Asim Kumar Jana

Development of corn starch based green composites reinforced with Saccharum spontaneum L fiber and graft copolymers--evaluation of thermal, physico-chemical and mechanical properties.

In this paper, corn starch based green composites reinforced with graft copolymers of Saccharum spontaneum L. (Ss) fiber and methyl methacrylates (MMA) and its mixture with acrylamide (AAm), acrylonitrile (AN), acrylic acid (AA) were prepared. Resorcinol-formaldehyde (Rf) was used as the cross-linking agent in corn starch matrix and different physico-chemical, thermal and mechanical properties were evaluated. The matrix and composites were found to be thermally more stable than the natural corn starch backbone. Further the matrix and composites were subjected for biodegradation studies through soil composting method. Different stages of biodegradation were evaluated through FT-IR and scanning electron microscopic (SEM) techniques. S. spontaneum L fiber-reinforced composites were found to exhibit better tensile strength. On the other hand Ss-g-poly (MMA) reinforced composites showed maximum compressive strength and wear resistance than other graft copolymers reinforced composite and the basic matrix.

Preparation, characterization and targeted delivery of serratiopeptidase immobilized on amino-functionalized magnetic nanoparticles.

Targeted delivery of serratiopeptidase enzyme immobilized on magnetic nanoparticles (MNPs) of Fe3O4 has been reported for the treatment using this enzyme. The enzyme was immobilized by covalent bonding through glutaraldehyde after amino functionalization of MNPs and parameters was studied. The enzyme bound MNPs (EMNPs) were characterized for size, crystallographic identity, phase purity, zeta potential and magnetic properties along with elemental and thermal analysis. The binding of enzyme had little effect on sizes (~10-17 nm) and on magnetic properties, but the zeta potential increased from -25 mV to +14.5 mV with surface amino groups up to 350 μmoles g(-1) MNPs, to stabilize its suspensions. In the molecular level, maximum of 17 molecules of enzyme could bind to each particle of MNPs that showed residual activity 67%, decreased KM and Vmax, good storage stability. Magnetic targeting of EMNPs increased the delivery (permeation) of drug through the membrane in in vitro study and enhanced the anti-inflammatory effect on carrageenan induced paw oedema in rats in in vivo study at much lower doses of enzyme than the doses required for treatment with free enzyme.

Synthesis, crystal structure investigation, DFT analyses and antimicrobial studies of silver(I) complexes with N,N,N′,N′′-tetrakis(2-hydroxyethyl/propyl) ethylenediamine and tris(2-hydroxyethyl)amine

The synthesis, crystal structures, DFT and antimicrobial studies of three novel complexes of silver: [Ag(THEEN)]2(PIC)2 (1), [Ag(THPEN)]2(PIC)2 (2) and [Ag(TEAH3)2](PIC) (3), have been reported in the present work, where THEEN/THPEN (N,N,N′,N′′-tetrakis(2-hydroxyethyl/propyl)ethylenediamine) are tetrapodal ligands and TEAH3 (tris(2-hydroxyethyl)amine) is a tripodal ligand. Complexes (1) and (2) are dinuclear, whereas (3) is mononuclear. Complex (1) adopted a see-saw geometry with coordination number four, whereas (2) and (3) are five coordinated. Complex (2) acquired distorted square-pyramidal geometry, whereas complex (3) acquired distorted trigonal-bipyramidal geometry. Extensive hydrogen bonding interactions have been found in all three complexes. The primary coordination sphere of the newly synthesized silver(I) complexes has been optimized, structural parameters have been calculated and the energy gaps of the frontier orbitals have been predicted with the B3LYP/6-31G/LANL2DZ level of theory. Structural parameters from the crystallographic and DFT studies are in good agreement with each other. The relatively smaller calculated HOMO–LUMO energy gaps (HLG) suggest charge transfer transitions. Antimicrobial studies have been performed with the new silver(I) complexes against gram +ve bacteria (Staphylococcus aureus), gram −ve bacteria (Serratia marcescens, Sphingobium japonicum and Stenotrophomonas maltophilia) and fungal species (Candida albicans, Aspergillus niger and Saccharomyces cerevisiae). Dinuclear complexes (1) and (2) exhibited remarkable results. All the synthesized silver(I) complexes have been proven to be better antibacterial and antifungal agents, even than their standard drugs (ciprofloxacin and fluconazole) and can be used as effective antimicrobial agents and potential drugs in the future.

