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The iron oxide nanoparticles have been synthesized in co-precipitation method using aqueous solution of ferric and ferrous ions with sodium salt. The synthesis of iron-oxide nanoparticles were validated by UV-Visible spectroscopy which showed higher peak at 370 nm as valid standard reference. An average size of iron oxide nanoparticle found by Diffraction Light scattering (DLS) particle size analyser, ranges approximately between 10 nm to 120 nm with mean particle size of 66 nm. The X-ray power diffraction (XRD) analysis revealed the crystallographic structure of magnetic particles. Characterization of the mean particle size and morphology of iron oxide nanoparticles confirmed that the iron oxide nanoparticles are nearly spherical and crystalline in shape. Further the antibacterial effect of iron oxide nanoparticles was evaluated against ten pathogenic bacteria which showed that the nanoparticles have moderate antibacterial activity against both Gram positive and Gram negative pathogenic bacterial strains and retains potential application in pharmaceutical and biomedical industries

Rice varieties having a moderate level of resistance to the brown planthopper, Nitaparvata lugens, were evaluated to determine the mechanisms of resistance. The host plant-insect interactions were studied in the greenhouse and insectary to determine the levels of antibiosis and tolerance in the moderately resistant varieties. Parametersmeasured as the tolerance indicator were plant damage, plant weight loss, and yield reduction due to insect feeding. The insect biomass production, growth index, and population growth rate on the test varieties were used as antibiosis indicators. A regression of plant weight loss, due to N. lugens feeding, on N. tugens weight for five varieties indicated that the variety 'Utri Rajapan' has a high level of tolerance and no antibiosis. The resistance in 'IR46,' 'Kencana,' and 'Triveni' is due to a combination of antibiosis and tolerance. The relative amount of each of the two resistance components was measured by using the tolerance-antibiosis index. Field studies confirmed results obtained in the greenhouse and insectary studies. Although 'Utri Rajapan' had field populationsof N. tugens equal to that of the susceptiblecheck, yield reduction was only 25'7c, compared with 100'70 in the susceptible check.

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Natural biomaterials such as collagen, silk fibroin, and chitosan, and synthetic biopolymers such as polylactic acid, polycaprolactone, polyglycolic acid, and their copolymers are being used as scaffold for tissue engineering applications. In the present work, a fibrous mat was electrospun from eri silk fibroin (ESF). A composite of hydroxyapatite (Hap) and the ESF scaffold was prepared by soaking the ESF scaffold in a solution of calcium chloride and then in sodium diammonium phosphate. The average tensile stress of the pure ESF and hydroxyapatite-coated ESF scaffold (ESF-Hap) was found to be 1.84 and 0.378 MPa, respectively. Pure ESF and ESF-Hap scaffolds were evaluated for their characteristics by a themogravimetric analyzer and Fourier transform infrared spectroscope. The crystallinity and thermal stability of the ESF-Hap scaffold were found to be more than that of uncoated eri silk nanofiber scaffold. The water uptake of the pure ESF and ESF-Hap scaffolds was found to be 69% and 340%, respectively, in distilled water as well as phosphate buffer saline. The hemolysis percentage of both scaffolds was less than 5%, which indicate their good blood compatibility. The cytocompatibility studied by 3-(4,5-dimethyl) thiazol-2-yl-2,5-dimethyl tetrazolium bromide assay showed that the scaffold is biocompatible. To assess cell attachment and growth on the scaffold, human mesenchymal stem cells were cultured on the scaffolds. The results from scanning electron microscopy and fluorescent microscopy showed a notable cellular growth and favorable morphological features. Hence, the ESF-Hap scaffold is better suited for cell growth than the pure ESF scaffold.Electronic supplementary materialThe online version of this article (doi:10.1186/2194-0517-2-6) contains supplementary material, which is available to authorized users.