-differentiation of hepatocytes in vitro that is generally observed in integrin-mediated adhesion. The aim of the present study is to verify the role of ASGPR in hepatocyte adhesion and proliferation in scaffolds for hepatic tissue engineering. Scanning Electrochemical Microscopy (SECM) is emerging as a suitable non-invasive analytical tool due to its high sensitivity and capability to correlate the morphology and activity of live cells. HepG2 cells and rat primary hepatocytes cultured in Polyvinyl alcohol (PVA)/Gelatin hydrogel scaffolds with and without galactose (a ligand for ASGPR) modification are studied using SECM. Systematic investigation of live cells cultured for different durations in scaffolds of different compositions (9:1 and 8:2 PVA:Gelatin with and without galactose) reveals significant improvement in cell–cell communication and proliferation on galactose incorporated scaffolds, thereby demonstrating the positive influence of ASGPR-mediated adhesion. In this work, we have also developed a methodology to quantify the respiratory activity and intracellular redox activity of live cells cultured in porous tissue engineering scaffolds. Using this methodology, SECM results are compared with routine cell culture assays viz., MTS ((1-Oxyl-2,2,5,5,-tetramethyl-Δ3-pyrroline-3-methyl) Methanethiosulfonate) and Albumin assays to demonstrate the better sensitivity of SECM. In addition, the present study demonstrates SECM as a reliable and sensitive tool to monitor the activity of live cells cultured in scaffolds for tissue engineering, which could be used on a routine basis.     

Pyrolysis of sorghum bagasse biomass into bio-char and bio-oil products

The transformation of renewable biomass into valuable products as alternatives to fossil fuels is essential for sustainable energy in sustainable society. This work systematically investigates the pyrolysis of sorghum bagasse biomass into bio-char and bio-oil products and studies the effect of temperature (623–823 K) on the conversion of sorghum bagasse and products yields. The physicochemical properties of bio-char were thoroughly studied using powder X-ray diffraction, elemental analysis (CHNSO), scanning electronic microscope, calorific value (CV), and Fourier transform infrared (FTIR) spectroscopy techniques. Also, gas chromatography–mass spectrometry (GC–MS), CV, and FTIR were used to understand the properties of bio-oil. The results obtained indicate that an increase in the pyrolysis temperature from 623 to 823 K leads to a decrease in the bio-char yield from 42.55 to 30.38%. On the other hand, the maximum bio-oil yield of 15.94% was obtained at 723 K. The bio-char obtained at 673 and 773 K was found by FTIR analysis to be composed of a highly ordered aromatic carbon structure. The calorific value of bio-oil, which contains a greater amount of acidic compounds, was found to be 6740 kcal/kg. The GC–MS analyses revealed the presence of octadecenoic acid, p-cresol, 2,6-dimethoxy phenol, 4-ethyl 2-methoxy phenol, phenol, o-guaiacol, and octadecanoic acid in the bio-oil obtained from the pyrolysis of sorghum bagasse biomass. The present study provides useful information for understanding the quality of bio-oil and bio-char obtained from high biomass sorghum bagasse.     

Synthesis of 6‐Fluoro‐7‐cyclic Amino‐substituted Dicarboxylic Acid Quinolones and their Antibacterial Activity

Novel 1‐carboxymethyl‐6‐fluoro‐7‐cyclic amino‐substituted‐4‐oxo‐1,4‐dihydroquinolone‐3‐carboxylic acids 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h , 7i , 7j , 7k , 7l , 7m , 7n were synthesized as a new class of quinolones. Ethyl‐6‐fluoro‐7‐chloro‐1,4‐dihydro‐4‐quinoline‐3‐carboxylic acid was prepared from conventional method and reacted with ethyl bromoacetate to furnish N‐carboxymethyl derivatives. The compounds were screed against various Gram‐positive and Gram‐negative bacterial strains. Antibacterial activity data is validated by molecular docking studies.     

Antibacterial activity of conjugated polyelectrolytes with variable chain lengths

Cationic poly(phenylene ethynylene)- (PPE-) based conjugated polyelectrolytes (CPEs) with six different chain lengths ranging in degree of polymerization from ～7 to ～49 were synthesized from organic-soluble precursor polymers. The molecular weight of the precursor polymers was controlled by the amount of a monofunctional "end-capping" agent added to the polymerization reaction. Cationic CPEs were prepared by quaternization of amine groups to tetraalkylammonium groups. Their structure-property relationships were investigated by observing their photophysical properties and antibacterial activity. The polymers were found to exhibit a chain-length dependence in their photophysical properties. It has also been observed that the polymers exhibit effective antibacterial activity against both Gram-positive and Gram-negative bacteria under UV irradiation, whereas they show little antibacterial activity in the dark. An effect of chain length on the light-activated antibacterial activity was also found: The shortest polymer (n=7) exhibited the most effective antibacterial activity against both Gram-positive and Gram-negative bacteria.     

Synthesis of biarylketones and phthalides from organoboronic acids and aldehydes catalyzed by cobalt complexes

A cobalt-catalyzed addition of aryl- and alkenylboronic acids to aldehydes and phthalaldehyde to give the corresponding biarylketones and 3-aryl phthalides in good to excellent yields in one pot is described.     

Control strategies for laser separation of carbon isotopes

Laser isotope separation (LIS) by infrared laser chemistry of polyatomic molecules has come a long way since its discovery. The last decade has seen considerable efforts in scaling up of the process for light elements like carbon, oxygen and silicon. These efforts aim at ways to improve both the enrichment factor and the throughput. The achievement is quite significant especially for carbon isotope separation wherein macroscopic operating scales have been realized. We report our studies on the IR laser chemistry of two promising systems, viz. neat CF₂HCl and CF₃Br/Cl₂. We have investigated conditions for optimizing the dissociation yield and selectivity using natural samples containing l.l%C-13.Wealso highlight our current efforts for scaling up the process. These include the design aspects of a photochemical reactor with multipass refocusing Herriott optics for efficient photon utilization, development of a cryogenic distillation set up and a preparative gas chromatograph for large scale separation/collection of the isotopically enriched photoproduct in the post-irradiation stage.     

The performance of a quartz oscillator in liquids Part I

Experiments are described to measure the ultrasonic output from a quartz transducer by a calorimetric method. The electrical input power has also been estimated. The efficiency of conversion is examined in the light of available physical data for several liquids     

Kolmogorov’s existence theorem for Markov processes inC* algebras

Given a family of transition probability functions between measure spaces and an initial distribution Kolmogorov’s existence theorem associates a unique Markov process on the product space. Here a canonical non-commutative analogue of this result is established for families of completely positive maps betweenC* algebras satisfying the Chapman-Kolmogorov equations. This could be the starting point for a theory of quantum Markov processes. Dedicated to the memory of Professor K G Ramanathan     

Electrical transport and high pressure studies on bulk Ge20Te80 glass

The electrical resistivity of bulk Ge₂₀Te₈₀ has been measured as a function of pressure and temperature. At 5 GPa, an amorphous semiconductor-to-crystalline metal transition has been observed. The sample recovered from the high pressure cell, after the application of 7 GPa, has a face-centred cubic structure with a lattice constant of 6·42 A. In crystalline sample, the semiconductor-to-metal transition occurs at 7 GPa. The thermoelectric power has also been measured for glassy samples in the temperature range 300–240 K.