Superparamagnetic Contrast Agents
Michel M. J. Modo, Jeff W. M. Bulte in Molecular and Cellular MR Imaging, 2007
Iron oxide nanoparticles composed of maghemite and magnetite (Fe2O3, Fe3O4) stabilized by various coating agents are characterized by a large magnetic moment in the presence of a static external magnetic field, which makes them suitable as MR contrast agents. This large magnetic moment is caused by a crystal ordering (spinels) that induces a cooperativity between the individual paramagnetic ions constituting the crystal. These small superparamagnetic crystals are smaller than a magnetic domain (approximately 30 nm), and they consequently do not show any magnetic remanence (i.e., restoration of the induced magnetization to zero upon removal of the external magnetic field), unlike ferromagnetic materials. Several classes of iron oxide nanoparticles are investigated. Structure-activity relationship programs are based on optimization of blood clearance, biocompatibility, tissue accessibility, and cellular targeting.
Phototherapy Using Nanomaterials
D. Sakthi Kumar, Aswathy Ravindran Girija in Bionanotechnology in Cancer, 2023
Advances in nanotechnology allow researchers to develop nanoparticle-based MRI contract agents with higher magnetization and the required surface characteristics to satisfy the specific requirements for effective biodistribution [184]. There are two types of iron oxide that were specifically investigated for use in magnetic NP formulation: maghemite (α-Fe2O3) and magnetite (Fe3O4), both biocompatible, while the most promising candidate is magnetite. Typically, they are coated with dextran, phospholipids, or other compounds to inhibit aggregation and improve stability [185]. A nanocarrier made up of polymeric diacyl phospholipid– PEG micelles co-loaded with the photosensitizer 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH) and magnetic Fe3O4 nanoparticles showed excellent stability and effective uptake by HeLa cells. The magnetic response of nanocarriers was demonstrated by their targeted delivery to tumor cells in vitro when exposed to an external magnetic field. The magnetophoretic regulation of the cellular uptake improved imaging and phototoxicity [186]. The magnetic core containing chitosan nanoparticles and photosensitizer carriers encapsulating photosensitizer 2,7,12,18-tetramethyl-3,8-di(1-propoxyethyl)-13,17-bis(3-hydroxypropyl) porphyrin (PHPP) was found to have excellent targeting and imaging ability. With these nanoparticles at the level of 0–100 mM, non-toxicity and high photodynamic efficacy on SW480 carcinoma cells were achieved, both in vitro and in vivo [187].
An Introduction to Two-Piece Hard Capsules and Their Marketing Benefits
Larry L. Augsburger, Stephen W. Hoag in Pharmaceutical Dosage Forms, 2017
The term globally acceptable generally refers to the regions of the United States, the European Union, and Japan. For a global presentation, the available palette of colorants is vastly reduced and mainly consists of the iron oxides, titanium dioxide, and blue #2. It is important to note that blue #2 is a light-sensitive dye that is prone to fading; therefore, light protective packaging should be used to avoid capsule discoloration. Iron oxides present a special challenge as they contain elemental iron, which can be toxic at elevated levels. This is an especially important consideration since the iron oxides are one of the few classes of globally acceptable coloring agents. For reasons of patient safety, guidelines have been established for the daily intake of iron oxides and elemental iron. For example, the World Health Organization has established a limit of 0.5 mg/day/kg of iron oxide, while the US Code of Federal Regulations has an established limit of 5 mg/day of elemental iron. It is therefore incumbent on the formulator to be aware of the levels of iron oxide in their capsule color formulation. This information enables the back calculation of elemental iron levels per capsule; the maximum theoretical intake of elemental iron can be calculated based on the number of capsules to be dosed daily. A reputable capsule supplier can provide assistance in this matter and reformulate to lower iron oxide levels if necessary.