Preparation and cyclodextrin assisted dissolution rate enhancement of itraconazolium dinitrate salt

The poor solubility of itraconazole (ITR) results in its variable oral absorption and bioavailability and has also proven to be a major setback in developing an efficient oral delivery system. To improve its solubility and dissolution profile, itraconazolium dinitrate salt (ITRDNT) was prepared and characterized using various spectral and thermal techniques. The morphology of the salt was studied using optical and scanning electron microscopy (SEM). Broth microdilution assay demonstrated antifungal efficacy of ITRDNT similar to ITR against four different fungal strains namely, Asparagillus fumigatus, Microsporum canis, Microsporum gypsum and Trichophyton rubrum. The salt exhibited better solubility profile than ITR in water and a number of pharmaceutical solvents. Dissolution studies revealed the total amount of drug released from ITRDNT in 3 h was four times greater than that of ITR. To further improve dissolution characteristics, the physical mixtures of ITR and ITRDNT with two cyclodextrins, β-cyclodextrin (β-CD) and HP-β-cyclodextrin (HP-β-CD) were prepared and their molar ratios were optimized. It was observed that about 75% of drug was released in 30 min from 1:3 molar ratio of ITRDNT and HP-β-CD physical mixture, which was distinctly higher than ITR commercial capsules (70%). Owing to its facile and economical preparation and substantially better in vitro release profile, the ITRDNT and its CD physical mixtures could be better and cost effective alternatives to ITR and commercial ITR capsules.

The effect of N-alkyl substituents on the usability of imidazolium cation-based ionic liquids in microemulsion systems: a technical note.

Ionic liquids (ILs) are predominantly hailed as green solvents, due to their non-volatile, recyclable and non-hazardous nature. Their wide-spectrum applications can be implemented into conventional fields like lubricants, battery electrolytes and synthetic reaction media as well as newer arenas including supramolecular chemistry, separation techniques, and nuclear fuel reprocessing (1–4). However, due to their tunable physicochemical properties, some recent reports have suggested novel pharmaceutical uses of ionic liquids, including their use as active pharmaceutical ingredient salts (5), antimicrobials (6), solubilizers (7), and drug delivery systems (8,9). ILs are known to enhance the solubility profile of poorly water-soluble drugs (7,10). Therefore, the use of IL-based drug carrier systems could be a rational approach for delivery of insoluble drugs. Microemulsions are thermodynamically stable, isotropic systems composed of a polar phase (usually water), a nonpolar phase (oils) and amphiphilic phase (surfactant or mixture of surfactants). These systems provide numerous advantages over conventional drug delivery vehicles including nanometer sized aggregations, long-term stability, biocompatibility, easy preparation, and high solubilization tendency (11). Nevertheless, drug delivery using microemulsions is yet to fully attain its true potential, considering that only type and content of oils and surfactants have been customized, in general, by formulators to achieve different desirable characteristics. Little efforts have been performed in the direction of modifying the polar phase of microemulsion systems. We attempted to use ILs as alternative polar dispersed phase (in place of water) in the microemulsion systems. Moniruzzaman et al., recently have prepared the IL-based microemulsion carrier for drug delivery of poorly hydrophilic drugs (12). The report describes the use of dimethylimidazolium dimethylphosphate for successful transdermal delivery of poorly soluble drugs. However, to the best of our knowledge, we are for the first time reporting the screening of room temperature ionic liquids from two different series of 1- and 3-alkyl substituted imidazolium bromides to be used as components of microemulsion vehicles. The current study explains the synthesis of some imidazolium cation-based ILs with varying carbon chain length. Also, preliminary in vivo toxicity of these compounds was assessed by hemolysis assay using human blood to establish the possibility of using the ILs safely, and investigating relationship between N-alkyl substituents and their toxicity. Further, their effect on the microemulsion phase behavior was studied by constructing their pseudoternary phase diagrams using isopropyl myristate (IPM) as oil phase and Span 80 and Tween 80 mixture as emulgent phase. Model microemulsion systems consisting of the above mentioned ingredients were prepared and characterized.

Rapid Synthesis of Graft Copolymer of MMA Onto Saccharum spontaneum L. Under Microwave Irradiation for Enhanced Thermal Modifications

Abstract In this article, synthesis of graft copolymers of methyl methacrylate (MMA) onto Saccharum spontaneum L. fiber under the influence of microwave radiation (MWR) was carried out. Different reaction parameters such as time, initiator molar ratio, monomer concentrations, microwave power, pH, and solvent were optimized for maximum graft yield (62.3%). The graft copolymers thus formed were characterized by FT-IR, SEM, XRD, and TGA, DTA, and DTG techniques. Moreover, graft copolymers have been found to be more moisture resistant and also showed higher chemical and thermal resistance.

Effect of cross linking of PVA/starch and reinforcement of modified barley husk on the properties of composite films.

