Paula S. Haddad

State of the art, challenges and perspectives in the design of nitric oxide-releasing polymeric nanomaterials for biomedical applications

Recently, an increasing number of publications have demonstrated the importance of the small molecule nitric oxide (NO) in several physiological and pathophysiological processes. NO acts as a key modulator in cardiovascular, immunological, neurological, and respiratory systems, and deficiencies in the production of NO or its inactivation has been associated with several pathologic conditions, ranging from hypertension to sexual dysfunction. Although the clinical administration of NO is still a challenge owing to its transient chemical nature, the combination of NO and nanocarriers based on biocompatible polymeric scaffolds has emerged as an efficient approach to overcome the difficulties associated with the biomedical administration of NO. Indeed, significant progress has been achieved by designing NO-releasing polymeric nanomaterials able to promote the spatiotemporal generation of physiologically relevant amounts of NO in diverse pharmacological applications. In this review, we summarize the recent advances in the preparation of versatile NO-releasing nanocarriers based on polymeric nanoparticles, dendrimers and micelles. Despite the significant innovative progress achieved using nanomaterials to tailor NO release, certain drawbacks still need to be overcome to successfully translate these research innovations into clinical applications. In this regard, this review discusses the state of the art regarding the preparation of innovative NO-releasing polymeric nanomaterials, their impact in the biological field and the challenges that need to be overcome. We hope to inspire new research in this exciting area based on NO and nanotechnology.

Preparation, characterization, cytotoxicity, and genotoxicity evaluations of thiolated- and s-nitrosated superparamagnetic iron oxide nanoparticles: implications for cancer treatment.

Iron oxide magnetic nanoparticles have been proposed for an increasing number of biomedical applications, such as drug delivery. To this end, toxicological studies of their potent effects in biological media must be better evaluated. The aim of this study was to synthesize, characterize, and examine the potential in vitro cytotoxicity and genotoxicity of thiolated (SH) and S-nitrosated (S-NO) iron oxide superparamagnetic nanoparticles toward healthy and cancer cell lines. Fe3O4 nanoparticles were synthesized by coprecipitation techniques and coated with small thiol-containing molecules, such as mercaptosuccinic acid (MSA) or meso-2,3-dimercaptosuccinic acid (DMSA). The physical-chemical, morphological, and magnetic properties of thiol-coating Fe3O4 nanoparticles were characterized by different techniques. The thiol groups on the surface of the nanoparticles were nitrosated, leading to the formation of S-nitroso-MSA- or S-nitroso-DMSA-Fe3O4 nanoparticles. The cytotoxicity and genotoxicity of thiolated and S-nitrosated nanoparticles were more deeply evaluated in healthy (3T3, human lymphocytes cells, and chinese hamster ovary cells) and cancer cell lines (MCF-7). The results demonstrated that thiol-coating iron oxide magnetic nanoparticles have few toxic effects in cells, whereas S-nitrosated-coated particles did cause toxic effects. Moreover, due to the superaramagnetic behavior of S-nitroso-Fe3O4 nanoparticles, those particles can be guided to the target site upon the application of an external magnetic field, leading to local toxic effects in the tumor cells. Taken together, the results suggest the promise of S-nitroso-magnetic nanoparticles in cancer treatment.

Nitric oxide donor superparamagnetic iron oxide nanoparticles

This work reports a new strategy for delivering nitric oxide (NO), based on magnetic nanoparticles (MNPs), with great potential for biomedical applications. Water-soluble magnetic nanoparticles were prepared through a co-precipitation method by using ferrous and ferric chlorides in acidic solution, followed by a mercaptosuccinic acid (MSA) coating. The thiolated nanoparticles (SH-NPs) were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The results showed that the SH-NPs have a mean diameter of 10nm and display superparamagnetic behavior at room temperature. Free thiol groups on the magnetite surface were nitrosated through the addition of an acidified nitrite solution, yielding nitrosated magnetic nanoparticles (SNO-NPs). The amount of NO covalently bound to the nanoparticles surface was evaluated by chemiluminescense. The SNO-NPs spontaneously released NO in aqueous solution at levels required for biomedical applications. This new magnetic NO-delivery vehicle has a great potential to generate desired amounts of NO directed to the target location.

