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The radiolabeled iron oxide nanoparticles constitute an attractive choice to be used as dual-modality contrast agents (DMCAs) in nuclear medical diagnosis, due to their ability to combine the benefits of two imaging modalities, for instance single photon emission computed tomography (SPECT) with magnetic resonance imaging (MRI). Before the use of any DMCA, the investigation of its plasma extra- and on/intra cellular distribution in peripheral human blood is of paramount importance. Here, we focus on the in vitro investigation of the distribution of 99mTc-DPD-Fe3O4 DMCA in donated peripheral human blood (the ligand 2-3-dicarboxypropane-1-1-diphosphonic-acid is denoted as DPD). Initially, we described the experimental methods we performed for the radiosynthesis of the 99mTc-DPD-Fe3O4, the preparation of whole blood and blood plasma samples, and their incubation conditions with 99mTc-DPD-Fe3O4. More importantly, we employed a gamma-camera apparatus for the direct imaging of the 99mTc-DPD-Fe3O4-loaded whole blood and blood plasma samples when subjected to specialized centrifugation protocols. The direct comparison of the gamma-camera data obtained at the exact same samples before and after their centrifugation enabled us to clearly identify the distribution of the 99mTc-DPD-Fe3O4 in the two components, plasma and cells, of peripheral human blood.

The combination of two imaging modalities in a single agent has received increasing attention during the last few years, since its synergistic action guarantees both accurate and timely diagnosis. For this reason, dual-modality contrast agents (DMCAs), such as radiolabeled iron oxide (namely Fe3O4) nanoparticles, constitute a powerful tool in diagnostic applications. In this respect, here we focus on the synthesis of a potential single photon emission computed tomography/magnetic resonance imaging (SPECT/MRI) DMCA, which consists of Fe3O4 nanoparticles, surface functionalized with 2,3-dicarboxypropane-1,1-diphosphonic acid (DPD) and radiolabeled with 99mTc, [99mTc]Tc-DPD-Fe3O4. The in vitro stability results showed that this DMCA is highly stable after 24 h of incubation in phosphate buffer saline (~92.3% intact), while it is adequately stable after 24 h of incubation with human serum (~67.3% intact). Subsequently, [99mTc]Tc-DPD-Fe3O4 DMCA was evaluated in vivo in mice models through standard biodistribution studies, MR imaging and gamma-camera imaging. All techniques provided consistent results, clearly evidencing noticeable liver uptake. Our work documents that [99mTc]Tc-DPD-Fe3O4 has all the necessary characteristics to be a potential DMCA.

Magnetoelectric (ME) composites that exhibit both ferroelectric and ferromagnetic properties have attracted significant attention, thanks to their potential applications, e.g., low-energy-consumption storage devices. Here, we study bulk composites based on Pb(Zr0.52Ti0.48)O3 (PZT) as a piezoelectric (PE) matrix and Fe3O4 nanoparticles (NPs) as soft ferromagnetic (FM) and magnetostrictive additives, in the form PZT-xFe3O4 with 0% ≤ x ≤ 50 wt. %, all sintered at T = 1000 °C for 2 h in air. We focus our study on a completely insulating sample x = 5% and measure its properties at room temperature upon an out-of-plane external electric field, Eex: namely, piezoelectric response [in-plane strain, S(Eex)], polarization [P(Eex)], and relaxation of the remanent magnetization, [mrem(t,Eex)], prepared upon application and removal of an external magnetic field. The peaks observed in the butterflylike S(Eex) curves at E±peak= ±6 kV/cm and the nucleation field recorded in the P(Eex) loops at the same range around E±nuc= ±6 kV/cm (both referring to the PZT PE matrix) are clearly imprinted on the relaxation behavior of the mrem(t,Eex) data (referring to the Fe3O4 FM NPs). This experimental fact proves the ME coupling between the PZT matrix and the embedded Fe3O4 NPs. We ascribe this feature to the comparable piezoelectricity of the PZT matrix and the magnetostriction of the Fe3O4 NPs that probably motivate and/or promote a strain transfer mechanism occurring at the PZT matrix-Fe3O4 NP interfaces. Our work proves that the low cost PZT-xFe3O4 composite is a promising candidate ME material for future studies, aiming to potential applications.

Composite magnetoelectric compounds that combine ferroelectricity/piezoelectricity and ferromagnetism/magnetostriction are investigated intensively for room-temperature applications. Here, we studied bulk composites of a magnetostrictive constituent, ferromagnetic Fe 3 O 4 nanoparticles, homogeneously embedded in a ferroelectric/piezoelectric matrix, Pb(Zr 0.52 Ti 0.48 )O 3 (PZT). Specifically, we focused on PZT-5%Fe 3 O 4 samples which are strongly insulating and thus sustain a relatively high out-of-plane external electric field, E ex,z . The in-plane strain-electric field curve (S(E ex,z )) was carefully recorded upon successive application and removal of an out-of-plane external magnetic field, H ex,z . The obtained S(E ex,z ) data exhibited two main features. First, the respective in-plane piezoelectric coefficients, d(E ex,z ) = 200-250 pm/V, show a dramatic decrease, 50-60%, upon application of a relatively low H ex,z = 1 kOe. Second, the process is completely reversible since the initial value of d(E ex,z ) is recovered upon removal of H ex,z . Polarization data, P(E ex,z ), evidenced that the Fe 3 O 4 nanoparticles introduced static structural disorder that made PZT harder. Taken together, these results prove that the Fe 3 O 4 nanoparticles, except for static structural disorder, introduce reconfigurable magnetic disorder that modifies the in-plane S(E ex,z ) curve and the accompanying d(E ex,z ) of PZT when an external magnetic field is applied at will. The room-temperature feasibility of these findings renders the PZT-x%Fe 3 O 4 system a solid basis for the development of magnetic-field-controlled PE devices.