Barley husk (BH) was graft copolymerized by palmitic acid. The crystalline behavior of BH decreased after grafting. Poly vinyl alcohol (PVA)/starch (St) blend film, urea formaldehyde cross linked PVA/St films and composite films containing natural BH, grafted BH were prepared separately. The effect of urea/starch ratio, content of BH and grafted BH on the mechanical properties, water uptake (%), and biodegradability of the composite films was observed. With increase in urea: starch ratio from 0 to 0.5 in the blend, tensile strength of cross linked film increased by 40.23% compared to the PVA/St film. However, in grafted BH composite film, the tensile strength increased by 72.4% than PVA/St film. The degradation rate of natural BH composite film was faster than PVA/St film. Various films were characterized by SEM, FT-IR and thermal analysis.

Fungal pretreatment of sweet sorghum bagasse with supplements: improvement in lignin degradation, selectivity and enzymatic saccharification

Sweet sorghum bagasse (SSB) from food processing and agricultural industry has attracted the attention for uses in production of biofuel, enzymes and other products. The alteration in lignocellulolytic enzymes by use of supplements in fungal pretreatment of SSB to achieve higher lignin degradation, selectivity value and enzymatic hydrolysis to fermentable sugar was studied. Fungal strain Coriolus versicolor was selected for pretreatment due to high ligninolytic and low cellulolytic enzyme production resulting in high lignin degradation and selectivity value. SSB was pretreated with supplements of veratryl alcohol, syringic acid, catechol, gallic acid, vanillin, guaiacol, CuSO4 and MnSO4. The best results were obtained with CuSO4, gallic acid and syringic acid supplements. CuSO4 increased the activities of laccase (4.9-fold) and polyphenol oxidase (1.9-fold); gallic acid increased laccase (3.5-fold) and manganese peroxidase (2.5-fold); and syringic acid increased laccase (5.6-fold), lignin peroxidase (13-fold) and arylalcohol oxidase (2.8-fold) resulting in enhanced lignin degradations and selectivity values than the control. Reduced cellulolytic enzyme activities resulted in high cellulose recovery. Enzymatic hydrolysis of pretreated SSB yielded higher sugar due to degradation of lignin and reduced the crystallinity of cellulose. The study showed that supplements could be used to improve the pretreatment process. The results were confirmed by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric/differential thermogravimetric analysis of SSB.

Chitosan-assisted immobilization of serratiopeptidase on magnetic nanoparticles, characterization and its target delivery

Abstract Background: Magnetic nanoparticles (MNPs) gained attentions as universal carrier for drug delivery and for enzyme immobilization. Purpose: Target delivery of serratiopeptidase for treatment using this enzyme and applications in drug delivery. Method: Serratiopeptidase was immobilized on chitosan amino-functionalized MNPs by covalent bonding through glutaraldehyde. Targeting of MNPs with immobilized enzyme (EMNPs) was carried out in vitro in modified diffusion cell and in vivo in rats. Results and discussion: MNPs and EMNPs were 15.43 ± 5.22 and 18.43 ± 3.23 nm (transmission electron microscopy), crystallite size 16.89 and 21.05 nm (X-ray diffraction) and saturation magnetization 62 and 35.2 emug−1, respectively. Maximum protein and enzyme loading on EMNPs were 264 mg g−1 and 325 U g−1, respectively. In the molecular level, maximum 52 enzyme molecules could bind to each particle showing residual activity 68%, little effect on KM and Vmax, good storage stability. Magnetic targeting of EMNPs increased the delivery (permeation) of drug through membrane in vitro and the enhanced anti-inflammatory effect on carrageenan-induced paw oedema in rats in vivo at much lower doses of enzyme than the doses required for treatment with free enzyme. Conclusions: The enzymatic preparation of MNPs showed enhanced effects (permeation enhancement and anti-inflammatory activity) at lower concentration with magnetic targeting.

Synthesis of cross-linked starch based polymers for sorption of organic pollutants from aqueous solutions

Abstract Three cross-linked starch based polymers (1–3) were prepared by reaction between starch and hexamethylene diisocynate in the presence of dimethylformamide. The cross-linked adsorbents were used for the recovery of 4-nitrophenol (pNP) and 4-chlorophenol (pCIP) from aqueous solutions. Characterization of the polymers was performed by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy thermogravimetric analysis (TG) and differential thermal analysis (DTA). It was observed that the X-ray diffraction patterns of native starch and cross-linked starch were similar. TG-DTA studies revealed that the decomposition temperature of cross-linked starch was higher than that of native starch. The influence of pH, adsorbent dose and contact time on the percentage sorption capacity was examined using batch study. Adsorption results revealed that the starch-based bio-adsorbents showed high sorption capacity towards pNP and pCIP. At optimized conditions the maximum sorption capacity observed for polymer 3 was 83% for pNP. Substitution of experimental data values in the Freundlich model showed favourable results as compared with the Langmuir model.