Interplay between crystallization and particle growth during the isothermal annealing of colloidal iron oxide nanoparticles

The relationship between crystallization and growth of colloidal iron oxide nanoparticles during isothermal annealing was addressed in this work. The structural, morphological and chemical modifications of the nanoparticles during thermal treatments were followed by combination of electron microscopy, X-ray diffraction and spectroscopic methods. The initially monodisperse spherical nanoparticles with amorphous and partially oxidized structure evolved during the treatments, depending on the temperature and treatment time. Core-void-shell nanoparticles or single crystal nanoparticles and hollow polycrystalline nanoparticles, both with well defined Fe(3)O(4) oxide phase, are formed depending on the conditions. This evolution was interpreted as a result of the Kirkendall effect associated to mass redistribution and fragmentation of the nanoparticles, bringing new information about the effect of post-synthesis treatments on the crystallinity and morphology of colloidal nanoparticles.

Nitric oxide releasing iron oxide magnetic nanoparticles for biomedical applications: cell viability, apoptosis and cell death evaluations

Nitric oxide (NO) is involved in several physiological and pathophysiological processes, such as control of vascular tone and immune responses against microbes. Thus, there is great interest in the development of NO-releasing materials to carry and deliver NO for biomedical applications. Magnetic iron oxide nanoparticles have been used in important pharmacological applications, including drug-delivery. In this work, magnetic iron oxide nanoparticles were coated with thiol-containing hydrophilic ligands: mercaptosuccinic acid (MSA) and dimercaptosuccinic acid (DMSA). Free thiol groups on the surface of MSA- or DMSA- coated nanoparticles were nitrosated, leading to the formation of NO-releasing iron oxide nanoparticles. The cytotoxicity of MSA- or DMSA-coated magnetic nanoparticles (MNP) (thiolated nanoparticles) and nitrosated MSA- or nitrosated DMSA- coated MNPs (NO-releasing nanoparticles) were evaluated towards human lymphocytes. The results showed that MNP-MSA and MNP-DMSA have low cytotoxicity effects. On the other hand, NO-releasing MNPs were found to increase apoptosis and cell death compared to free NO-nanoparticles. Therefore, the cytotoxicity effects observed for NO-releasing MNPs may result in important biomedical applications, such as the treatment of tumors cells.

Superparamagnetic iron oxide nanoparticles dispersed in Pluronic F127 hydrogel: potential uses in topical applications

The present study is focused on the synthesis and characterization of nitric oxide (NO)-releasing superparamagnetic iron oxide nanoparticles (Fe3O4 NPs), and their incorporation in Pluronic F127 hydrogel with great potential for topical applications. Magnetite nanoparticles (Fe3O4 NPs) were synthesized by thermal decomposition of acetylacetonate iron (Fe(acac)3), and coated with the thiol containing molecule mercaptosuccinic acid (MSA), leading to Fe3O4-MSA NPs. The obtained NPs were characterized using different techniques. The results showed that the Fe3O4-MSA NPs have a mean diameter of 11 nm, in the solid state, and superparamagnetic behavior at room temperature. Fe3O4-MSA NPs have an average hydrodynamic size of (78.0 ± 0.9) nm, average size distribution (PDI) of 0.302 ± 0.04, and zeta potential of (−22.10 ± 0.55) mV. Free thiol groups on the Fe3O4-MSA NP surface were nitrosated by the addition of sodium nitrite, yielding S-nitrosated magnetic nanoparticles (Fe3O4-S-nitroso-MSA NPs), which act as spontaneous NO donors upon S–N bond cleavage. The amount of (86.4 ± 4.7) μmol of NO was released per gram of Fe3O4-S-nitroso-MSA NPs. In order to enhance NP dispersion, Fe3O4-MSA NPs were incorporated in Pluronic F127 hydrogel (3.4% w/w), and characterized using different techniques. Rheological measurements suggest a potential use for Fe3O4-MSA NPs dispersed in Pluronic hydrogel for topical applications. Atomic force microscopy (AFM) showed that the NPs are embedded within the Pluronic film while the X-ray photoelectron spectroscopy (XPS) spectrum of the Fe3O4-MSA NPs samples revealed the presence of iron, oxygen, carbon and sulfur, confirming the presence of MSA molecules on the NP surface.

