Physico-chemical changes of ZnO nanoparticles with different size and surface chemistry under physiological pH conditions

- Physico-chemical properties of ZnO nanoparticles in physiological pH were studied.
- Size and surface chemistry of ZnO nanoparticles affected their colloidal behaviors.
- ZnO predominantly dissolved in gastric pH compared with intestinal or plasma pH.
- ZnO formed zinc hydroxide at surface under intestinal and plasma pH conditions.