Photosensitizer-Loaded Magnetic Nanoemulsion for Use in Synergic Photodynamic and Magnetohyperthermia Therapies of Neoplastic Cells

2008 ◽  
Vol 8 (11) ◽  
pp. 5873-5877 ◽  
Author(s):  
Fernando L. Primo ◽  
Marcilene M. A. Rodrigues ◽  
Andreza Ribeiro Simioni ◽  
Zulmira G. M. Lacava ◽  
Paulo C. Morais ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Photodynamic Therapy ◽  
Magnetic Fields ◽  
Zeta Potential ◽  
Cobalt Ferrite ◽  
Hydrodynamic Diameter ◽  
Synergic Effect ◽  
Average Hydrodynamic Diameter

In this study a magnetic nanoemulsion (MNE) was developed from a mixture of two components, namely biodegradable surfactants and biocompatible citrate-coated cobalt ferrite-based magnetic fluid, for entrapment of Zn(II)-Phthalocyanine (ZnPc), the latter a classical photosensitizer (PS) species used in photodynamic therapy (PDT) procedures. The sample's stability was evaluated as a function of time using photocorrelation spectroscopy (PCS) for determination of the average hydrodynamic diameter, diameter dispersion and zeta potential. The ZnPc-loaded magneto nanoemulstion (ZnPc/MNE) formulation was evaluated in vitro assays to access the phototoxicity and the effect of application of AC magnetic fields (magnetohyperthermia damage) after incubation with J774-A1 macrophages cells. Darkness toxicity, phototoxicity and AC magnetic field exposures revealed an enhancement response for combined photodynamic and magnetohyperthermia (MHT) processes, indicating the presence of the synergic effect.

MRE Damping Characteristics Evaluation

2016 ◽  
Vol 699 ◽  
pp. 31-36 ◽  
Author(s):  
Eduard Chirila ◽  
Ionel Chirica ◽  
Doina Boazu ◽  
Elena Felicia Beznea
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Smart Materials ◽  
Magnetorheological Elastomers ◽  
Damping Characteristics ◽  
The Subject ◽  
Energy Absorbing ◽  
The Magnetic Field ◽  
Material Form

The paper addresses the study of the damping characteristics estimation and behaviour of the magnetorheological elastomers (MREs) in the absence of magnetic field. This type of material actively changes the size, internal structure and viscoelastic characteristics under the external influences. These particular composite materials whose characteristics can vary in the presence of a magnetic fields are known as smart materials. The feature which causes the variation of properties in magnetic fields is explained by the existence of polarized particles which change the material form by energy absorbing. Damping is a special characteristic that influences the vibratory of the mechanical system. As an effect of this property is the reducing of the vibration amplitudes by dissipating the energy stored during the vibratory moving. The main characteristic that is based on the determination of the damping coefficient is the energy loss, which is the subject of the present paper. Before to start the characteristics determination in the presence of the magnetic field, it is necessary to study these characteristics in the absence of magnetic field. The MRE specimens have been manufactured and tested under the light conditions (non magnetic field). A special experimental test rig was built to investigate the response of the MRE specimens under the charging force. The experimental results show that the loss energy of the MRE specimen can be determined from the charging-discharging curves versus displacement. The results of the MRE specimen are presented in this paper: MRE with feromagnetic particles not exposed in magnetic field during fabrication.

scholarly journals Studying the Cellular Distribution of Highly Phototoxic Platinated Metalloporphyrins Using Isotope Labelling

2020 ◽  
Author(s):  
Riccardo Rubbiani ◽  
Wenyu Wu ◽  
Anu Naik ◽  
Michele Larocca ◽  
Lukas Schneider ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Cellular Distribution ◽  
Isotopic Labelling ◽  
Isotope Labelling ◽  
Anticancer Properties ◽  
Naturally Occurring ◽  
Icp Ms ◽  
Cell Penetrating

We report the synthesis of novel tetraplatinated metalloporphyrin-based photosensitizers (PSs) for photodynamic therapy (PDT), their characterization, cellular uptake and localization, as well as the determination of their <i>in vitro</i> light-induced anticancer properties. The PSs show excellent phototoxic indexes up to 5800 against HeLa cells, which is, to the best of our knowledge, the highest value reported for any porphyrin so far. Furthermore, isotopic labelling of the porphyrin with a highly enriched <sup>67</sup>Zn isotope was performed in order to determine the distribution ratio of zinc to platinum by ICP-MS, allowing to differentiate between naturally occurring zinc and <sup>67</sup>Zn that was introduced into the cells by the PS. We conclude that the platinum units within the platinum-PS conjugates help to solubilize the PS and, at the same time, act as cell-penetrating vectors, enhancing the efficiency of the PS without causing a significant dark toxicity.<br>

scholarly journals On a limitation of Zeeman polarimetry and imperfect instrumentation in representing solar magnetic fields with weaker polarization signal

