Magnetically assisted hemodialysis is a development of conventional hemodialysis and is based on the circulation of ferromagnetic nanoparticle-targeted binding substance conjugates (FN-TBS Cs) in the bloodstream of the patient and their eventual removal by means of a 'magnetic dialyzer'. Presented here is an in vitro investigation on the biocompatibility of bare Fe3O4 FNs and Fe3O4-bovine serum albumin Cs with blood cells, namely red blood cells (RBCs), white blood cells (WBCs) and platelets (Plts). Atomic force microscopy (AFM) and optical microscopy (OM) enabled the examination of blood cells at the nanometer and micrometer level, respectively. The observations made on FN- and C-maturated blood samples are contrasted to those obtained on FN- and C-free reference blood samples subjected to exactly the same maturation procedure. Qualitatively, both AFM and OM revealed no changes in the overall shape of RBCs, WBCs and Plts. Incidents where bare FNs or Cs were bound onto the surface of RBCs or internalized by WBCs were very rare. Detailed examination by means of OM proved that impaired coagulation of Plts is not initiated/promoted either by FNs or Cs. Quantitatively, the statistical analysis of the obtained AFM images from RBC surfaces clearly revealed that the mean surface roughness of RBCs maturated with bare FNs or Cs was identical to the one of reference RBCs.

We propose a new method for the rejection of the comparatively strong diamagnetic contribution usually observed in SQUID magnetization measurements, originating from the substrates that are widely used for the preparation of thin magnetic films either by sputtering or by laser ablation techniques. Our method relies on the use of a substrate of length exceeding significantly the scan length employed in the magnetization measurements. Simple symmetry considerations reveal that the substrate's signal can be removed efficiently. This is also verified by a simple quantitative model, which is based on the form of total response of the four SQUID pick-up coils for a long sample. Our experimental data show clear evidence that the direct rejection of the substrate's undesired diamagnetic signal is complete in all the different categories of films (CoPt uniform single layers, CoPt isolated nanoparticles and La(1-x)Ca(x)MnO(3) multilayered specimens) studied in the present work. As a result, the real underlying mechanism that governs the physics of these magnetic films was uncovered. (C) 2008 Elsevier B.V. All rights reserved.

By using x-ray diffraction, magnetization and Mossbauer spectroscopy techniques we have studied the magnetoelectric Al2-xFexO3 (x = 0.8, 0.9 and 1.0) compound. Ac-susceptibility and magnetization measurements revealed magnetic transitions at T-N = 180, 210 and 260 K for x = 0.8, 0.9 and 1.0 respectively, that can be attributed to the Neel temperatures of ferrimagnetic to paramagnetic phase transition for all samples. Mossbauer spectra for the three samples were recorded between 4.2 and 295 K. Above the Neel temperature the paramagnetic spectra can be analyzed by three quadrupole doublets associated with the octahedral Fe1, Fe2 and Fe4 sites. The values of the hyperfine parameters show that iron ions are in the high spin Fe3+ state. The spectrum area of the doublet with larger quadrupole splitting increases with x, and in combination with x-ray diffraction results it can be attributed to the iron which occupies the Fe4 site. Below T-N(x) the Mossbauer spectra are magnetically split and at T = 4.2 K consist of six broad lines, indicating either a hyperfine magnetic field distribution (P(H-hyp)) or that the three octahedral sites give three unresolved sextets. The most probable value of H-hyp (the maximum value of P(H-hyp)) follows a power law indicative of a second order transition, in agreement with ac-susceptibility and magnetization measurements. The width of P(H-hyp) increases drastically toward low hyperfine magnetic fields as temperature increases. In addition, an appreciable percentage of the iron nuclei sense a hyperfine field with values in the interval [0, H-max]. This behavior can be explained by assuming that several magnetic sites with different superexchange parameters exist.

Background. The utilization of modern achievements from nanobiotechnology has resulted in novel modalities for renal replacement therapy. For conventional intermittent haemodialysis (HD), sophisticated membranes are currently being manufactured that guarantee selective removal of target toxins. These membranes have a narrow pore-size distribution that is focused around a mean value at the nanometre level. For continuous HD, novel artificial renal devices are currently being designed and evaluated in in vitro experiments that will be both implantable and have continuous function. Methods. We present mock-dialysis experiments using magnetically assisted HD (MAHD) that we very recently introduced for the selective removal of target toxins. MAHD is based on the preparation of conjugates (Cs) made up of biocompatible ferromagnetic nanoparticles (FNs) and a specifically designed targeted binding substance that must have a high affinity for a specific target toxin substance. The FN-targeted binding substance Cs should be administered to the patient prior to MAHD to allow for binding with the target toxin substance in the bloodstream. The complex FN-targeted binding substance-target toxin substance will then be removed by a 'magnetic dialyzer' that is installed in the dialysis machine in series to the conventional dialyzer. In the present work, we compared the in vitro efficiency of MAHD to conventional HD for the removal of homocysteine (Hcy) during mock-dialysis experiments. Results. These mock-dialysis experiments performed on Hcy revealed that both the removal rate and the overall removal efficiency of MAHD were significantly greater than conventional HD. Conclusions. MAHD appears to be a promising method that can be employed for the selective and more efficient extraction of toxins that are not adequately removed by conventional HD.

Owing to vast technological advances, hemodialysis (HD) has become a mature modality significantly increasing the survival of end-stage renal disease (ESRD) patients. However, many HD complications still exist that mainly relate to the nature of middle-molecular-weight and/or protein-bound toxins that both low- and high-flux dialysers cannot efficiently remove. For instance, hyperhomocysteinemia and amyloidosis are two dialysis-related disorders that motivate serious health complications. Here, we introduce a new method for the selective removal of specific toxins that is based on the preparation of Ferromagnetic Nanoparticle-Targeted Binding Substance Conjugates (FN-TBS Cs) constituted of biocompatible FNs and a specifically designed TBS that must have high affinity for the respective Target Toxin Substance (TTS). The FN-TBS Cs should be administered to the patient timely prior to the dialysis session so that they will be able to bind with the specific TTS owing to their free circulation in the bloodstream. The complex FN-TBS-TTS can be selectively removed from the ESRD patient during the HD session by means of a magnetic dialyser (MD). For the in vitro evaluation of this proposal we employed highly biocompatible Fe3O4 and Bovine Serum Albumin (BSA) as constituents of the FN-TBS Cs and an array of permanent magnets placed along the circulation line as a simple MD. We have evaluated the binding affinity and capacity of both bare Fe3O4 FNs and Fe3O4-BSA Cs by employing homocysteine (Hcy) as a model TTS. We investigate Hcy concentrations ranging from mild to severe hyperhomocysteinemia. Most importantly, we investigate the effectiveness of low concentrations of Fe3O4 that are within the safety levels established from the treatment of iron-deficiency anemia, thus making a preliminary evaluation of future in vivo applications. We observed that Hcy is readily adsorbed onto both bare Fe3O4 FNs and Fe3O4-BSA Cs. The obtained results prove the successful in vitro applicability of the proposed method since pathological Hcy concentrations may be adequately handled by relatively low Fe3O4 concentrations, thus making feasible future in vivo applications.