Toxicity of Nanomaterials-Physicochemical Effects

Special Issue

Austin J Nanomed Nanotechnol. 2014;2(6): 1034.

Toxicity of Nanomaterials-Physicochemical Effects

Rahi1, Sattarahmady N1,2,3 and Heli H1,2*

1Department of Nanomedicine, Shiraz University of Medical Sciences, Iran

2Nanomedicine and Nanobiology Research Center, Shiraz University of Medical Science, Iran

3Department of Medical Physics, School of Medicine, Shiraz University of Medical Sciences, Iran

*Corresponding author: Heli H, Department of Nanomedicine, Nanomedicine and Nanobiology Research Center, Shiraz University of Medical Science, Shiraz, Iran

Received: August 20, 2014; Accepted: September 19, 2014; Published: September 24, 2014


Nanomaterials are the structures with at least one dimension of <100 nm. Recently, development in nanotechnology has led to use of nanomaterials in many different fields. On other hand, increasing in the use of nanomaterials has led to release of these materials to the environment. Therefore, before employing of these materials in biological and environmental and living systems, they should evaluate in terms of biocompatibility and distribution. Although the toxic effects of nanomaterials on living organisms, human health and the environment have been studied by some researchers, however, there are too much uncertainty about the effects and mechanisms of toxicity of nanomaterials. Therefore, understanding the toxicity effects of nanomaterials is highly desirable. Cellular uptake mechanisms and dispersion of nanomaterials in biological environments depend on their physicochemical properties. Therefore, knowledge the unique characteristics of nanomaterials and the interactions of nanomaterials with biological systems, are important criteria for the safe use of nanomaterials. Properties of nanomaterials such as size, shape, aspect ratio, density, and surface and structural defects and dissolving rate are the main cause of cytotoxicity and side effects of these materials in the body. Exposure to nanomaterials may be cause a range of acute and chronic effects, including inflammation, exacerbation of asthma, metal fume fever, fibrosis, chronic inflammatory diseases and cancer.

Keywords: Nanotechnology; Nanomaterials; Safety; Toxicity


Nanomaterials have been greatly interested due to their novel properties arising from their high effective surface area and high reactivity. Moreover, with rapid developments in nanotechnology, nanomaterials have been synthesized in a wide variety of shapes and sizes, and are used in fabrication of various industrial and medical products. Typical applications of nanomaterials are in cancer treatment [1,2], drug design [3-5], drug and gene delivery [6,7], antibacterial and self-cleaning coatings [8-10], biological tags [11,12], identification of proteins [13-15], tissue engineering [16,17], hyperthermia [18], sensors [19-23], biosensors [24-28], and coatings [29,30]. However, recent studies have confirmed negative effects of these materials on the growth and survival of organisms; these lead to a range of acute and chronic effects [31-33]. Nanomaterials can transport in the body and the environment, while have a high surface-to-volume ratio, and can affect the organisms and the environment in a negative way. Therefore, the toxicity assessment of these materials is of a great importance. Beside, due to their small size, nanomaterials are absorbed by solid, liquid, or gas surfaces in heterogeneous environments. Therefore, in order to study their toxicity risks, we should pay special attentions to the nanomaterials floating in liquids, or those dispersed in gases. Since nanotechnology is a rather new technology, little information is available on the epidemiological effects of nanomaterials. In the past few years, hundreds of tons of nanomaterials have entered into the environment without having enough knowledge on their potential reactions with biological systems [34]. For instance, in England about 2000 die annually due to exposure to asbestos and the consequent asbestosis [35].

Recently, the number of articles published on nanomaterials has increased dramatically. But most of these studies focus on the synthesis and application of the nanomaterials and less than 1% of the studies deal with their biological effects. While the toxicity of many materials is well recognized, it is not yet know what concentration or quantities of them can causes new toxic properties at the nanoscale. Lack of adequate information about the nanomaterials properties and their toxic features, prevents the safe design of nanomaterials.

Based on the studies conducted on the biological and toxic effects of nanomaterials, there is a meaningful relationship between human exposure to nanomaterials and the occurrence of lung diseases, cardiovascular diseases, and mortality [36]. However, information on primary mechanisms which lead to toxicity of nanomaterials is lacking. For instance, nanomaterials penetration to different intracellular and extracellular parts, such as cytoplasm of mesothelial and epithelial cells of lung; it was verified by electron microscopy [37]. Therefore, identifying the potential risks of new improvements using nanomaterials is essential in order to avoid human injuries.

During the toxicology of nanomaterials, interactions between nanomaterials and biological systems are investigated to gain a logical relationship between the physicochemical properties of nanomaterials and biological responses [38]. Biological activity and toxicity of nanomaterials depends on their physicochemical properties to a great extent. In order to understand the biological activity and toxic effects of nanomaterials, studies on the certain physiochemical properties (such as size, shape, aspect ratio, density, structure and surface defects, and dissolution rate) are recommended. But the great variety of nanomaterials and their different properties make comparison between findings of the studies difficult. In spite of the vast number of studies in recent years, there is still a great gap in toxicology of nanomaterials. Toxicology of nanomaterials has caused complications in nanotechnology so that researchers have realized that methods used for studying the toxic effects of nanomaterials are not always useful, because nanomaterials show different behavior and can have negative impact in toxicity assessments. Besides having unique physical and chemical properties, nanomaterials represent different responses in biological systems [34,35].

During recent years, there has been an increase in the number of studies on toxicology of nanomaterials. Among these studies, those on the mechanism of interaction of cells with nanomaterials show that the cells can easily bind to nanomaterials via active intracellular mechanisms. These mechanisms are hard to recognize because of these materials indicating different behaviors. For instance, differences in the surface coating, agglomeration rate, density, charge, and size of nanomaterials make their categorization in biological systems and identifying their potential risks difficult. Toxicological studies on animals indicate that respiratory system s exposure to nanomaterials causes more harmful inflammatory responses compared to bigger particles having similar chemical composition and concentration [39]. Nowadays, people working in factories or nanomaterials research centers have the most exposure to these materials. Nanomaterials have commercial uses which in turn endanger the people. Therefore, knowledge about the mechanisms of toxicity inhibiting induced by nanomaterials as a health risk factor is of a great importance.

Toxicity of Nanomaterials

Biological toxicity

Nanomaterials can enter the body via intravenous, dermal, subcutaneous, respiratory, intraperitoneal and oral ways. After entrance to the body, they may distribute in different organs. The absorption of nanomaterials may happen via first interaction with biological components (cells and proteins). Nanomaterials which have entered the cells can stay there for a long time or leave the cells and move toward another cells and organs, or even leave the body without being absorbed [40]. Nanomaterials interactions with biological systems can cause toxic effects including allergies [38], fibrosis [41], metal fume fever [32], deposition in organs (causing defects and insufficiency in organs) [41], inflammation [4], cytotoxicity [41], tissue damage [42], producing reactive oxygen species [43] and DNA damage [42]. Potential damages caused by nanomaterials are summarized in Table 1.

Citation: Rahi, Sattarahmady N and Heli H. Toxicity of Nanomaterials-Physicochemical Effects. Austin J Nanomed Nanotechnol. 2014;2(6): 1034. ISSN:2381-8956