Abstract
Novel breakthroughs and innovative applications of nanotechnology have revolutionized the industrial innovations of the twenty-first century. The exciting potential of nanomaterials continues to fascinate people from all walks of life. Various types of nanomaterials are used in different applications and are currently applied in almost all areas, such as electronics, cosmetics, medical purposes, sporting goods, sunscreens, tires, paints, and aviation, among many others. Therefore, the exposure of humans and all fauna and flora to nanoparticles is inevitable. Nanomaterials, including metal nanoparticles, are being increasingly used for different biological and medical applications. Plasmon-resonant nanoparticles in which free electrons collectively oscillate at the metal surface have been recently used in biological imaging. Metal nanoparticles are potential candidates for novel biocides and antibiotic treatments. The novel properties of nanoparticles, especially the physical properties of size and shape, enable them to penetrate all living organisms easily. The widespread use of nanotechnology raises many serious concerns, such as toxicity and the environmental impact of nanomaterials. More work is required to fully understand the basis of nanoparticle toxicity and ameliorate its adverse effect. This review summarizes the biomedical applications and the molecular mechanisms of nanoparticle toxicity in general and the metal nanoparticles in particular.