Activity of glucose oxidase functionalized onto magnetic nanoparticles

BACKGROUND: Magnetic nanoparticles have been significantly used for coupling with biomolecules, due to their unique properties. METHODS: Magnetic nanoparticles were synthesized by thermal co-precipitation of ferric and ferrous chloride using two different base solutions. Glucose oxidase was bound to the particles by direct attachment via carbodiimide activation or by thiophene acetylation of magnetic nanoparticles. Transmission electron microscopy was used to characterize the size and structure of the particles while the binding of glucose oxidase to the particles was confirmed using Fourier transform infrared spectroscopy. RESULTS: The direct binding of glucose oxidase via carbodiimide activity was found to be more effective, resulting in bound enzyme efficiencies between 94–100% while thiophene acetylation was 66–72% efficient. Kinetic and stability studies showed that the enzyme activity was more preserved upon binding onto the nanoparticles when subjected to thermal and various pH conditions. The overall activity of glucose oxidase was improved when bound to magnetic nanoparticles CONCLUSION: Binding of enzyme onto magnetic nanoparticles via carbodiimide activation is a very efficient method for developing bioconjugates for biological application

Examination of Cholesterol oxidase attachment to magnetic nanoparticles

Abstract Magnetic nanoparticles (Fe3O4) were synthesized by thermal co-precipitation of ferric and ferrous chlorides. The sizes and structure of the particles were characterized using transmission electron microscopy (TEM). The size of the particles was in the range between 9.7 and 56.4 nm. Cholesterol oxidase (CHO) was successfully bound to the particles via carbodiimide activation. FTIR spectroscopy was used to confirm the binding of CHO to the particles. The binding efficiency was between 98 and 100% irrespective of the amount of particles used. Kinetic studies of the free and bound CHO revealed that the stability and activity of the enzyme were significantly improved upon binding to the nanoparticles. Furthermore, the bound enzyme exhibited a better tolerance to pH, temperature and substrate concentration. The activation energy for free and bound CHO was 13.6 and 9.3 kJ/mol, respectively. This indicated that the energy barrier of CHO activity was reduced upon binding onto Fe3O4 nanoparticles. The improvements observed in activity, stability, and functionality of CHO resulted from structural and conformational changes of the bound enzyme. The study indicates that the stability and activity of CHO could be enhanced via attachment to magnetic nanoparticles and subsequently will contribute to better uses of this enzyme in various biological and clinical applications.</p

[A new focus of human paragonimosis discovered in Côte d'Ivoire (West Africa): the case of the Lauzoua Island]

International audienceFifteen cases of human paragonimosis were detected in Ivory Coast from 1974 to 1999. Since no further cases have been reported, an epidemiological survey was carried out in local health centers. The purpose of this paper is to described a new focus of paragonimosis discovered on Lauzoua Island. Clinical and parasitological examinations were performed on 17 patients presenting chronic cough, haemoptysis and/or epilepsy. Stools belonging to cats, dogs and pigs as well as river crustaceans were also examined to identify parasite eggs and metacercariae respectively. Paragonimus eggs were found in stools and/or sputum of five patients. Measurements of these eggs after fixation in formalin allowed division into three groups. Stools from cats, dogs and pigs were negative. Small Paragonimus metacercariae (mean: 277 to 323 microm) were found in three Callinectes marginatus crabs (out of 15 caught near the island). No metacercariae were found in local prawns. The presence of these three Paragonimus egg groups as well as of infected crabs near the island will require further study to identify the species and determine the prevalence of each in human infection

Investigation of a Large Collection of <i>Pseudomonas aeruginosa</i> Bacteriophages Collected from a Single Environmental Source in Abidjan, Côte d’Ivoire

<div><p>Twenty two distinct bacteriophages were isolated from sewage water from five locations in the city of Abidjan, Côte d'Ivoire over a two-year period, using a collection of <i>Pseudomonas aeruginosa</i> strains with diverse genotypes. The phages were characterized by their virulence spectrum on a panel of selected <i>P</i>. <i>aeruginosa</i> strains from cystic fibrosis patients and by whole genome sequencing. Twelve virions representing the observed diversity were visualised by electron microscopy. The combined observations showed that 17 phages, distributed into seven genera, were virulent, and that five phages were related to temperate phages belonging to three genera. Some showed similarity with known phages only at the protein level. The vast majority of the genetic variations among virulent phages from the same genus resulted from seemingly non-random horizontal transfer events, inside a population of <i>P</i>. <i>aeruginosa</i> phages with limited diversity. This suggests the existence of a single environmental reservoir or ecotype in which continuous selection is taking place. In contrast, mostly point mutations were observed among phages potentially capable of lysogenisation. This is the first study of <i>P</i>. <i>aeruginosa</i> phage diversity in an African city and it shows that a large variety of phage species can be recovered in a limited geographical site at least when different bacterial strains are used. The relative temporal and spatial stability of the Abidjan phage population might reflect equilibrium in the microbial community from which they are released.</p></div

Genomic organization of N4-like phage Ab09.

<p>The different ORFs are colored according to their putative function: yellow, unknown; grey, transcription; green, morphogenesis; blue, DNA replication; purple, lysis.</p

Genomic organization of LUZ24-like phage Ab22.

<p>The different ORFs are colored according to their putative function: yellow, unknown; red, biosynthesis; green, morphogenesis; blue, DNA replication; purple, lysis. Vertical arrows indicate the position of single-strand DNA interruptions.</p

Characteristics of the new phages.

<p>^a according to [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130548#pone.0130548.ref030" target="_blank">30</a>]</p><p>^b showing only a few SNPs</p><p>Characteristics of the new phages.</p