Abstract: The invention provides tissue marking pigment or dye particle retained within a tissue cell, the cellular cytoplasm, or one or more intracellular organelles. Also, the invention provides nanoparticles, which are phagocytosed, engulfed or otherwise entrapped by cells.

Abstract: Tattoo inks are composed of pigments or dyes combined with a tattoo pigment vehicle which entraps, encases, incorporates, complexes, encapsulates, or is otherwise associated with the pigment to form pigment/vehicle complexes that retain the pigment in the tissue. The vehicle can be chosen so that pigments which alone are unsuitable for tattooing can be used for tattooing and optionally can be retained in the tissue permanently. Alternatively, the vehicle renders the tattoo erasable, wherein the tattoo disappears after imposition of an exogenous energy. Alternatively, the tattoo pigment vehicle renders the tattoo semi-permanent, so that the tattoo spontaneously disappears at a predetermined time.