Design and Synthesis of Novel Pegylated 4‐Methylcoumarins

Coumarins are well known for their antioxidant and anti‐edema activities. Their antioxidant property gets enhanced with a methyl group at the C‐4 position of the pyran ring. To increase the antioxidant potential and their hydrophilicity, a lipase (Novozyme 435) catalyzed copolymerization of 4‐methylcoumarin diesters and polyethylene glycols (PEGs) has been carried out to give novel copolymers.     

Design and Biocatalytic Synthesis of Pluronics-based Nanomicellar Self-assembly Systems for Drug Encapsulation Applications

Nano medicine is an emerging branch of pharmaceuticals, which is gaining considerable attention mainly due to its new and effective way of drug delivery. Various modes of drug delivery are still in their adolescent stage, polymer-based drug delivery system is one among these. In order to develop a novel and biocompatible nano-carrier for drug delivery through a “green” and, environmentally benign approach, herein, we report the design, synthesis and characterization of four novel pluronic-based amphiphilic copolymers. Candida antartica lipase was used to catalyze polymerization in the presence of molecular sieves under solventless conditions. The resulting copolymers were also investigated for their supramolecular organization and drug encapsulation capacity for biomedical applications.     

Synthesis of fluorescent carbon dots via microwave carbonization of citric acid in presence of tetraoctylammonium ion,and their application to cellular bioimaging

A jelly-like form of carbon dots (C-dots) was prepared by microwave-assisted synthesis from citric acid in the presence of tetraoctylammonium bromide. The effect of the concentration of tetraoctylammonium bromide was examined. The synthesized carbon dots were characterized by UV–vis, XRD, FTIR, fluorescence and HR-TEM. Fluorescence extends from 350 to 600 nm, and the corresponding excitation wavelengths range from 300 to 460 nm. Quantum yields are at around 0.11. A cytotoxicity study showed carbon dots to be cell permeable and biocompatible which renders them appropriate for imaging applications. The dots were used to image HeLa cell lines via the blue fluorescence of the dots.

C-dots were synthesized from citric acid by microwave heating in presence of varying concentrations of tetraoctylammonium bromide (TOAB) as a micellar template. The excellent optical properties of the nanoparticles make them well suitable for bio-imaging of HeLa cells.

     

Immobilization of Xylanase from <Emphasis Type="Italic">Bacillus pumilus</Emphasis> Strain MK001 and its Application in Production of Xylo-oligosaccharides

Xylanase from Bacillus pumilus strain MK001 was immobilized on different matrices following varied immobilization methods. Entrapment using gelatin (GE) (40.0%), physical adsorption on chitin (CH) (35.0%), ionic binding with Q-sepharose (Q-S) (45.0%), and covalent binding with HP-20 beads (42.0%) showed the maximum xylanase immobilization efficiency. The optimum pH of immobilized xylanase shifted up to 1.0 unit (pH 7.0) as compared to free enzyme (pH 6.0). The immobilized xylanase exhibited higher pH stability (up to 28.0%) in the alkaline pH range (7.0–10.0) as compared to free enzyme. Optimum temperature of immobilized xylanase was observed to be 8 °C higher (68.0 °C) than free enzyme (60.0 °C). The free xylanase retained 50.0% activity, whereas xylanase immobilized on HP-20, Q-S, CH, and GE retained 68.0, 64.0, 58.0, and 57.0% residual activity, respectively, after 3 h of incubation at 80.0 °C. The immobilized xylanase registered marginal increase and decrease in K _m and V _max values, respectively, as compared to free enzyme. The immobilized xylanase retained up to 70.0% of its initial hydrolysis activity after seven enzyme reaction cycles. The immobilized xylanase was found to produce higher levels of high-quality xylo-oligosaccharides from birchwood xylan, indicating its potential in the nutraceutical industry.     

A new intramolecular charge transfer receptor as a selective ratiometric ‘off-on’ sensor for Zn

A new intramolecular charge transfer (ICT) probe 3 is found to display a highly selective photophysical response in the presence of Zn²⁺, among various biologically significant metal ions examined. The absorption band of 3 is red shifted by 84 nm and the fluorescence intensity increases 13-fold in the presence of Zn²⁺. The binding interaction follows the order Zn²⁺ > Cd²⁺ > Mg²⁺ > Ba²⁺ > Ca²⁺ > K⁺ ≅ Na⁺ ≅ Li⁺ and the stability constant for 3 + Zn²⁺ is over an order of magnitude higher compared to biologically competing Ca²⁺ and Mg²⁺.     

Biofouling and biodegradation of polyolefins in ocean waters

High density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP) coupons were immersed for a period of 6 months in Bay of Bengal near Chennai Port (Port) and Fisheries Survey of India (FSI). Samples were retrieved every month and the extent of biofouling and biodegradation were monitored by measuring biological and physicochemical parameters. Dissolved oxygen and oxidation reduction potential were higher at Port than at FSI. Total suspended solids and organic matter were more on PP, followed by HDPE and LDPE indicating hydrophobic surfaces favour more biofouling. Pseudomonas sp., anaerobic, heterotrophic and iron-reducing bacteria were observed on polymer surface. Biofouling was found to depend on the season, loading being highest in the month of August. Chlorophyll was higher at FSI than at Port due to higher pollution levels and also being closer to the shores. Maximum weight loss was seen in LDPE (1.5-2.5%), followed by that in HDPE (0.5-0.8%) and finally in PP (0.5-0.6%) samples deployed at Port in the six month time period.     

An algorithm for a fuzzy transportation problem to select a new type of coal for a steel manufacturing unit

Manufacturing of steel involves thermal energy intensive processes with coal as the major input. Energy generated is a direct function of ash content of coal and as such it weighs very high as regards the choice of coal. In this paper, we study a multiobjective transportation problem to introduce a new type of coal in a steel manufacturing unit in India. The use of new type of coal serves three non-prioritized objectives, viz. minimization of the total freight cost, the transportation time and the ratio of ash content to the production of hot metal. It has been observed from the past data that the supply and demand points have shown fluctuations around their estimated values because of changing economic conditions. To deal with uncertainties of supply and demand parameters, we transform the past data pertaining to the amount of supply of the ith supply point and the amount of demand of the jth demand point using level (λ,ρ) interval-valued fuzzy numbers. We use a linear ranking function to defuzzify the fuzzy transportation problem. A transportation algorithm is developed to find the non-dominated solutions for the defuzzified problem. The application of the algorithm is illustrated by numerical examples constructed from the data provided by the manufacturing unit.      

Important Properties of Sulfur–Bonded Organoboron (III) Complexes with Biologically Potent Ligands

Abstract

Important properties of sulfur/oxygen and nitrogen bonded organoboron (III) complexes with biologically potent ligands viz., semicarbazone, thiosemicarbazone, and dithiocarbazate having the donor groups ONX and NS have been studied. The unimolar and bimolar reactions of phenylboronic acid with monobasic bidentate and dibasic tridentate ligands result in the formation of colored solids which have been characterized by the elemental analysis, molecular weight determinations, and conductance measurements. The UV, IR, and NMR ( ¹ H, ¹³ C, and ¹¹ B) spectral studies indicate tetracoordinated geometry for the resulting complexes. Both the ligands and their complexes have been screened for their fungicidal and bactericidal activities, and the results indicate that they exhibit significant antimicrobial properties.