2021 ◽  
Vol 11 ◽  
pp. 14
Author(s):  
A.A. Pevtsov ◽  
Y. Liu ◽  
I. Virtanen ◽  
L. Bertello ◽  
K. Mursula ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Transverse Field ◽  
Vector Magnetic Field ◽  
Field Orientation ◽  
Fill Fraction ◽  
Structure Morphology ◽  
Full Disk

Full disk vector magnetic fields are used widely for developing better understanding of large-scale structure, morphology, and patterns of the solar magnetic field. The data are also important for modeling various solar phenomena. However, observations of vector magnetic fields have one important limitation that may affect the determination of the true magnetic field orientation. This limitation stems from our ability to interpret the differing character of the Zeeman polarization signals which arise from the photospheric line-of-sight vs. the transverse components of the solar vector magnetic field, and is likely exacerbated by unresolved structure (non-unity fill fraction) as well as the disambiguation of the 180° degeneracy in the transverse-field azimuth. Here we provide a description of this phenomenon, and discuss issues, which require additional investigation.

Experiments on the instability of a layer of mercury heated from below and subject to the simultaneous action of a magnetic field and rotation. II

1959 ◽  
Vol 249 (1256) ◽  
pp. 138-145 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Strength ◽  
Wave Number ◽  
Simultaneous Action ◽  
Marginal Stability ◽  
Discontinuous Change ◽  
Theoretical Predictions

Experiments are described which are devoted to the determination of the sizes of the convection cells which appear at marginal stability in a layer of mercury heated from below and subject to the action of a magnetic field either alone or in the presence of rotation. The experiments confirm the theoretical predictions of Chandrasekhar regarding the wave number of the disturbance which is manifested at marginal stability. In particular, under the simultaneous action of magnetic fields and rotation, the present experiments fully confirm the predicted discontinuous change in the wave number at the point where, for increasing field strength (for given rotation), the transition from cellular convection to overstable convection takes place.

scholarly journals Spectroscopic Diagnosis of Magnetic Fields of AP Stars

1998 ◽  
Vol 11 (2) ◽  
pp. 676-678
Author(s):  
G. Mathys
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Weighted Average ◽  
High Dispersion ◽  
Spectroscopic Methods ◽  
Magnetic Vector ◽  
Model Independent ◽  
The Mean ◽  
Ap Stars

Diagnosis of Ap star magnetic fields through spectroscopic methods is a broad topic, which cannot be fully covered within the rather tight limits of this contribution. Accordingly, the latter is devoted to only one particular approach, namely the determination of the mean magnetic field modulus from the observation of resolved magnetically split lines in high-dispersion spectra taken in unpolarized light. This determination is straightforward, mostly approximation free and model independent. The derived quantity, the mean magnetic field modulus, is the line-intensity weighted average over the visible stellar hemisphere of the modulus of the magnetic vector.

scholarly journals The Fine-Tuned Release of Antioxidant from Superparamagnetic Nanocarriers under the Combination of Stationary and Alternating Magnetic Fields

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1212
Author(s):  
Lucija Mandić ◽  
Anja Sadžak ◽  
Ina Erceg ◽  
Goran Baranović ◽  
Suzana Šegota
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Quantum Interference ◽  
Fine Tuning ◽  
Force Microscopy ◽  
Peg 4000 ◽  
Vis Spectroscopy ◽  
Poly Ethylene ◽  
Alternating Magnetic Fields

Superparamagnetic magnetite nanoparticles (MNPs) with excellent biocompatibility and negligible toxicity were prepared by solvothermal method and stabilized by widely used and biocompatible polymer poly(ethylene glycol) PEG-4000 Da. The unique properties of the synthesized MNPs enable them to host the unstable and water-insoluble quercetin as well as deliver and localize quercetin directly to the desired site. The chemical and physical properties were validated by X-ray powder diffraction (XRPD), field emission scanning electron microscopy (FE–SEM), atomic force microscopy (AFM), superconducting quantum interference device (SQUID) magnetometer, FTIR spectroscopy and dynamic light scattering (DLS). The kinetics of in vitro quercetin release from MNPs followed by UV/VIS spectroscopy was controlled by employing combined stationary and alternating magnetic fields. The obtained results have shown an increased response of quercetin from superparamagnetic MNPs under a lower stationary magnetic field and s higher frequency of alternating magnetic field. The achieved findings suggested that we designed promising targeted quercetin delivery with fine-tuning drug release from magnetic MNPs.