Iron oxide nanoparticles show no toxicity in the comet assay in lymphocytes: A promising vehicle as a nitric oxide releasing nanocarrier in biomedical applications

This work reports the synthesis and toxicological evaluation of surface modified magnetic iron oxide nanoparticles as vehicles to carry and deliver nitric oxide (NO). The surface of the magnetic nanoparticles (MNPs) was coated with two thiol-containing hydrophilic ligands: mercaptosuccinic acid (MSA) or dimercaptosuccinic acid (DMSA), leading to thiolated MNPs. Free thiols groups on the surface of MSA- or DMSA-MNPs were nitrosated leading to NO-releasing MNPs. The genotoxicity of thiolated-coated MNPs was evaluated towards human lymphocyte cells by the comet assay. No genotoxicity was observed due to exposure of human lymphocytes to MSA- or DMSA-MNPs, indicating that these nanovectors can be used as inert vehicles in drug delivery, in biomedical applications. On the other hand, NO-releasing MPNs showed genotoxicity and apoptotic activities towards human lymphocyte cell cultures. These results indicate that NO-releasing MNPs may result in important biomedical applications, such as the treatment of tumors, in which MNPs can be guided to the target site through the application of an external magnetic field, and release NO directly to the desired site of action.

Spreading of bio-adhesive vesicles on DNA carpets†‡

Cell-adhesion events involve often the formation of a contact region between phospholipid membranes decorated with a variety of bio-macromolecular species. We mimic here such hairy bio-adhesive contact zones by spreading phospholipid vesicles onto surfaces carpeted with end-grafted λ-phage DNA. Our study reveals that the spreading front acts as a scraper that strongly stretches the DNA molecules, and that the multiple bonds created during vesicle spreading effectively staple the stretched chains in the gap between the membrane and the substrate. The scraping and stapling mechanisms revealed here for the long DNA molecules are expected to also play a role in actual bio-adhesion events of cell walls and tissues.

Preparation, Characterization and Tests of Incorporation in Stem Cells of Superparamagnetic Iron Oxide

Superparamagnetic iron oxide nanoparticles (SPIONs) have been produced and used as contrast-enhancing agents in magnetic resonance imaging (MRI) for diagnostic use in a wide range of maladies including cardiovascular, neurological disorders, and cancer. The reasons why these SPIONs are attractive for medical purposes are based on their important and unique features. The large surface area of the nanoparticles and their manipulation through an external magnetic field are features that allow their use for carrying a large number of molecules such as biomolecules or drugs. In this scenario, the present work reports on the synthesis and characterization of SPIONs and in vitro MRI experiments to increase their capacity as probes for MRI applications on stem cells therapy. Initially, the SPIONs were prepared through the co-precipitation method using ferrous and ferric chlorides in acidic solution. The SPIONs were coated with two thiolmolecules such as mercaptosuccinic acid (MSA) and cysteine (Cys) (molar ratio SPIONs:ligand = 1:20), leading to the formation of a stable aqueous dispersion of thiolated nanoparticles (SH-SPIONs). The SH-SPIONs were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The results showed that the SH-SPIONs have a mean diameter of 14 nm and display superparamagnetic behavior at room temperature. Preliminary tests of incorporation of SH-SPIONs were evaluated stem cells. The results showed that the thiolated nanoparticles have no toxic effects for stem cells and successfully internalized and enhance the contrast in MRI.

Cytotoxicity and Genotoxicity of Iron Oxides Nanoparticles

The interest in the development of nanoparticles for diverse applications, mainly biomedical and technological purposes, has been greatly increasing in recent years. Among the nanostructured materials, metallic nanoparticles, in particular, iron oxide magnetic nanoparticles have been the focus of intensive research. Recently, the biomedical applications of iron oxide magnetic nanoparticles, such as magnetite (Fe3O4) and maghemite (γ-Fe2O3), have been increasing. Due to their special properties, such as small sizes and superparamagnetic behavior at room temperature, these nanoparticles find important pharmacological applications, such as drug delivery and contrast agents in magnetic resonance imaging. Iron oxide nanoparticles, with different sizes and coating surfaces, can be synthesized by well-established physical, chemical, and, more recent, biogenic techniques. Biogenic synthesis of iron oxide nanoparticles has emerged as a new and environment-friendly approach to obtain biocompatible nanomaterials. It must be noted that, for biomedical or technological applications of iron oxide nanoparticles, it is of paramount importance to fully characterize the in vitro and in vivo toxicity of these nanoparticles. In recent years, important studies have been characterized the cyto- and genotoxicity, as well as the biological consequences due to in vivo administration of iron oxide nanoparticles. In despite of these advances in toxicological evaluations of these nanoparticles, there are still some important questions to be answered. For biomedical or technological applications, it is mandatory to characterize in details the toxicity of this nanomaterial, as well as its fate upon in vivo administration. In this regard, this chapter summarizes the recent progress in the synthesis of iron oxide nanoparticles and the in vitro and in vivo characterization of nanoparticle toxicities.