The chemical dissolution of micro-scale materials was per- formed by incubation of 0.1 g materials in solutions simulat- ing stomach and intestine conditions. For simulated stomach conditions 0.1 g of the materials was introduced into vials containing hydrochloric acid (HCl) at pH 1.5 and incubated at 37 1C at 100 rpm. The vials were taken out every 30 min, and were centrifuged at 5000 rpm. Then the supernatants were discarded and the pellets were oven dried overnight at 40 1C. For simulated intestine conditions 0.1 g of the materials were introduced into vials containing phosphate buffer at pH 8.5, and then incubated at 37 1C at 100 rpm. The vials were taken out at every one hour interval, and centrifuged at 5000 rpm. The supernatants were discarded, and the resulting pellets were oven dried overnight at 40 1C. The degree of dissolution was calculated at percentage weight loss.