Iron-gold Alloy Research Articles

Hyperthermia-Induced Controlled Local Anesthesia Administration Using Gelatin-Coated Iron-Gold Alloy Nanoparticles.

The lack of optimal methods employing nanoparticles to administer local anesthesia often results in posing severe risks such as non-biocompatibility, in vivo cytotoxicity, and drug overdose to patients. Here, we employed magnetic field-induced hyperthermia to achieve localized anesthesia. We synthesized iron–gold alloy nanoparticles (FeAu Nps), conjugated an anesthetic drug, Lidocaine, and coated the product with gelatin to increase the biocompatibility, resulting in a FeAu@Gelatin–Lidocaine nano-complex formation. The biocompatibility of this drug–nanoparticle conjugate was evaluated in vitro, and its ability to trigger local anesthesia was also evaluated in vivo. Upon exposure to high-frequency induction waves (HFIW), 7.2 ± 2.8 nm sized superparamagnetic nanoparticles generated heat, which dissociated the gelatin coating, thereby triggering Lidocaine release. MTT assay revealed that 82% of cells were viable at 5 mg/mL concentration of Lidocaine, indicating that no significant cytotoxicity was induced. In vivo experiments revealed that unless stimulated with HFIW, Lidocaine was not released from the FeAu@Gelatin–Lidocaine complex. In a proof-of-concept experiment, an intramuscular injection of FeAu@Gelatin–Lidocaine complex was administered to the rat posterior leg, which upon HFIW stimulation triggered an anesthetic effect to the injected muscle. Based on our findings, the FeAu@Gelatin–Lidocaine complex can deliver hyperthermia-induced controlled anesthetic drug release and serve as an ideal candidate for site-specific anesthesia administration.

Picosecond laser-induced surface structures on alloys in liquids and their influence on nanoparticle productivity during laser ablation.

The productivity of nanoparticles formed by laser ablation of gold-silver and iron-gold alloy as well as copper and iron-nickel alloy targets in water is correlated with the formation of laser-induced surface structures. At a laser fluence optimized for maximum nanoparticle productivity, it is found that a binary alloy with an equimolar ratio forms laser-induced periodic surface structures (LIPSS) after ablation, if one of the constituent metals also form LIPSS. The ablation rate of nanoparticles linearly depends on the laser fluence if LIPSS is not formed, while a logarithmic trend and a decrease in productivity is evident when LIPSS is formed. To cancel LIPSS formation and recover from this decrease, a change to circularly polarized light is performed and an increase in nanoparticle productivity of more than 30% is observed.

Glioma-sensitive delivery of Angiopep-2 conjugated iron gold alloy nanoparticles ensuring simultaneous tumor imaging and hyperthermia mediated cancer theranostics

Gliomas display a poor disease prognosis causing death within 15 months after diagnosis. Chemotherapy has offered some hope to target this, however, it is majorly ineffective due to the low therapeutic window, poor efficacy and high cytotoxicity. To overcome these challenges, we conjugated Angiopep-2, a cell penetrating peptide (CPP) to Iron Gold (Fe-Au) alloy nanoparticles and investigated the ability of Ang-Fe-Au Nps conjugate to limit glioma growth via magnetic field induced hyperthermia. Our results show that 6.44 nm sized conjugated Fe-Au Nps were superparamagnetic, enhanced negative Glioma image contrast and displayed a 12 °C temperature elevation when magnetically stimulated, indicating applications in medical imaging and hyperthermia-based therapy. Angiopep-2 conjugation resulted in 1.5-fold higher ingestion by C6 glioma cells than L929 fibroblasts, indicating specific glioma targeting and resulting in 90 % decrement in cell viability due to magnetic field induced hyperthermia. Immunohistochemical analysis showed an enhanced coagulative necrosis, glial fibrillary acidic protein (GFAP) expression and decreased Ki67 labelling index in rat treated with Ang-Fe-Au Nps which translated to a 5-fold decrement in tumor volume, consequently resulting in an increased survival time by 7 days. The dual application of this platform opens new doors towards cancer theranostics with minimal invasiveness.

Iron-gold alloy nanoparticles serve as a cornerstone in hyperthermia-mediated controlled drug release for cancer therapy.

