Results 1 - 9 of 9
Results 1 - 9 of 9. Search took: 0.013 seconds
|Sort by: date | relevance|
[en] In this work, nanoparticles of chitosan embedded with 25% (w/w) of iron oxide magnetic nanoparticles (magnetite/maghemite) with narrow size-distribution and with a loading efficiency of about 80% for 5-hydroxytryptophan (5-HTP), which is a chemical precursor in the biosynthesis of important neurotransmitters as serotonin, were synthesized with an initial mass ratio of 5-HTP/magnetic chitosan=1.2, using homogeneous precipitation by urea decomposition, in an efficient one-step procedure. Characterization of morphology, structure and surface were performed by XRD, TEM, FTIR, TGA, magnetization and zeta potential measurements, while drug loading and drug releasing were investigated using UV–vis spectroscopy. Kinetic drug release experiments under different pH conditions revealed a pH-sensitivecontrolled-release system, ruled by polymer swelling and/or particle dissolution. - Highlights: • One-step synthesis and incorporation of drug in magnetic chitosan. • Synthesis utilizes a cost-effective and environmentally friendly procedure. • Narrow size distribution of magnetic nanoparticles in the composite. • Composite is a basis for a magnetic pH triggered drug release system
[en] Magnetite was doped with rare earth ions (europium) to produce core-shell materials with both magnetic and luminescent properties, i.e., a magnetic Fe3O4 oxide core and a SiO2 :phen:Eu3+ shell. The resulting material was analyzed by X-ray powder diffraction and transmission electron microscopy, and subjected to magnetic and luminescence emission measurements. All the synthesized materials exhibited superparamagnetic behavior and luminescence emission. The magnetic behavior of Fe3O4 and luminescence emission of SiO2 :phen:Eu3+ of the materials were compared to precursors. (author)
[en] Full text: Several different cancer therapy modalities, besides the most known surgery, chemotherapy and radiotherapy, are becoming more common in the clinic, for example: hormone therapy, photodynamic therapy, radiofrequency ablation and microwave ablation. The last two methods deliver heat to treat tumors usually by using invasive probes. More recently, new nanotechnology-based methods had appeared, which has the advantage of being non-invasive and potential to be highly selective. One of those methods is known as magnetic nanoparticle hyperthermia, which uses the heat generation of magnetic nanoparticles when their magnetic moments interact with alternating magnetic fields. In this work, we will present the latest achievements of our group for pre-clinical applications. In particular, we will show how one can translate the knowledge from the lab bench to pre-clinical cancer treatment. The nanoparticle used in this work consisted of a soft-ferrite based material capable of promoting heat under low-field amplitude conditions. This property has the advantage of inhibiting non-specific tissue heating. The sample was extensively characterized by several techniques (transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM)). Surface temperature measurements were performed using real-time thermography and fibre-optic thermometers. The precision of this temperature by this non-invasive technique was found to be less than 0.3K. The experiments consisted of a 30-minute magnetic hyperthermia procedure performed at 300kHz in Swiss mouse induced tumors, sarcoma S180, with a field amplitude of the order of 10kA/m. The success of the treatment is clearly correlated with the heat deposition. In particular, we will show a case of total tumor regression, where the animal was followed for more than 90 days. Finally, we will correlate the infrared surface temperature data with three-dimensional numerical simulations. (author)
[en] Magnetic exfoliated vermiculite is a synthetic nanocomposite that quickly and efficiently absorbs organic compounds such as oil from water bodies. It was developed primarily to mitigate pollution, but the possible adverse impacts of its application have not yet been evaluated. In this context, the acute toxicity of magnetic exfoliated vermiculite and exfoliated vermiculite was herein assessed by genotoxic and histopathological biomarkers in zebrafish (Danio rerio). DNA fragmentation was statistically significant for all groups exposed to the magnetic exfoliated vermiculite and for fish exposed to the highest concentration (200 mg/L) of exfoliated vermiculite, whereas the micronucleus frequency, nuclear abnormalities and histopathological alterations were not statistically significant for the fish exposed to these materials. In the intestinal lumen, epithelial cells and goblet cells, we found the presence of magnetic exfoliated vermiculite and exfoliated vermiculite, but no alterations or presence of the materials-test in the gills or liver were observed. Our findings suggest that the use of magnetic exfoliated vermiculite and exfoliated vermiculite during standard ecotoxicological assays caused DNA damage in D. rerio, whose alterations may be likely to be repaired, indicating that the magnetic nanoparticles have the ability to promote genotoxic damage, such as DNA fragmentation, but not mutagenic effects. - Highlights: • MEV is a synthetic nanocomposite that quickly and efficiently absorbs organic compounds such as oil from water bodies. • The use of MEV and EV during standard ecotoxicological assays caused DNA fragmentation in zebrafish. • The magnetic nanoparticles showed ability to promote genotoxic damage, but did not induce micronucleus in peripheral erythrocytes at 96 h of exposure. • The tested concentrations of MEV and EV do not cause significant histopathological alterations in the gills, liver and intestine of zebrafish.
