Biocompatibility and biotoxicity of in-situ synthesized carboxylated nanodiamond-cobalt oxide nanocomposite

A nanocomposite that incorporates cobalt oxide（Co3O4） and nanodiamond（ND） can present both high magnetism（Co3O4） and high hardness（ND）. ND particles have potential applications in a variety of fields such as protein immobilization, biosensors, therapeutic molecule delivery and bio-imaging. However,limited information is available in literature on the in-situ synthesis of biocompatible magnetic materials and also on their potential biotoxicity as a result of their entry into environmental compartments and subsequent interaction with biota. In this work, a new kind of bio-compatible magnetic material –carboxylated nanodiamond（c ND） and Co3O4 was synthesized to obtain the c ND-Co3O4 nanocomposite.The synthesis procedure involved in-situ and chemical reduction of cobalt chloride（CoCl（26）H2O） and sodium borohydrate（NaBH4）. The synthesized cND-Co3O4 nanocomposite was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The cyto-genotoxicity of the synthesized nanocomposite material was studied by using onion（Allium cepa L.） as a test model with concentrations of 5, 10 and 20 μg/ml. The study was also extended to cND and Co3O4 materials for comparison purpose. Co3O4 and cND exhibited their contrasting effects on mitosis and other cyto-genotoxic indices studied herein. This work provided fundamental data on the synthesis and the bio-toxicity of the c ND-Co3O4 nanocomposite, which, in turn, can help to expand their multidisciplinary applications.

Competition among rare earth elements on sorption onto six seaweeds

Sorption has been proposed as a promising approach towards a sustainable water decontamination and recently to the recycling of rare earth elements(REE).Although living seaweed have been shown to be capable of removing REE from contaminated solutions,no studies have yet compared the effects of REE competition on sorption onto different groups of seaweed.These effects were analysed in the present study by exposing six living seaweeds(Ulva lactuca,Ulva intestinalis,Fucus spiralis,Fucus vesiculosus,Gracilaria sp.and Osmundea pinnatifida)(3 g/L,fresh weight) to mono-element and multi-element solutions of Y,La,Ce,Pr,Nd,Eu,Gd,Tb and Dy(1 μmol/L).Results show a preference towards light REE in mono-element solutions,which is reduced when in competition with other REE.The competitive effect is less pronounced in heavy REE indicating that these are still able to bind to the macroalgae despite the presence of competing ions.Contrary to water content(%),seaweed specific surface area(cm^(2)/g) shows to be an important factor in the sorption of REE,since larger surface area is associated with higher removal and larger competitive effect.