Development and utilization of reflectance confocal laser scanning microscopy to locate reaction sites in modified starch granules

A new method of locating reaction sites within modified starch granules was developed and applied. The method involves converting anionic groups introduced into starch granules into their silver salt form, reducing the silver cations to silver atoms, and locating the silver atoms by means of reflectance confocal laser scanning microscopy. The method was tested on three types of starch (normal maize, waxy maize, potato) containing two types of derivatizing groups (mono- and distarch phosphate ester groups and the 2-hydroxy-3-sulfonylpropyl ether group). The method also revealed anionic sites in native granules, presumably due to proteins, ionic lipids, or native phosphate ester groups.