scholarly journals Numerical determination of the cutoff frequency in solar models

2020 ◽  
Vol 640 ◽  
pp. A4 ◽  
Author(s):  
T. Felipe ◽  
C. R. Sangeetha
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
Magnetic Fields ◽  
Numerical Simulations ◽  
Acoustic Waves ◽  
Cutoff Frequency ◽  
Quiet Sun ◽  
Radiative Losses ◽  
The Magnetic Field

Context. In stratified atmospheres, acoustic waves can only propagate if their frequency is higher than the cutoff value. The determination of the cutoff frequency is fundamental for several topics in solar physics, such as evaluating the contribution of the acoustic waves to the chromospheric heating or the application of seismic techniques. However, different theories provide different cutoff values. Aims. We developed an alternative method to derive the cutoff frequency in several standard solar models, including various quiet-Sun and umbral atmospheres. The effects of magnetic field and radiative losses on the cutoff are examined. Methods. We performed numerical simulations of wave propagation in the solar atmosphere using the code MANCHA. The cutoff frequency is determined from the inspection of phase-difference spectra computed between the velocity signal at two atmospheric heights. The process is performed by choosing pairs of heights across all the layers between the photosphere and the chromosphere to derive the vertical stratification of the cutoff in the solar models. Result. The cutoff frequency predicted by the theoretical calculations departs significantly from the measurements obtained from the numerical simulations. In quiet-Sun atmospheres, the cutoff shows a strong dependence on the magnetic field for adiabatic wave propagation. When radiative losses are taken into account, the cutoff frequency is greatly reduced and the variation of the cutoff with the strength of the magnetic field is lower. The effect of the radiative losses in the cutoff is necessary to understand recent quiet-Sun and sunspot observations. In the presence of inclined magnetic fields, our numerical calculations confirm that the cutoff frequency is reduced as a result of the reduced gravity experienced by waves that propagate along field lines. An additional reduction is also found in regions with significant changes in the temperature, which is due to the lower temperature gradient along the path of field-guided waves. Conclusions. Our results show solid evidence that the cutoff frequency in the solar atmosphere is stratified. The cutoff values are not correctly captured by theoretical estimates. In addition, most of the widely used analytical cutoff formulae neglect the effect of magnetic fields and radiative losses, whose role is critical for determining the evanescent or propagating nature of the waves.

scholarly journals Detecting GPC3-Expressing Hepatocellular Carcinoma with L5 Peptide-Guided Pretargeting Approach: In Vitro and In Vivo MR Imaging Experiments

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Weiyue Li ◽  
Xiang Xiao ◽  
Xiaodan Li ◽  
Yikai Xu ◽  
Lichao Ma ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Mr Imaging ◽  
Zeta Potential ◽  
Hepg2 Cells ◽  
High Specificity ◽  
Iron Deposition ◽  
Blue Staining ◽  
Hydrodynamic Diameter

Objective. To investigate the potential of L5 peptide-guided pretargeting approach to identify GPC3-expressing hepatocellular carcinoma (HCC) using ultrasmall superparamagnetic iron oxide (USPIO) as the MR probe. Methods. Immunofluorescence with carboxyfluorescein- (FAM-) labeled L5 peptide was performed in HepG2 cells. Polyethylene glycol-modified USPIO (PEG-USPIO) and its conjugation with streptavidin (SA-PEG-USPIO) were synthesized, and their hydrodynamic diameters, zeta potential, T2 relaxivity, and cytotoxicity were measured. In vitro and in vivo two-step pretargeting MR imaging was performed on HepG2 cells and tumor-bearing mice after the administration of biotinylated L5 peptide (first step), followed by SA-PEG-USPIO (second step). Prussian blue staining was performed to assess iron deposition in tumors. Results. The high specificity of L5 peptide for GPC3 was demonstrated. Generation of SA-PEG-USPIO nanoparticles with good biocompatibility (an average hydrodynamic diameter of 35.97 nm and a zeta potential of −7.91 mV), superparamagnetism (R2 = 0.1039 × 103 mM−1s−1), and low toxicity was achieved. The pretargeting group showed more enhancement than the nonpretargeting group both in vitro (60% vs 20%, P<0.05) and in vivo (32% vs 6%, P<0.001). Substantial iron deposition was only observed in HepG2 cells and tumors in the pretargeting group. Conclusion. L5 peptide-guided, two-step pretargeting approach with USPIO as the MR imaging probe is a lucrative strategy to specifically identify GPC3-expressing HCC.

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