The Effect of Polyol Composition on the Structural and Magnetic Properties of Magnetite Nanoparticles for Magnetic Particle Hyperthermia

A study of the influence of polyols, with or without an additional reducing agent, on crystallites’ size and magnetic features in Fe3O4 nanoparticles and on their performance in magnetic particle hyperthermia is presented. Three different samples were synthesized by thermal decomposition of an iron precursor in the presence of NaBH4 in a polyol. So far, triethylene glycol (TrEG) and polyethylene glycol (PEG 1000 and PEG 8000) that exhibit different physical and chemical properties have been used in order to investigate the influence of the polyols on the composition and the size of the NPs. Additionally, the presence of a different reducing agent such as hydrazine, has been tested for comparison reasons in case of TrEG. Three more samples were prepared solvothermally by using the same polyols, which led to different crystallite sizes. The magnetic core of the nanoparticles was characterized, while the presence of the surfactant was studied qualitatively and quantitatively. Concerning the magnetic features, all samples present magnetic hysteresis including remanence and coercivity revealing that they are thermally blocked at room temperature. Finally, a study on the influence of the MNPs heating efficiency from their size and the field amplitude was accomplished. In our polyol process the main idea was to control the specific loss power (SLP) values by the nanoparticles’ size and consequently by the polyol itself

Numerical Simulation of Temperature Variations during the Application of Safety Protocols in Magnetic Particle Hyperthermia

Unavoidably, magnetic particle hyperthermia is limited by the unwanted heating of the neighboring healthy tissues, due to the generation of eddy currents. Eddy currents naturally occur, due to the applied alternating magnetic field, which is used to excite the nanoparticles in the tumor and, therefore, restrict treatment efficiency in clinical application. In this work, we present two simply applicable methods for reducing the heating of healthy tissues by simultaneously keeping the heating of cancer tissue, due to magnetic nanoparticles, at an adequate level. The first method involves moving the induction coil relative to the phantom tissue during the exposure. More specifically, the coil is moving symmetrically—left and right relative to the specimen—in a bidirectional fashion. In this case, the impact of the maximum distance (2–8 cm) between the coil and the phantom is investigated. In the second method, the magnetic field is applied intermittently (in an ON/OFF pulsed mode), instead of the continuous field mode usually employed. The parameters of the intermittent field mode, such as the time intervals (ON time and OFF time) and field amplitude, are optimized based on the numerical assessment of temperature increase in healthy tissue and cancer tissue phantoms. Different ON and OFF times were tested in the range of 25–100 s and 50–200 s, respectively, and under variable field amplitudes (45–70 mT). In all the protocols studied here, the main goal is to generate inside the cancer tissue phantom the maximum temperature increase, possible (preferably within the magnetic hyperthermia window of 4–8 °C), while restricting the temperature increase in the healthy tissue phantom to below 4 °C, signifying eddy current mitigation

Toxic and Microbiological Effects of Iron Oxide and Silver Nanoparticles as Additives on Extended Ram Semen

The aim of the study was to investigate the effect of iron oxide (Fe) and silver (Ag) nanoparticles (NPs) on ram semen. A skim milk extender without antibiotics was used as a diluent of 21 ejaculates (8 rams; 2–3 ejaculates/ram). The groups of control (C; semen without NPs), Fe NPs (3.072 mg Fe3O4/mL semen), and Ag NPs (2.048 mg Ag-Fe/mL semen) were incubated (15 °C; 30 min), and then a magnetic field was used for NPs’ removal. Standard microbiological procedures were performed for all groups. Post-treated samples were stored (15 °C) for 24 h, and sperm variables (kinetics by computer assisted sperm analysis (CASA); viability; morphology; HOST; DNA integrity) were evaluated at 6 and 24 h. Semen data were analyzed by a mixed model for repeated measures and microbiological data with Student’s t-test for paired samples. At 6 h of storage, VCL and rapid movement-spermatozoa, and at 24 h, total/progressive motility and amplitude of lateral head displacement (ALH) were significantly decreased in group Ag compared to control. In group Fe, progressive/rapid movement-spermatozoa were significantly lower compared to control after 24 h of storage. Only in group Ag was a significant reduction of total bacterial count revealed. In conclusion, the examined Fe NPs demonstrated slight antibacterial effect, while the examined Ag NPs provided higher antibacterial properties accompanied by cytotoxicity

Iron Oxide Nanoparticles as an Alternative to Antibiotics Additive on Extended Boar Semen

This study examined the effect of Fe3O4 nanoparticles on boar semen. Beltsville thawing solution without antibiotics was used to extend ejaculates from 5 boars (4 ejaculates/boar). Semen samples of control group (C) and group with Fe3O4 (Fe; 0.192 mg/mL semen) were incubated under routine boar semen storage temperature (17 °C) for 0.5 h and nanoparticles were removed by a magnetic field. Before and after treatment, aliquots of all groups were cultured using standard microbiological methods. The samples after treatment were stored (17 °C) for 48 h and sperm parameters (computer-assisted sperm analyzer (CASA) variables; morphology; viability; hypo-osmotic swelling test (HOST); DNA integrity) were evaluated at storage times 0, 24, 48 h. Semen data were analyzed by a repeated measures mixed model and microbial data with Student’s t-test for paired samples. Regarding CASA parameters, Fe group did not differ from C at any time point. In group C, total motility after 24 h and progressive motility after 48 h of storage decreased significantly compared to 0 h. In group Fe, linearity (LIN) after 48 h and head abnormalities after 24 h of storage increased significantly compared to 0 h. The microbiological results revealed a significant reduction of the bacterial load in group Fe compared to control at both 24 and 48 h. In conclusion, the use of Fe3O4 nanoparticles during semen processing provided a slight anti-microbiological effect with no adverse effects on sperm characteristics

A novel strategy combining magnetic particle hyperthermia pulses with enhanced performance binary ferrite carriers for effective <i>in vitro</i> manipulation of primary human osteogenic sarcoma cells

<p>The present study examines the heating efficiency of a combination of manganese or cobalt ferrites in a binary (Co- or Mn-) ferrite nanoparticle form with magnetite, covered with citric acid to improve biocompatibility. The nanoparticle synthesis is based on the aqueous co-precipitation of proper salts, a facile, low-cost, environmentally friendly and high yield synthetic approach. By detailed structural and magnetic characterisation, the direct influence of structural and magnetic features on magnetic hyperthermia concludes to optimum heating efficiency. At a second stage, best performing magnetic nanoparticles undergo <i>in vitro</i> testing in three cell lines: one cancer cell line and two reference healthy cell lines. Both binary ferrite (MnFe₂O₄/Fe₃O₄ and CoFe₂O₄/Fe₃O₄) appear to be internalised and well tolerated by the cells while a versatile hyperthermia protocol is attempted in an effort to further improve their <i>in vitro</i> performance. Within this protocol, hyperthermia sequences are split in two runs with an intermediate 48 h time interval cell incubation stage while in each run a variable field mode (single or multiple pulses) is applied. Single-pulse field mode represents a typical hyperthermia application scheme where cells undergo the thermal shock continuously. On the other hand multiple-pulses mode refers to multiple, much shorter in duration AC field changes (field ON/OFFs), at each hyperthermia run, resulting eventually in high heating rate and much more harmful cell treatment. Consequently, we propose a novel series of improved performance heat mediators based on ferrite structures which show maximum efficiency at cancer cells when combined with a versatile multiple-pulse hyperthermia module.</p