Metal Nanoparticles in Infection and Immunity
Published in Immunological Investigations, 2020
John K. Crane
Other metals which have been investigated as nanoparticles, include those composed of copper, iron, and zinc. In addition, semi-metals such as gallium and bismuth have been incorporated into nanoparticles as well (Hernandez-Delgadillo et al. 2013; Vega-Jimenez et al. 2017). Iron and zinc may decompose into the ionic forms of those elements in acidic cellular compartments, and therefore might be considered partially biodegradable. In addition to pure metal, metal oxides feature prominently in the field of nanoparticles, such as iron oxide NPs, zinc oxide (ZnO) NPs, titanium oxide (TiO2) NPs, and others. Iron oxide can be in the form of Fe2O3 (ferric iron, Fe III) or Fe3O4 (Fe II/III). The latter is magnetic, which means it can be used to separate a target from background in vitro or in vivo. Fe3O4 nanoparticles can also be injected into a target tissue (such as cancerous tumor) and then heated by application of a high frequency alternating magnetic field, known as magnetic hyperthermia.
Current trends in chemical modifications of magnetic nanoparticles for targeted drug delivery in cancer chemotherapy
Published in Drug Metabolism Reviews, 2020
Ahmad Gholami, Seyyed Mojtaba Mousavi, Seyyed Alireza Hashemi, Younes Ghasemi, Wei-Hung Chiang, Najmeh Parvin
In another research, magnetite nanoparticles like iron oxide with core/shell structure are primarily used as sources of magnetic materials (Drbohlavova et al. 2009; Ebrahimi et al. 2016). Iron oxide has several crystalline polymorphs called Fe2O3 hematite, Fe2O3 maghemite, Fe3O4 magnetite, and a few other forms (high-pressure forms and amorphous) (Zboril et al. 2002). Nevertheless, only maghemite and magnetite are found to be the most significant interest in bioapplications. Until now, widely MNPs synthesis methods have been investigated. There are many favorable methods to get MNPs by high stability, monodisperse nanoparticles, and shape-controlling (Chen et al. 2018). There are used several methods in the synthesis of MNPs such as coprecipitation (Hashemi et al. 2019), thermal decomposition, microemulsion, sol–gel, and additional chemical processes that are shown in Figure 1 (Avval et al. 2019).
Characterization of an aerosol generation system to assess inhalation risks of aerosolized nano-enabled consumer products
Published in Inhalation Toxicology, 2019
K. Pearce, W.T. Goldsmith, R. Greenwald, C. Yang, G. Mainelis, C. Wright
Nano-enabled products (NEPs) are diverse consumer goods that utilize various facets of nanotechnology. In 2013, NEP global revenues were valued at ∼$1 trillion with a projected market value of $4.4 trillion by 2018 (Lux Research 2014; NSF 2014). Some consumer products such as sunscreens, lotions, and cosmetics are now considered NEPs as they contain various forms of engineered nanomaterials including metal oxide nanoparticles (Kessler 2011; Adeleye et al. 2016; Valavanidis and Vlachogianni 2016; US NNI 2018). Currently, almost all major cosmetic brands utilize nanotechnology in their products for durability, color enhancement, and to promote product stability (Raj et al. 2012). Of these metal nanoparticles, titanium dioxide (TiO2) is the most widely used as a UV protectant. Similarly, iron oxide (Fe2O3) is commonly used as a pigment to produce various shades of cosmetics, such as red and orange (Wawrzynczak and Nowak 2011; Borowska and Brzóska 2015). While these nanoparticles have been deemed safe for dermal application, limited information exists regarding hazards associated with potential inhalation of aerosolized forms of NEPs including nanoparticles (Pflücker et al. 1999; Schulz et al. 2002; Newman et al. 2009; Sadrieh et al. 2010; Skocaj et al. 2011; Shi et al. 2013; Osmond-McLeod et al. 2015; Remya et al. 2016). As aerosolized application of nano-enabled cosmetics has gained popularity, inadvertent consumer inhalation exposure to constituent metal nanoparticles, inorganic, and organic NEP components may become more prevalent, potentially causing negative respiratory effects.
Related Knowledge Centers
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