Nanomaterials and nanoparticles: Sources and toxicity

Abstract

This review is presented as a common foundation for scientists interested in nanoparticles, their origin, activity, and biological toxicity. It is written with the goal of rationalizing and informing public health concerns related to this sometimes-strange new science of 'nano', while raising awareness of nanomaterials' toxicity among scientists and manufacturers handling them. We show that humans have always been exposed to tiny particles via dust storms, volcanic ash, and other natural processes, and that our bodily systems are well adapted to protect us from these potentially harmful intruders. The reticuloendothelial system in particular actively neutralizes and eliminates foreign matter in the body, including viruses and non-biological particles. Particles originating from human activities have existed for millennia, e.g. smoke from combustion and lint from garments, but the recent development of industry and combustion-based engine transportation has profoundly increased anthropogenic particulate pollution. Significantly, technological advancement has also changed the character of particulate pollution, increasing the proportion of nanometer-sized particles -"nanoparticles" and expanding the variety of chemical compositions. Recent epidemiological studies have shown a strong correlation between particulate air pollution levels, respiratory and cardiovascular diseases, various cancers, and mortality. Adverse effects of nanoparticles on human health depend on individual factors such as genetics and existing disease, as well as exposure, and nanoparticle chemistry, size, shape, agglomeration state, and electromagnetic properties. Animal and human studies show that inhaled nanoparticles are less efficiently removed than larger particles by the macrophage clearance mechanisms in the lung, causing lung damage, and that nanoparticles can translocate through the circulatory, lymphatic, and nervous systems to many tissues and organs, including the brain. The key to understanding the toxicity of nanoparticles is that their minute size, smaller than cells and cellular organelles, allows them to penetrate these basic biological structures, disrupting their normal function. Examples of toxic effects include tissue inflammation, and altered cellular redox balance toward oxidation, causing abnormal function or cell death. The manipulation of matter at the scale of atoms, "nanotechnology", is creating many new materials with characteristics not always easily predicted from current knowledge. Within the near-limitless diversity of these materials, some happen to be toxic to biological systems, others are relatively benign, while others confer health benefits. Some of these materials have desirable characteristics for industrial applications, as nanostructured materials often exhibit beneficial properties, from UV absorbance in sunscreen to oil-less lubrication of motors. A rational science-based approach is needed to minimize harm caused by these materials, while supporting continued study and appropriate industrial develop...

(Q)SAR modelling of nanomaterial toxicity: A critical review

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Investigação <i>ab initio</i> dos mecanismos de formação de nanoligas <i>core-shell</i> com platina e metais de transição dos períodos 3<i>d</i>, 4<i>d</i> e 5<i>d</i>

“…Quando o termo C nm ({R}, ∇) é nulo, é possível escrever a equação de Schrödinger à luz da abordagem de Born-Oppenheimer para cada movimento nuclear, isto é, 9) em que E ele,m ({R}) é o potencial efetivo para o movimento nuclear para um conjunto de pontos fixos em {R}, definindo uma superfície de energia potencial (SEP). Por sua vez, quando C nm ({R}, ∇) é não-nulo, diz-se que o sistema é não-adiabático, pois diferentes estados encontram-se acoplados.…”

“…Os efeitos quânticos ocorrem devido à discretização dos estados eletrônicos devido ao confinamento dos elétrons no espaço. 8,9 Nesse texto, o termo nanocluster unário é usado para se referir a partículas compostas por um único metal e o termo nanoliga é usado para se referir a partículas compostas por dois ou mais metais. Os nanoclusters metálicos são altamente sensíveis à variação de tamanho e geometria, podendo apresentar propriedades físico-químicas diferenciadas pelo acréscimo ou decréscimo de um único átomo na estrutura.…”

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