IntroductionThe efficacy of a chemotherapy drug in cancer therapy is highly determined by the ability to control the rate and extent of its release in vivo. However, the lack of techniques to accurately control drug release drastically limits the potency of a chemotherapy drug.Materials and methodsHere, we present a novel strategy to precisely monitor drug release under magnetic stimulation. Methotrexate (MTX), an anticancer drug, was covalently functionalized onto iron–gold alloy magnetic nanoparticles (Fe–Au alloy nanoparticles or NFAs) through 2-aminoethanethiol grafting and the ability of this drug–nanoparticle conjugate (NFA–MTX) in limiting HepG2 (liver carcinoma) cell growth was studied. Well-dispersed NFAs were prepared through pyrolysis.Results and discussionTransmission electron microscopy revealed the average nanoparticle size to be 7.22±2.6 nm, while X-ray diffraction showed distinct 2θ peaks for iron and gold, confirming the presence of iron and gold nanoparticles. Inductively coupled plasma mass spectrometry revealed that the amount of NFA–MTX conjugate ingested by HepG2 cancer cells was 1.5 times higher than that ingested by L929 fibroblasts, thereby proving a higher selective ingestion by cancer cells compared to normal cells. Fourier-transform infrared spectroscopy revealed the breakage of Au-S bonds by the heat generated under magnetic field stimulation to release MTX from the NFA–MTX conjugate, triggering a 95% decrease in cellular viability at 100 µg/mL.ConclusionThe ability of NFA–MTX to dissociate under the influence of an applied magnetic field provides a new strategy to induce cancer cell death via hyperthermia. Applications in drug delivery, drug development, and cancer research are expected.

Quantification of MRI visibility and artifacts at 3T of liquid fiducial marker in a pancreas tissue-mimicking phantom.

X-ray-based position verification of the target volume in image-guided radiation therapy (IGRT) of patients with pancreatic ductal adenocarcinoma (PDAC) is currently performed on solid fiducial markers that are implanted under endoscopic ultrasonography. A new biodegradable liquid fiducial marker has recently been introduced. To assess its potential use for magnetic resonance imaging (MRI)-guided photon or proton radiotherapy of PDAC, the MRI visibility and artifacts of this marker were quantified and compared against solid gold markers. Different spherical volumes (10 μL, 25 μL, 50 μL, and 100 μL) of a biodegradable liquid fiducial marker as well as seven differently sized and oriented solid gold (0.35 mm diameter; 5 mm and 10 mm length) and iron-gold alloy fiducial markers (0.28 mm diameter; 1 cm and 2 cm length) were implanted in a spherical gel phantom, mimicking the proton spin relaxation properties of healthy pancreatic tissue at 3 Tesla. MR relaxometry was performed to quantify the size and magnitude of the decrease in the effective transversal relaxation time T2∗ and relative proton density ρ(H) as a measure of potential visibility and to quantify the size and magnitude of the increase in magnetic field inhomogeneity ΔB0 as a measure of potential signal artifacts. The phantom was scanned in a 3.0 T PET/MR scanner with an eight-channel head coil. The solid fiducial markers showed a direct linear relationship between the potentially visible size and artifact size. The liquid fiducial marker showed a tendency toward a potentially visible size at smaller artifacts. Liquid markers from 25 to 100 μL generated visible volumes comparable to the size of the solid markers. The magnitude of visibility was the highest for the liquid fiducial marker with volumes of 25-100 μL showing no correlation with the magnitude of artifact. The solid markers showed a strong nonlinear correlation between magnitude of visibility and artifact, whereas the solid marker consisting of a gold-iron alloy induced the strongest artifacts. The liquid fiducial marker causes signal voids on MRI due to its absence of water hydrogen atoms without strongly affecting the magnetic field in the surrounding tissue. The alteration of the static magnetic field was found to be the main effect leading to the visibility of the solid fiducial markers. Hence, especially when a low level of image distortion is required, MRI characteristics of the liquid marker surpass those of solid gold markers currently being used for IGRT of PDAC.

EPR-effect: Utilizing size-dependent Nanoparticle Delivery to Solid Tumors

EPR-effect: Utilizing size-dependent Nanoparticle Delivery to Solid Tumors

Fractal‐like behaviour of the BCC/FCC phase separation in the iron‐gold alloys

Iron-gold alloys with compositions Fe(70)Au(30) and Fe(50)Au(50) were prepared by arc melting. The alloys were investigated by means of the high-resolution scanning electron microscopy (SEM-FEG) in the as-cast state and upon annealing in two steps, i.e. at 250 degrees C for 24 h and subsequently at 500 degrees C for 48 h. The alloys were composed of two phases, i.e. a BCC phase rich in iron and a FCC phase rich in gold. The single-phase regions have equivalent diameter of about 50 nm. SEM images show self-similar structure for the spatial distribution of the above phases on scales ranging from about 1 mm till about 100 nm. The roughness of the images has been used to estimate a fractal dimension of the phase mixture. For larger scales of the as-cast samples one finds fractal dimension of about 1.7 for Fe(70)Au(30) composition, i.e. very close to the dimension of typical diffusion limited aggregation (DLA) fractals. For annealed samples, dimension 1.1 was found.

