Abstract: Disclosed is a method for manufacturing a plurality of gold nanoparticles in a plant, the method comprising growing the plant hydroponically, contacting at least a first part of the plant with a substance comprising at least one gold salt, providing an average photosynthetic active radiation (PAR) to at least second part of the plant, waiting a period of time sufficient for formation of a plurality of gold nanoparticles in at least a portion of the plant, thereby manufacturing the plurality of gold nanoparticles in the plant. Disclosed also are, inter alia, a plurality of gold nanoparticles manufactured by such a method; an article of manufacture comprising a plurality of gold nanoparticles manufactured by such a method; and a plurality of triangular gold nanoparticles manufactured by such a method.