Nanoparticles are a current target for the media in all fields: environment, food, plastics, pharmaceuticals and cosmetics. Although the media are conscious of the technological advance that they represent, they accuse nanoparticles of many evils; often without understanding them or knowing their impact on organisms.
Firstly, they really ought to know what they are talking about. In the area of cosmetics, are we talking about inorganic and/or organic particles, and within the organic particles are we talking about solid and/or liquid particles?
A definition supplied by an ISO standard indicates nothing more specific than "nanoparticles are ultra-thin particles of which at least one of the dimensions is between 1 and 100 nm". A more 'physical' definition indicates that nanoparticles exhibit a radical change in a material's physicochemical properties when they are a homogenous material. This definition cannot apply to composite materials like nanocapsules or nanospheres. Nanospheres are formed from a porous polymeric mass.