Hyperfine interactions on iron nuclei in the BCC and fractally decomposed BCC/FCC mixed phase iron–gold alloys

Iron–gold alloys for the gold concentration ranging from 1 at.% till 70 at.% were investigated by means of the 57Fe-14.4 keV Mössbauer spectroscopy, X-ray diffraction and scanning electron microscopy. Samples were prepared by arc melting of the elements, and investigated as cast and after annealing. A single BCC phase is obtained for the gold concentration up to about 3 at.%, while for the higher gold concentration one obtains mixed phase samples containing BCC and FCC phases both. The BCC phase is ferromagnetically ordered at room temperature. Contributions to the charge and spin density on iron atoms in the BCC phase due to the gold impurities were determined up to the second neighbors. The FCC phase is either magnetically ordered at room temperature or it is paramagnetic at the above temperature depending upon iron concentration, as the magnetic transition temperature is increasing with the increasing iron concentration. BCC/FCC mixed phase samples are characterized by very small crystallites (nanoparticles) of both phases. These nanoparticles form hierarchical fractal structures on the scale ranging from more than 1 mm till less than 30 nm.

Domain structures and magnetization processes of ultrathin ordered iron–gold alloys films

Thickness-dependent changes of the domain period, initial susceptibility and saturation field in ultrathin films was theoretically analyzed considering the equilibrium state of the domain. The experiment was performed on artificially stabilized tetragonal-ordered gold–iron films with thickness varying from 3 up to 50 monolayers. Domain structure and magnetization processes were studied using magneto-optical techniques. Square hysteresis loops were registered for intermediate film thickness.

Characterization of neutron-irradiated FeAu alloys

The yield strength of a series of neutron-irradiated iron-gold alloys was found to be significantly higher than a similar series of iron-copper alloys that were irradiated at the same fluence and irradiation temperature. An atom probe field ion microscopy and transmission electron microscopy characterization of these alloys has been performed. Atom probe analysis revealed significant depletions of copper and gold in the matrices after neutron irradiation. High number densities of small coherent zones on the thesz100thesz α planes were observed by both transmission electron microscopy and field ion microscopy. A maximum gold concentration of ∼ 4 at% Au was found in the coherent zones for material neutron-irradiated at 290°C to a fluence of ∼ 1.2 × 10 23nm −2.

The g-Factor of the First Excited Level of 196Pt

The perturbed angular correlations of 333.0 keV–355.7 keV gamma-gamma cascade in 196 Pt were measured on iron-gold alloy samples containing 0.2–0.5 at% gold impurity prepared by various thermal treatments. The shift of angular correlation pattern was obtained as ωτ=0.095 ±0.003 rad. The g -factor of the first excited level of 196 Pt was determined to be g =0.346 ±0.013.

Magnetic and transport properties of Fe-Au and Co-Au films

Thin film cobalt-gold and iron-gold alloys have been prepared by sputtering onto water cooled substrates. These alloys are crystalline with residual electrical resistivity (ρ) a factor of five greater than bulk alloys. For FexAu100−x the X-ray diffraction patterns are characteristic of fcc structures (high Au content) and bcc structures (low Au content); CoxAu100−x shows mixed fcc and hexagonal diffraction patterns. Fe-Au exhibits a constant magnetic moment per Fe of μB = 2.2 over the range 26 to 92% Fe. The resistivity of Fe-Au at 4.2°K is about 40μΩcm and is independent of composition. The Hall effect expressed as Rs/ρ2 where Rs is the spontaneous Hall coefficient increases with Fe dilution. Co-Au shows a concentration dependent magnetic moment which decreases with increasing Au and a Hall effect as given by Rs/ρ2 which increases in magnitude as the Co moment decreases. In addition the resistivity at 4.2 °K of Co-Au is composition dependent increasing with decreasing Co content. The anisotropic magneto-resistance in both Fe-Au and Co-Au behave similarly with the interesting feature that Δρ(Δρ = ρ∥−ρ⊥) has a maximum at about the same average magnetization as found for other alloys such as Ni-Fe and Ni-Co2. At the same composition of maximum Δρ the saturation magnetostriction becomes almost zero.

Thermodynamic properties of dissolved oxygen in iron-gold alloys

Thermodynamic properties of dissolved oxygen in iron-gold alloys

Thermodynamic properties of dissolved oxygen in iron-gold alloys

Thermodynamic properties of dissolved oxygen in iron-gold alloys