Sunny Kuriakose

Studies on the antimicrobial properties of colloidal silver nanoparticles stabilized by bovine serum albumin

Colloidal silver nanoparticles were synthesised using sol-gel method and these nanoparticles were stabilised by encapsulated into the scaffolds of bovine serum albumin. Silver nanoparticles and encapsulated products were characterised by FTIR, NMR, XRD, TG, SEM and TEM analyses. Silver nanoparticle encapsulated bovine serum albumin showed highly potent antibacterial activity towards the bacterial strains such as Staphylococcus aureus, Serratia marcescens, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae.

Catalytic properties of cobalt(II) porphyrins supported on styrene-divinylbenzene copolymer

Polymeric pyridinium chloride was synthesized by treating pyridine with 2% divinylbenzene (DVB)-crosslinked chloromethyl polystyrene. Sodium 5,10,15,20-tetrakis(4-sulfophenyl)porphyrin was synthesized and appended on the above polymer through an ionic linkage. Cobalt(II) complex of the polymeric porphyrin was synthesized and characterized chemically and spectroscopically. This complex was employed as catalyst for the oxidation of dithiocarbamates to thiuram disulfide. Electronic and ESR spectra of the complex were analyzed before and after catalysis. pH dependence of catalytic reactions was also studied. These studies provide evidence for the catalytic ability of the polymeric cobalt(II) porphyrin system. A mechanism for the catalytic reaction is suggested on the basis of the above results.

Antifungal activity of silver nanoparticle-encapsulated β-cyclodextrin against human opportunistic pathogens

Silver nanoparticles were synthesised by reducing silver acetate with a long-chain aliphatic amine. β-Cyclodextrin (CD)-stabilised silver nanoparticles were successfully synthesised and characterised by the UV–vis spectroscopy and scanning electron microscopy analysis. This system was examined for their antifungal activity against opportunistic human pathogens such as Aspergillus fumigatus, Mucor ramosissimus and Chrysosporium species. This study clearly demonstrates that the present system is a powerful antifungal agent against human opportunistic pathogenic fungi.

Synthesis, characterisation and antibacterial applications of water-soluble, silver nanoparticle-encapsulated β-cyclodextrin

This paper describes a simple method for the synthesis of water-soluble, silver nanoparticle-encapsulated β-cyclodextrin by phase transfer of silver nanoparticles from organic to aqueous phase using β-cyclodextrin as a capping agent. β-Cyclodextrin–silver nanoparticle inclusion complex was purified, characterised by spectroscopic and microscopic analyses and tested in vitro against Pseudomonas aeruginosa, Staphylococcus aureus, Serratia marcescens, Escherichia coli and Klebsiella pneumoniae. The silver nanoparticle-encapsulated β-cyclodextrin inclusion complex displayed considerable antimicrobial activity and stability.

Antimicrobial Activity of Carbon Nanoparticles Isolated from Natural Sources against Pathogenic Gram-Negative and Gram-Positive Bacteria

This paper describes the isolation of carbon nanoparticles (CNPs) from kitchen soot, characterization of the CNPs by UV/visible spectroscopy, SEM and XRD, and their antimicrobial action. The antibacterial activity of the isolated carbon nanoparticles was tested against various pathogenic bacterial strains such as Gram-negative Proteus refrigere and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus and Streptococcus haemolyticus. The inhibition zones were measured, and it was found that the carbon nanoparticles isolated from natural sources are active against these Gram-negative and Gram-positive bacterial strains.

Cobalt(II) Porphyrins Supported on Crosslinked Polymer Matrix as Model Compounds

Polymer-bound cobalt(II) porphyrins were studied for their dioxygen—binding capacity. Tetra—aminoporphyrins were anchored on a divinylbenzene (DVB)-crosslinked chloromethyl polystyrene network. The crosslinked, solid polymers were swelled in chloroform and the swollen polymers were used for the entire studies. Ortho-, meta- and para-substituted porphyrin systems were developed by adjusting the bonding position with the help of suitably substituted aminoporphyrins. The products were characterized by chemical and spectroscopic methods. Cobalt(II) complexes of polymeric porphyrins were synthesized and characterized by electronic and ESR spectral methods. The spectra gave evidence for the systematic variation of electronic properties in ortho, meta and para compounds and for the dioxygen-binding capacity of cobalt complexes. These results are discussed.

Benzil-benzilic acid rearrangement in crosslinked macromolecular systems: effect of crosslinking

Abstract The effect of the molecular character and extent of crosslinking units on polymer-analogous benzil-benzilic acid rearrangement was investigated. A typical hydrophobic styrene-divinylbenzene copolymer and a hydrophilic styrene-tetraethyleneglycol diacrylate copolymer were used as the polymer supports. Supports with crosslink densities varying from 2 to 20% were functionalized. The polymer-bound aldehydes were subjected to crossed benzoin condensation in the presence of benzaldehyde. The benzoin analogues were converted to benzils and then subjected to benzil-benzilic acid rearrangement. The products were characterized by i.r. and 13C n.m.r. spectroscopy and the extent of rearrangement was determined by chemical methods.

Alkali salts of heteropoly tungstates： Efficient catalysts for the synthesis of biodiesel from edible and non-edible oils

Abstract Alkali salts of tungsten based heteropoly acids with different central atom such as P, Si and Co were prepared and evaluated for transesterification of both edible and non-edible oils to their corresponding fatty acid methyl esters. The catalyst of sodium salt of tungstic acid with Co as central atom (Na5CoW12O40) showed optimum activity towards transesterification compared with other heteropoly tungstates. The catalysts activities were correlated with the observed physico-chemical characteristics derived from FT-infrared (FT-IR), X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH3-TPD) and carbon dioxide (CO2-TPD). The Na5CoW12O40 catalyst exhibiting high activity even at 65 °C is due to the presence of strong acidic as well as basic sites. The disclosed catalyst is tolerable towards water and free fatty acids present in the oils. The influence of catalyst loading, reaction time and reaction temperature is studied to optimize the reaction parameters.

Synthesis and characterization of sodium–lithium niobate ceramic structures and their composites with biopolymers

Ceramic powders of Na1−xLixNbO3 (LNN) have been synthesized by an aqueous sol-gel route. These solid solutions were prepared from Na-Li-Nb precursor gel. The precursor was synthesized from Na-EDTA, Li-EDTA and Nb-citrate complexes and they acted as the source of Na, Li and Nb, respectively. Citric acid and ethylenediaminetetraacetic acid (EDTA) were used as the chelating agents for Na, Li and Nb. The precursor gel was calcinated on a muffle furnace at 750 °C for one hour and this provided the ceramic structures. Composites of LNN-biopolymers were prepared by the encapsulation of the ceramic structures into the biopolymeric scaffolds. The ceramic structures and composites were characterized by FTIR, NMR, TG and SEM analysis.

Copper (II) and silver (II) complexes of polymer‐bound porphyrins with Schiff base linkage

Two percent divinylbenzene (DVB)–crosslinked polystyrene was prepared and functionalized to obtain its aldehyde analog. Amino porphyrins were anchored on this polymer support by Schiff base condensation. The anchoring positions were adjusted so as to obtain ortho-, meta-, and para-isomeric systems. The polymer-bound free-base porphyrins were metallated to obtain the corresponding Cu(II) and Ag(II) complexes by treating them with the corresponding metal salt solutions. The products were characterized chemically and spectroscopically. Electronic and ESR spectral analysis shows the microenvironmental participation of the polymer network on the electronic levels of the porphyrin system. The extents of steric and electronic participation were evaluated and are presented.