[en] Highlights: • Humic acid-HA, NaHCO3, MgSO4, KCl and CaCl2 change the stability and oxidation state of silver nanoparticle-AgNPs surface. • Ag3+ is formed on AgNPs surface mainly in presence of NaHCO3, MgSO4 and HA. • Toxicological endpoints in zebrafish embryos exposed to Ag3+ were not significant for acute exposure. • HA coated on AgNPs surface reduces the concentration of Ag ions released and the toxicity in zebrafish embryos. • HA acts as a natural attenuator/remediator of polluted water with AgNPs. - Abstract: The use of silver nanoparticles (AgNPs) result in an inevitable contact with aquatic environments. Here we study the behavior of AgNPs and the developmental toxicity in zebrafish embryos exposed to these nanoparticles (0–10 mg/L) with and without the presence of HA (20 mg/L), using zebrafish facility water (ZFW) and zebrafish growing media (ZGM). The presence of cations and HA gave rise to a decrease in Ag ion release and ζ-potential, an increase in the hydrodynamic diameter and oxidation of the AgNP surface. The results show that the presence of HA and cations in the media, as well as the silver speciation, i.e., the unusual presence of Ag3+, decreases the toxicity of AgNPs (LC50AgNPs: 1.19 mg/L; LC50AgNPs+HA: 3.56 mg/L), as well as silver bioavailability and toxicity in zebrafish embryos. Developmental alterations and the LC50 (1.19 mg/L) of AgNPs in ZFW were more relevant (p ≤ 0.05) than for AgNPs in ZGM (LC50 > 10 mg/L). It was demonstrated that the bioaccumulation and toxicity of AgNPs depends on several factors including AgNPs concentration, nanoparticle aggregation, dissolved silver ions, speciation of silver ions, the amount of salt in the environment, the presence of humic substances and others, and different combinations of all of these factors.
[en] Highlights: • Remotely-actuated chitosan/alginate magnetic nanoplatforms were synthesized. • Layer-by-layer deposition was optimized by conductimetric-potentiometric titrations. • Reversal of the surface charge is achieved by biopolymer polyions capping layers. • Nanoplatforms presented enhanced loading capacity for curcumin. • Biopolymer deposition improved the cell viability of magnetic nanoplatforms. - Abstract: Remotely assisted drug delivery by means of magnetic biopolymeric nanoplatforms has been utilized as an important tool to improve the delivery/release of hydrophobic drugs and to address their low cargo capacity. In this work, MnFe2O4 magnetic nanoparticles (MNPs) were synthesized by thermal decomposition, coated with citrate and then functionalized with the layer-by-layer (LbL) assembly of polyelectrolyte multilayers, with chitosan as polycation and sodium alginate as polyanion. Simultaneous conductimetric and potentiometric titrations were employed to optimize the LbL deposition and to enhance the loading capacity of nanoplatforms for curcumin, a hydrophobic drug used in cancer treatment. ~200 nm sized biopolymer platforms with ~12 nm homogeneously embedded MNPs were obtained and characterized by means of XRD, HRTEM, DLS, TGA, FTIR, XPS and fluorescence spectroscopy techniques to access structural, morphological and surface properties, to probe biopolymer functionalization and to quantify drug-loading. Charge reversals (±30 mV) after each deposition confirmed polyelectrolyte adsorption and a stable LbL assembly. Magnetic interparticle interaction was reduced in the biopolymeric structure, hinting at an optimized performance in magnetic hyperthermia for magneto-assisted drug release applications. Curcumin was encapsulated, resulting in an enhanced payload (~100 μg/mg). Nanocytotoxicity assays showed that the biopolymer capping enhanced the biocompatibility of nanoplatforms, maintaining entrapped curcumin. Our results indicate the potential of synthesized nanoplatforms as an alternative way of remotely delivering/releasing curcumin for medical purposes, upon application of an alternating magnetic field, demonstrating improved efficiency and reduced toxicity.