Nanoparticles toxic effects

Nanoparticles such as those of the heavy metals, like cadmium selenide, cadmium sulfide, lead sulfide, and cadmium telluride are potentially toxic [14,15]. The possible mechanisms by which nanoparticles cause toxicity inside cells are schematically shown in Fig. 2. They need to be coated or capped with low toxicity or nontoxic organic molecules or polymers (e.g., PEG) or with inorganic layers (e.g., ZnS and silica) for most of the biomedical applications. In fact, many biomedical imaging and detection applications of QDs encapsulated by complex molecules do not exhibit noticeable toxic effects [16]. One report shows that the tumor cells labeled with QDs survived in circulation and extravasated into tissues... 

The pH value of dialyzed solutions was within the 7.0-7.4 range that corresponds to the normal pH of biological systems. Taking into account that the average thickness of cell membranes is about 8-10 nm, we can suppose that the synthesized nanoparticles ( 2 nm) can penetrate through the cell membranes. The particles can be used in native, solubilized and modified forms. The senthisyzed nanoparticles were tested on the rat hepatocyte cells using the standard procedure of trypan blue dye exclusion [7]. For a particle concentration up to 50 mg/1, the toxic effect has not been detected. 

To complicate further our perceptions of nanoparticle toxicity, some recent evidence suggests that, on a mass basis, not all nanoparticle-types are more toxic than fine-sized particles of similar chemical composition. As mentioned previously, the limited numbers of studies that have been reported suggest that ultrafine Ti02 particles produced greater pulmonary inflammation when compared with fine-sized Ti02 particles. However, in contrast to the conclusions of the earlier findings, the results of recent preliminary studies comparing the effects of nano- versus... 

New technology, for example, nanotechnology, must be carefully evaluated for toxic consequences prior to widespread introduction. In the example of nanoparticles, unanticipated toxic effects have been found as these circulate throughout the human body. 

A lower incidence of myelosuppression has been observed and reported during studies on Abraxane but other toxic effects (sensory neuropathy, mucositis) are similar to those seen with Taxol given at high doses. Abraxane has been reported to produce keratopathy, which is a toxic effect rarely seen with drugs. Thus, as with the liposomal formulations described earlier (Section VIII.A.), the administration of nanoparticle based formnlations can dramatically alter the pharmacokinetics, the distribution of the drug in both tissnes and tumors, and the toxicity profile. Also, similar to what has been found with liposomes, the mechanism(s) by which nanoparticles release their drug payload is not well nnderstood as yet. 

The toxic effects of nanoparticles have not been clearly characterized. Based on analogy to fibers and particles and what we know about their toxicity and mechanisms, it seems possible that some nanomaterials may act similarly as those carcinogenic fibers and particles. It has been suggested that carbon nanotubes could have features of both nanoparticles and fibers and may exhibit some of their effects through oxidative stress and infianunation (Donaldson et al. 2006). Nanoparticles of... 

Mesenchymal stem cells isolated from murine bone marrow were applied in a study designed to evaluate the molecular toxicity of hydroxyapatite nanoparticles (Remya et al., 2014). Hydroxyapatite nanoparticles (50 nm) were used to study the cytotoxicity, nanoparticle uptake, effect on cytoskeletal arrangement, oxidative stress response and apoptotic behaviour with the confluent cells as per standard protocols. The results of the MTT assay indicated that hydroxyapatite nanoparticles do not induce cytotoxicity up to 800 pg ml-1. It was also observed that apoptosis related to oxidative stress and reactive oxygen species (ROS) production following nanoparticle treatment was comparable to that of the control (cells without treatment). Hence, it can be concluded that mesenchymal stem cell in vitro cultures can be used as a model to evaluate the potential toxicity of nanomaterials. 

In polyalkylcyanoacrylate nanoparticles, CyDs are able to slightly decrease the toxic effect induced by polymer degradation on Caco-2 cells [42]. However, saquinavir-loaded CyD nanospheres are not able to promote the transport of this drug through Caco-2 cell monolayers [104]. In contrast, HP-j8-CyD is useful in metoclopramide-loaded nanopartides, where it enhances the absorption of meto-clopramide by a factor of 2 after subcutaneous administration in rat [43]. 

Bourges et al. studied the kinetics of polylactide (PLA) nanoparticle (NP) localization within the intraocular tissues and to evaluate their potential to release encapsulated material. Environmental scanning electron microscopy (ESEM) showed the flow of the NPs from the site of injection into the vitreous cavity and their rapid settling on the internal limiting membrane. Histology demonstrated the anatomic integrity of the injected eyes and showed no toxic effects. A mild inflammatory cell infiltrate was observed in the ciliary body 6 h after the injection and in the posterior vitreous and retina at 18-24 h. The intensity of inflammation decreased markedly by 48 h. Confocal and fluorescence microscopy and immunohistochemistry showed that a transretinal movement of the NPs was... 

The intranasal route delivery is an easy non-invasive approach to deliver biomolecules via the olfactory and trigeminal neuronal pathways to the brain, bypassing the BBB. It is considered to be the fastest and most effective way to cross the BBB to reach the CNS. Malhotra et al. developed TAT- and MGF-tagged PEGylated chitosan nanoparticles to deliver siRNA to the brain via an intranasal route. The results demonstrated maximum siRNA delivery to the brain compared with other tissues, with no cellular toxic effects. 

Nanoscale debris from CoCrMo, which is also a widely used orthopedic implant material, may also induce DNA and chromosome damage as well as cytotoxicity. For instance, CoCr nanoparticles demonstrated more severe DNA damage, chromosomal damage, and toxic effects compared to micron-sized CoCr particles [8,9]. For orthopedic implants made of stainless steels, Fe or Ni nanoparticles are also possible sources for triggering toxicity and adverse effects at local or systemic levels. For example, Ni particles implanted in rat soft tissues were found to cause just allergic reactions when... 

In general, it may be concluded that despite the endeavor described earlier to develop low-fouling membranes via surface modification with nanoparticles, further research is still needed to investigate the combined effects of the water chanistry, the nature of the nanoparticles, and the coating conditions on the modified-manbrane performance and fouling mitigation. Also, careful control and monitoring of the nanoparticles released from the modified membranes are necessary to minimize potential environment (eco) toxicity effects (Tiede et al. 2009). 

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