There is consensus that the surface structure of nanoparticles plays a crucial role in the interaction with cells and should therefore be considered when evaluating their health effects. The discussion often centers around mechanisms of action involving free radical development after nanoparticle uptake into the cell. Free radicals play an important role in oxygen-dependent aerobic living systems. They are an important component in cell respiration and other vital cellular processes, but are also involved in aging and in disease development.
Free radicals are unstable molecules with free outer electrons unpaired electrons. They are highly reactive because the free electrons always strive to bond with other electrons and form covalent pairs. In this process the free radicals strip the electrons from other molecules.
This chain reaction is omnipresent in every cell of the human body. Beyond affecting cellular regulation, it can also damage molecules such as carbohydrates, fats, proteins and nucleic acids.
This makes many free radicals highly reactive, i. To this end, the free radicals gain electrons from any available donor or donate an electron to a suitable acceptor, which in turn become modified into a secondary free radical.
This chain reaction can cause biological damage Fig. Figure 1: Attack by and defense against free radicals; sites of nutrients with antioxidative effect red and enzymes green. Molecules , 24 24 , 07 Dec To arrive at the top five similar articles we use a word-weighted algorithm to compare words from the Title and Abstract of each citation.
Cited by articles PMID: Chem Biol Interact , 1 , 23 Jan Diabetes Care , 31 Suppl 2:S, 01 Feb Cardiovasc Res , 71 2 , 09 May Sakac V , Sakac M. In addition, free radicals have been implicated in the mechanism of senescence.
Free radicals and antioxidants in normal physiological functions and human disease. Free radicals, mitochondria, and oxidized lipids: the emerging role in signal transduction in vascular cells. Ballinger , Victor M. Reactive oxygen species: toxic molecules or spark of life? Sheldon A. Magder Biology, Medicine Critical care Madkour Chemistry Click here to find out more about how the information was compiled.
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The science of free radicals in living organisms entered a second era after McCord and Fridovich discovered the enzyme superoxide dismutase SOD and, finally, convinced most colleagues that free radicals are important in biology.