A comparison of the magnetic properties of polysaccharide iron complex (PIC) and ferritin

Abstract

The synthetic polysaccharide iron complex (PIC) molecule has been suggested as a 'biomimic', i.e. a counterpart, to the naturally occurring biological molecule ferritin with respect to its magnetic properties based on the identification of ferrihydrite as the major mineral in both. Magnetization measurements were used to investigate the magnetic properties of PIC in relation to those of ferritin, as well as to identify differences in such properties between naturally occurring ferritin, which we designate here as Ferritin-I, and ferritin with an artificially high content of Fe 2 + ions bound to its core, which is designated here as Ferritin II. The anisotropy constants K, blocking temperatures TB' magnetic moments m per particle, and number of magnetic moments 'spins' per particle-N sp were found to fit the following relations for PIC and ferritin: K(Ferritin I) < K(PIC) ::s; K(Ferritin 11), TB(FerritinThe magnetic moment per Fe ion was found to be smaller in PIC than Ferritin II due to a stronger antiferromag netic interaction between the Fe ions of PIC. Susceptibility measurements indicated the existence of superantiferro magnetism in PIC and Ferritin I and also showed that most Fe 2 + ions in Ferritin II are bound to its core surface. The enhanced values of K and TB as well as the reduced effect of superantiferromagnetism and the antiferromag netic interaction between the molecules at low temperatures for the Ferritin II indicates the importance of the surface magnetic moments in dominating the magnetic behavior of both PIC and femtin (Ferritin I).

Bioinorganic transformations of liver iron deposits observed by tissue magnetic characterisation in a rat model

“…the net particle moments, v AF (>0) the bulk susceptibility of the material constituting the particles (which is typically antiferromagnetic as in the case of ferrihydrite and akaganéite) due to intraparticle spin canting [7,41], and v D (<0) the total diamagnetic susceptibility which includes the contributions of the sample holder and other organic matter.…”

“…Detailed low temperature magnetic experiments have mostly been focused on biochemically extracted iron containing proteins. In particular, in the case of ferritin, besides the internal antiferromagnetic order of the iron oxyhydroxide nanoparticles, superparamagnetic behaviour, together with a magnetic relaxation anomaly in the vicinity of 20 K as result of blocking of the particle magnetic moments, has been observed [7][8][9].…”

Magnetic and structural study of the state of iron in the oral haematinic ferrimannitol ovoalbumin

“…[22] were taken at 9 Hz, the presented curve has been calculated for 10 Hz by considering the frequency dependence behaviour also studied in that work. As it can be seen, the v 00 (T) maximum of FMOA results at lower temperature than that of ferritin, and is narrower than what might be expected from the published DC data of other oral haematinic (iron polysaccharide complex) [13].…”

“…Since iron is a minority element, especially in oral drugs, this study is not free of difficulties. However, the magnetogenic character of iron allows the selective characterisation of these iron containing species by using magnetic probes of high sensitivity [10][11][12][13]. The knowledge of the magnetic properties of these drugs is also the necessary first step in iron metabolism investigations that involve magnetic monitoring of iron containing compounds after their administration [14].…”

Proton NMR and susceptibility measurements on the magnetic core of ferritin

“…It is commonly reported [1][2][3][4] that ferritin becomes antiferromagnetic (AF), although the evidence is largely indirect and the Nèel temperature reported varies widely in the range 50 K < TN < 240 K. Moreover, for T < 30 K, magnetization measurements give evidence of superparamagnetic relaxation and of spin freezing of the total magnetic moment associated with the uncompensated spins at the boundary of the cluster of iron ions [5]. Recently, interest in the magnetic behavior of ferritin has been revived by the confirmation [6,7] of an early report [8] of the occurrence of macroscopic quantum coherence phenomena at low temperature.…”