The controlled modification of superconductivity by any means is a long-standing issue in low-temperature physics. In this work, we present data on the control of the superconducting properties of conventional low critical-temperature (T C ) Nb thin films with thickness (d Nb ) = 15 and 20 nm under application of reconfigurable strain, S induced by an external electric field, and E ex to a piezoelectric (PE) single crystal, namely (1 − x)Pb(Mg 1/3 Nb 2/3 )O 3 − x PbTiO 3 (PMN-PT) with x = 0.30-0.31. The experimental results (reduction of T C and critical current (J C ) on the order of 6% and 90-100%, respectively) are nicely reproduced with a phenomenological model that incorporates the constitutive relation S(E ex ) that describes the electro-mechanical response of the PE crystal to well-established formulas that describe T C and J C of the SC thin films.

The aim of this study was to develop a dual-modality PET/MR imaging probe by radiolabeling iron oxide magnetic nanoparticles (IONPs), surface functionalized with water soluble stabilizer 2,3-dicarboxypropane-1,1-diphosphonic acid (DPD), with the positron emitter Gallium-68. Magnetite nanoparticles (Fe3O4 MNPs) were synthesized via coprecipitation method and were stabilized with DPD. The Fe3O4-DPD MNPs were characterized based on their structure, morphology, size, surface charge, and magnetic properties. In vitro cytotoxicity studies showed reduced toxicity in normal cells, compared to cancer cells. Fe3O4-DPD MNPs were successfully labeled with Gallium-68 at high radiochemical purity ( GT 91%) and their stability in human serum and in PBS was demonstrated, along with their further characterization on size and magnetic properties. The ex vivo biodistribution studies in normal Swiss mice showed high uptake in the liver followed by spleen. The acquired PET images were in accordance with the ex vivo biodistribution results. Our findings indicate that 68 Ga-Fe3O4-DPD MNPs could serve as an important diagnostic tool for biomedical imaging.

Low-dimensional hybrid structures of heterogeneous constituents usually exhibit abnormal properties, a fact that makes such hybrids attractive for various cryogenic and room-temperature applications. Here, we studied Co/(1 - x)Pb(Mg 1/3 Nb 2/3 )O 3 -xPbTiO 3 /Co (Co/PMN-xPT/Co) with x=0.29 and 0.30, specifically focusing on the evolution of the remanent ferromagnetic state, m rem of the Co outer layers in the whole temperature range from 300K down to 10K, upon application of an external electric field, E ex . We observed that m rem was vulnerable to degradation through the occurrence of electric field-induced magnetic instabilities (EMIs) that appeared only when E ex ≠0kV/cm and were facilitated as E ex increases. However, EMIs completely ceased below a characteristic temperature T ces =170K even for the maximum |E ex |=5kV/cm applied in this work. A direct comparison of the magnetization data of the Co/PMN-xPT/Co hybrids reported here with the electromechanical properties of the parent PMN-xPT crystals plausibly indicates that EMIs are motivated by the coupling of the ferromagnetic domains of the Co outer layers with the ferroelectric domains of the PMN-xPT crystal. These results highlight the drawback of EMIs in relevant hybrids and delimit the temperature regime for the reliable operation of the Co/PMN-xPT/Co ones studied here.

Dimosthenis Stamopoulos,1 Nerantzoula Bakirtzi,2,3 Efthymios Manios,1 Eirini Grapsa41Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, National Center for Scientific Research 'Demokritos,' Athens, Greece; 2Department of Nephrology, Hospital 'G. Gennimatas,' Athens, Greece; 3Renal Unit, Hospital 'Alexandra,' Athens, Greece; 4Renal Unit, Hospital 'Aretaieion,' Athens, GreeceBackground: In hemodialysis (HD) patients, anemia relates to three main factors: insufficient production of erythropoietin; impaired management of iron; and decreased lifespan of red blood cells (RBCs). The third factor can relate to structural deterioration of RBCs due to extrinsic (extracorporeal circuit; biochemical activation and/or mechanical stress during dialysis) and intrinsic (uremic milieu; biochemical interference of the RBC membrane constituents with toxins) mechanisms. Herein, we evaluate information accessed with advanced imaging techniques at the cellular level.Methods: Atomic force and scanning electron microscopes were employed to survey intact RBCs (iRBCs) of seven HD patients in comparison to seven healthy donors. The extrinsic factor was investigated by contrasting pre- and post-HD samples. The intrinsic environment was investigated by comparing the microscopy data with the clinical ones.Results: The iRBC membranes of the enrolled HD patients were overpopulated with orifice-like (high incidence; typical size within 100–1,000 nm) and crevice-like (low incidence; typical size within 500–4,000 nm) defects that exhibited a statistically significant (P < 0.05) relative increase (+55% and +350%, respectively) in respect to healthy donors. The relative variation of the orifice and crevice indices (mean population of orifices and crevices per top membrane surface) between pre- and post-HD was not statistically significant (−3.3% and +4.5%, respe