Solucionario

21. – 23. 9. 2011, Brno, Czech Republic, EU

BACTERIAL MAGNETITE NANOPARTICLES - MAGNETOSPIRILLUM MAGNETOTACTICUM sp. AMB-1 MAGNETOSOMES A. HASHIM a, M. MOLČAN a, P. KOPČANSKÝ a, J. KOVÁČ a, H.GOJZEWSKI b, M. MAKOWSKI c,b, A. SKUMIEl b, A. JOZEFCZAK b, M.TIMKO a
a b

Institute of Experimental Physics, SAS, Watsonova 47, 040 01 Kosice, Slovakia

Institute of Physics, Poznan University ofTechnology, Nieszawska 13A, 60-965 Poznan, Poland
c

Max Planck Institute for Polymer Research, Ackermannweg 10, 55-128 Mainz, Germany

Abstract The objective of this contribution is to prepare the biological magnetic nanoparticles (magnetosomes) as a product of biomineralization process of magnetotactic bacteria Magnetospirillum sp.AMB-1. at various conditions of cultivation. By adding ofhigher amount of Wolfe's vitamin solution (WVS) or or ferric quinate (FQ) the mean diameter of magnetosomes is increasing. Sample cultivated at normal condition (NP) shows no coercivity and behaves superparamagnetically. The increasing of coercivity (6.5 Oe for WVS and 20 Oe for FQ) may be caused by higher value of shape anisotropy and reveals stronger magnetic correlations between particles ofmagnetite chains. The low values for coercivity is connected with the fact that magnetosomes are still single-magnetic domain particles. The found values for the specific rate absorption (SAR) of 949 W/g for NP, 911 W/g for FQ and 890 W/g for WVS at 10 kA/m are comparable to values found for similar sample. From obtained values of SAR it can be said that only small differences exist in samples preparedvarious conditions. Keywords: bacterial magnetic nanoparticles, magnetosomes, Magnetospirillum Magnetotacticum sp. AMB-1

1.

INTRODUCTION

Magnetic nanoparticles offer a diverse range of applications not only in technical but also in medical applications (targeted drug delivery, hyperthermia, imaging methods, etc.). The sensitive area such as medicine can be managed successfully requiresdetailed preparation and characterization of magnetic nanoparticles for bioapplications. It is now handling the preparation of particles in a laboratory process called the biomineralization in magnetotactic bacteria (MTB). They create in their body the chains of magnetic crystals called magnetosomes [1]. The magnetosomes mineral phase consists of single crystals of either the ferrimagnetic ironoxide, magnetite (Fe3O4), or the iron sulfide, greigite (Fe3S4). The size of magnetosome crystals, regardless of whether they consist of magnetite or greigite, depends on the species of MTB and generally ranges from 35–120 nm. This is the size range where magnetite crystals are expected to be limited to a single magnetic domain. This means that each crystal is a tiny permanent magnet [2, 3]. Magneticproperties of MTB have been a subject of growing interest in recent years. The advantage of these bacterial particles [4] based on iron particles is the uniform morphology and narrow size distribution and also the fact that they closed the cytoplasmic membrane (bilayer containing phospholipids and proteins) [5], preventing mutual aggregation of particles and provides biocompatibility, respectivelybinding of bioactive substances. The aim of this work was isolation of magnetosomes from MTB and characterization of magnetosomes in terms of morphological, magnetically, and also hyperthermical properties with a view of bio-applications.

21. – 23. 9. 2011, Brno, Czech Republic, EU

Techniques for the isolation and purification of magnetosome particles from Magnetospirillum sp. AMB-1 arebased on combination of centrifugation and the magnetic separation [6]. Owing to the presence of the enveloping membrane, isolated magnetosome particles form stable, well-dispersed suspensions in water solution of HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonicacid). Magnetization measurements of the prepared magnetosomes suspension were carried out by SQUID magnetometer of Quantum Design in...