Mini-reviewToxicological effects of silver nanoparticles
Section snippets
Preface to AgNPs
Nanotechnology is a rapidly emerging field, with a funding across the globe in 2010 amassed at 17.8 billion dollars (Sargent, 2012). Industrial and household applications have led to the increased exposure of engineered nanoparticles to humans (Nowack and Bucheli, 2007). Among the engineered nanoparticles, silver exposure is the hit of highest point as it is used in medical implants (DeVasConCellos et al., 2012). Metallic nanoparticles are synthesized with the goal of drug delivery, treatment,
Optimistic face of AgNPs
AgNPs are a multitude better in cytotoxic effects on cancer cell line evaluated against normal liver cell line (Faedmaleki et al., 2014). The liver is most probably the primary site for accumulation of AgNPs (Arora et al., 2009, Takenaka et al., 2001). It is capable of excreting the AgNPs, through bile, absorbed from GI tract. Since the liver cells showed relatively less effects as indicated by Faedmaleki et al. (2014), AgNPs could be a potential candidate for in vivo studies. Therefore, the
Toxicity of AgNPs in vivo in animal models
Though the AgNPs have potential biomedical applications, emphasis on nanotoxicology has made it an important field of research due to the impact it poses on the human environment (Mahmoudi et al., 2012). Biosynthesized AgNPs are less toxic compared to chemically synthesized AgNPs (de Lima et al., 2012).
AgNPs showed L(E)C50 values below 10 mg/L approximately to organisms such as crustaceans, fish and protozoa (Bondarenko et al., 2013). They were cytotoxic to rainbow trout cell lines and its
Toxicity of AgNPs against immune cells
AgNPs have no significant biological function in humans and therefore reach and cause damage to liver when exposed intravenously (Sandstead, 1995, Li et al., 2014a). They have been known to interact with human primary PBMC and increase oxidative stress in human neutrophils (Paino and Zucolotto, 2015). AgNPs of small size (10 nm) were found to be toxic to human blood mononuclear cells and the toxicity was both time- and dose-dependent (Barkhordari et al., 2014). Though the AgNPs were not clearly
Digestive system
AgNPs were shown to penetrate cell membrane and enter mitochondria leading to oxidative stress, inflammation and thereby leading to apoptosis when incubated with human gingival fibroblast cells (Inkielewicz-Stepniak et al., 2014). Treatment of AgNPs through oral route to mice resulted in impediment of function of small intestine mucosa due to destruction of microvilli. It was hypothesized that reduction in absorption by intestinal epithelium led to weight loss in mice (Shahare et al., 2013).
Unfavorable effects of AgNPs
At lower doses, 10 nm AgNPs induced cell proliferation of HepG2 cells called the “hormesis” effect rather being cytotoxic (Jiao et al., 2014). Studies on all the normal cell lines indicate that study in vivo of the toxicity of AgNPs is necessary for further evaluation. Though found to be toxic, human cells in vivo are highly resistant to AgNPs compared to other organisms (de Lima et al., 2012). This is well supported by another study, where exposure of AgNPs to healthy human population showed
Safety of antibacterial ointments on the integumentary system
When exposed orally, the AgNPs can induce oxidative damage to cell organelles and membranes and are usually excreted through bile and urine (Gaillet and Rouanet, 2015). Topical exposure compared to other routes is less toxic as the AgNPs are released in more volume in feces, rather than being accumulated in the major organs. Hence, antibacterial formulations of AgNPs that are topical are safe to use (Brandt et al., 2012). AgNPs of even up to 5000 ppm are safe to apply through skin of animals
Conclusion
Though AgNPs have prospective biomedical applications, the toxicity studies elucidate that AgNPs are toxic to a human and his environment. The size, dose and route of exposure of AgNPs are major criteria to be taken into consideration for its biomedical appliance.
Conflict of interest statement
None declared.
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