Various bacteria are able to produce starch nanoparticles, You can feed them from wastes. But if You want to have a product on medical market, better find a other raw material...
The nanoparticles would be synthesized using various agricultural waste such as peels, husk and skins of fruit and other vegetables then, modified to be used for biological activities. The waste products were picked due to the availability of iron oxides in them. Therefore they can be used as a form of thermotherapy and drug delivery.